Terpenes as renewable monomers for biobased materials

Emelie Norström KKTH~

VETENSKAP ~Q OCH KONST ~

KTH Chemical Science and Engineering

Master of Science Thesis Stockholm, Sweden 2011

Supervisors: Ph. D Linda Fogeiström Ph. D student Carl Bruce Ph. D Järg Brucher, Holmen Energi

Examiner: Prof. Eva Malmström Jonsson

Terpenes as renewable monomers for biobased materials

Emelie Norström

Master of Science Thesis Stockholm, Sweden 2011

Supervisors: Ph. D Linda Fogelström Ph. D student Carl Bruce Ph. D Jörg Brucher, Holmen Energi

Examiner: Prof. Eva Malmström Jonsson

Abstract With the ambition to decrease the utilization of fossil fuels, a development of those raw materials that today only are seen as waste products is necessary. One of those waste products is . Turpentine is the largest natural source of terpenes in the world today. The main components are the terpenes α‐, β‐pinene and 3‐carene.

In this project, different polymerisation techniques have been evaluated to polymerise with the aim to make a material out of the green raw material, turpentine. Limonene is a that can be found in turpentine. It has a planar structure and should work as a model for other terpenes.

Previous work on polymerising terpenes has focused on succeeding with performing polymerisations of terpenes utilizing the techniques of cationic polymerisation and radical polymerisation. However, this has been done without the aim to make a material out of the . In this project, on the other hand, the main focus has been to obtain a that can be used as a basis for a material. Techniques that have been applied are: radical polymerisation, cationic polymerisation and ‐ene polymerisation.

In this study, attempts to homopolymerise limonene and also copolymerise it with other synthetic monomers, such as styrene, have been performed with both radical polymerisation and cationic polymerisation. The procedure for the radical polymerisation has been conducted following the work by Sharma and Srivastava. [1] Even though several articles have been published about radical copolymerisations of limonene with other synthetic monomers, the radical polymerisations have not succeeded in this project.

Further, the technique of thiol‐ene chemistry has shown that limonene can be used in polymerisations; limonene reacts spontaneously with 2‐mercaptoethyl ether forming a viscous polymer.

The obtained polymers have been characterized with proton nuclear magnetic resonance (1H‐NMR), size exclusion chromatography (SEC), matrix‐assisted laser desorption ionization‐time of flight mass spectroscopy (MALDI‐TOF MS), differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy.

Sammanfattning Ambitionen att minska beroendet av fossila bränslen nödvändiggör en målmedveten utveckling av möjligheterna att ur avfallströmmar utvinna komponenter för materialframställning. En av dessa komponenter är terpentin. Terpentin är den volymmässigt största källan till terpener i världen och består främst av terpenerna α‐pinen, β‐pinen och 3‐karen.

I detta projekt har olika polymerisationsmetoder utvärderats för att polymerisera limonen, med målet att göra ett material av det gröna råmaterialet terpentin. Limonen är en terpen som finns i terpentin. Den har en plan struktur och kan användas som en modellsubstans för terpener generellt.

Tidigare forskning om polymerisation av terpener har fokuserat på katjonpolymerisation respektive radikalpolymerisation. Dock har detta genomförts utan målet att tillverka ett material av polymererna. Därför har målet med detta projekt varit att ta fram en polymer som sedan ska kunna användas i ett material. Polymerisationsteknikerna som har undersökts i detta arbete är: radikalpolymerisation, katjonpolymerisation och tiol‐en polymerisation.

I projektet har försök gjorts att homopolymerisera limonen samt att sampolymerisera limonen med syntetiska monomerer till exempel styren, både genom radikalpolymerisation och katjonpolymerisation. Trots att flera artiklar har publicerats om sampolymerisation av limonen med syntetiska monomerer genom radikalkemi, har försöken med radikalpolymerisation inte lyckats i detta arbete.

Vidare har det har visat sig att limonen kan användas i tiol‐en polymerisationer. Limonen reagerar spontant med 2‐merkaptoetyleter och bildar då en viskös polymer.

Polymererna har analyserats med proton‐kärnmagnetisk resonans (1H‐NMR), gelfiltrering (SEC), matris‐assisterad laserdesorptionsjonisering‐flygtidsmasspektroskopi (MALDI‐TOF MS), differentialsvepkalorimetri (DSC), fourier transform‐infraröd spektroskopi (FTIR) och Raman‐ spektroskopi

List of Abbreviations 1H‐NMR Proton Nuclear Magnetic Resonance AIBN Azobisisobutyronitrile AlBr3 Aluminium tribromide AlCl3 Aluminium trichloride ‐ AsF6 Hexafluoroarsinate BF3 Boron trifluoride BF3OEt2 Boron trifluoride diethyl etherate ‐ BF4 Tetrafluoroborate BPO Benzoyl peroxide BVE Butyl vinyl ether DCM Dichloromethane DSC Differential Scanning Calorimetry EtOH Ethanol FTIR Fourier Transform Infrared spectroscopy H2SO4 Sulphuric acid HCl Hydrochloric acid Irgacure 184 UV‐initiator Lim Limonene MALDI‐TOF MS Matrix‐Assisted Laser Desorption Ionization‐ Time of Flight Mass Spectroscopy MeOH Methanol MMA Methyl methacrylate NaOH Sodium hydroxide ‐ PF6 Hexafluorophosphate PMMA Poly(methyl methacrylate) RT Room temperature SbCl3 Antimony trichloride ‐ SbF6 Hexafluoroantimonate SEC Size Exclusion Chromatography SnCl4 Tin tetrachloride Sty Styrene THF Tetrahydrofuran TiCl4 Titanium tetrachloride TiI4 Titanium tetraiodide TLC Thin Layer Chromatography Tol Toluene TRIS Trimethylolpropane‐tris(3‐mercaptopropionate) UVI‐6974 Onium salt Xyl Xylene ZrCl4 Zirconium tetrachloride

Table of Contents 1. Background ...... 1 2. Introduction ...... 2 2.1 Turpentine ...... 2 2.2 Terpenes ...... 3 2.3 Limonene ...... 4 2.4 Polymers ...... 4 2.5 Polymerisation techniques ...... 4 2.5.1 Radical polymerisation ...... 4 2.5.2 Cationic polymerisation ...... 5 2.5.3 Thiol‐ene polymerisation ...... 7 2.6 Previous work on polymerisations of terpenes ...... 7 2.6.1 Cationic polymerisation ...... 7 2.6.2 Radical polymerisation ...... 11 3. Aim of study ...... 12 4. Experimental ...... 13 4.1 Materials ...... 13 4.1.1 Radical polymerisation ...... 13 4.1.2 Cationic polymerisation ...... 13 4.1.2 Thiol‐ene polymerisation ...... 13 4.2 Characterization methods ...... 14 4.3 Experimental procedures ...... 15 4.3.1 Radical polymerisation ...... 15

4.3.2 Cationic polymerisation using AlCl3 ...... 17

4.3.3 Cationic polymerisation using BF3OEt2 ...... 18 4.3.4 Cationic polymerisation using onium salts ...... 19 4.3.5 Cationic polymerisation using a strong acid ...... 20 4.3.6 Thiol‐ene polymerisation ...... 20 4.4 Characterization ...... 24 4.4.1 Size Exclusion Chromatography (SEC) ...... 24 4.4.2 Matrix‐Assisted Laser Desorption Ionization‐Time of Flight mass spectroscopy (MALDI‐ TOF MS) 24 4.4.3 Fourier transform infrared spectroscopy (FTIR) ...... 24 4.4.4 Raman spectroscopy ...... 24

4.4.5 Pressing ...... 24 4.4.6 Differential scanning calorimetry ...... 25 5. Results and discussion ...... 26 5.1 Radical polymerisation ...... 27 5.1.1 Homopolymerisation of limonene ...... 27 5.1.2 Homopolymerisation of styrene ...... 27 5.1.3 Copolymerisation of limonene with styrene ...... 27 5.1.4 Copolymerisation of limonene with methyl methacrylate ...... 32 5.1.5 Copolymerisation of limonene with synthetic monomers through radical polymerisation ...... 35

5.2 Cationic polymerisation using AlCl3 ...... 36 5.2.1 Homopolymerisation of limonene ...... 36 5.2.2 Homopolymerisation of styrene ...... 40 5.2.3 Copolymerisation of limonene with styrene ...... 40 5.2.4 Copolymerisation of limonene with tetrahydrofuran ...... 44

5.3 Cationic polymerisation using BF3OEt2 ...... 44 5.3.1 Homopolymerisation of limonene ...... 44 5.3.2 Homopolymerisation of butyl vinyl ether ...... 44 5.3.3 Copolymerisation of limonene with butyl vinyl ether ...... 45 5.3.4 Copolymerisation of limonene with styrene ...... 46 5.4 Cationic polymerisation using onium salts ...... 47 5.5 Cationic polymerization using a strong acid ...... 47 5.6 Thiol‐ene polymerisation ...... 47 5.6.1 Copolymerisation of limonene with 2‐mercaptoethyl ether using AIBN as initiator .... 49 5.6.2 Copolymerisation of limonene with 2‐mercaptoethyl ether using Irgacure 184 as initiator 53 5.6.3 Spontaneous copolymerisation of limonene with 2‐mercaptoethyl ether ...... 54 5.6.4 Crosslinking of limonene and 2‐mercaptoethyl ether with TRIS...... 55 5.6.5 Copolymerisation of the thiol‐ene polymer with maleic anhydride...... 57 6 Conclusions ...... 58 7 Future work ...... 59 8 Acknowledgements ...... 60 9 References ...... 61

‐‐‐‐‐‐‐‐‐‐Background‐‐‐‐‐‐‐‐‐‐

1. Background With the ambition to decrease the utilization of fossil fuels, a development of those raw materials that today only are seen as waste products is a necessity. One of those waste products is turpentine. Turpentine is a by‐product from the pulp industry that today is burned directly at the mill for energy production. Each year, 3000‐5000 tons of turpentine are extracted and burned at Iggesund’s mill. It would probably be more beneficial to find other applications for the turpentine, instead of just burning it all. Furthermore, turpentine is the largest source by volume of terpenes in the world. The main components are α‐pinene, β‐pinene and 3‐carene. In this project, polymerisations of terpenes, with the focus on the terpene limonene, are investigated with the aim to create a new material. Limonene was chosen, as a representative substance of terpenes, because it is a nontoxic terpene that is easy to work with, and it can be purchased in a pure state. It has a planar structure that should work as a model for other planar terpenes. Additionally, α‐pinene is a substance that can be isomerised into a planar structure, which make the study of planar structures just as important as bulky ones.

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2. Introduction

2.1 Turpentine Turpentine is a complex liquid mixture of different terpenes and . Terpenoids are various derivatives of terpenes, such as: alcohols, aldehydes, ketones and esters. Turpentine is the largest natural source of terpenes in the world today. It is a volatile fraction that is isolated from . At first turpentine is a colourless liquid, however, since the terpenes are easily oxidised the liquid soon turns yellow. Turpentine has a very distinct smell due to the fragrant terpenes. Three different types of turpentine are distinguished depending on the way the pine is isolated from the : gum turpentine, wood turpentine and sulphate turpentine. The oldest procedure, which extracts gum turpentine, is to tap turpentine gum from living , and distil it to obtain the turpentine. Another method uses extraction after harvesting to get the second type of turpentine, wood turpentine. Nowadays, turpentine is extracted primarily as a by‐product from the pulp industry recovered during Kraft pulping of wood, generating sulphate turpentine. It is obtained from the gas during the pre‐heating of chips before the digesting. Almost all turpentine is then burned to use it as a source of energy at the mill. The two types of trees that give the highest yield of turpentine are pine and spruce. The chemical composition of turpentine can vary depending on the specie of the , the geographic location, the age of the tree, the procedure to isolate it, etc. The main components of turpentine are unsaturated such as α‐pinene, β‐pinene and 3‐carene, see Figure 1 for schematic images of these three and some other of the most common terpenes. Trees in Sweden have an approximate distribution of these three as follows: 60 % α‐ pinene, 10 % β‐pinene and 30 % 3‐carene.

Turpentine has mainly been used as a solvent, but has been replaced by other based on petroleum. Furthermore, it has also been used in production and as insecticides, fragrances and flavours and other fine chemicals as well as polyterpene resins. [2‐4] Pinova and Arizona chemical are companies that are producing polyterpene resins. [5‐7] Limonene based products from Pinova can work as polymer modifiers for block copolymers. They can be used as tackifiers for rubber‐based, pressure sensitive and hot melt systems. It can also be used as sealants and in chewing gums. [5] However, no scientific reports with the aim to produce a material out of polyterpenes have been found.

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α‐pinene β‐pinene 3‐carene Limonene

Tricyclene β‐phellandrene Terpinolene p‐cymene β‐

Figure 1. The chemical structures of some components in turpentine. 2.2 Terpenes Terpenes are a group of mainly cyclic compounds that are primarily synthesized in , particularly in coniferous trees such as pine. However, to some extent, the origin is also synthesized by a limited number of insects, marine microorganisms and fungi. They are fragrant molecules, and are therefore, generally found in essential oils and oleoresins of plants, and this characteristic property is suitable in flavour and fragrance applications. Terpenes are built up from units (2‐methyl‐1,3‐ butadiene), see Figure 2, in a head‐to‐tail orientation. They are divided into different subclasses, ordered by the number of isoprene units in the skeleton, see Table 1. For a long time terpenes were considered as waste products with no biological or ecological role. However, this is no longer the case, since it is now found that some terpenes are involved in various processes, such as: intermediates in biosynthetic processes; the defence of the , e.g. acting as insect repellents; and, finally, to stimulate cross pollination, they take part in various symbiotic mechanisms, which include for example acting as attractants to specific insects species. [4] Isoprene can be polymerised to polyisoprene through radical, cationic, anionic or coordination polymerisations. Anionic polymerisation is the technique that is used most. [8]

Figure 2. The chemical structure of isoprene.

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Table 1. The classification of terpenes according to the number of isoprene units.

Classification Isoprene units Carbon atoms Hemiterpenes 1 5 Monoterpenes 2 10 3 15 4 20 Sesterpenes 5 25 6 30 8 40 Polyterpenes N N

2.3 Limonene Limonene is an optically active and monocyclic terpene. As can be seen in Figure 1, limonene exhibit one internal double bond and one external double bond that should be susceptible in polymerisations. [1] Besides from being a component in turpentine you can find limonene as a by‐ product from the industry. Limonene has been evaluated in ring‐opening metathesis polymerisations as a renewable polymerisation solvent and chain transfer agent. [9] It has also been evaluated as a solvent in the recycling process of polystyrene and showed good results. Limonene can replace a variety of solvents such as , toluene and chlorinated organic solvents. It is effective, non‐toxic and biodegradable. The compatibility with other materials such as PET, Nylon, aluminium, stainless steel and ceramic is good. [10]

2.4 Polymers There are some commercial polymers based on terpenes, mostly made from β‐pinene, but also made from limonene and α‐pinene. They are polymerised by Lewis acid‐catalysts and are called terpene resins. These resins are often thermoplastics that can vary from viscous polymers to hard materials, with relatively low molecular weights, light colours and weak mechanical properties. They are, however, stable to heat and UV irradiation. The terpene resins are most often used as tackifying resins and additives in plastic compositions. They can be used as , thermoplastic mouldings and electroconductive parts. Such compositions can be used for medical purposes such as drug‐ delivery and active compound release. Furthermore, the terpene resins are chemically inactive, nontoxic and nonirritating. Therefore, they are of use in food packaging industry. [11, 12] Polymers from β‐pinene and α‐pinene used in adhesives have several advantages: they provide high gloss, good moisture vapour transmission resistance, and good flexibility for wax coating, and they ensure control and density increase to casting waxes. Since these polymers contain unsaturated double bonds the adhesives, are by nature, sensitive to oxidation. [4]

2.5 Polymerisation techniques

2.5.1 Radical polymerisation Radical polymerisation is a chain reaction that consists of four steps: pre‐initiation, initiation, propagation and termination as shown in Figure 3. The initiators that can be used in this polymerisation technique are thermal, redox, photo and high energy initiators. The thermal initiator is generally most used. It is important to know the half‐life (the time for half of all the molecules to decompose to radicals) of the initiator to decide what temperature and reaction time that is necessary for the polymerisation to be initiated. Azobisisobutyronitrile (AIBN), see Figure 4 is a normal initiator to use. At 80 °C AIBN has a half‐life of two hours. [13]

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Pre‐initiation I 2R I=inititor R●=radical

Initiation R M Mn M=monomer

Propagation Mn M Mn+1

Termination: Combination Mx My Mx+y

Termination: Disproportionation Mx My Mx My

Figure 3. The general mechanism for radical polymerisation.

CN CN

H3C C N N C CH3

CH3 CH3

Figure 4. The chemical structure of the initiator AIBN.

2.5.2 Cationic polymerisation Cationic polymerisation is, as radical polymerisation, a chain reaction that consists of four steps: pre‐ initiaton, initiation, propagation and termination, see Figure 5. Suitable monomers for cationic polymerisations are for instance monomers that have electron donating substituents, cyclic ethers or conjugated olefins. Initiators can be Lewis acids, Brønsted acids, stable organic cation salts, ionizing radiation or onium salts. Onium salt is a salt in which the positive ion (onium ion) is formed by the attachment of a proton to a neutral compound. Example of onium salts are ammonium, oxonium and sulphonium compounds. The Lewis acids are generally the most used catalyst; examples of them are: aluminium trichloride (AlCl3), boron trifluoride (BF3) and tin tetrachloride (SnCl4). Brønsted acids, such as sulphuric acid (H2SO4) or hydrochloric acid (HCl), can also be used as catalyst. Most cationic polymerisation of olefins has a negative temperature coefficient of reaction rate. This means that the polymerisation proceeds more rapidly at lower temperatures. Furthermore, cationic polymerisations are very dependent on the right reaction conditions; impurities such as water, physical parameters, e.g. temperature, and the type of solvent used are important parameters to control in order to succeed with the polymerisation. However, especially to get the right amount of water is difficult, since a small amount is necessary to initiate the polymerisation, but a larger amount will terminate it. The polarity of the solvent will affect how strongly the cation is attached to the anion. Free ions are more reactive than ion pairs, and loose ion pairs are more reactive than tight ion pairs. A more polar solvent will favour the separation of the ions, but it will also react with most initiators and propagating species and terminate the polymerisation or form stable complexes with the initiator, preventing the polymerisation from proceeding. Low or moderately polar solvents are therefore used. [14, 15]

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+ - Initiation: Lewis acid ZXn BA A (ZXnB) ZXn=coinitiator (Lewis acid) BA=initiator (proton donor, for A+(ZX B)- M AM+(ZX B)- example water) n n M=monomer

Propagation + - M AM M+(ZX B)- AMnM (ZXnB) n+1 n

Termination + - + - AMnM (ZXnB) M Mn+1 AM (ZXnB) Chain transfer to monomer

Termination AM M+(ZX B)- + - n n Mn+1 A (ZXnB) Spontaneous termination

+ - Termination AMnM (ZXnB) AMnM(ZXnB) Combination with counterion

Initiation: Brønsted acid H+X- M HM+X-

Initiation: Onium salts - ‐ ‐ ‐ Ar2S MtXn Ar MtXn = PF6 or SbF6 + - hv Ar3S MtXn HMtXn + - Ar2S Ar MtXn + - HMtXn M HM MtXn

Figure 5. The general mechanism for cationic polymerisation using Lewis‐acids and the initiation steps with Brønsted acids and onium salt.

Onium salts produces a strong Brønsted acid or an initiating carbenium ion when initiating cationic polymerisations. The cation in the salt works as a light‐absorbing component, and the anion determines the strength of the acid and the acid’s initiation efficiency. Example of onium salts are: ‐ ‐ diaryliodinium with anion tetrafluoroborate (BF4 ), hexafluorophosphate (PF6 ), hexafluoroarsinate ‐ ‐ ‐ ‐ (AsF6 ) or hexafluoroantimonate (SbF6 ) and triarylsulfonium with anion PF6 or SbF6 . The compound that is the actual initiator for the cationic polymerisation is formed with UV‐induced photolysis of the diaryliondonium salt or triarylsulfonium salt, see Figure 6, where HMtXn is the strong acid. Additionally, almost all monomers that can be polymerised cationically can be polymerised with triarylsulfonium salt and diaryliodonium salt. [16]

- Ar2S MtXn Ar + - hv Ar3S MtXn HMtXn + - Ar2S Ar MtXn

- ArI MtXn + - hv Ar Ar2I MtXn HMtXn ArI Ar+MtX - n

‐ Figure 6. The UV‐induced photolysis of triarylsulfonium salt and diaryliodonium salt. MtXn is the anion and HMtXn is the formed initiator.

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2.5.3 Thiol‐ene polymerisation The thiol‐ene polymerisation is a free radical polymerisation that proceeds via a step‐growth mechanism, involving a radical addition followed by a chain‐transfer reaction, see Figure 7. Both heat and light can be used to generate radicals that can initiate the thiol‐ene radical chain process, by forming a thiyl radical. The thiyl radical then reacts with the double bond of the ene to generate a secondary free radical, which abstracts a hydrogen atom from a second molecule of thiol, forming a new thiyl radical and the cycle repeats. Eventually, the reaction terminates through radical‐radical coupling. Thiol‐ene reactions have the ability to initiate itself in UV‐light without the presence of an initiator, i.e. spontaneous initiated. The monomers then absorb light, which generates the radicals. [17, 18] When irradiated with UV‐light, almost any type of unsaturated monomer can react with . Electron‐rich unsaturated monomers react with a rapid reaction rate, and electron deficient monomers can also react with thiols at a somewhat lower, but still reasonable, reaction rate. [19] The thiol‐ene polymerisation exhibit several advantages, such as: rapid reaction rate, low polymerisation shrinkage, reduced oxygen inhibition and formation of homogenous polymer structures. Unfortunately, it also has some drawbacks, such as: yielding materials with poor mechanical properties and low surface hardness when it is cured. Additionally, the pot life is relatively short and the thiol itself is a compound that could give rise to odour problems. [20]

Initiation: I+hv 2R Photochemical R-H R -S I=initiator R R1-SH 1 R●=radical

Initiation: I R Thermally and Redox R R1-SH R-H R1-S

Propagation and R1S chain transfer R1-S

R2 R2

R S R1S 1 R1-SH R1-S

R R2 2 R -S Termination 1 R1-S Polymer R1-S R2-C Polymer R2-C R2-C Polymer Figure 7. The general thiol‐ene reaction mechanism for a monofunctional thiol and a monofunctional ene. 2.6 Previous work on polymerisations of terpenes

2.6.1 Cationic polymerisation Bishop Watson reported in 1798 that the addition of a drop of sulphuric acid to turpentine transformed it to a sticky resin. A century later, the chemists discovered that the properties of that resin resembled those of . This was the beginning of the studies of polymers from

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‐‐‐‐‐‐‐‐‐‐ Introduction ‐‐‐‐‐‐‐‐‐‐ terpenes. However, it took another half century until studies of polymerisations of terpenes were reported. Radical and cationic homo‐ and copolymerisations of terpenes have been reported during the last century. [4]

It is very difficult to homopolymerise terpenes by radical polymerisation, due to steric hindrance and low stabilization energy between monomer and radical in transition state. However, some reports exist on homopolymerisations of terpenes [1] by cationic polymerisation. In the 1940s Roberts et al. studied the cationic homopolymerisation of β‐pinene and α‐pinene with Friedel‐Crafts type catalysts (Lewis acid metal halides). Several Lewis acid metal halides were used as catalysts, such as aluminium trichloride (AlCl3), aluminium tribromide (AlBr3), tin tetrachloride (SnCl4) and zirconium tetrachloride

(ZrCl4). Both the polymerisation of β‐pinene and α‐pinene gave polymers. Eventually, after some investigations of the chemical and physical properties, Roberts et al. concluded that AlCl3 can polymerise β‐pinene to a solid polymer. α‐pinene, on the other hand, was less reactive than β‐pinene and yielded a lower molecular weight polymer and a dimer. Additionally, they suggested that at least a part of α‐pinene was isomerised to the terpene limonene, using AlCl3 as a catalyst. After the isomerisation, limonene reacted further and yielded the solid polymer. The dimer, on the other hand, was built up from two α‐pinene units. Furthermore, pure limonene was also polymerised to see the resemblance with the polymer from α‐pinene. However, all the experiments gave very low yields, and the products had very low molecular weight. [21]

A proposed mechanism for the polymerisation of β‐pinene is shown in Figure 8. The Lewis acid reacts with water, which creates a strong proton donor, the catalyst. It is very important to control the moisture content to avoid the deactivation of the catalyst by hydrolysis; [12] some water is, however, needed for the catalyst to be formed. The catalyst that is formed attacks the double bond of β‐ pinene, creating a carbenium ion as can be seen in Figure 8. The carbenium ion rearranges and then the reaction propagates. The polymerisation is exothermic and very rapid. A molecular weight of a few thousand was obtained at low temperatures. At low temperatures is the chain transfer reaction slower than the chain propagation reaction. [4, 21] The driving forces for the reaction are the strain release from opening the cyclobutane ring, the high reactivity of the external double bond and the formation of a tertiary carbenium ion. [4]

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Carbenium ion

Figure 8. Cationic polymerisation of β‐pinene, catalyzed by AlCl3. [4]

A follow‐up was made in the 1960s by Modena et al. who continued and studied the structure of polylimonene. They polymerised low molecular weight polymers of limonene through Ziegler‐type catalysis. Furthermore, the catalyst that was used was either triisobutylaluminium or diisobutylaluminium monochloride, which was used together with either titanium tetrachloride

(TiCl4) or titanium tetraiodide (TiI4) as cocatalyst. The obtained polymer had the same properties as those prepared by cationic polymerisation of limonene, but it showed differences compared to the polymer polymerised from α‐pinene. [22]

Several methods to polymerise β‐pinene through cationic polymerisation have been reported after Roberts and Day, where the initiator (Lewis acid), solvent and temperature have been varied.

Examples of different Lewis acids evaluated are: BF3, TiCl4 and Et2AlCl. Martinez et al. reported that the most efficient initiators were Et2AlCl and TiCl4, together with the solvent dichloromethane (DCM) at a temperature ranging from ‐80 °C to 0 °C. Under those conditions, polymers with molecular weights of 720‐2800 were obtained. [23]

Guiné et al. investigated the use of EtAlCl2 as an initiator, instead of the more common Lewis acid

AlCl3. AlCl3 have limitations such as high cost of cooling, which is needed to maintain a low reaction temperature, and that high purity levels are necessary. Friedel‐Crafts acids like AlCl3 and EtAlCl2, can catalyse the initiation step in systems with reduced levels of moisture. Furthermore, a low concentration of water and cationogenic impurities is sufficient to catalyse the initiation step.

However, it is important to evaluate how sensitive the catalyst is to impurities. AlCl3 does only work well as a catalyst if the concentration of impurities is sufficiently low. On the other hand, EtAlCl2 is less sensitive to impurities, almost insensitive to moisture and can be activated of the impurities and

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the moisture regardless of the quantity. Et2AlCl and Et3Al are weaker acids and a cationogenic initiator, such as HCl or Cl2 are needed for them to be as strong acids as EtAlCl2 and AlCl3 in the presence of water. Another advantage of using EtAlCl2 instead of AlCl3, is thaat the polymerisation temperatures is ‐10 °C to 30 °C, instead of ‐50 °C to ‐10 °C. A drawback of using alkyl‐aluminium chloride is that those compounds can ignite when they come in contact with air, and it may cause violent reactions with water or strong oxidising agents. [12]

Two mechanisms for the polymerisation of α‐pinene have been proposed, see Figure 9. A tertiary carbocation is formed when α‐pinene is protonated. This can then rearrange to an unsaturated p‐ menthane isomer, and then propagate. However, the attack of the endocyclic double bond of the isopropenyl cationic site is limited by steric hindrance. This makes α‐pinene lless reactive than β‐ pinene. In the other proposed mechanism, a rearrangement of the tertiary pinene carbocation gives a saturated secondary bornane isomer. These isomers, both bornane and p‐menthane, have been detected in both homopolymers and copolymers of α‐pinene. [24]

Figure 9. A schematic image of the two alternative mechanisms for the cationic polymerisation of α‐pinene. [4]

Several reports have focused on the use of antimony trichloride (SbCl3) as an activator in combination with conventional Lewis acids in polymerisations of α‐pinene. By using SbCl3 as an activatorr, negligible proportions of dimers are obtained compared to only using AAlCl3 as initiator. [24‐

26] However, in polymerisations of β‐pineene, the role of SbCl3 is rather negative in terms of molecular weight distribution and reaction rate. [27] Additionally, other Lewis acids, such as other aluminium halides: AlBr3, EtAlCl2 and metal halides BF3OEt2, SnCl4 have also been evaluated together with SbCl3, and it results in polymers of α‐pinene. The other aluminium halides gave rise to polymers with lower molecular weights and yields compared to AlCl3. The metal halides gave higher proportions of dimers than oligomers. [24] Furthermore, the use of SbCl3 together with AlCl3 has also been favoured in the cationic polymerisation of limonene. [4]

Using cationic polymerisation to copolymeerise terpenes with other synthetic monomers has also been studied. β‐pinene has been copolymerised with styrene and α‐methyllstyrene at different temperatures using AlCl3 as catalyst and methylene dichloride or m‐xylene as solvents. [28‐30] β‐ pinene has also been copolymerised with isobutene and tetrahydrofuran. α–pinene has been copolymerised with isobutene and styrene. [4]

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2.6.2 Radical polymerisation In 1980 Doiuchi, Yamaguchi and Minoura reported that limonene was successfully copolymerised with maleic anhydride in tetrahydrofuran using AIBN as an initiator at 40 °C. [31] Limonene is a non‐ conjugated diolefin. Non‐conjugated olefins are regarded as electron‐rich monomers and they rarely homopolymerise. However, copolymerisation is possible with electron‐deficient monomers such as maleic anhydride. [31]

More recent, the work of polymerising limonene was followed up by Sharma and Srivastava. They have studied copolymerisation between different kind of terpenes and synthetic monomers. The work focused on limonene as one of the monomers, including the following copolymerizations: limonene‐co‐styrene/AIBN/80 °C [1], limonene‐co‐vinyl acetate/AIBN/65 °C [32], limonene‐co‐ acrylonitrile/BPO/70 °C [33], limonene‐co‐butyl methacrylate/BPO/80 °C [34] and limonene‐co‐ styrene‐co‐methyl methacrylate/BPO/80 °C [35]. In all these polymerisations it was reported that it was the external double bond that had reacted during the polymerisation. The proposed mechanism for the polymerisation of limonene with styrene is shown in Figure 10. The maximum conversions of these polymerisations were, however, all very low; none reached above 20%.

Initiation:

CN CN CN

H3CCN N C CH3 H3CC= I + N2

CH3 CH3 CH3

I I +

Propagation:

I I +

Termination:

* * I * + + + n n

n n

Figure 10. The proposed mechanism for radical copolymerisation of limonene with styrene. [1]

11

‐‐‐‐‐‐‐‐‐‐ Introduction ‐‐‐‐‐‐‐‐‐‐

There have also been some reports on copolymerisations of β‐pinene using radical polymerisation. With conventional free radical polymerisation β‐pinene has been copolymerised with methyl methacrylate [4], styrene [11], methyl acrylate [36] and acrylonitrile [37], using AIBN as an initiator. β‐pinene has also been copolymerised using controlled radical polymerisation. The method that has been used is reversible addition‐fragmentation chain transfer radical copolymerisation, RAFT. β‐ pinene has been copolymerised with acrylonitrile [37], methyl acrylate [36] and butyl acrylate [38] using this method. The copolymerisation with acrylonitrile and butyl acrylate showed good results.

The RAFT method gave rise to better controlled polymerisation and lower polydispersities. Et2AlCl was added to the controlled polymerisation and the copolymerisation rate increased and also the incorporation of β‐pinene increased. The copolymerisation with methyl acrylate did not show as good results as the other two.

Maria Teresa Barros et al. studied potentially biodegradable polymers based on homopolymers of α‐ and β‐pinene and the copolymers of α‐pinene or β‐pinene with styrene, obtained under normal conditions and on microwave irradiation. They indicated that the radical copolymerisations of α‐ pinene with styrene and β‐pinene with styrene yielded polymers with higher molecular weights if the reaction was conducted during exposure of microwave irradiation compared to the conventional polymerisation. They compared cationic and free radical polymerisation as well as microwave irradiation and conventional heating for free radical polymerisation. Microwave irradiation could be used as an alternative to conventional heating when the monomers in the reaction are sensitive or/and have low reactivity. By using microwave irradiation, the energy is applied more homogeneously compared to conventional heating, and this can allow the reaction to be performed without a solvent, which gives a more economic and cleaner system. [11]

3. Aim of study The aim of this study is to investigate whether it is possible to develop new biobased materials from turpentine. The terpene limonene is chosen as a representative model compound for terpenes and will be used as the corresponding monomer in polymerisations.

12

‐‐‐‐‐‐‐‐‐‐ Experimental ‐‐‐‐‐‐‐‐‐‐

4. Experimental

4.1 Materials

4.1.1 Radical polymerisation The monomers: styrene (ReagentPlus, >=99 %) from Sigma‐Aldrich and methyl methacrylate (99 %, containing <=30 ppm monomethyl ether hydroquinone as inhibitor) from Sigma‐Aldrich were passed through a column of aluminium oxide (activated, neutral, Brockmann I) from Sigma‐Aldrich prior to use.

The following solvents and chemicals were used as received: (R)‐(+)‐Limonene (97 % stab.) from Alfa Aesar, benzoyl peroxide (>98 %) from Merck‐Schuchardt, azobisisobutyronitrile (>98 %) from Fluka, xylenes (isomers plus ethylbenzene) from Aldrich, methanol (for analysis) and dichloromethane (for analysis) from Merck, ethanol (96 % vol GPR RECTAPUR 2VWR, BDH PROLABO) from VWR.

4.1.2 Cationic polymerisation

4.1.1.1 Thermal initiation The monomer styrene (ReagentPlus, >=99 %) from Sigma‐Aldrich was passed through a column of aluminium oxide (activated, neutral, Brockmann I) from Sigma‐Aldrich prior to use.

The following solvents and chemicals were used as received: (R)‐(+)‐Limonene (97 % stab.) from Alfa Aesar, tetrahydrofuran (99.5+ %, spectrophotometric grade, inhibitor‐free), aluminium chloride (anhydrous), boron trifluoride diethyl etherate and sulphuric acid from Sigma‐Aldrich, butyl vinyl ether (98 %) and hydrochloric acid (volumetric standard, 0.2 N solution in water) from Aldrich, toluene from Fischer Scientific, hydrochloric acid (for analysis, fuming, 37 % solution in water) and magnesium sulphate (99 % extra pure, dried, contains 3 to 4 moles of water) from Acros Organics, sodium hydroxide (pellets GR for analysis), tetrahydrofuran (for analysis), methanol (for analysis) and (BRINE) sodium chloride (for analysis) from Merck.

4.1.1.2 Photoinitiation The monomer and the initiators: (R)‐(+)‐Limonene (97 % stab.) from Alfa Aesar and Cyracure UVI‐ 6974 (mixed arylsulfonium hexafluoroantimonate, 50 % in propylene carbonate) from Cyracure were used as received. The initiator diphenyliodoniumoctyl ether hexafluoroantimonate was made by Per‐ Erik Sundell. [15]

4.1.2 Thiol‐ene polymerisation The following solvents and chemicals were used as received: (R)‐(+)‐Limonene (97 % stab.) from Alfa Aesar, 2‐mercaptoethyl ether (95 %) from Aldrich, Trimethylolpropane Tri(3‐ mercaptopropionate) from Bruno Bock, azobisisobutyronitrile (>98 %) from Fluka, chloroform from Fisher Scientific, tetrahydrofuran (for analysis) and maleic anhydride from Merck, methanol (for analysis) from Merck. The photoinitiator 1‐hydroxy‐cyclohexyl‐phenyl‐ketone (Irgacure 184) was supplied from CIBA.

13

‐‐‐‐‐‐‐‐‐‐ Experimental ‐‐‐‐‐‐‐‐‐‐

4.2 Characterization methods Differential Scanning Calorimetry (DSC) was performed on a Mettler Toledo DSC820 equipped with a sample robot and a cryocooler. It was carried out in a closed sample pan in air using the following temperature program: heating from 25°C to 160°C (10°C min‐1), isothermal for 3 minutes at 160°C, cooling from 160°C to ‐30°C, isothermal for 3 minutes at ‐30°C and then a second heating cycle from ‐

30°C to 160°C. The glass transition temperature, Tg, was recorded in the second heating cycle.

Fourier Transform Infrared Spectroscopy (FTIR) spectra were recorded on a Perkin‐Elmer Spectrum 2000 FTIR equipped with a heat‐controlled single reflection attenuated total reflection (ATR) accessory from Specac Ltd.

Matrix‐Assisted Laser Desorption Ionization‐Time of Flight Mass Spectroscopy (MALDI‐TOF MS) was performed on a Bruker Uniflex MALDI‐TOF MS with SCOUT‐MTP Ion Soource (Bruker Daltonics) equipped with a N2‐laser (337 nm), a gridless ion source and reflector design. 9‐Nitroanthracene (10 mg in 1 mL THF) was used as matrix with added sodium trifluoroacetate (1 mg in 1 mL THF) or silver trifluoroacid (1 mg in 1mL THF). The obtained spectra were analyzed using FlexAnalysis (Bruker Daltonics)

Nuclear Magnetic Resonance (1H‐NMR) spectra were recorded on a 400 MHz Bruker Avance instrument, using CDCl3 as a solvent.

Pressing was performed in a Fontijne Grotnes Lab Pro 400 hydraulically operated platen press with vacuum control between PET‐films in air atmosphere.

Raman spectroscopy was acquired using a Perkin‐Elmer Spectrum 2000 NIR FT‐Raman instrument. Each spectrum was based on 32 scans using 1000 mW laser power.

Size Exclusion Chromatography (SEC) using THF (1.0 mL min‐1) as the mobile phase at 35°C was performed on a Viscotek TDA model 301 equipped with 2T5000 columns, a VE5200 GPC autosample, a VE1121 GPC solvent pump and a VE5710 GPC degasser (all from Viscotek/Malvern). Conventional calibration using linear polystyrene standards and triple detection calibration using a single linear polystyrene standard were used and the samples were evaluated using OmniSEC 4.5 software.

Size Exclusion Chromatography (SEC) using chloroform (1.0 mL min‐1) as the mobile phase was performed on a Waters 717 plus auto‐sampler and a Waters model 515 apparatus equipped with three PLgel 10 µm mixed B columns, 300×7.5 mm (Polymer Labs., UK). Spectra were recorded with a PL‐ELS 1000 evaporative light‐scattering detector (Polymer Labs., UK). Millenium version 3.05.01 software was used to process the data. Polystyrene standards were used for calibration.

Photo‐initiated polymerisations were performed with a Fusion UV Curing System Model F300, equipped with an H‐bulb. The dose was measured in the wavelength interval 320‐390 nm with a UVICURE Plus from EIT Inc., Sterling, VA, USA.

Photo‐initiated polymerisations were also performed with an Oriel 82410, 1000 W Xenon‐mercury lamp.

14

‐‐‐‐‐‐‐‐‐‐ Experimental ‐‐‐‐‐‐‐‐‐‐

4.3 Experimental procedures Chemical structures of the monomers that have been used in this project are shown in Table I in appendix 1.

4.3.1 Radical polymerisation

4.3.1.1 Homopolymerisation of limonene Three experiments were performed concerning homopolymerisations of limonene by radical polymerisation. The polymerisation procedure was conducted by following the work of Sharma and Srivastava [1]. However, the conditions of the polymerisation were not exactly followed, for conditions see Table 2. Limonene was added to a round bottom flask and stirred under argon atmosphere for about 15 minutes. One of the polymerisations was conducted in solution, using xylene as a solvent, as conducted in the article, and the others were performed in bulk. After 15 minutes the initiator, AIBN, was added quickly and the solution was lowered into a pre‐heated oil bath. The argon was turned off after another 15 minutes. Two experiments were conducted at 80°C for two hours and the third one was carried out at 60 °C for 16 hours. 1H‐NMR analysis was used to follow the reactions. The solution was then drop‐wise addition into cold methanol (‐78 °C). No precipitate was obtained.

Table 2. The different parameters that were used to homopolymerise limonene by radical polymerization.

Temperature Solvent Time Precipitated in: Molar ratio Lim:AIBN:Xyl EN003 80 °C Xylene 2 h Cold methanol 1:0.002:1 EN004 80 °C None 2 h Cold methanol 1:0.002:0 EN005 60 °C None 16 h Cold methanol 1:0.002:0

4.3.1.2 Homopolymerisation of styrene Two homopolymerisations of styrene were performed as references to the copolymerisation of limonene with styrene, see Table 3. The polymerisations were conducted according to the same procedure as the homopolymerisation of limonene, see section 4.3.1.1. One experiment was conducted at 80 °C for two hours under argon atmosphere with xylene as a solvent, and the other was carried out under argon atmosphere at 60 °C for 16 hours without any solvent. The polymerisations were initiated by AIBN. 1H‐NMR analysis was used to follow the reactions. The polymers were precipitated in cold methanol (‐78 °C) and dried under vacuum.

Table 3. The different parameters that were used to homopolymerise styrene by radical polymerisation.

Temperature Solvent Time Precipitated in: Molar ratio Sty:AIBN:Xyl EN006 60 °C None 16 h Cold methanol 1:0.002:0 EN009 80 °C Xylene 2 h Cold methanol 1:0.002:1.5

4.3.1.3 Copolymerisation of limonene with styrene The radical copolymerisation of limonene with styrene was conducted according to the method of Sharma and Srivastava. [1] However, the conditions of the polymerisations were not exactly followed, for conditions, see Table 4. The monomers were mixed and stirred under argon atmosphere for about 15 minutes. Xylene was used as a solvent in two experiments as described by

15

‐‐‐‐‐‐‐‐‐‐ Experimental ‐‐‐‐‐‐‐‐‐‐

Sharma and Srivastava and the other experiments were performed in bulk. After 15 minutes the initiator, AIBN, was added to initiate the polymerisation and the solution was lowered into an oil bath that was set on 60 °C or 80 °C. Then the polymerisations were left to react for different times. The polymers were precipitated and dried under vacuum. All polymers, except EN017 and EN022 were precipitated in cold methanol (‐78 °C). EN017 was instead precipitated in cold ethanol (‐72 °C), to evaluate if any differences could be seen. EN022 was performed exactly as in the above‐ mentioned article and precipitated in acidified methanol. 1H‐NMR analysis was used to follow the reactions. In the article the copolymers were refluxed with toluene to remove polystyrene after precipitation. This has not been conducted in this project.

In the results from 1H‐NMR and FTIR it could be seen that the obtained polymer contained limonene but it was difficult to see if it was a copolymer or a plasticised homopolymer. The polymer from EN011 was washed with ethanol, to see if the polymer had been plasticised with limonene. If the amount of limonene decreases during the washing, limonene is not bound to the polymer. It is rather limonene monomers that have plasticised the homopolymer, polystyrene. The washing procedure was performed by immersing the polymer into a vial filled with ethanol over night, followed by filtration. This was performed two times.

Table 4. The different parameters that were used to copolymerise limonene with styrene by radical polymerisation.

Temperature Solvent Time Precipitated in: Molar ratio Lim:Sty:AIBN:Xyl EN001 80 °C Xylene 2 h Cold methanol 1:2:0.007:4 EN002 80 °C None 2 h Cold methanol 1:2:0.008:0 EN007 60 °C None 16 h Cold methanol 1:2:0.008:0 EN011 80 °C None 2 h Cold methanol 1:2:0.007:0 EN013 60 °C None 25 h Cold methanol 1:2:0.007:0 EN014 80 °C None 2 h Cold methanol 1:2:0.040:0 EN017 80 °C None 68 h Cold ethanol 1:2:0.007:0 EN022 80 °C Xylene 17 h Cold acidified 1:2:0.040:4 methanol

4.3.1.4 Copolymerisation of limonene with methyl methacrylate The copolymerisation of limonene with methyl methacrylate was initiated by AIBN and conducted at 80 °C for 21 hours under argon atmosphere, according to the same procedure as for the copolymerisation of limonene with styrene, see section 4.3.1.3. For conditions, see Table 5. The polymer was precipitated in cold ethanol (‐72 °C) and dried under vacuum. 1H‐NMR analysis was used to follow the reaction.

Table 5. The different parameters that were used to copolymerise limonene with methyl methacrylate by radical polymerisation.

Temperature Solvent Time Precipitated in: Molar ratio Lim:MMA:AIBN EN019 80 °C None 21 h Cold ethanol 1:2:0.007

16

‐‐‐‐‐‐‐‐‐‐ Experimental ‐‐‐‐‐‐‐‐‐‐

4.3.2 Cationic polymerisation using AlCl3

4.3.2.1 Homopolymerisation of limonene Five homopolymerisations of limonene by cationic polymerisation were conducted, see Table 6. Equal parts by weight of limonene and dried toluene were cooled to either 0 °C or ‐10 °C under argon atmosphere in a round bottom flask. AlCl3 was used to catalyze the polymerisations. 5 wt% AlCl3 (based on limonene) was added to the solution. The polymerisations were then carried out at different temperatures. One polymerisation was carried out at an increasing temperature from 0 °C to 50 °C at intervals of 20 minutes, see Table 6. 1H‐NMR analysis was used to follow the reactions. ‐1 AlCl3 was removed by stirring with 0.1 M HCl (10 mL HCl mmol limonene) until the colour disappeared and the organic phase was washed four times with 0.1 M NaOH and two times with de‐ ionized water. The organic phase was then dried with magnesium sulphate and toluene was evaporated. The products were dissolved in THF, precipitated in cold MeOH (‐78 °C) and dried in vacuum, at 50 °C over night.

The polymer obtained in EN025 was used in a solvent casting. The polymer (6.4 g) was dissolved in quantity small amount of THF. The amount of polymer used was calculated to give a 1 mm thick film in a Petri dish with a radius of 4.5 centimetres. The solution was poured into the Petri dish and left in the hood without a lid on for 72 hours. Afterwards, it was put in an oven at 50 °C over night, followed by drying in a 50 °C vacuum oven.

Table 6. The different parameters that were used to homopolymerise limonene by cationic polymerisation, using AlCl3.

Mixing Reaction temperature Reaction Molar ratio temperature time Lim:AlCl3:Tol EN020 0 °C 50 °C 4.5 h 1:0.05:1.5 EN021 0 °C 0‐20‐30‐40‐50 °C 2 h 1:0.05:1.5 EN023 ‐10 °C ‐10 °C 3 h 1:0.05:1.5 EN024 0 °C 30 °C 3 h 1:0.05:1.5 EN025 (larger ‐10 °C ‐10 °C 3 h 1:0.05:1.5 batch)

4.3.2.2 Homopolymerisation of styrene The homopolymerisation of styrene was performed see Table 7, as a reference to the copolymerisations of limonene with styrene. Equal parts by weight of styrene and dried toluene were mixed and cooled to ‐10 °C under argon atmosphere. 5 wt% of AlCl3 based on styrene was added to the solution. 1H‐NMR analysis was used to follow the reaction. The reaction proceeded for four hours. The removal of AlCl3 and precipitation of the polymer was performed according to the same procedure as the homopolymerisation of limonene, see section 4.3.2.1 .

Table 7. The different parameters that were used to homopolymerise styrene by cationic polymerisation, using AlCl3.

Reaction temperature Reaction time Molar ratio Sty:AlCl3:Tol EN040 ‐10 °C 4 h 1:1:0,04

17

‐‐‐‐‐‐‐‐‐‐ Experimental ‐‐‐‐‐‐‐‐‐‐

4.3.2.3 Copolymerisation of limonene with styrene Four copolymerisations of limonene with styrene with different molar ratio; 1:1, 1:3 and 3:1 (limonene:styrene), were performed, see Table 8. Equal parts by weight of monomers and dried toluene were cooled to 0 °C or ‐10 °C under argon atmosphere. The polymerisations were performed by the same procedure as the homopolymerisation of limonene, see section 4.3.2.1. The reactions were followed with 1H‐NMR analysis.

Table 8. The different parameters that were used to copolymerise limonene with styrene by cationic polymerisation, using AlCl3.

Reaction temperature Reaction time Molar ratio Lim:Sty:AlCl3:Tol EN027 0 °C 3 h 1:1.0:0.09:1.8 EN028 0 °C 3 h 1:3.0:0.17:4.0 EN029 0 °C 3 h 1:0.3:0.06:1.8 EN039 ‐10 °C 3 h 1:1.0:0.09:1.8

4.3.2.4 Copolymerisation of limonene with tetrahydrofuran One experiment, EN032, was performed to copolymerise limonene with THF, see Table 9. The polymerisation was performed in the same procedure as the homopolymerisation of limonene. Equal parts of limonene and destabilized THF were dissolved in dry toluene and cooled to 0 °C under argon atmosphere. 5 wt% AlCl3 (based on the monomers) was added to the solution. The reaction time was five hours. The reaction was followed with 1H‐NMR analysis.

Table 9. The different parameters that were used to copolymerise limonene with THF by cationic polymerisation, using AlCl3.

Reaction temperature Reaction time Molar ratio Lim:THF:AlCl3:Tol EN032 0 °C 5 h 1:1:2.3:0.08

4.3.3 Cationic polymerisation using BF3OEt2

4.3.3.1 Homopolymerisation of limonene

One experiment was performed using BF3OEt2 as an initiator in the homopolymerisation of limonene, EN037. Prior to use, all glassware were flame dried and put in the oven for about an hour. A master batch was prepared with 2.5 mM BF3OEt2 in dry toluene. 1.6 mL limonene (0.01 mol) was dissolved in 14.8 mL dry toluene and cooled to ‐10 °C under argon atmosphere followed by adding 10 mL (0.025 1 mmol BF3OEt2) of the master batch. The reaction was followed with H‐NMR analysis. No reaction had occurred after 30 minutes; therefore, an additional amount of 25 µL of BF3OEt2 was added to the remaining 60 mL of the master batch. 10 mL (0.058 mmol BF3OEt2) of the new master batch was added to the solution and the reaction was allowed to proceed for 1 hour and 30 minutes. The reaction was stopped by adding a few drops of MeOH. The solvent was evaporated and the product was collected.

4.3.3.2 Homopolymerisation of butyl vinyl ether

A homopolymerisation of butyl vinyl ether (BVE), EN036, using BF3OEt2 as an initiator was performed as a reference to the copolymerisation of limonene with BVE. To a round‐bottom flask, 1.3 mL BVE

18

‐‐‐‐‐‐‐‐‐‐ Experimental ‐‐‐‐‐‐‐‐‐‐

(0.01 mol) and 14.8 mL toluene were added. The procedure was the same as for the homopolymerisation of limonene see section 4.3.3.1, except for the purification after the polymerisation. The product was dissolved in THF and then drop‐wise added to cold methanol (‐78 °C), no precipitate was obtained. The solvents were evaporated, and the mixture was again dissolved in THF. An attempt to precipitate it again was conducted. However, no precipitate could be obtained. The solvents were again evaporated and the mixture was then dissolved in toluene and drop‐wise added to cold MeOH (‐78 °C). A yellow precipitate was obtained, but during the filtration it dissolved. The solvents were evaporated again, and the mixture was collected.

4.3.3.3 Copolymerisation of limonene with butyl vinyl ether

The copolymerisation of limonene with BVE, EN038, was performed using BF3OEt2 as an initiator. The molar ratio of limonene and BVE was set to 1:1. To a round‐bottom flask, 0.8 mL limonene (0.005 mol), 0.65 mL BVE (0.005 mol), and 14.8 mL toluene were added. The procedure was the same as for the homopolymerisation of limonene, see section 4.3.3.1.

4.3.3.4 Copolymerisation of limonene with styrene

The copolymerisation of limonene with styrene, EN044, using BF3OEt2 as an initiator has been evaluated. All glassware was flame dried and put in an oven at 150 °C for one hour. A master batch was prepared with 5 mM BF3OEt2 in dry toluene. Limonene (0.8 mL, 0.005 mol) and styrene (0.6 mL, 0.005 mol) were mixed in 14.8 mL dry toluene and cooled to ‐10 °C under argon atmosphere. 10 mL

(0.05 mmol BF3OEt2) of the master batch was added to the solution. The reaction was followed with 1H‐NMR analysis. No reaction had occurred after two hours; therefore, an additional amount of 25 µL

(0.2 mmol) of BF3OEt2 was added directly to the solution. The reaction was left for two hours and then stopped by adding a few drops of MeOH. The toluene was evaporated. The mixture was then dissolved in THF, followed by an attempt to precipitate it by drop‐wise adding it to cold MeOH (‐78 °C). A tacky, transparent and gel like polymer was obtained.

4.3.4 Cationic polymerisation using onium salts Six experiments on using onium salts as an initiator to homopolymerise limonene have been performed, see Table 10. 1 g of limonene was mixed with 40 mg of UV‐initiator, mixed arylsulfonium hexafluoroantimonate 50 % in propylene carbonate (UVI‐6974) in all experiments. In the first test, the mixture was dropped on a glass substrate and put in the Oriel lamp to give a total dose of 12 J cm‐2.

In EN026, the mixture was collected in a vial with a lid on and put in the window for four days. The mixture was then dissolved in THF followed by an attempt to precipitate it by drop‐wise addition into cold MeOH (‐78 °C). No polymer was obtained.

A new vial with limonene and UV‐initiator was put in the window and was left to react for two months and three weeks, after which a brown viscous layer had formed on the bottom of the mixture, EN030. The liquid on top was removed from the vial, and 1H‐NMR analysis was performed on the brown viscous product at the bottom of the vial. The product was dissolved in THF followed by an attempt to precipitate it by drop‐wise added it to cold MeOH (‐78 °C). No polymer was obtained.

Another UV‐initiator, diphenyliodoniumoctyl ether hexafluoroantimonate was used in EN041. The mixture was added in a vial that was put in the Oriel lamp to give a total dose of 6 J cm‐2. After that,

19

‐‐‐‐‐‐‐‐‐‐ Experimental ‐‐‐‐‐‐‐‐‐‐ the vial was put in the window for two months and one week, yielding the same two‐layer appearance as described above. The liquid was removed from the vial and 1H‐NMR analysis was performed on the brown viscous product at the bottom of the vial. The product was dissolved in THF followed by an attempt to precipitate it by drop‐wise addition into cold MeOH (‐78 °C). No polymer was obtained.

EN055 was prepared in a vial and passed 25 times in the fusion lamp to give a total dose of 2.56 J cm‐ 2. 1H‐NMR analysis was performed on the brown viscous product at the bottom of the vial. The product was dissolved in THF followed by an attempt to precipitate it by drop‐wise addition into cold MeOH (‐78 °C). No polymer was obtained.

In EN056 a film was prepared at a glass substrate and passed 15 times in the fusion lamp to give a total dose of 1.5 J cm‐2.

Table 10. The different parameters that were used to homopolymerise limonene by cationic polymerisation, using onium salts.

Type of onium salt Source, UV Dose [J cm‐2] Performed: Test UVI‐6974 Oriel lamp 12 On a glass substrate EN026 UVI‐6974 Window ‐ In a vial EN030 UVI‐6974 Window ‐ In a vial

EN041 SbF6 Oriel lamp/ 6/‐ In a vial

I Window

OC8H17 EN055 UVI‐6974 Fusion lamp 2.6 In a vial EN056 UVI‐6974 Fusion lamp 1.5 On a glass substrate

4.3.5 Cationic polymerisation using a strong acid To a vial, 10 mL limonene and 0.1 mL of sulphuric acid were added. 1H‐NMR was performed on both phases that had formed after the reaction. The viscous phase was dissolved in DCM and precipitated in cold MeOH (‐78 °C).

4.3.6 Thiol‐ene polymerisation

4.3.6.1 Copolymerisation of limonene with 2‐mercaptoethyl ether using AIBN The copolymerisation of limonene with 2‐mercaptoethyl ether using AIBN as an initiator has been evaluated. Limonene and 2‐mercaptoethyl ether were mixed and stirred under argon atmosphere for 15 minutes. In EN043, chloroform was used as a solvent. EN042 and EN053 were performed in bulk, see Table 11. After 15 minutes AIBN was added, 1 wt% (based on the monomer). The mixture was lowered into a pre‐heated oil bath that was set to 80 °C, and the polymerisation was left to proceed for three hours. The polymerisations were followed with 1H‐NMR analysis. The mixture was then dissolved in THF and drop‐wise added to cold MeOH (‐78 °C). The polymer was collected by decanting the solvent.

20

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Table 11 The different parameters that were used to copolymerise limonene with 2‐mercaptoethyl ether by thiol‐ene polymerisation, using AIBN. Reaction 1 of EN042 and EN043 and also EN053.

Solvent Initiator Temperature Time Molar ratio Lim:Thiol:Chloroform EN042 None AIBN 80 °C 3 h 1:1:0 reaction 1 EN043 Chloroform AIBN 80 °C 3 h 1:1:2.5 reaction 1 EN053 None AIBN 80 °C 3 h 2:1:0

EN042 and EN043 was used to do further reactions with limonene with the aim to obtain polymers with higher molecular weights see Table 12 and Table 13. The procedure was the same as before, except that instead of using 2‐mercaptoethyl ether, the obtained oligomer was used. In EN043, no solvent was used in the following reactions and the temperature was lowered to 60 °C in reaction 2. It was assumed that the polymers from reaction 1 mainly consisted of trimers with a molecular weight of 400 g mol‐1, and that the end groups consisted of thiols. The calculations of the amounts that were used in the second reaction were based on this assumption. It was assumed that the polymer from reaction 2, mainly consisted of oligomers with seven monomer units, (two oligomers connected by limonene) with a molecular weight of 950 g mol‐1. The amounts that were used in the third reaction were calculated after that assumption.

Table 12. The different parameters that were used in the second reaction of EN042 and EN043.

Solvent Initiator Temperature Time Molar ratio Lim:Polymer EN042 None AIBN 80 °C 70 h 1:1 reaction 2 EN043 None AIBN 60 °C 70 h 1:1 reaction 2

Table 13. The different parameters that were used in the third reaction of EN042 and EN043.

Solvent Initiator Temperature Time Molar ratio Lim:Polymer EN042 None AIBN 80 °C 120 h 1:1 reaction 3 EN043 None AIBN 80 °C 120 h 1:1 reaction 3

4.3.6.2 Copolymerisation of limonene with 2‐mercaptoethyl ether using Irgacure 184 The copolymerisation of limonene with 2‐mercaptoethyl ether using the photoinitiator Irgacure 184 has been evaluated. Limonene and 2‐mercaptoethyl ether were mixed together in a vial and 2 wt% of photoinitiator, Irgacure 184, was added. A molar ratio of 1:1 was used in EN047 and EN049 and a molar ratio of 3:1 (limonene:2‐mercaptoethyl ether) was used in EN048 and EN050. The vials were put in the Oriel lamp in different intensities for different times, see Table 14. The polymerisations were followed with 1H‐NMR analysis.

21

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Table 14. The different parameters that were used to copolymerise limonene with 2‐mercaptoethyl ether by thiol‐ene polymerisation using Irgacure 184.

Molar ratio Intensity Time Dose [J cm‐2] Total dose [J cm‐2] Lim:Thiol [mW cm‐2] [min] EN047 1:1 30 5 0.019 0.99 50 5 0.97 EN048 3:1 30 5 0.019 0.99 50 5 0.97 EN049 1:1 50 30 5.8 5.8 EN050 3:1 50 30 5.8 5.8

4.3.6.3 Spontaneous copolymerisation of limonene with 2‐mercaptoethyl ether The spontaneous copolymerisation of limonene with 2‐mercaptoethyl ether has been investigated. Limonene and 2‐mercaptoethyl ether with molar ratio 1:1 (EN045) and 3:1 (EN046) (limonene:2‐ mercaptoethyl ether), were mixed and stirred under argon atmosphere for 15 minutes, and then lowered into an oil bath that was set to 60°C. The polymerisation was left to proceed for different times, see Table 15. The polymerisations were followed with 1H‐NMR analysis. The mixture was then dissolved in THF and drop‐wise added to cold MeOH (‐78 °C). The polymer was collected by decanting the solvent.

Table 15. The different parameters that were used to copolymerise limonene with 2‐mercaptoethyl ether by spontaneous thiol‐ene polymerisation at an increased temperature.

Solvent Initiator Temperature Time Molar ratio Lim:Thiol EN045 None None 60 °C 22 h 1:1 EN046 None None 60 °C 16 h 3:1

To obtain polymers with lower molecular weights (mainly trimers), cold syntheses were conducted, see Table 16. The objective was to produce a homogenous product with a known chemical structure that could be used for further reactions and crosslinking. Three cold polymerisations of limonene with 2‐mercaptoethyl ether were performed: EN051 (molar ratio 3:1), EN052 (molar ratio 1:1) and EN054 (molar ratio 2:1) (limonene:2‐mercaptoethyl ether). A two‐necked round‐bottom flask with a dropping funnel attached was used. Additionally, both the funnel and the flask were sealed with one septum each. The system was flushed with argon for 30 minutes before the monomers were added. The round bottom flask was lowered down into an ice bath and limonene was added. 2‐ mercaptoethyl ether was added through the dropping funnel with approximately one drop per second. When all monomers had been added, the reaction was left under stirring in the ice bath for two hours, and then left under stirring in room temperature to further react for 16 hours. The reaction was followed with 1H‐NMR analysis. EN051 and EN052 were also followed with TLC to see if the polymerisation yields more than one product. The products were dissolved in THF and precipitated in cold MeOH (‐78 °C). The polymers were collected by decanting the solvent.

22

‐‐‐‐‐‐‐‐‐‐ Experimental ‐‐‐‐‐‐‐‐‐‐

Table 16. The different parameters that were used to copolymerise limonene with 2‐mercaptoethyl ether by spontaneous thiol‐ene polymerisation at a decreased temperature.

Solvent Initiator Temperature Time Molar ratio Lim:Thiol EN051 None None 0 °C 2 h 3:1 RT 16 h EN052 None None 0 °C 2 h 1:1 RT 16 h EN054 None None 0 °C 2h 2:1 RT 16 h

4.3.6.4 Crosslinking of the thiol‐ene polymer with TRIS. The limonene‐thiol copolymer, EN051, was used in a further step in an attempt to crosslink it. It was assumed that the copolymer EN051 mainly consisted of trimers, see Figure 11. The trimer was mixed with the crosslinker trimethylolpropane tri(3‐mercaptopropionate) (TRIS) and 1 wt% of the photoinitiator Irgacure 184. 1H‐NMR spectrum of TRIS is shown in Figure LXXV in appendix 9. The formulation was coated on a glass substrate with a frame applicator (90 µm) and put in the Oriel lamp to receive a total dose of 5.8 J cm‐2. The material from the glass substrate was then scraped off into a vial. To see if the crosslinking had succeeded a dissolution test was performed. Chloroform and DCM were dropped onto the material that remained on the glass substrate. The material was also scraped onto a spoon that was placed in a vial containing chloroform. The spoon was stirred around in the vial for about a minute.

According to SEC results, EN051 was not a trimer, the polymer had a molecular weight of 2300 g mol‐ 1 (16 monomer units). The values were recalculated, based on the SEC results, and the same procedure as described above was performed with the new amounts.

O S S

Figure 11. The assumed trimer from EN051.

4.3.6.5 Copolymerisation of the thiol‐ene polymer with maleic anhydride. The thiol‐ene polymer, EN053, was used in a further reaction to polymerise it with maleic anhydride. Maleic anhydride (0.1 g, 0.001 mol) was dissolved in THF and mixed with 0.5 g of the polymer EN053. The mixture was left for 30 minutes to let the solvent evaporate. 2 wt% of Irgacure 184 was added to the mixture. The mixture was dropped into moulds on a Teflon plate. The Teflon plate was then run in the fusion lamp to give a total dose of 2.6 J cm‐2. The reaction was followed with 1H‐NMR analysis.

23

‐‐‐‐‐‐‐‐‐‐ Experimental ‐‐‐‐‐‐‐‐‐‐

4.4 Characterization

4.4.1 Size Exclusion Chromatography (SEC) SEC using THF as a mobile phase was used in order to get the average molecular weights of the obtained polymers. The following polymers were analyzed with SEC‐THF: EN001, EN002, EN006, EN007, EN020, EN021, EN023, EN024, EN025, EN027, EN028, EN029, EN036, EN038, EN039, EN040, EN042 reaction 1 and EN043 reaction 1.

Due to technical issues with the THF‐SEC in the middle of the project, a SEC using chloroform as a mobile phase was used instead in order to obtain the molecular weights of the polymers. The following polymers were analyzed with chloroform‐SEC: EN042 reaction 3, EN043 reaction 3, EN044, EN045, EN046, EN049, EN050, EN051, EN052, EN053 and EN054.

4.4.2 Matrix‐Assisted Laser Desorption Ionization‐Time of Flight mass spectroscopy (MALDI‐TOF MS) MALDI‐TOF MS was used to obtain the molecular weights of all fractions of the polymers. The following polymers were analyzed with MALDI‐TOF MS: EN021, EN023, EN025, EN027, EN028, EN029, EN039, EN040, EN043 reaction 1, EN042 reaction 2, EN043 reaction 2, EN045, EN046, EN049 and EN050.

4.4.3 Fourier transform infrared spectroscopy (FTIR) The limonene FTIR assignment is shown in Figure IV and Table II in appendix 3.

FTIR was used in order to follow the reactions and see which groups that are reacting during the polymerisations. The following polymers were analyzed with FTIR: EN001, EN002, EN006, EN007, EN009, EN011, EN014, EN019, EN020, EN021, EN022 EN023, EN024, EN025, EN027, EN028, EN029, EN036, EN038, EN039, EN040, EN042, EN043, EN044, EN045, EN046, EN051 and crosslinked EN051.

4.4.4 Raman spectroscopy Raman spectroscopy was used for three main purposes: to follow the cationic polymerisation and the thiol‐ene polymerisation, to get a more clear view about what happens with the internal double bond of limonene and to see what happens with the thiol during the thiol‐ene polymerisations. The following polymers were analyzed with Raman spectroscopy: EN020, EN021, EN023, EN024, EN025, EN027, EN028, EN029, EN039, EN040, EN042, EN043, EN045, EN046, EN051 and crosslinked EN051.

4.4.5 Pressing In order to investigate the properties of a potential material made from the homopolymer EN023 and the copolymers: EN027 and EN028, they were pressed into films.

Since the DSC results had not yet been obtained for the homopolymer, EN023, the polymer was gradually heated in an oven to obtain an approximate glass transition temperature, Tg. The temperature on the oven was set to 70 °C, and then the temperature was increased every 15 minutes. The polymer seemed to have a Tg somewhere between 95°C and 110°C.

The parameters that were varied to obtain as good films as possible were: the temperature, the pressure, the pressing time, and the cooling time, see Table 17, Table 18 and Table 19.

24

‐‐‐‐‐‐‐‐‐‐ Experimental ‐‐‐‐‐‐‐‐‐‐

Table 17. The different parameters that were used in the pressing of EN023 (polylimonene).

EN023 Temperature Pre‐ Pre‐ Pressing time Pressing: Cooling [°C] pressing pressing: [min] Pressure time [s] Pressure [kN cm‐2] [kN cm‐2] 1 100 ‐ ‐ 5 15.6 ‐ 2 110 ‐ ‐ 5 15.6 ‐ 3 110 ‐ ‐ 5 15.6 RT 5 min 4 110 30 2.1 5 15.6 RT 5 min 5 100 30 2.1 5 15.6 RT 5 min 6 100 30 2.1 5 31.2 RT 5 min

Table 18. The different parameters that were used in the pressing of EN027 (poly(limonene‐co‐styrene)).

EN027 Temperature Pre‐ Pre‐ Pressing time Pressing: Cooling [°C] pressing pressing: [min] Pressure time [s] Pressure [kN cm‐2] [kN cm‐2] 1 100 30 2.1 5 15.6 RT 5 min 2 105 30 2.1 5 15.6 RT 5 min

Table 19. The different parameters that were used in the pressing of EN028 (poly(limonene‐co‐styrene)).

EN028 Temperature Pre‐ Pre‐ Pressing time Pressing: Cooling [°C] pressing pressing: [min] Pressure time [s] Pressure [kN cm‐2] [kN cm‐2] 1 105 30 2.1 5 15.6 RT 5 min

4.4.6 Differential scanning calorimetry DSC analysis was conducted to evaluate the glass transition temperature of the obtained polymers and to see if the copolymers were copolymers or two homopolymers. The following polymers were analyzed with DSC: EN001, EN002, EN007, EN009, EN011, EN021, EN023, EN024, EN025, EN027, EN028, EN029, EN040, EN051 and EN052.

25

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

5. Results and discussion In this project have polymerizations of the terpene limonene been evaluated. The polymerization techniques that have been used are radical polymerisation, cationic polymerisation and thiol‐ene polymerisation. Polymerisations that have been performed during this project are shown in Table 20.

Table 20. The performed polymerisations of limonene during this project.

Polymerisation Homopolymerisation/Copolymerisation Monomers Initiator technique Radical Homopolymerisation Limonene AIBN polymerisation Radical Homopolymerisation Styrene AIBN polymerisation Radical Copolymerisation Limonene and AIBN polymerisation styrene Radical Copolymerisation Limonene and AIBN polymerisation methyl methacrylate Cationic Homopolymerisation Limonene AlCl3 polymerisation Cationic Homopolymerisation Styrene AlCl3 polymerisation Cationic Copolymerisation Limonene and AlCl3 polymerisation styrene Cationic Copolymerisation Limonene and AlCl3 polymerisation tetrahydrofuran Cationic Homopolymerisation Limonene BF3OEt2 polymerisation Cationic Homopolymerisation Butyl vinyl BF3OEt2 polymerisation ether Cationic Copolymerisation Limonene and BF3OEt2 polymerisation butyl vinyl ether Cationic Copolymerisation Limonene and BF3OEt2 polymerisation styrene Cationic Homopolymerisation Limonene Onium polymerisation salt Cationic Homopolymerisation Limonene H2SO4 polymerisation Thiol‐ene Copolymerisation Limonene and AIBN polymerisation 2‐ mercaptoethyl ether Thiol‐ene Copolymerisation Limonene and Irgacure polymerisation 2‐ 184 mercaptoethyl ether Thiol‐ene Copolymerisation Limonene and ‐ polymerisation 2‐ mercaptoethyl

26

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

ether Cationic Copolymerisation Thiol‐ene Irgacure polymerisation polymer and 184 TRIS Cationic Copolymerisation Thiol‐ene Irgacure polymerisation polymer 184

Reference 1H‐NMR spectra of pure limonene, pure styrene and pure 2‐mercaptoethyl ether are shown in appendix 2. A reference FTIR spectrum of limonene is shown in appendix 3.

5.1 Radical polymerisation The radical polymerisation of limonene using AIBN to initiate the polymerisation has been evaluated. Both homopolymerisation and copolymerisations have been performed. Supplement results of the radical polymerisations are shown in appendix 4.

5.1.1 Homopolymerisation of limonene Attempts to homopolymerise limonene by radical polymerisations have been conducted using AIBN as an initiator. However, no polymer was obtained after precipitation of the crude reaction mixture. In Figure V in appendix 4, the 1H‐NMR spectrum of EN004 (homopolymerisation of limonene) is shown. No polymer peaks can be seen in the spectrum. Neither could any decrease of the peaks originating from the internal double bond a (5.4 ppm) and the external double bond b (4.7 ppm) be seen during the reaction time. Radical polymerisation of limonene during these conditions does not yield any polymer.

5.1.2 Homopolymerisation of styrene Homopolymerisations of styrene was performed as a reference to the copolymerisation of limonene with styrene. The polymerisation yielded a white polymer that looked like flakes. A yield of 7 % was obtained when performed at 60 °C for 16 hours in bulk and a yield of 18 % when carried out at 80 °C for 2 hours with xylene as a solvent. A 1H‐NMR spectrum of the polymer is shown in Figure VI in appendix 4. The average molecular weight of the polymer (EN006), determined by SEC was 70 000 g mol‐1, see Table III in appendix 4. The obtained polymer (EN009), analysed by DSC, had a glass transition temperature, Tg of 84 °C.

5.1.3 Copolymerisation of limonene with styrene The attempt to copolymerise limonene with styrene was conducted according to the method of Sharma and Srivastava [1] who successfully polymerised limonene with styrene by this method. The polymerisations were now performed at 60 °C or 80 °C, with or without solvent and at different reaction times. A white powdery polymer was obtained in the attempt to copolymerise limonene with styrene by radical polymerisation. The yields of the polymerisations are shown in Table IV in appendix 4. The 1H‐NMR spectra of EN014 are shown in Figure 12, Figure 13 and Figure 14. These spectra represent all the attempts to copolymerise limonene with styrene by radical polymerisation. According to the 1H‐NMR spectra, styrene and limonene are consumed during the reaction. This can be seen at the representative peaks for styrene; h (5.73 ppm) and i (5.23 ppm) and for limonene; a (5.4 ppm) and b (4.7 ppm). Styrene is, however, consumed much faster than limonene. The spectrum taken of the polymer after precipitation and vacuum drying in Figure 14 can be compared with the spectrum of EN009 (polystyrene) that was taken after precipitation and vacuum drying, see Figure VI

27

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐ in appendix 4. These two spectra are almost identical to each other when focusing on the polymer peaks. It is the peaks of the monomer residues in Figure 14 that separates them from each other. The 1H‐NMR spectrum indicates that the obtained polymer is the homopolymer polystyrene. However, the peaks originating from limonene also decreased during the reaction. This may be due to that limonene evaporates during the polymerisation.

Figure 12. 1H‐NMR spectrum of EN014 (copolymerisation of limonene with styrene), t=0.

28

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

Figure 13. 1H‐NMR spectrum of EN014 (copolymerisation of limonene with styrene), t=2 h.

Figure 14. 1H‐NMR spectrum of EN014 (copolymerisation of limonene with styrene). Taken after precipitation and vacuum drying.

29

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

The results from SEC analysis are shown in Table V in appendix 4. The average molecular weights of the polymers obtained from radical polymerisation of limonene with styrene were between 14 000 g mol‐1 and 37 000 g mol‐1. Polystyrene that had been prepared by the same procedure had twice as high average molecular weight, 70 000 g mol‐1.

Results from DSC are shown in Table VI in appendix 4. The Tg of the polymers varied in between 57 °C and 75 °C and only one glass transition could be seen in the results. If more than one glass transition had appeared it would have indicated that the sample contained more than one polymer, e.g. the homopolymers polylimonene and polystyrene. Tg of polystyrene is 100°C. Polystyrene that was made in this project by radical polymerisation as a reference had a glass transition temperature of 84 °C. A copolymer of limonene with styrene should probable have a lower Tg than polystyrene since limonene does not have the conjugated benzene ring, and is therefore more flexible than styrene. However, if polystyrene has been plasticised with limonene, it would also obtain a lower Tg. Therefore, no conclusion could be drawn from this result concerning whether the polymer is a copolymer or only polystyrene that has been plasticised with limonene.

The normalized FTIR‐spectrum of the polymer, EN014, obtained by radical copolymerisation of limonene with styrene is shown in Figure 15. This spectrum is representative for all polymers obtained in the attempt to copolymerise limonene with styrene by radical polymerisation. In the figure can also spectra of limonene, styrene and polystyrene (EN009) be seen. The spectrum of EN014 is almost identical to the spectrum of polystyrene (EN009), except at the wave numbers in the interval 1660‐1620 cm‐1, where an indication of a small peak can be seen. It is probably the external double bond of limonene that has a peak at wave number 1640 cm‐1. This peak should decrease if the external double reacts during the polymerisation, or it should disappear when the polymer is precipitated, unless the polymer is unsaturated. If the polymer is unsaturated, peaks originating from the double bonds of limonene should also be seen in the polymer.

30

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

Limonene

Styrene A

EN009 (Polystyrene)

EN014 (polymer obtained by radical polymerization of limonene with styrene)

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600.0 cm-1

Figure 15. Normalized FTIR‐spectra of pure limonene, pure styrene, EN009 (polystyrene) and EN014 (polymer obtained by radical polymerisation of limonene with styrene). The spectrum of EN014 also represents the polymers EN001, EN002, EN007, EN011, EN013, EN014, EN017 and EN022.

Since the 1H‐NMR spectra of the obtained polymer and polystyrene were almost identical and so also the FTIR spectra, except for the area where the external double bond of limonene can be seen, it seems as the obtained polymer only is polystyrene. The fact that the average molecular weight was half for the obtained polymers compared to the reference polystyrene could be explained as the system was more diluted, limonene can act as a solvent. The reaction rate is then decreased and lower molecular weights are obtained. The lower Tg for the obtained polymer can either be due to that it is a copolymer, but it does not look like that in the other results. More likely is that it is polystyrene that has been plasticised with limonene.

To investigate whether the obtained polymer was plasticised with limonene or not, a washing test was performed. The polymer, EN011, was washed with ethanol to see if the peak at 1640 cm‐1 in the FTIR spectrum decreased. The results can are shown in Figure 16 and Table 21. The area of the peak decreases after each washing step. It could be concluded that the polymers obtained were pure polystyrene that had been plasticised with limonene. Limonene has not reacted during the radical polymerisation.

31

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

EN011

EN011 wash 1

A

EN011 wash 2

EN009 Polystyrene

1660.7 1655 1650 1645 1640 1635 1630 1625 1620.3 cm-1

Figure 16. Normalized FTIR‐spectra of EN011 (copolymerisation of limonene with styrene), EN011 wash 1, EN011 wash 2 and EN009 (polystyrene).

Table 21. Areas of the peaks from the FTIR‐spectra in Figure 16.

Sample Area of the peak (1650‐1630 cm‐1) EN011 23.4 EN011 wash 1 21.5 EN011 wash 2 19.4 EN009 Polystyrene 9.16

All polymers except EN017 and EN022 were precipitated in cold methanol (‐78 °C). EN017 was instead precipitated in cold ethanol (‐72 °C), this to see if any difference could be observed with the amount of limonene in the polymer. The result was the same for this polymerisation as for the others. Since limonene has been polymerised successfully with styrene in the article by Sharma and Srivastava [1] and now only polystyrene was obtained, one final test was performed following the article exactly. EN022 was precipitated in acidified methanol according to the article to investigate whether limonene maybe polymerises through cationic polymerisation during the precipitation. This can be one possible explanation for how they have succeeded in the article. This was however not the case, the results were the same for EN022 as for the other polymerisations, i.e. no copolymer was obtained.

5.1.4 Copolymerisation of limonene with methyl methacrylate Copolymerisation of limonene with methyl methacrylate (MMA) was also attempted. The isolated precipitated polymer looked like small white round spheres that were stuck to each other. The polymerisation gave a yield of 48 %. A reference 1H‐NMR spectrum of poly(methyl methacrylate)

32

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

(PMMA) is shown in Figure 17 and the 1H‐NMR spectrum of the polymer obtained from the copolymerisation is shown in Figure 18. Both these spectra were taken after precipitation and vacuum drying at 50 °C over night. The polymer peaks in Figure 18 are identical to the reference spectrum of PMMA in Figure 17, peaks from limonene can however still be seen in the spectrum. The polymer is probably only the homopolymer PMMA, and limonene has not reacted during the polymerisation.

Figure 17. 1H‐NMR spectrum of the reference: poly(methyl methacrylate). Taken after precipitation and vacuum drying.

33

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

Figure 18. 1H‐NMR spectrum of EN019 (copolymerisation of limonene with methyl methacrylate). Taken after precipitation and vacuum drying.

The polymer was also analyzed by FTIR. The spectrum is shown in Figure 19. It can be seen in the figure that the spectrum of the obtained polymer is identical to the reference spectrum of PMMA. The obtained polymer is PMMA.

34

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

Poly(methyl methacrylate)

A

EN019 Copolymer of limonene with methyl methacrylate

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600.0 cm-1

Figure 19. Normalized FTIR‐spectra of the reference poly(methyl methacrylate) (top) and EN019 (polymer obtained by radical polymerisation of limonene with MMA) (bottom).

5.1.5 Copolymerisation of limonene with synthetic monomers through radical polymerisation Finally, based on the attempts to copolymerise limonene with styrene and methyl methacrylate by radical polymerisation were of unsuccessful outcome, the conclusion can be drawn that limonene does not seem to polymerise through radical polymerisation.

The external double bond of limonene should be more susceptible for polymerisation than the internal double bond due to steric hindrance. However, the external double bond can be resembled to isobutene, see Figure 20, and isobutene does not polymerise by radical polymerisation, and through that it is indicated that limonene cannot be polymerised in the same way. It is, on the other hand, strange that the copolymerisation of limonene with other synthetic monomers does not work since several articles have been published in the beginning of the 2000s by Sharma and Srivastava in this subject. They have shown that limonene can be polymerised with styrene, methyl methacrylate and other synthetic monomers. [1, 32‐35] In their work to copolymerise limonene with styrene they characterized the obtained polymer by FTIR. The spectra of the copolymer showed the characteristic frequencies at 1715 cm‐1 which are said to correspond to the internal double bond of limonene. This peak can neither be seen in the spectra of the obtained polymers in this project, nor in the spectrum of pure limonene. If it is a characteristic wave number of the internal double bond, it should definitely be seen in the obtained copolymer. The question is how trustworthy the published articles are, can limonene copolymerise with other monomers through radical polymerisation at all?

35

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

Isobutene

Limonene

Figure 20. The chemical structures of limonene and isobutene.

5.2 Cationic polymerisation using AlCl3

The cationic polymerisation of limonene using AlCl3 to initiate the polymerisation has been evaluated. Both homopolymerisation and copolymerisations have been performed. Supplement results of the cationic polymerisations are shown in appendix 5.

5.2.1 Homopolymerisation of limonene

Cationic homopolymerisaton of limonene was performed with AlCl3 as an initiator. The polymerisation was conducted at different temperature and reaction times. The reaction mixture turned orange when AlCl3 was added. Further, it turned darker and more viscous along with the polymerisation. The polymers that were obtained after purification and precipitation from the homopolymerisations of limonene were white or light yellow powders with the yields; EN020: 58 %; EN021: 61 %; EN023: 75 %; EN024: 56 % and EN025: 66 %.

Examples of 1H‐NMR spectra of the homopolymerisation of limonene are shown in Figure 21. The spectra are shown more clearly in Figures VII‐XVII in appendix 5. The polymerisations were performed at different temperatures to see which temperature is optimal for the polymerisation. They were all mixed at a low temperature, 0 °C or ‐10 °C, and then set to the reaction temperature: 50 °C, 30 °C, ‐10 °C or an increasing temperature interval. Since most cationic polymerisation of olefins has a negative temperature coefficient of reaction rate [15] the polymerisation should proceed more rapidly at lower temperature.

36

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

5000

4500

4000 After precipitaion and vacuum drying 3500

3000 2h 45 min

2500 2 h 2000

1500 50 min 1000

500 Before initiation

0 6 4 2 0 ppm

Figure 21. 1H‐NMR spectra of the polymerisation of limonene by cationic polymerisation, EN023.

The polymerisation, EN023, was performed at ‐10 °C. 1H‐NMR spectra of the reaction are shown in Figure 21 or more clearer in Figures VII‐X in appendix 5. After 50 minutes reaction time a peak at 0.9 ppm can be seen and that the integral (3‐0.5 ppm) has increased, see Figure VIII. The peak assigned to the internal double bond a (5.4 ppm) has not decreased and the peak assigned to the external double bond b (4.7 ppm) has only decreased somewhat. After 2 hours, more polymer peaks can be seen and both peaks assigning the double bonds have decreased, see Figure IX. After 2 hours and 45 minutes the monomer peaks have disappeared and only polymer peaks and solvent peaks can be seen in the spectrum, see Figure X. All limonene has been consumed and the reaction had reached 100 % conversion.

In another reaction, EN020, the temperature was rapidly increased from the mixing temperature, 0 °C to the reaction temperature, 50 °C. 1H‐NMR spectra of the reaction are shown in Figures XI and XII in appendix 5. As can be seen in Figure XI, essentially all limonene has been consumed during the heating and yielded polymers. This is a more rapid reaction than EN023 that was performed at a lower temperature. This behaviour differs from theory, the reaction should be more rapid at a lower temperature due to the negative temperature coefficient of the reaction rate for cationic polymerisations, but this is evidently not the case for this reaction. After 2 hours reaction, the peaks originating from limonene have disappeared and only polymer peaks and solvent peaks can be seen in the spectrum, see Figure XII in appendix 5.

One polymerisation was performed, increasing the temperature, EN021. The temperature was raised in four intervals, 0‐20, 20‐30, 30‐40 and 40‐50 °C with approximately 20 minutes reaction time at each temperature. The polymerisation was followed with 1H‐NMR to see at what temperature the polymerisation is most rapid. The 1H‐NMR spectra are shown in Figure XIII‐XVII in appendix 5. Peak b (4.7 ppm), assigned to the external double bond, decreases more rapidly than peak a (5.4 ppm),

37

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐ assigned to the internal double bond. Peak a (5.4 ppm) had only decreased from 0.8 to 0.74 after 1 hour and 10 minutes, when the temperature had reached 30 °C. Peak b (4.7 ppm) had decreased slightly more from 1.94 to 1.58, when the temperature had reached 30 °C. However, when the temperature was further increased to 40 °C and the total reaction time had been 1 hour and 30 minutes, limonene had been rapidly consumed. The monomer peaks had disappeared and only polymer peaks and solvent peaks can be seen in the spectrum, see Figure XVII in appendix 5. The conclusions are that all limonene molecules have been consumed, the reaction reached 100 % conversion and that the polymerisation was most rapid at a temperature of 40 °C. However, it could not be concluded whether this is a temperature effect or if it is a time effect.

The FTIR‐spectra of limonene and polylimonene are shown in Figure 22. The peak at 1640 cm‐1 corresponds to the external double bond. It disappears during the polymerisation indicating that all external double bonds react. In a closer look, it can also be seen that peaks at 1311, 1293, 1243, 957, 914 and 889 cm‐1 which also corresponds to the double bonds in limonene see Table II in appendix 3 decreases and disappears.

External double bond

Limonene

A

EN023 Polylimonene (represents all homopolymers of limonene)

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600.0 cm-1 Figure 22. Normalized FTIR‐spectra of pure limonene (top) and EN023 (polylimonene) (bottom).

The Raman spectra of limonene and polylimonene are shown in Figure 23. Both the peak corresponding to the external double bond at 1640 cm‐1 and the peak corresponding to the internal double bond at 1670 cm‐1 can clearly be seen in the Raman spectrum of limonene. In polylimonene no well resolved peaks can be observed in this region. However a broader peak indicates residual unsaturation.

38

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

Internal External double double bond bond

Limonene Egy

EN023 Polylimonene (represents all homopolymers of limonene)

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600.0 Raman Shift / cm-1 Figure 23. Raman spectra of pure limonene (top) and EN023 (polylimonene) (bottom).

The homopolymer polylimonene obtained through cationic polymerisation had a low average molecular weight, between 400 and 600 g mol‐1, see Table VII in appendix 5. The intention of polymerising limonene into a polymer yielded an oligomer that consists mainly of trimers and tetramers. However, it should be noted that in results from MALDI‐TOF it can be seen that small fractions reaches molecular weights up to 2041 g mol‐1. This is equivalent to 15 monomer units, since the molecular weight of limonene is 136 g mol‐1. An example of a MALDI‐TOF spectrum of EN025 is shown in Figure XVIII in appendix 5.

With the intention of make a material out of the polymer obtained from EN025, it was solvent casted from a minimal quantity of THF. A clear film was formed in the Petri dish when the solvent evaporated from the polymer. However, after three days of evaporation, the film was still tacky. The Petri dish was put in an oven at 50 °C over night so that the solvent could evaporate more rapid. After this treatment, bubbles had turned up in the film, and the film was still tacky, so it was put in the vacuum oven. Unfortunately, the film was destroyed in the vacuum oven when the solvent evaporated to rapid and the film bubbled up.

An attempt to press polylimonene to a material was performed with EN023, see Table 17; the results are shown in Table VIII in appendix 5. The obtained films were brittle and fell apart into fragments. The best film was obtained at a temperature of 100 °C, 30 s pre‐pressing at a pressure of 2.1 kN cm‐ 2, 5 minutes pressing at a pressure of 31.2 kN cm‐2 and cooling in RT for 5 minutes. It was however also very brittle. The reason for the brittle films is probably due to the low molecular weight of the polymer. The polymers are too short to form strong entanglements with each other. It is desirable to increase the molecular weights of the polymers.

Results from DSC are shown in Table IX in appendix 5. Polylimonene has a Tg around 60 °C.

39

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

5.2.2 Homopolymerisation of styrene Homopolymerisations of styrene was performed as a reference to the copolymerisation of limonene with styrene. The reference, EN040, was performed with the same procedure as polylimonene had been prepared, at ‐10 °C for four hours. When AlCl3 was added to initiate the polymerisation, the solution turned dark orange and emitted gas. The yield of the obtained polymer was 91 % and the appearance was like a glass, almost transparent and hard. The 1H‐NMR spectrum taken after 30 minutes reaction is shown in Figure XIX in appendix 5. No monomer peaks can be observed, the reaction had reached 100 % conversion.

Results from SEC shows that the average molecular weight of the polymer is only 900 g mol‐1, but according to MALDI‐TOF results, see Figure XX in appendix 5, fractions of polymer with higher molecular weights exist, peaks up to 4600 g mol‐1 can be seen.

5.2.3 Copolymerisation of limonene with styrene As a further development, the copolymerisation of limonene with styrene by cationic polymerisation was investigated. It was performed at 0 °C or ‐10 °C for three hours. When AlCl3 was added to initiate the copolymerisation, the solution turned orange. Then it turned darker and more viscous along with the polymerisation. After precipitation was white powdery polymers obtained with the yields; EN027: 67 %; EN028: 83 % and EN029: 83 %. The 1H‐NMR spectra of EN027 (molar ratio 1:1) are shown in Figure 24 and Figure 25. After 3 hours and 30 minutes all monomers had reacted. Peaks originating from the protons in the double bonds in limonene; a (5.4 ppm) and b (4.7 ppm) had disappeared, and also the peaks originating from the protons in the double bond of styrene at h (5.73 ppm) and i (5.23 ppm). The reaction had reached 100 % conversion. Additionally, the copolymerisation was also performed at molar ratios 1:3 and 3:1 (limonene:styrene). EN028 (molar ratio 1:3) that contained more styrene than limonene had not reached 100 % conversion after 3 hours and 30 minutes. Monomer peaks could be seen for both limonene and styrene, see Figure XXI in appendix 5. In EN029 (molar ratio 3:1) which contained more limonene than styrene, no peaks originating from styrene could be seen after 3 hours and 30 minutes, see Figure XXII in appendix 5. Peaks originating from the double bonds of limonene could however still be seen. A polymerisation was also performed at a lower temperature, ‐10 °C (EN039) instead of 0 °C (EN027), to see if the polymerisation would be more rapid at a lower temperature. No specific differences could be seen in the 1H‐NMR spectra of EN039 compared to EN027.

40

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

Figure 24. 1H‐NMR spectrum of EN027 (copolymerisation of limonene with styrene), molar ratio 1:1 and t=30 min.

Figure 25. 1H‐NMR spectrum of EN027 (copolymerisation of limonene with styrene), molar ratio 1:1 and t=3.5 h.

41

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

The normalized FTIR spectrum of EN027 is shown in Figure 26. The spectra of EN028 and EN029 were identical to EN027 so these spectra are not shown. For comparison, normalized FTIR spectra of pure limonene, pure styrene, EN023 (polylimonene) and EN009 (polystyrene) can also be seen in the figure. Peaks that can be found in both polylimonene and polystyrene are also present in the spectrum for the copolymer. The peak at 1490 cm‐1 can be seen in both styrene and in polystyrene and the peak at 1370 cm‐1 can be seen in both limonene and in polylimonene. Two clear peaks in the interval 800‐600 cm‐1 can also be seen in both styrene and in polystyrene. The peak at 1640 cm‐1 originating from the external double bond of limonene has disappeared during the copolymerisation. In a closer look into the spectra it could also be seen that peaks at 1311, 1293, 1243, 957, 914 and 889 cm‐1, which also corresponds to the double bonds in limonene, see Table II in appendix 3, decreases and disappears. The large peak at 1740 cm‐1 in EN027 can be explained as an impurity in the sample, since this is the specific wave number for carbonyl groups, and no such should be present in the polymer.

Limonene

Styrene

A EN023 Polylimonene

EN009 Polystyrene

EN027 Poly(limonene- co- styrene)

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600.0 cm-1

Figure 26. Normalized FTIR‐spectra of pure limonene, pure styrene, EN023 (polylimonene), EN009 (polystyrene) and EN027 (poly(limonene‐co‐styrene).

In the Raman spectra presented in Figure 27, it can be even more clear that the polymer consist of both limonene and styrene. The spectrum of the copolymer is almost identical to the spectra of polylimonene together with polystyrene. The peak corresponding to the external double bond at 1640 cm‐1 and also the peak corresponding to the internal double bond at 1670 cm‐1 can clearly be seen in the Raman spectrum of limonene. Neither of these peaks can be seen in the copolymer. Both double bonds in limonene have reacted during the cationic polymerisation, the polymer is saturated.

42

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

Limonene

Styrene

Egy

EN023 Polylimonene

EN009 Polystyrene

EN027 Poly(limonene-co-styrene)

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600.0 Raman Shift / cm-1 Figure 27. Raman spectra of pure limonene, pure styrene, EN023 (polylimonene), EN009 (polystyrene) and EN027 (poly(limonene‐co‐styrene).

The SEC‐results are shown in Table X in appendix 5. The average molecular weights are varying between 900‐1400 g mol‐1. It can be concluded that, the intention of polymerising limonene into a polymer yielded an oligomer. As expected, EN028 has the highest molecular weight of 1400 g mol‐1, since it contains most styrene which is easier to polymerise. EN027 has a molecular weight of 1300 g mol‐1, and EN029, with the lowest amount of styrene, has the lowest molecular weight of 900 g mol‐ 1. This trend can also be seen in the results from MALDI‐TOF MS, see Figures XXIII‐XXV in appendix 5. Smaller fractions of the polymer have higher molecular weights. In EN028, peaks can be seen up to 5000 g mol‐1, in EN027 up to 4000 g mol‐1 and in EN029 up to 3000 g mol‐1. In comparison with the homopolymers of limonene, see Table VII and Figure XVIII in appendix 5, it can be seen that the copolymers has twice as high molecular weights as the homopolymers.

The Tg of the obtained copolymers poly(limonene‐co‐styrene) are between 36 °C and 90°C and are lower than the Tg of polystyrene, which is 100 °C. The Tg of the copolymers are not always higher than the Tg for the obtained polylimonene, which had a Tg of 60 °C. EN027 (molar ratio 1:1) had the highest Tg of 90 °C. EN028, that contained more styrene, should have a higher Tg. However, it has a Tg of 77 °C. EN029, with the lowest amount of styrene, had a Tg of 36 °C. It should have the lowest Tg, because of the high amount of limonene, but it should not have lower than the Tg of polylimonene.

The reason for the low Tg may be due to the low molecular weights of the polymers. In the DSC‐ results, only one peak for the glass transition is seen. This is evidence for that the obtained polymers are copolymers, and not separate homopolymers, polystyrene and polylimonene.

The copolymers EN027 (molar ratio 1:1) and EN028 (molar ratio 1:3), (limonene:styrene), were hot‐ pressed in an attempt to make a material out of them. The results from this are shown in Tables XI and XII in appendix 5. EN028 (with the larger amount of styrene) yielded a better film than EN027. However, they both yielded very brittle films, and they were less fragile than the films obtained from

43

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐ polylimonene, EN023. The reason why the films are so brittle is probably due to the low molecular weights of the polymers. The chains are too short to be able to form strong entanglements with each other. It is desirable to increase the molecular weights of the polymer.

5.2.4 Copolymerisation of limonene with tetrahydrofuran Due to the fact that the obtained films of poly(limonene) and poly(limonene‐co‐styrene) were very brittle was a test to polymerise limonene with other more flexible synthetic monomers performed. A copolymerisation of limonene with THF was evaluated using AlCl3 as a catalyst. In the attempt to copolymerise limonene with THF was no polymer obtained. In the 1H‐NMR spectra, see Figure XXVI and XXVII in appendix 5, of the polymerisation can no polymer peaks be seen.

5.3 Cationic polymerisation using BF3OEt2 Further was an evaluation performed to see if limonene can be polymerised with butyl vinyl ether and styrene using BF3OEt2 as a catalyst. Both homopolymerisations and copolymerisations were performed. Supplement results are shown in appendix 6.

5.3.1 Homopolymerisation of limonene

In the attempt to polymerise limonene using BF3OEt2 as a catalyst was no polymer obtained. In the 1H‐NMR spectra of the polymerisation, see Figure XXVIII and XXIX in appendix 6, can no polymer peaks be seen. However, the peaks originating from the two double bonds of limonene decreased during the polymerisation. To be sure that no polymer had been formed, a crude sample of the product obtained was taken and analysed by SEC. The sample did not contain any polymer. Due to the volatility of limonene, it has probably evaporated somewhat during the reaction.

5.3.2 Homopolymerisation of butyl vinyl ether A polymerisation of BVE, EN036, was performed with the same procedure as the homopolymerisation of limonene see section 5.3.1 and the copolymerisation of limonene with butyl vinyl ether see section 5.3.3 to get a reference for the copolymerisation. At first, when the master batch of BF3OEt2 and toluene was added nothing happened. When more master batch with a higher concentration was added, the solution turned yellow and after an hour the solution had turned brown. 1H‐NMR spectra of the polymerisation are shown in Figure XXX and XXXI in appendix 6. After 1 hour and 15 minutes reaction all peaks corresponding to the protons in the double bond of BVE; a (6.46 ppm), b (4.18 ppm) and c (3.96 ppm) has disappeared, and polymer peaks have appeared; D (3.43 ppm), E (1.49 ppm), F (1.37 ppm) and G (0.91 ppm). The reaction has reached 100 % conversion.

When the mixture was dissolved in THF the solution turned yellow. No polymer was obtained in an attempt to precipitate the product. The mixture turned purple when the solvents were evaporated. When the mixture was dissolved in THF a second time, the solution turned yellow. No polymer was obtained in the second attempt to precipitate the product either. Again the mixture turned purple when the solvents were evaporated, and yellow when dissolved in THF. A yellow precipitate was then obtained but during the filtration it dissolved. The mixture was then collected for analysis.

SEC analysis showed that the average molecular weight of the homopolymer was 6500 g mol‐1.

44

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

5.3.3 Copolymerisation of limonene with butyl vinyl ether The copolymerisation of limonene with BVE, EN038, has been investigated. The films pressed from poly(limonene) and poly(limonene‐co‐styrene) were very brittle, see section 5.2.1 and 5.2.3. The idée was to polymerise limonene with a more flexible monomer such as BVE to obtain a better film. At first, when the master batch of BF3OEt2 was added, nothing happened in the copolymerisation. Further, when more master batch with a higher concentration was added, nothing could be seen at first, but after an hour the solution had turned yellow. 1H‐NMR spectra of the polymerisation are shown in Figure 28 and Figure 29. A clear polymer peak can be seen at I (3.43 ppm), and also at J (1.49 ppm), K (1.37 ppm) and L (0.91 ppm). The peaks originating from the double bond in BVE at f (6.46 ppm), g (4.18 ppm) and h (3.96 ppm) disappears during the reaction. The reaction reaches 100 % conversion with respect to butyl vinyl ether. However, the peaks originating from the double bonds in limonene do not disappear, but the area under them decreases during the reaction.

Figure 28. 1H‐NMR spectrum of EN038 (copolymerisation of limonene with BVE), t=0.

45

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

Figure 29. 1H‐NMR spectrum of EN038 (copolymerisation of limonene with BVE), t=1 h 15 min.

Results from SEC, see Table XIII in appendix 6, shows that the average molecular weight of the polymer obtained was 5200 g mol‐1, which was less than the average molecular weight of polyBVE.

In the FTIR spectrum in Figure XXXII in appendix 6 can the spectra of EN036 (polyBVE) and EN038 (the obtained polymer from the copolymerisation of limonene with BVE) be compared to each other. It can be seen that these two spectra are almost the same except for the peak at 1740 cm‐1 in EN038. At that area, usually carbonyl groups appear, so this probably due to an impurity in the sample. In the spectrum of EN038 a small peak can be seen at 1640 cm‐1, which represents the external double bond of limonene. It appears as the polymer obtained in the attempt to copolymerise limonene with BVE only is the homopolymer of BVE that has been plasticised with limonene.

5.3.4 Copolymerisation of limonene with styrene The copolymerisation of limonene with styrene by cationic polymerisation has been evaluated with

BF3OEt2 as a catalyst instead of AlCl3. When BF3OEt2 was added directly to the solution it turned yellow. The obtained polymer, EN044, was tacky, transparent and gel like. 1H‐NMR spectra of the polymerisation are shown in Figure XXXIII and XXXIV in appendix 6. Polymer peaks appeared after 3 hours and 30 minutes reaction and the monomer peaks of limonene and styrene had slightly decreased.

The FTIR spectrum of EN044 is shown in Figure XXXV in appendix 6. The spectrum of EN044 looks the same as the spectrum of EN027 (poly(limonene‐co‐styrene) using AlCl3). BF3OEt2 can be used as a catalyst for the polymerisation of limonene with styrene.

The average molecular weight of the polymer was 1600 g mol‐1. For SEC results, see Table XIV in appendix 6. The molecular weights of the copolymers obtained by using AlCl3 as a catalyst, were 900,

46

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

‐1 1300 and 1400 g mol . It seems like using BF3OEt2 as a catalyst yields higher molecular weights.

However, the copolymer obtained by using AlCl3 were analysed by a THF‐SEC and EN044 was analysed by a chloroform‐SEC, so the results should not be directly compared to each other.

5.4 Cationic polymerisation using onium salts The cationic polymerisation of limonene using onium salts to initiate the polymerisation has been evaluated. In the first test, all limonene was evaporated from the glass substrate during one hour and nothing was left on the glass substrate. Therefore, a sample, EN026, was prepared, where the limonene together with UVI‐6974 was placed in a sealed vial in air atmosphere and exposed to natural UV‐light. After four days in a window, a brown viscous layer had formed on the bottom of the vial. However, no polymer could be obtained through precipitation. A brown viscous layer was also formed in EN030 that stood in the window for two months and three weeks, but now with the difference that the liquid above the viscous layer that before was transparent was now also brown. However, no polymer was obtained after precipitation. In EN041 a brown layer was formed when it was in the Oriel lamp and the amount of layer increased and got darker during the time in the window. The 1H‐NMR spectrum taken on the brown layer is shown in Figure XXXVI in appendix 7. The peak originating from the internal double bond of limonene at a (5.4 ppm) has not decreased. The peak originating from the external double bond b (4.7 ppm) has however decreased slightly. Some new peaks, see * in Figure XXXVI, have appeared at the shifts 0.6‐1.3, 2.32, 2.6, and 2.74 ppm, that could be polymer peaks. No polymer was obtained in the precipitation. A brown layer was also formed in EN055 that was initiated with a higher dose in the Fusion lamp. The 1H‐NMR spectrum taken on the brown layer is shown in Figure XXXVII in appendix 7. The peaks originating from the double bonds in limonene at a (5.4 ppm) and b (4.7 ppm) have not decreased. Some new peaks, *, have appeared that could be polymer peaks. No polymer was obtained in the precipitation. Nothing happened with EN056, limonene evaporated from the glass substrate.

5.5 Cationic polymerization using a strong acid A test to see if limonene can be polymerised by sulphuric acid was conducted. When sulphuric acid was added to limonene it turned orange and after some seconds a black viscous phase appeared in the bottom of the vial. The vial became hot during the reaction, and cooled down shortly afterwards. The 1H‐NMR spectrum of the liquid phase was identical to the 1H‐NMR spectrum of limonene. The 1H‐NMR spectrum of the viscous phase is shown in Figure XXXVIII in appendix 8. No monomer peaks can be seen in the spectrum, all limonene molecules have been consumed. The reaction had reached 100 % conversion. The amount of precipitate was too small to be obtained. No further analyses were performed, since it is difficult to know exactly what happens when using acids together with monomers. It is probably more reactions than the polymerisation that initiates by sulphuric acid.

5.6 Thiol‐ene polymerisation As a further development, the copolymerisation of limonene with 2‐mercaptoethyl ether utilizing thiol‐ene chemistry has been investigated. The reaction was initiated thermally with AIBN and photochemically with Irgacure 184. Additionally, it has also been shown that this polymerisation can be initiated spontaneously. The obtained polymers from the copolymerisations of limonene with 2‐ mercaptoethyl ether were viscous. Example of 1H‐NMR spectra of the polymerisation are shown in Figure 30 and Figure 31. The first spectrum was taken directly after that the two monomers had been added. It can be seen that limonene reacts spontaneously with 2‐mercaptoethyl ether. Polymer peaks can be seen directly and monomer peaks have decreased. The structure of the trimer in all 1H‐

47

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

NMR spectra of the copolymerisation of limonene with 2‐mercaptoethyl ether is the assumed structure to be formed. However, this structure does not correspond completely to the obtained spectra, but was used as a support to assign peaks in the spectra. The monomer peaks a (5.4 ppm) and b (4.7 ppm) represent the external and internal double bond in limonene decreases and disappears during the polymerisation. The monomer peaks have already decreased in the 1H‐NMR spectrum taken directly after the mixing of the monomers, see Figure 30 and then disappeared totally after 17 hours reaction time, see Figure 31. The formed peaks: A* (5.36 ppm), F* (3.60 ppm), G* (2.70 ppm), J*(2.40 ppm), E*(1.63 ppm) and D*(0.97 ppm) can be assigned to protons in the trimer. The peak * (1.25 ppm) and *’ (1.1 ppm) cannot be assigned to the assumed structure. Investigating the peak a (5.4 ppm) with A* (5.36 ppm) and e (1.65 ppm) with E* (1.63 ppm). A* and E* does not look like polymer peaks. They are not broad like polymer peaks usually are. They increases with the decrease of the peaks a and e. This can easily be seen in Figure 34. A possible explanation for this can be that the internal double bond rearranges when thiols are present. This could then lead to a possible polymerisation of only limonene molecules in some units before another thiol reacts with limonene again.

Figure 30. 1H‐NMR spectrum of EN052 (copolymerisation of limonene with 2‐mercaptoethyl ether), t=0.

48

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

Figure 31. 1H‐NMR spectrum of EN052 (copolymerisation of limonene with 2‐mercaptoethyl ether), t=1 h at 0 °C and t=16 h at RT.

5.6.1 Copolymerisation of limonene with 2‐mercaptoethyl ether using AIBN as initiator The copolymerisation of limonene with 2‐mercaptoethyl ether using the thermally initiator AIBN has been investigated. In the first tests, EN042 and EN043, AIBN was used as an initiator. The polymer obtained after precipitation in cold MeOH was viscous. 1H‐NMR spectra of the polymerisation, taken after 30 minutes reaction, is shown in Figure XXXIX and XL in appendix 9. As can be seen in the figures, EN042 is a much more rapid reaction than EN043. This could be due to that EN042 is performed as a bulk polymerisation and EN043 as a solvent polymerisation.

The average molecular weights of the compounds formed in the two polymerisations are shown in Table XV in appendix 9. EN042 (bulk polymerisation) has an average molecular weight of 900 g mol‐1 and EN043 (solvent polymerisation) has an average molecular weight of 800 g mol‐1. Since the bulk polymerisation was more rapid than the solvent polymerisation and that the polymer had higher molecular weight it seems as the bulk polymerisation is the preferable technique for this polymerisation. Furthermore, it is desirable to work without solvents in the industry and, therefore, the following polymerisations were performed as bulk polymerisations.

To be able to develop a material out of the polymer, it is desirable to increase the molecular weight. Therefore, in an attempt to increase the molecular weight, were the polymers obtained from these polymerisations used in further reactions together with limonene. It was assumed that the polymer mostly consisted of trimers, with thiol groups as end functionalities. Limonene was added in a 1:1 molar ratio, based on the assumption that it only could react at the end groups. In reaction 2, when more limonene was added, EN042 was performed at 80 °C and EN043 was performed at 60 °C. No significant differences could be seen in the 1H‐NMR after the reaction, a part from that limonene had

49

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐ reacted with the thiol‐ene polymer (trimer). Unfortunately, no SEC results could be obtained, due to long‐lasting malfunctioning of the THF‐SEC. It was assumed that limonene had added to the trimer and then reacted with two new thiols during the reaction 2 and that the obtained polymer should have seven monomer units. Limonene was again added in a 1:1 molar ratio with the assumption that it only could react on the thiol end groups. Limonene reacts during the reaction, besides from that could no significant differences be seen in the 1H‐NMR spectrum after the reaction.

The average molecular weights of EN042 and EN043, after reaction 3 were measured with a chloroform‐SEC. The results are shown in Table XVI in appendix 9. EN042 had an average molecular weight of 3500 g mol‐1 and EN043 had an average molecular weight of 1900 g mol‐1. A comparison should not be made between the different types of SEC, but since no other results exist, an exception was made. The molecular weights of the polymers have increased during the three reactions. EN042 has increased more than EN043, maybe due to the higher reaction temperature in reaction 2, but since no SEC results were obtained from the polymer formed in that reaction, no conclusion could be drawn. However, MALDI‐TOF results could be obtained and are shown in Figures XLI and XLII in appendix 9. An indication that EN042 has a higher molecular weight could be seen since the largest peaks are at higher molecular weights than EN043. However, peaks can be seen at higher molecular weights for EN043 compared to EN042.

The assumption that the polymer mostly consisted of trimers, with thiol groups as end functionalities was shown to be wrong. It is more likely that the trimer has limonene groups in the end and by that unsaturated internal double bonds as end functionalities, if the external double bond in limonene reacts first with the thiol group due to the steric hindrance of the internal double bond. This was realised when the structure was drawn later in the project and a better understanding of the basics in thiol‐ene polymerisation was understood. A better way to increase the molecular weight would probably have been to add 2‐mercaptoethyl ether instead of limonene. This due to that a structure with limonene double bonds as end functionalities is more likely to be formed than the assumed one. However, both structures do exist, but the assumed one should be present in a smaller amount since, if that would be the case, the internal double bond also has to react. An indication to an increased molecular weight can be seen from reaction 1 to reaction 3, see Tables XV and XVI in appendix 9, even though the assumption probably was wrong.

The FTIR spectrum of the polymer obtained after the first reaction of EN042 is shown in Figure 32. FTIR‐spectra of limonene, 2‐mercaptoethyl ether and a mixture of these monomers can also be seen in the same spectrum. It can clearly be seen that the two monomers reacts spontaneously with each other. The peaks at 1640 cm‐1 and 889 cm‐1 originating from the external double bond of limonene decreases when limonene is mixed with 2‐mercaptoethyl ether, but it can still be seen in the spectrum afterwards, indicating that not all double bonds have reacted. The peaks have disappeared in the product of EN042, all external double bonds have reacted. An indication to the peak originating from the thiol in 2‐mercaptoethyl ether can be seen at the peak 2560 cm‐1. This peak also decreases when limonene is mixed with 2‐mercaptoethyl ether. Peaks originating from thiols are easier seen in Raman spectroscopy. In Raman spectroscopy can also peaks be seen originating from both the external and the internal double bond in limonene. The decrease of the thiol peak are clearly seen in the Raman spectra, see Figure 33. The peak at 2560 cm‐1 significantly decreases when the monomers are mixed, and no further decrease can be seen in the polymer EN042. The peak originating from the external double bond of limonene at 1640 cm‐1 disappears directly when the

50

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐ monomers are mixed. The peak originating from the internal double bond of limonene at 1670 cm‐1 decreases when the monomers are mixed with each other. At first, it does not look like the peak decreases further in the initiated polymerisation EN042. However, when the areas of the peak are measured it shows that more reacts in the initiated polymerisation. The areas of the peak are shown in Table XVII in appendix 9.

Limonene

2-mercaptoethyl ether A

Limonene mixed with 2-mercaptoethyl ether

EN042 Poly(limonene-co-2-mercaptoethyl ether)

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600.0 cm-1

Figure 32. Normalized FTIR‐spectra of pure limonene, pure 2‐mercaptoethyl ether, mixture of limonene and 2‐mercaptoethyl ether and the polymer after reaction 1 of EN042 (poly(limonene‐co‐2‐mercaptoethyl ether)).

51

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

Limonene

2-mercaptoethyl ether Egy

Limonene mixed with 2-mercaptoethyl ether

EN0042 Poly(limonene-co-2-mercaptoethyl ether)

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600.0 Raman Shift / cm-1

Figure 33. Raman spectra of pure limonene, pure 2‐mercaptoethyl ether, mixture of limonene and 2‐ mercaptoethyl ether and the polymer after reaction 1 of EN042 (poly(limonene‐co‐2‐mercaptoethyl ether)).

EN053 was made according to the same procedure as reaction 1 of EN042, except that it was made with a surplus of limonene, molar ratio 2:1. The hypothesis was that only the external double bond would react in limonene, therefore the molar ratio was set to 2:1 (molar ratio 1:1 in regard to the external double bond). As shown in the 1H‐NMR spectra in Figure 34 and more clearly in Figures XLIII‐ XLVII in appendix 9, both double bonds react during the reaction. The behaviour of the internal peak can still be seen with the molar ratio 2:1. In those five spectra the behaviour of the internal double bond can easily be followed.

Along with the decrease of the monomer peaks a (5.4 ppm) and e (1.65 ppm), new peaks are formed at A* (5.36 ppm) and E* (1.63 ppm). However, the reaction goes more rapid in EN042 than EN053. This can be seen in a comparison with Figure XXXIX (EN042, taken after 30 minutes) and Figure XLIV (EN053, taken after an hour) in appendix 9. Even though EN053 has reacted 30 minutes longer it has not reached the same conversion as EN042.

52

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

6000

5000

4000

After precipitation 3000 3 h 2 h

2000 1 h 0 h

1000

0 7 6 5 4 3 2 1 0 ppm

Figure 34. 1H‐NMR spectra of the thiol‐ene polymerisation of limonene with 2‐mercaptoethyl ether, EN053.

The average molecular weight of the polymer obtained in EN053 was 2700 g mol‐1. It could be seen in the results from chloroform‐SEC that the spectrum of the polymer contained fractions of polymers with different molecular weights, see Figure XLVIII and XLIX in appendix 9. In Figure XLVIII, the molecular weight of each peak has been evaluated by the Millennium version 3.05.01 software and in Figure XLIX the total average molecular weight of the polymer has been evaluated by the same software. The SEC results for EN053 are shown in Table XVIII in appendix 9. The molecular weight was higher for EN053 compared to EN042, but it is difficult to compare the results since EN042 was analysed by the THF‐SEC and EN053 was analysed by the chloroform‐SEC.

5.6.2 Copolymerisation of limonene with 2‐mercaptoethyl ether using Irgacure 184 as initiator As a further investigation, the copolymerisation of limonene with 2‐mercaptoethyl ether initiated photochemically with the UV‐initiator Irgacure 184 was investigated. The same behaviour of the polymerisation could be seen when using Irgacure 184 as when using AIBN as initiator. The molar ratios 1:1 and 3:1 (limonene:2‐mercaptoethyl ether) were evaluated to see if any differences could be seen. The obtained polymers were all viscous. The 1H‐NMR spectra of the two molar ratios are shown and compared in Figures L‐LVII in appendix 9. The same polymer peaks appears regardless of the molar ratio. The reaction is, however, much more rapid with the molar ratio 1:1. After a dose of 0.019 J cm‐2, in the oriel lamp the monomer peaks had decreased much more in EN047 (molar ratio 1:1), than in EN048 (molar ratio 3:1), see Figures LII and LIII. When, the samples were exposed to an additional dose of 0.97 J cm‐2, the monomer peaks disappeared in EN047, whereas they were still present in EN048, see Figures LIV and LV. In another test, a dose of 5.8 J cm‐2 was given to the samples, see Figures LVI and LVII. Here, the monomer peaks of EN050 (molar ratio 3:1) did not disappear either.

53

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

The molecular weights of EN049 (molar ratio 1:1) and EN050 (molar ratio 3:1) are shown in Table XIX and XX in appendix 9. EN049 had an average molecular weight of 1200 g mol‐1 and EN050 had twice as high average molecular weight, 2500 g mol‐1. It can be concluded that, a higher molar ratio gives a higher molecular weight of the final product.

The FTIR spectrum and Raman spectrum for the copolymers obtained photochemically using Irgacure 184 looked the same as the spectra of the copolymers obtained thermally using AIBN. For example spectra see Figure 32 and Figure 33.

5.6.3 Spontaneous copolymerisation of limonene with 2‐mercaptoethyl ether Since it was discovered that limonene and 2‐mercaptoethyl ether reacts spontaneously with each other, several experiments has been conducted without any initiator. All obtained polymers were viscous. The first tests were performed at 60 °C at two different molar ratios: EN045 (molar ratio 1:1) and EN046 (molar ratio 3:1). 1H‐NMR spectra of these polymerisations are shown in Figures LVIII‐LXII in appendix 9. No different polymer peaks can be seen in these spectra compared to the spectra of the copolymerisation that was initiated with Irgacure 184 or AIBN. The polymerisation proceeded much more rapid with molar ratio 1:1 (EN045) than molar ratio 3:1 (EN046), as the previous experiments.

Results from SEC are shown in Table XXI and XXII in appendix 9. No significant difference in the molecular weight can be seen, between EN045 (molar ratio 1:1) that had an average molecular weight of 1200 g mol‐1 and EN046 (molar ratio 3:1) had an average molecular weight of 1100 g mol‐1.

EN052 molar ratios 1:1, EN054 molar ratio 2:1 and EN051 molar ratio 3:1 (limonene:2‐mercaptoethyl ether) were used in the cold synthesis. Cold syntheses were performed to decrease the molecular weight to get a more homogenous product (mainly trimers) with a known chemical structure that could be used for further reactions and crosslinking. The polymerisations were performed at 0 °C for 2 hours and then for 16 hours at room temperature. The average molecular weights of these are shown in Table XXIII‐XXV) in appendix 9. The attempt to decrease the average molecular weights with cold synthesis was unsuccessful. With molar ratio 1:1 the molecular weight 1200 g mol‐1 was obtained when performed at 60 °C (EN045) and 5600 g mol‐1 when performed at the lower temperature 0 °C for 2 hours and then room temperature (EN052). The obtained average molecular weight of the molar ratios 3:1 and 2:1 (limonene:2‐mercaptoethyl ether), were 2300 g mol‐1 and 2400 g mol‐1 when performed at cold synthesis compared to molar ratio 3:1 (EN046) performed at 60 °C, which gave an average molecular weight of 1100 g mol‐1. One explanation to this may be that two different reactions are competing with each other; the thiol‐ene polymerisation of limonene and 2‐ mercaptoethyl ether and the homopolymerisation of limonene, are occurring at the same time. The homopolymerisation of limonene can probably occur since a rearrangement of the internal double bond of limonene appears when thiols are present. Additionally, it could also be explained by that the homopolymerisation of limonene has higher activation energy than the thiol‐ene polymerisation, and therefore is more rapid at a lower temperature according to Arrhenius equation. A homopolymerisation of limonene will yield a higher molecular weight, this could be the reason for the higher molecular weight obtained at a lower temperature.

The 1H‐NMR spectra of EN051 (molar ratio 3:1) are shown in Figure LXIII to LXVII in appendix 9. In the last spectrum taken after the precipitation, it can be seen that not all double bonds in limonene have reacted. Peak a (5.4 ppm) originating from the internal double bond and b (4.7 ppm) originating from

54

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐ the external double bond can still be seen. The1H‐NMR spectra of EN052 (molar ratio 1:1) are shown in Figures LXVIII‐LXXII in appendix 9. The peak A* (5.36 ppm) appears in the same way as in the other polymerisation, but in these spectra it first appears during the first 2 hours at 0 °C and then start to decrease at room temperature. The internal double bond first rearranges in the first 2 hours at 0 °C and then starts to polymerise in room temperature for 16 hours. However, the polymerisation EN054 (molar ratio 2:1) proceeded in the same way as EN051 (molar ratio 3:1). The reason why this only can be seen for molar ratio 1:1 can be due to that a thiol is needed to activate the rearrangment of the internal double bond, and after that it can continue to react further. EN051 (molar ratio 3:1) and EN054 (molar ratio 2:1) contains less thiols that can activate the polymerisation, and that is probably the reason why the double bond do not activates and polymerises further. The activating step of the internal double in limonene is shown in Figure 35. A relatively stable radical is formed that maybe can continue to do further reactions, and not only hydrogen abstraction as in the thiol‐ene polymerisation. It is probably that radical, that is the origin to other polymerisations and not just the thiol‐ene polymerisation.

R R-S S

Figure 35. The activating step of the internal double bond in limonene by the thiol.

The polymerisations EN051 and EN052 were also followed with TLC to see if the polymerisation yields different products. It could be seen that the polymer consisted of different fractions.

Results from DSC showed that EN051 and EN052 did not have any glass transition temperature in the temperature interval: ‐30°C to 160°C. The polymers are viscous at a temperature of ‐30 °C.

5.6.4 Crosslinking of limonene and 2‐mercaptoethyl ether with TRIS. Since it appears that the polymer obtained from polymerising limonene with 2‐mercaptoethyl ether is unsaturated, and some internal double bonds still remains in the polymer, an attempt to crosslink the polymer, EN051, with trimethylolpropane‐tris(3‐mercaptopropionate), (TRIS), was conducted on glass substrates. The material that formed was gelled to some extent and transparent. It was a heterogeneous material, where some parts of it still were viscous and other parts were gel like. When chloroform and DCM was dropped onto the material, in an attempt to dissolve it, it remained on the glass substrate and it was still there after some time. When the material was put on a spoon and stirred in chloroform some of the material dissolved, but some was still on the spoon afterwards. It seemed like the material had not been completely crosslinked.

The FTIR spectrum of the gelled part is shown in Figure 36. Peaks from both the polymer EN051 at 1100 cm‐1 and TRIS at 1150 cm‐1 can be seen in the spectrum of the crosslinked material. In the Raman spectrum, see Figure 37, it can be seen that the thiol group, see peak 2570 cm‐1, of TRIS reacts during the reaction. The peak corresponding to the internal double bond of limonene at 1670

55

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐ cm‐1 decrease and also the residues of the external double bonds at 1640 cm‐1 has disappeared during the crosslinking.

When the crosslinking was re‐conducted based on the molecular weight obtained from the SEC, no crosslinking occurred, the material was still viscous after the reaction. The chemical structure of the polymer is not known for example is not the functionality known. In thiol‐ene polymerisation is the stoichiometric balance an important factor and it will not succeed without the balance. A more thorough investigation of the polymer is necessary to know how to crosslink it. Another explanation why the polymer did not fully crosslinked could be that the crosslinker was not pure. In the 1H‐NMR spectrum in Figure LXXIII in appendix 9 it can be observed that the chemical used contained impurities.

TRIS

A

EN051 Poly(limonene-co-2-mercaptoethyl ether)

Crosslinked EN051

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600.0 cm-1

Figure 36. Normalized FTIR‐spectra of TRIS (top), EN051 (poly(limonene‐co‐2‐mercaptoethyl ether)) (middle) and crosslinked EN051 (bottom).

56

‐‐‐‐‐‐‐‐‐‐ Results and discussion ‐‐‐‐‐‐‐‐‐‐

TRIS

Egy

EN051 Poly(limonene-co-2-mercaptoethyl ether)

Crosslinked EN051

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600.0 Raman Shift / cm-1

Figure 37. Raman spectra of TRIS (top), EN051 (poly(limonene‐co‐2‐mercaptoethyl ether)) (middle) and crosslinked EN051 (bottom).

5.6.5 Copolymerisation of the thiol‐ene polymer with maleic anhydride. As a further development of the thiol‐ene polymer, the copolymerisation the thiol‐ene polymer with maleic anhydride has been investigated. When Irgacure 184 was added to the mixture of maleic anhydride and thiol‐ene polymer, the mixture turned yellow and after the sample had been run in the fusion lamp, the mixture turned brown. The 1H‐NMR spectra from the polymerisation are shown in Figure LXXIV and LXXV in appendix 9. The peak A* (5.36 ppm) corresponding to the rearranged internal double bond does not decrease during the reaction. However the peak k (7.04 ppm) corresponding to the protons in maleic anhydride decreases. Maleic anhydride probably reacts with residual monomers of 2‐mercaptoethyl ether that did not react with the thiol‐ene polymerisation.

57

‐‐‐‐‐‐‐‐‐‐ Conclusions ‐‐‐‐‐‐‐‐‐‐

6 Conclusions Several methods to polymerise the terpene limonene have been evaluated in the attempt to create a new green material based on terpenes. The polymerisation techniques that have been evaluated are radical polymerisation, cationic polymerisation and thiol‐ene polymerisation. Homopolymerisations of limonene has been conducted as well as copolymerisations of limonene together with synthetic monomers such as styrene, methyl methacrylate, butyl vinyl ether, tetrahydrofuran and 2‐ mercaptoethyl ether.

The work with radical polymerisation did not yield any homopolymers of limonene. On the other hand, a polymer was obtained in the copolymerisation of limonene with synthetic monomers. However, it was shown that the polymer only consisted of the homopolymer of the synthetic monomer that had been plasticised with limonene.

Polylimonene was successfully polymerised by cationic polymerisation using AlCl3 as a catalyst. However, the average molecular weight of the product was low, around 600 g mol‐1, and when the polymer was hot‐pressed, it yielded a brittle material.

Furthermore, a copolymer of limonene with styrene could also be obtained by cationic polymerisation using AlCl3 as a catalyst. The average molecular weight was somewhat higher for the copolymers than the homopolymer, around 1400 g mol‐1. The obtained films were brittle but not as much as the films of polylimonene. Additionally, it was also shown that the catalyst BF3OEt2 can copolymerise limonene with styrene in cationic polymerisation.

Viscous polymers were obtained with thiol‐ene polymerisation of limonene with 2‐mercaptoethyl ether initiated either thermally or photochemically. It was shown that limonene and 2‐mercaptoethyl ether reacts spontaneously with each other. An indication can be seen that the formed polymer is an unsaturated polymer and that the internal double bond in limonene has rearranged during the polymerisation. It also appears like limonene can react with itself after the rearrangement of the internal double bond.

As an overall conclusion it has been shown that limonene has potential to be polymerised and by that has the character that is necessary to later create a material.

58

‐‐‐‐‐‐‐‐‐‐ Future work ‐‐‐‐‐‐‐‐‐‐

7 Future work • It would be interesting to try other catalysts in the cationic polymerisation and to vary the reaction parameters to see if an increased molecular weight can be obtained. Further, it would also be interesting to copolymerise limonene with other synthetic monomers, for example more flexible monomers that perhaps makes the pressed films less brittle and, thereby, more useful as materials.

• A more thorough investigation of the reaction mechanism of limonene with thiols should be performed to get a better understanding, and through that facilitate further developments of the polymer that was created. With a better understanding of the product, the product can perhaps be used for further reactions to eventually form a material.

• Other thiols should be polymerised with limonene to see what properties that can be obtained.

• Cationic polymerisation and thiol‐ene polymerisation should also be evaluated with other terpenes than limonene. Further, also evaluated with a mixture of different terpenes and finally with turpentine, since the goal is to make a material out of turpentine.

59

‐‐‐‐‐‐‐‐‐‐ Acknowledgements ‐‐‐‐‐‐‐‐‐‐

8 Acknowledgements First of all I would like to thank my supervisors Ph. D. student Carl Bruce, Ph. D. Linda Fogelström and Professor Eva Malmström Jonsson for all their support and guidance throughout this work. Thank you for your encouragement and all the knowledge you shared to me.

I would also like to thank my supervisor Ph. D. Jörg Brucher at Holmen Energi for his support and encouragement, as well as for his enthusiasm.

Holmen Energi AB and BiMaC Innovation are gratefully thanked for financial support.

Professor Mats Johansson is greatly thanked for all the help and guidance with FTIR and Raman, as well as thiol‐ene polymerisations.

Furthermore I would like to thank everyone in “Ytgruppen” for welcoming me into the group and making this such a wonderful place to work.

Finally, I would like to thank David and my family for their love and support. Jag älskar er!

60

‐‐‐‐‐‐‐‐‐‐ References ‐‐‐‐‐‐‐‐‐‐

9 References

1. Sharma, S. and A.K. Srivastava, Synthesis and characterization of copolymers of limonene with styrene initiated by azobisisobutyronitrile. European Polymer Journal, 2004. 40(9): p. 2235‐ 2240. 2. Kemikalieinspektionen ‐ terpentin. [cited 2010 0908]; Available from: http://apps.kemi.se/flodessok/floden/kemamne/terpentin.htm. 3. Kirk‐Othmer, Encyclopedia of chemical technology, sugar to thin films. 1997, John Wiley & Sons Inc: New York p. 833‐877. 4. Silvestre, A.J.D. and A. Gandini, Terpenes: Major Sources, Properties and Applications, in Monomers, Polymers and Composites from Renewable Resources, M.N. Belgacem and A. Gandini, Editors. 2008, ELSEVIER. p. 17‐38. 5. Pinova ‐ Polyterpene resins. [cited 2011 0323]; Available from: http://www.pinovasolutions.com/polyterpeneresins.php 6. Arizona Chemical ‐ Polyterpenes. [cited 2011 0323]; Available from: http://www.arizonachemical.com/en/Products/Adhesive‐Resins/Polyterpenes/ 7. Arizona Chemical ‐ Styrenated terpenes. [cited 2011 0323]; Available from: http://www.arizonachemical.com/en/Products/Adhesive‐Resins/Styrenated‐Terpenes/ 8. Jitchum, V. and S. Perrier, Living Radical Polymerization of Isoprene via the RAFT Process. Macromolecules FIELD Full Journal Title:Macromolecules, 2007. 40(5): p. 1408‐1412. 9. Mathers, R.T., et al., Ring‐opening metathesis polymerizations in D‐limonene: A renewable polymerization solvent and chain transfer agent for the synthesis of macromonomers. Macromolecules, 2006. 39(26): p. 8982‐8986. 10. Shin, C. and G.G. Chase, Nanofibers from recycle waste expanded polystyrene using natural solvent. Polymer Bulletin (Heidelberg, Germany), 2005. 55(3): p. 209‐215. 11. Barros, M.T., K.T. Petrova, and A.M. Ramos, Potentially biodegradable polymers based on alpha ‐ or beta ‐pinene and sugar derivatives or styrene, obtained under normal conditions and on microwave irradiation. European Journal of , 2007(8): p. 1357‐ 1363. 12. Guine, R.P.F. and J.A.A.M. Castro, Polymerization of beta ‐pinene with ethylaluminum dichloride (C2H5AlCl2). Journal of Applied Polymer Science, 2001. 82(10): p. 2558‐2565. 13. Manas, C., Introduction to Polymer Science and Chemistry‐A Problem Solving Approach. 2006. 315‐419. 14. Manas, C., Introduction to Polymer Science and Chemistry‐A Problem Solving Approach. 2006. 512‐530. 15. Sundell, P.‐E., Cationic Polymerization of Vinyl Ethers using Iodonium and Sulfonium Salts, in Department of Polymer Technology 1990, The Royal Institute of Technology: Stockholm. p. 3‐ 13. 16. Crivello, J.V., The discovery and development of onium salt cationic photoinitiators. Journal of Polymer Science, Part A: Polymer Chemistry, 1999. 37(23): p. 4241‐4254. 17. Hoyle, C.E., A.B. Lowe, and C.N. Bowman, Thiol‐click chemistry: a multifaceted toolbox for and polymer synthesis. Chemical Society Reviews. 39(4): p. 1355‐1387. 18. Hoyle, C.E., T.Y. Lee, and T. Roper, Thiol‐enes: Chemistry of the past with promise for the future. Journal of Polymer Science, Part A: Polymer Chemistry, 2004. 42(21): p. 5301‐5338. 19. Ortiz, R.A., et al., Effect of introducing a cationic system into a thiol‐ene photopolymerizable formulation. Journal of Polymer Science, Part A: Polymer Chemistry, 2007. 45(21): p. 4829‐ 4843. 20. Sangermano, M., et al., Preparation and characterization of hybrid thiol‐ene/epoxy UV‐ thermal dual‐cured systems. Polymer International. 59(8): p. 1046‐1051.

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21. Roberts, W.J. and A.R. Day, Polymerization of alpha ‐ and beta ‐pinene with Friedel‐Crafts type catalysts. Journal of the American Chemical Society, 1950. 72: p. 1226‐30. 22. Modena, M., R.B. Bates, and C.S. Marvel, Some low‐molecular‐weight polymers of d‐limonene and related terpenes obtained by Ziegler‐type catalysts. Journal of Polymer Science, Part A: General Papers, 1965. 3(3): p. 949‐60. 23. Martinez, F., Cationic polymerization of beta ‐pinene. Journal of Polymer Science, Polymer Chemistry Edition, 1984. 22(3): p. 673‐7. 24. Higashimura, T., et al., Cationic polymerization of alpha ‐pinene with aluminum‐based binary catalysts. 2. Survey of catalyst systems. Makromolekulare Chemie, 1993. 194(12): p. 3441‐53. 25. Higashimura, T., et al., Cationic polymerization of alpha ‐pinene with aluminum‐based binary catalysts. 3. Effects of added base. Makromolekulare Chemie, 1993. 194(12): p. 3455‐65. 26. Higashimura, T., et al., Cationic polymerization of alpha ‐pinene with the binary catalyst aluminum chloride/antimony(III) chloride. Makromolekulare Chemie, 1992. 193(9): p. 2311‐ 21. 27. Lu, J., et al., Cationic polymerization of beta ‐pinene with the AlCl3/SbCl3 binary catalyst: comparison with alpha ‐pinene polymerization. Journal of Applied Polymer Science, 1996. 61(6): p. 1011‐1016. 28. Sheffer, H., G. Greco, and G. Paik, The characterization of styrene‐beta ‐pinene polymers. Journal of Applied Polymer Science, 1983. 28(5): p. 1701‐5. 29. Pietila, H., A. Sivola, and H. Sheffer, Cationic polymerization of beta ‐pinene, styrene, and alpha ‐methylstyrene. Journal of Polymer Science, Part A‐1: Polymer Chemistry, 1970. 8(3): p. 727‐37. 30. Snyder, C., W. McIver, and H. Sheffer, Cationic polymerization of beta ‐pinene and styrene. Journal of Applied Polymer Science, 1977. 21(1): p. 131‐9. 31. Doiuchi, T., H. Yamaguchi, and Y. Minoura, Cyclocopolymerization of d‐limonene with maleic anhydride. European Polymer Journal, 1981. 17(9): p. 961‐8. 32. Sharma, S. and A.K. Srivastava, Azobisisobutyronitrile‐initiated free‐radical copolymerization of limonene with vinyl acetate: synthesis and characterization. Journal of Applied Polymer Science, 2007. 106(4): p. 2689‐2695. 33. Sharma, S. and A.K. Srivastava, Radical copolymerization of limonene with acrylonitrile: kinetics and mechanism. Polymer‐Plastics Technology and Engineering, 2003. 42(3): p. 485‐ 502. 34. Sharma, S. and A.K. Srivastava, Free radical copolymerization of limonene with butyl methacrylate: synthesis and characterization. Indian Journal of Chemical Technology, 2005. 12(1): p. 62‐67. 35. Sharma, S. and A.K. Srivastava, Synthesis and characterization of a terpolymer of limonene, styrene, and methyl methacrylate via a free‐radical route. Journal of Applied Polymer Science, 2004. 91(4): p. 2343‐2347. 36. Wang, Y., et al., Reversible addition‐fragmentation chain transfer radical copolymerization of beta ‐pinene and methyl acrylate. European Polymer Journal, 2006. 42(10): p. 2695‐2702. 37. Li, A.‐L., et al., Controlled radical copolymerization of beta ‐pinene and acrylonitrile. Journal of Polymer Science, Part A: Polymer Chemistry, 2006. 44(8): p. 2376‐2387. 38. Li, A.‐L., et al., Controlled radical copolymerization of beta ‐pinene and n‐butyl acrylate. Reactive & Functional Polymers, 2007. 67(5): p. 481‐488.

62

Appendix



Table of Contents Appendix 1. Chemical structures of the monomers ...... 1 Appendix 2. 1H‐NMR spectra ...... 2 Appendix 3. FTIR spectrum ...... 4 Appendix 4. Radical polymerisation ...... 5 Homopolymerisation of limonene ...... 5 Homopolymerisation of styrene ...... 6 Copolymerisation of limonene with styrene ...... 6

Appendix 5. Cationic polymerisation using AlCl3 ...... 8 Homopolymerisation of limonene ...... 8 EN023 – Performed at ‐10 °C ...... 8 EN020 – Performed at a rapid increase of the temperature from 0 °C to 50 °C ...... 10 EN021 – Performed at slowly increasing temperature intervals...... 11 Homopolymerisation of styrene ...... 16 Copolymerisation of limonene with styrene ...... 17 Copolymerisation of limonene with tetrahydrofuran ...... 20

Appendix 6. Cationic polymerisation using BF3OEt2 ...... 22 Homopolymerisation of limonene ...... 22 Homopolymerisation of butyl vinyl ether ...... 23 Copolymerisation of limonene with butyl vinyl ether ...... 24 Copolymerisation of limonene with styrene ...... 25 Appendix 7. Cationic polymerisation using onium salts ...... 28 Appendix 8: Cationic polymerisation using a strong acid ...... 30 Appendix 9. Thiol‐ene polymerisation ...... 31 Copolymerisation of limonene with 2‐mercaptoethyl ether using AIBN ...... 31 EN042 and EN043 – Molar ratio 1:1 ...... 31 EN053 ‐ Molar ratio 2:1 (limonene:2‐mercaptoethyl ether) ...... 34 Copolymerisation of limonene with 2‐mercaptoethyl ether using Irgacure 184 ...... 38 Spontaneously copolymerisation of limonene with 2‐mercaptoethyl ether ...... 43 EN045 ‐ Molar ratio 1:1, 60 °C ...... 43 EN046 ‐ Molar ratio 3:1 (limonene:2‐mercaptoethyl ether), 60 °C ...... 44 EN051 ‐ Molar ratio 3:1 (limonene:2‐mercaptoethyl ether), 0 °C ...... 46 EN052 ‐ Molar ratio 1:1, 0 °C ...... 49 Crosslinking of the thiol‐ene polymer with TRIS...... 51

Copolymerisation of the thiol‐ene polymer with maleic anhydride...... 52 References ...... 53

‐‐‐‐‐‐‐‐‐‐Appendix 1‐‐‐‐‐‐‐‐‐‐

Appendix 1. Chemical structures of the monomers

Table I. The chemical structures, the molecular weights and the density of the monomers that have been used in this project.

Monomer Structure Molecular weight Density Limonene 136 g mol‐1 0.8411 g mL‐1

Styrene 104 g mol‐1 0.909 g mL‐1

Methyl O 100 g mol‐1 0.94 g mL‐1 methacrylate

O Tetrahydrofuran O 72 g mol‐1 0.8892 g mL‐1

Butyl vinyl ether 100 g mol‐1 0.774 g mL‐1

O

‐1 ‐1 2‐mercaptoethyl SH O SH 138 g mol 1.116 g mL ether Trimethylolpropane‐ HS 342 g mol‐1 1.21 g mL‐1 tris(3‐ mercaptopropi O

O O

HS O O SH

O O ‐1 ‐1 Maleic anhydride O 98 g mol 1.48 g mL

O

1

‐‐‐‐‐‐‐‐‐‐Appendix 2‐‐‐‐‐‐‐‐‐‐

Appendix 2. 1H‐NMR spectra

Figure I. 1H‐NMR spectrum of pure limonene.

Figure II. 1H‐NMR spectrum of pure styrene.

2

‐‐‐‐‐‐‐‐‐‐Appendix 2‐‐‐‐‐‐‐‐‐‐

3.67 3.65 3.63 3.56 3.55 3.53 3.52 3.52 2.84 2.83 2.81 2.65 2.64 2.63 2.62 2.62 2.60 1.58 1.56 1.54 14000

13000

12000

11000

10000

9000 c 8000

a a 7000 c c

HS SH 6000 O b b b 5000

4000 a 3000

2000

1000

0

4.00 3.84 1.34 -1000

7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 f1 (ppm)

Figure III. 1H‐NMR spectrum of pure 2‐mercaptoethyl ether.

3

‐‐‐‐‐‐‐‐‐‐Appendix 3‐‐‐‐‐‐‐‐‐‐

Appendix 3. FTIR spectrum 175.6 170

160

150

140

130

120

110

100

90 A 80

70

60

50

40

30

20

10 Limonene 0.0 4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600.0 cm-1

Figure IV. Normalized FTIR‐spectrum of pure limonene.

Table II. Limonene FTIR band assignment. [1]

Wave number cm‐1 Assignment Wave number cm‐1 Assignment

3083 =C‐H (s) 1377 CH3 (d) 3069 =C‐H, =CH2 (s) 1311 =CH (b) 3042 =C‐H, =CH2 (s) 1293 =CH (b) 3004 CH3, CH2, CH (s) 1243 =CH (b) 2966 CH3, CH2, CH (s) 1155 C‐H (sk) 2918 C‐H asymmetric (s) 1147 C‐H (o.p) 2852 C‐H symmetric (s) 1051 C‐H (o.p) 2834 C‐H (s) 1016 C‐H (o.p) 1644 C=C (s) 957 =C‐H, =CH2 (b) 1450 CH2 (d) 914 =C‐H, =CH2 (b) 1436 CH2 (d) 889 =CH2 (o.p) (b) (s) = stretching vibration; (d) = deformation mode; (b) = bending vibration; (sk) = skeletal vibration; (o.p) = out of plane vibration.

4

‐‐‐‐‐‐‐‐‐‐Appendix 4‐‐‐‐‐‐‐‐‐‐

Appendix 4. Radical polymerisation

Homopolymerisation of limonene

Figure V. 1H‐NMR spectrum of EN004 (homopolymerisation of limonene), t=2 h.

5

‐‐‐‐‐‐‐‐‐‐Appendix 4‐‐‐‐‐‐‐‐‐‐

Homopolymerisation of styrene

Figure VI. 1H‐NMR spectrum of EN009 (homopolymerisation of styrene). Taken after precipitation and vacuum drying.

Table III. Results from SEC analysis of EN006 (polystyrene). THF‐SEC was used.

‐1 Sample Mn [g mol ] PDI EN006 70 000 1.58

Copolymerisation of limonene with styrene Table IV. The yields of the polymers obtained from copolymerisation of limonene with styrene.

Polymer Yield [%] EN001 ‐ EN002 8.6 EN007 9.0 EN011 10 EN013 9.2 EN014 16 EN017 25 EN022 43

6

‐‐‐‐‐‐‐‐‐‐Appendix 4‐‐‐‐‐‐‐‐‐‐

Table V. Results from SEC analysis of EN001, EN002 and EN007 (polymers obtained from the copolymerisation of limonene with styrene). THF was used as a mobile phase.

‐1 Sample Mn [g mol ] PDI EN001 14 000 1.63 EN002 16 000 1.81 EN007 37 000 1.70

Table VI. Results from DSC analysis of EN001, EN007 and EN011 (polymers obtained from the copolymerisation of limonene with styrene).

Sample Glass transition temperature EN001 64 °C EN007 75 °C EN011 57 °C

7

‐‐‐‐‐‐‐‐‐‐Appendix 5‐‐‐‐‐‐‐‐‐‐

Appendix 5. Cationic polymerisation using AlCl3

Homopolymerisation of limonene

EN023 – Performed at ‐10 °C

2400 7.27 7.25 7.23 7.23 7.18 7.17 7.17 7.16 7.16 7.15 5.40 4.70 2.35 2.10 2.05 2.05 2.04 1.73 1.65 2300

2200

EN023 2100 Solvent polymerization of limonene 2000 3 AlCl temp -10 1900 0min 1800

1700

d 1600 b 1500 H3C CH2 b d 1400

e 1300 c c 1200 c 1100

c a 1000 900

Toluene 800 CH3 e 700 600

c:2.4to1.2 500 400 Toluene a 300

200

100

0

-100

0.80 1.86 17.16 2.80 3.00 -200

7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 f1 (ppm)

Figure VII. 1H‐NMR spectrum of EN023 (homopolymerisation of limonene), t=0.

8

‐‐‐‐‐‐‐‐‐‐Appendix 5‐‐‐‐‐‐‐‐‐‐

7.25 7.18 5.40 4.70 2.35 1.73 1.65 2300

2200

2100 EN023 2000 Solvent polymerization of limonene AlCl 3 temp -10 1900

1h 1800

1700

1600 d b 1500 H C CH b 3 2 d 1400

e 1300 c c 1200 c 1100

1000 c a 900

Toluene 800 CH 3 700 e 600

c:2.4to1.2 500 400 Toluene a Polymer 300

200

100

0

-100

0.81 1.81 21.37 2.78 3.00 -200

7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 f1 (ppm)

Figure VIII. 1H‐NMR spectrum of EN023 (homopolymerisation of limonene), t=50 min.

1300 7.27 7.18 5.40 4.70 2.35 1.73 1.65

1200 EN023 Solvent polymerization of limonene 1100 AlCl 3 temp -10 2h 1000

900 d b H3C CH2 d 800

b e c 700 c c 600

c a 500 Toluene CH 3 Polymer 400 e Polymer

300 c:2.4to1.2

Toluene a 200

100

0

-100 0.67 1.38 2.55 35.40 3.00

7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 f1 (ppm) Figure IX. 1H‐NMR spectrum of EN023 (homopolymerisation of limonene), t=2 h.

.

9

‐‐‐‐‐‐‐‐‐‐Appendix 5‐‐‐‐‐‐‐‐‐‐ 7.27 7.25 7.24 7.23 7.18 7.17 7.17 7.16 7.16 7.15 5.20 4.78 4.56 2.35 1.69 0.94 0.93 0.92 0.91 0.91 0.90 0.89 0.88 0.86 0.86 0.84 350 EN023 Solvent polymerization of limonene AlCl 3 temp -10 2h 45 min 300

Polymer

250 d b H C CH 3 2 Toluene

200 c c c

c a 150

CH3

e 100

Polymer Toluene 50

0

7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 f1 (ppm)

Figure X. 1H‐NMR spectrum of EN023 (homopolymerisation of limonene), t=2 h 45 min.

EN020 – Performed at a rapid increase of the temperature from 0 °C to 50 °C

Figure XI. 1H‐NMR spectrum of EN020 (homopolymerisation of limonene). Taken when the temperature had reached 50 °C.

10

‐‐‐‐‐‐‐‐‐‐Appendix 5‐‐‐‐‐‐‐‐‐‐

Figure XII. 1H‐NMR spectrum of EN020 (homopolymerisation of limonene), t=2 h at 50 °C.

EN021 – Performed at slowly increasing temperature intervals.

Figure XIII. 1H‐NMR spectrum of EN021 (homopolymerisation of limonene), t=0.

11

‐‐‐‐‐‐‐‐‐‐Appendix 5‐‐‐‐‐‐‐‐‐‐

Figure XIV. 1H‐NMR spectrum of EN021 (homopolymerisation of limonene), t=20 min at 0 °C.

Figure XV. 1H‐NMR spectrum of EN021 (homopolymerisation of limonene), t=50 min at 20 °C.

12

‐‐‐‐‐‐‐‐‐‐Appendix 5‐‐‐‐‐‐‐‐‐‐

Figure XVI. 1H‐NMR spectrum of EN021 (homopolymerisation of limonene), t=1 h 10 min 30 °C.

Figure XVII. 1H‐NMR spectrum of EN021 (homopolymerisation of limonene), t=1 h 30 min at 40 °C.

13

‐‐‐‐‐‐‐‐‐‐Appendix 5‐‐‐‐‐‐‐‐‐‐

Table VII. Results from SEC analysis of EN020, EN021, EN023, EN024 and EN025 (polylimonene). THF was used as the mobile phase.

‐1 Sample Mn [g mol ] PDI EN020 400 1.92 EN021 600 1.56 EN023 600 1.75 EN024 500 1.60 EN025 600 1.65

4 x10 Emelie\EN025 9-nitroantracene Na 3200 shots 70 laser power RP\1SRef Intens. [a.u.]

3.0

2.5

2.0 679.619

1.5 815.196

1.0 951.859 1088.996 0.5 1224.113 1360.242 1496.370 1633.482 1769.607 1906.744 2041.859 0.0

400 600 800 1000 1200 1400 1600 1800 2000 m/z Figure XVIII. MALDI‐TOF spectrum of EN025 (polylimonene). Peaks can be seen up to 2041 g/mol. 9‐ Nitroanthracene was used as matrix with added sodium trifluoroacetate.

14

‐‐‐‐‐‐‐‐‐‐Appendix 5‐‐‐‐‐‐‐‐‐‐

Table VIII. Results from pressing EN023 (polylimonene).

EN023 Temperature Pre‐ Pre‐ Pressing Pressing Cooling Result [°C] pressing pressing time [min] force [kN] time [s] Force [kN] 1 100 ‐ ‐ 5 150 ‐ No film 2 110 ‐ ‐ 5 150 ‐ Film: tacky 3 110 ‐ ‐ 5 150 RT 5 min Film: very brittle 4 110 30 20 5 150 RT 5 min Film: brittle 5 100 30 20 5 150 RT 5 min Film: very brittle 6 100 30 20 5 300 RT 5 min Best film, brittle

Table IX. Results from DSC analysis of (polylimonene).

Sample Glass transition temperature EN021 47 °C EN023 60 °C EN024 58 °C EN025 63 °C

15

‐‐‐‐‐‐‐‐‐‐Appendix 5‐‐‐‐‐‐‐‐‐‐

Homopolymerisation of styrene

Figure XIX. 1H‐NMR spectrum of EN040 (polystyrene), t=30 min. Intens. [a.u.]

8000

941.421

6000

4000 1253.615

1565.804

1669.870

1773.935

1878.011

2000 2086.150

2294.321

2607.591

2814.786

3127.125 3544.618 3857.010 4169.475 4587.122

0

500 1000 1500 2000 2500 3000 3500 4000 4500 5000 m/z

Figure XX. MALDI‐TOF spectrum of EN040 (polystyrene). Peaks can be seen up to 4587 g/mol. 9‐ Nitroanthracene was used as matrix with added silver trifluoroacid.

16

‐‐‐‐‐‐‐‐‐‐Appendix 5‐‐‐‐‐‐‐‐‐‐

Copolymerisation of limonene with styrene 7.26 7.25 7.23 7.23 7.21 7.17 7.17 7.15 7.15 7.13 7.10 5.76 5.72 5.39 5.25 5.22 4.70 2.34 1.73 1.65 110

100 EN028 Toluene Solvent polymerization of limonene with styrene (1:3) 90 AlCl 3 temp 0 3h 30 min e 80 b Toluene Polymer d H3C CH2 h d 70 c H c c 60 g H c a i 50 f f

CH3 e 40 f f Polymer Polymer f 30

20 b

a 10 h i

0

0.02 0.23 0.11 0.39 2.03 3.00 94.98 -10

7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 f1 (ppm)

Figure XXI. 1H‐NMR spectrum of EN028 (copolymerisation of limonene with styrene). Molar ratio 1:3 (limonene:styrene), t=3.5 h.

180 7.27 7.27 7.25 7.24 7.23 7.22 7.18 7.17 7.16 7.16 7.15 7.13 5.40 5.20 4.70 2.35 1.73 1.65 0.93 0.92 0.92 0.91 0.90 0.89 0.88 0.88 0.87 0.86

170

160 EN029 150 Toluene Solvent polymerization of limonene with styrene (3:1) 140 AlCl 3 temp 0 3h 30 min Polymer 130

b Toluene 120 d H3C CH2 h 110 c H c 100 c g e 90 H d c i a 80 f f 70 CH3 e 60 f f 50 Polymer f 40 Polymer

30 b

20

a 10

0

-10 0.13 0.31 1.43 3.00 175.88

7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 f1 (ppm)

Figure XXII. 1H‐NMR spectrum of EN029 (copolymerisation of limonene with styrene). Molar ratio 3:1 (limonene:styrene), t=3.5 h.

17

‐‐‐‐‐‐‐‐‐‐Appendix 5‐‐‐‐‐‐‐‐‐‐

Table X. Results from SEC analysis of EN027, EN028, EN029 and EN039 (poly(limonene‐co‐styrene)). THF was used as the mobile phase.

‐1 Sample Mn [g mol ] PDI EN027 1300 1.91 EN028 1400 2.09 EN029 900 1.95 EN039 900 2.69

Intens. [a.u.]

1173.452

4000

1309.553 997.427

3000 1485.584 1653.733

1725.720

1829.769

2000 1861.819

1000

0

1000 1500 2000 2500 3000 3500 m/z

Figure XXIII. MALDI‐TOF spectrum of EN027. Peaks can be seen up to 4000 g/mol. 9‐Nitroanthracene was used as matrix with added silver trifluoroacid.

18

‐‐‐‐‐‐‐‐‐‐Appendix 5‐‐‐‐‐‐‐‐‐‐

1109.427

1317.516 Intens. [a.u.] 3000

1421.570

2500 1557.681

1661.727

2000 1765.787

1869.837

1500

1000

500

0

1000 1500 2000 2500 3000 3500 4000 4500 m/z

Figure XXIV. MALDI‐TOF spectrum of EN028. Peaks can be seen up to 5000 g/mol. . 9‐Nitroanthracene was used as matrix with added silver trifluoroacid.

x104

1.2 Intens. [a.u.]

1.0

0.8

0.6 997.542

1101.593

1205.642

0.4 1341.745

1445.797

1549.852

0.2 1685.963

1790.020 1926.135

2166.336

0.0

1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 m/z

Figure XXV. MALDI‐TOF spectrum of EN029. Peaks can be seen up to 3000 g/mol. . 9‐Nitroanthracene was used as matrix with added silver trifluoroacid.

19

‐‐‐‐‐‐‐‐‐‐Appendix 5‐‐‐‐‐‐‐‐‐‐

Table XI. Results from pressing EN027 (polylimonene‐co‐styrene) molar ratio 1:1.

EN027 Temperature Pre‐ Pre‐ Pressing Pressing Cooling Result [°C] pressing pressing time [min] force [kN] time [s] Force [kN] 1 100 30 20 5 150 RT 5 min No film 2 105 30 20 5 150 RT 5 min Film: brittle

Table XII. Results from pressing EN028 (polylimonene‐co‐styrene) molar ratio 1:3.

EN028 Temperature Pre‐ Pre‐ Pressing Pressing Cooling Result [°C] pressing pressing time [min] force [kN] time [s] Force [kN] 1 105 30 20 5 150 RT 5 min Nice film: brittle

Copolymerisation of limonene with tetrahydrofuran

Figure XXVI. 1H‐NMR spectrum of EN032 (copolymerisation of limonene with THF), t=0.

20

‐‐‐‐‐‐‐‐‐‐Appendix 5‐‐‐‐‐‐‐‐‐‐

Figure XXVII. 1H‐NMR‐spectrum of EN032 (copolymerisation of limonene with THF), t=4 h 45 min.

21

‐‐‐‐‐‐‐‐‐‐Appendix 6‐‐‐‐‐‐‐‐‐‐

Appendix 6. Cationic polymerisation using BF3OEt2

Homopolymerisation of limonene 7.27 7.27 7.25 7.24 7.23 7.21 7.18 7.17 7.16 7.16 7.15 7.14 7.13 5.40 4.71 2.35 1.73 1.65 1.48 750

700 EN037

Solvent polymerization of limonene 650 BF3Et2 temp -10

0min 600

550

d b b 500 H3C CH2 d 450 e c c 400 c

350 c a 300

Toluene Initiator CH3 250 e 200 Toluene

c:2.4to1.2 150

a 100

50

0

-50 0.72 1.87 2.84 3.00

7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 f1 (ppm)

Figure XXVIII. 1H‐NMR spectrum of EN037 (homopolymerisation of limonene), t=0.

22

‐‐‐‐‐‐‐‐‐‐Appendix 6‐‐‐‐‐‐‐‐‐‐

7.23 7.18 5.40 4.71 2.35 1.73 1.65 1.47 360

340

EN037 320 Solvent polymerization of limonene BF3Et2 temp -10 300 0min 280

260

d b 240 b H3C CH2 d 220

e 200 c c c 180

160 c a 140 Toluene Initiator 120 CH3

e 100 Toluene 80 c:2.4to1.2

60 a 40

20

0

-20 0.56 1.64 2.82 3.00

7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 f1 (ppm)

Figure XXIX. 1H‐NMR spectrum of EN037 (homopolymerisation of limonene), t=1 h 15 min. Homopolymerisation of butyl vinyl ether

Figure XXX. 1H‐NMR spectrum of EN036 (homopolymerisation of BVE), t=0.

23

‐‐‐‐‐‐‐‐‐‐Appendix 6‐‐‐‐‐‐‐‐‐‐

Figure XXXI. 1H‐NMR spectrum of EN036 (homopolymerisation of BVE), t=1 h 15 min. Copolymerisation of limonene with butyl vinyl ether Table XIII. Results from SEC analysis of EN036 (polyBVE) and EN038 (poly(limonene‐co‐BVE)). THF was used as the mobile phase.

‐1 Sample Mn [g mol ] PDI EN036 6500 3.84 EN038 5200 3.57

24

‐‐‐‐‐‐‐‐‐‐Appendix 6‐‐‐‐‐‐‐‐‐‐

Limonene

BVE

A

EN036 PolyBVE

EN038 Poly(limonene- co- BVE)

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600.0 cm-1

Figure XXXII. Normalized FTIR‐spectra of pure limonene, pure BVE, EN036 (poly(BVE)) and EN038 (polymer obtained in the cationic polymerisation of limonene with BVE). Copolymerisation of limonene with styrene

300 7.18 7.17 7.17 7.16 7.16 7.15 6.72 5.77 5.40 5.25 4.70 2.35 1.73 1.65 1.50

280 EN044 Solvent polymerization of limonene 260 and styrene BF3Et2 temp -10 240 0min

d 220 b h H3C CH2 H e b 200

c d c g 180 c H

i 160 c a f f Toluene 140

CH f Initiator 3 f 120 e f Toluene 100 h f:7.5to7.1 i 80

c:2.4to1.2 60

g a 40

20

0

-20 0.80 0.91 0.81 0.94 1.94 2.84 3.00

7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 f1 (ppm)

Figure XXXIII. 1H‐NMR spectrum of EN044 (copolymerisation of limonene with styrene), t=0.

25

‐‐‐‐‐‐‐‐‐‐Appendix 6‐‐‐‐‐‐‐‐‐‐

130 6.73 5.77 5.40 5.23 4.70 2.35 2.16 1.73 1.65

120 EN044 Solvent polymerization of limonene and styrene 110 BF3Et2 temp -10

3h 30 min 100 d b h H3C CH2 H e 90 b

c d 80 c g c H

i 70 c a f f Toluene 60

CH f 3 f e 50 f Toluene

40 h f:7.5to7.1 i

30 c:2.4to1.2

g a 20

Polymer 10

0

0.53 0.63 0.73 1.48 0.13 2.50 3.00 0.64 0.17 0.20 -10

7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 f1 (ppm)

Figure XXXIV. 1H‐NMR spectrum of EN044 (copolymerisation of limonene with styrene), t=3.5 h.

Limonene

Styrene

A

EN027 Poly(limonene-co-styrene) using AlCl3

EN044 Poly(limonene- co- styrene) using BF3OEt2

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600.0 cm-1

Figure XXXV. Normalized FTIR‐spectra of pure limonene, pure styrene, EN027 (poly(limonene‐co‐styrene) using AlCl3) and EN044 (poly(limonene‐co‐styrene)using BF3OEt2).

26

‐‐‐‐‐‐‐‐‐‐Appendix 6‐‐‐‐‐‐‐‐‐‐

Table XIV. Results from SEC analysis of EN044 (poly(limonene‐co‐styrene)). Chloroform was used as the mobile phase.

‐1 EN044 Mn [g mol ] PDI Total 1600 1.38 Peak 1 2500 1.16 Peak 2 1200 1.01 Peak 3 800 1.01

27

‐‐‐‐‐‐‐‐‐‐Appendix 7‐‐‐‐‐‐‐‐‐‐

Appendix 7. Cationic polymerisation using onium salts

Figure XXXVI. 1H‐NMR spectrum of EN041 (homopolymerisation of limonene), the brown viscous layer on the bottom of the vial, t=2 months 1 week.

28

‐‐‐‐‐‐‐‐‐‐Appendix 7‐‐‐‐‐‐‐‐‐‐

Figure XXXVII. 1H‐NMR spectrum of EN055 (homopolymerisation of limonene) the brown viscous layer at the bottom of the vial. Taken after a given dose of 2.6 J cm‐2 in the Fusion lamp.

29

‐‐‐‐‐‐‐‐‐‐Appendix 8‐‐‐‐‐‐‐‐‐‐

Appendix 8: Cationic polymerisation using a strong acid

Figure XXXVIII. 1H‐NMR spectrum of the product from the test to polymerise limonene with sulphuric acid as a catalyst, t=10 min.

30

‐‐‐‐‐‐‐‐‐‐Appendix 9‐‐‐‐‐‐‐‐‐‐

Appendix 9. Thiol‐ene polymerisation

Copolymerisation of limonene with 2‐mercaptoethyl ether using AIBN

EN042 and EN043 – Molar ratio 1:1

Figure XXXIX. 1H‐NMR spectrum of reaction 1 of EN042 (copolymerisation of limonene with 2‐mercaptoethyl ether, molar ratio 1:1), t=30 min.

31

‐‐‐‐‐‐‐‐‐‐Appendix 9‐‐‐‐‐‐‐‐‐‐

Figure XL. 1H‐NMR spectrum of reaction 1 of EN043 (copolymerisation of limonene with 2‐mercaptoethyl ether, molar ratio 1:1), t=30 min.

Table XV. Results from SEC analysis of reaction 1 of EN042 and EN043 (poly(limonene‐co‐2‐mercaptoethyl ether)). THF was used as the mobile phase.

‐1 Reaction 1 Mn [g mol ] PDI EN042 Total 900 1.33 EN043 Total 800 1.45

Table XVI. Results from SEC analysis of reaction 3 of EN042 and EN043 (poly(limonene‐co‐2‐mercaptoethyl ether)). Chloroform was used as the mobile phase.

‐1 Reaction 3 Mn [g mol ] PDI EN042 Total 3500 1.36 EN043 Total 1900 1.65

32

‐‐‐‐‐‐‐‐‐‐Appendix 9‐‐‐‐‐‐‐‐‐‐

957.296 Intens. [a.u.] 8000

6000

4000

1271.330

1127.198

2000 1407.293 1545.393 1681.370 1819.478 1957.453 2092.450 2215.564 2356.545

0 1000 1200 1400 1600 1800 2000 2200 2400 m/z

Figure XLI. MALDI‐TOF spectrum of EN042 after reaction 2. 9‐Nitroanthracene was used as matrix with added sodium trifluoroacetate.

Intens. [a.u.] 8000

6000

815.060

4000

997.350

2000 877.322 1255.446

1545.530 1957.620 2246.759 2504.922 2779.078 0 750 1000 1250 1500 1750 2000 2250 2500 2750 3000 m/z Figure XLII. MALDI‐TOF spectrum of EN043 after reaction 2. 9Nitroanthracene was used as matrix with added sodium trifluoroacetate.

33

‐‐‐‐‐‐‐‐‐‐Appendix 9‐‐‐‐‐‐‐‐‐‐

Table XVII. Areas of the peak representing the internal double bond of limonene at 1670 cm‐1 from the Raman spectra in figure 33.

Sample Area of the peak (1687‐1665 cm‐1) Limonene 30 2‐mercaptoethyl ether ‐ Limonene mixed with 2‐mercaptoethyl ether 11 EN042 Poly(limonene‐co‐2‐mercaptoethyl ether) 7.8

EN053 ‐ Molar ratio 2:1 (limonene:2‐mercaptoethyl ether)

Figure XLIII. 1H‐NMR spectrum of EN053 (copolymerisation of limonene with 2‐mercaptoethyl ether, molar ratio 2:1 (limonene:2‐mercaptoethyl ether)), t=0.

34

‐‐‐‐‐‐‐‐‐‐Appendix 9‐‐‐‐‐‐‐‐‐‐

Figure XLIV. 1H‐NMR spectrum of EN053 (copolymerisation of limonene with 2‐mercaptoethyl ether, molar ratio 2:1 (limonene:2‐mercaptoethyl ether)), t=1 h.

Figure XLV. 1H‐NMR spectrum of EN053 (copolymerisation of limonene with 2‐mercaptoethyl ether, molar ratio 2:1 (limonene:2‐mercaptoethyl ether)), t=2 h.

35

‐‐‐‐‐‐‐‐‐‐Appendix 9‐‐‐‐‐‐‐‐‐‐

Figure XLVI. 1H‐NMR spectrum of EN053 (copolymerisation of limonene with 2‐mercaptoethyl ether, molar ratio 2:1(limonene:2‐mercaptoethyl ether)), t=3 h.

Figure XLVII. 1H‐NMR spectrum of EN053 (copolymerisation of limonene with 2‐mercaptoethyl ether, molar ratio 2:1(limonene:2‐mercaptoethyl ether)). Taken after precipitation.

36

‐‐‐‐‐‐‐‐‐‐‐Appendix 9‐‐‐‐‐‐‐‐‐‐

Figure XLVIII. Results from SEC analysis showing how the average molecular weights foor the different fractions of polymers were obtained from EN0533.

Figure XLIX. Results from SEC analysis showing how the average molecular weight of the total polymer was obtained for EN053.

Table XVIII. Results from SEC analysis of EN053 (poly(limonene‐co‐2‐mercaptoethyl ether)). Chloroform was used as the mobile phase.

‐1 EN053 Mn [g mol ] PDI Total 2700 1.34 Peak 1 5400 1.09 Peak 2 3000 1.02 Peak 3 1900 1.01 Peak 4 1200 1.01

37

‐‐‐‐‐‐‐‐‐‐Appendix 9‐‐‐‐‐‐‐‐‐‐

Copolymerisation of limonene with 2‐mercaptoethyl ether using Irgacure 184

Figure L. 1H‐NMR spectrum of EN047 and EN49 (copolymerisation of limonene with 2‐mercaptoethyl ether molar ratio 1:1), t=0.

38

‐‐‐‐‐‐‐‐‐‐Appendix 9‐‐‐‐‐‐‐‐‐‐

Figure LI. 1H‐NMR spectrum of EN048 and EN50 (copolymerisation of limonene with 2‐mercaptoethyl ether molar ratio 3:1 (limonene:2‐mercaptoethyl ether)), t=0.

Figure LII. 1H‐NMR spectrum of EN047 (copolymerisation of limonene with 2‐mercaptoethyl ether molar ratio 1:1). Taken after a given dose of 0.019 J cm‐2 in the Oriel lamp.

39

‐‐‐‐‐‐‐‐‐‐Appendix 9‐‐‐‐‐‐‐‐‐‐

Figure LIII. 1H‐NMR spectrum of EN048 (copolymerisation of limonene with 2‐mercaptoethyl ether molar ratio 3:1 (limonene:2‐mercaptoethyl ether)). Taken after a given dose of 0.019 J cm‐2 in the Oriel lamp.

Figure LIV. 1H‐NMR spectrum of EN047 (copolymerisation of limonene with 2‐mercaptoethyl ether molar ratio 1:1). Taken after a given dose of 0.99 J cm‐2 in the Oriel lamp.

40

‐‐‐‐‐‐‐‐‐‐Appendix 9‐‐‐‐‐‐‐‐‐‐

Figure LV. 1H‐NMR spectrum of EN048 (copolymerisation of limonene with 2‐mercaptoethyl ether molar ratio 3:1 (limonene:2‐mercaptoethyl ether)). Taken after a given dose of 0.99 J cm‐2 in the Oriel lamp.

Figure LVI. 1H‐NMR spectrum of EN49 (copolymerisation of limonene with 2‐mercaptoethyl ether molar ratio 1:1). Taken after a given dose of 5.8 J cm‐2 in the Oriel lamp.

41

‐‐‐‐‐‐‐‐‐‐Appendix 9‐‐‐‐‐‐‐‐‐‐

Figure LVII. 1H‐NMR spectrum of EN50 (copolymerisation of limonene with 2‐mercaptoethyl ether molar ratio 3:1 (limonene:2‐mercaptoethyl ether)). Taken after a given dose of 5.8 J cm‐2 in the Oriel lamp.

Table XIX. Results from SEC analysis of EN049 (poly(limonene‐co‐2‐mercaptoethyl ether)). Chloroform was used as the mobile phase.

‐1 EN049 Mn [g mol ] PDI Total 1200 1.72 Peak 1 2000 1.16 Peak 2 900 1.00 Peak 3 700 1.00 Peak 4 500 1.00

Table XX. Results from SEC analysis of EN050 (poly(limonene‐co‐2‐mercaptoethyl ether)). Chloroform was used as the mobile phase.

‐1 EN050 Mn [g mol ] PDI Total 2500 1.27 Peak 1 5300 1.01 Peak 2 3000 1.02 Peak 3 1900 1.01 Peak 4 1200 1.01

42

‐‐‐‐‐‐‐‐‐‐Appendix 9‐‐‐‐‐‐‐‐‐‐

Spontaneously copolymerisation of limonene with 2‐mercaptoethyl ether

EN045 ‐ Molar ratio 1:1, 60 °C

Figure LVIII. 1H‐NMR spectrum of EN045 (copolymerisation of limonene with 2‐mercaptoethyl ether), t=0.

Figure LIX. 1H‐NMR spectrum of EN045 (copolymerisation of limonene with 2‐mercaptoethyl ether), t=2 h.

43

‐‐‐‐‐‐‐‐‐‐Appendix 9‐‐‐‐‐‐‐‐‐‐

Figure LX. 1H‐NMR spectrum of EN045 (copolymerisation of limonene with 2‐mercaptoethyl ether), t=70 h.

EN046 ‐ Molar ratio 3:1 (limonene:2‐mercaptoethyl ether), 60 °C

Figure LXI. 1H‐NMR spectrum of EN046 (copolymerisation of limonene with 2‐mercaptoethyl ether), t=0.

44

‐‐‐‐‐‐‐‐‐‐Appendix 9‐‐‐‐‐‐‐‐‐‐

Figure LXII. 1H‐NMR spectrum of EN046 (copolymerisation of limonene with 2‐mercaptoethyl ether), t=16 h.

Table XXI. Results from SEC analysis of EN045 (poly(limonene‐co‐2‐mercaptoethyl ether)). Chloroform was used as the mobile phase.

‐1 EN045 Mn [g mol ] PDI Total 1200 1.45 Peak 1 1900 1.06 Peak 2 1000 1.00 Peak 3 800 1.00 Peak 4 600 1.00

Table XXII. Results from SEC analysis of EN046 (poly(limonene‐co‐2‐mercaptoethyl ether)). Chloroform was used as the mobile phase.

‐1 EN046 Mn [g mol ] PDI Total 1100 1.28 Peak 1 1700 1.10 Peak 2 1000 1.01 Peak 3 600 1.01

Table XXIII. Results from SEC analysis of EN051 (poly(limonene‐co‐2‐mercaptoethyl ether) molar ratio 3:1). Chloroform was used as the mobile phase.

‐1 EN051 Mn [g mol ] PDI Total 2300 1.12 Peak 1 4800 1.03 Peak 2 3100 1.01

45

‐‐‐‐‐‐‐‐‐‐Appendix 9‐‐‐‐‐‐‐‐‐‐

Peak 3 1900 1.01 Peak 4 1200 1.01

Table XXIV. Results from SEC analysis of EN052 (poly(limonene‐co‐2‐mercaptoethyl ether) molar ratio 1:1). Chloroform was used as the mobile phase.

‐1 EN052 Mn [g mol ] PDI Total 5600 1.41 Peak 1 8400 1.01 Peak 2 4400 1.01 Peak 3 3100 1.01 Peak 4 2000 1.01

Table XXV. Results from SEC analysis of EN054 (poly(limonene‐co‐2‐mercaptoethyl ether) molar ratio 2:1). Chloroform was used as the mobile phase.

‐1 EN054 Mn [g mol ] PDI Total 2400 1.21 Peak 1 5000 1.05 Peak 2 3100 1.01 Peak 3 1900 1.01 Peak 4 1200 1.01

EN051 ‐ Molar ratio 3:1 (limonene:2‐mercaptoethyl ether), 0 °C

Figure LXIII. 1H‐NMR spectrum of EN051 (copolymerisation of limonene with 2‐mercaptoethyl ether), t=0.

46

‐‐‐‐‐‐‐‐‐‐Appendix 9‐‐‐‐‐‐‐‐‐‐

Figure LXIV. 1H‐NMR spectrum of EN051 (copolymerisation of limonene with 2‐mercaptoethyl ether), t=1 h at 0 °C.

Figure LXV. 1H‐NMR spectrum of EN051 (copolymerisation of limonene with 2‐mercaptoethyl ether), t=1 h at 0°C and t=20 min at RT.

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Figure LXVI. 1H‐NMR spectrum of EN051 (copolymerisation of limonene with 2‐mercaptoethyl ether), t=1 h at 0°C and t=16 h at RT.

Figure LXVII. 1H‐NMR spectrum of EN051 (copolymerisation of limonene with 2‐mercaptoethyl ether). Taken after precipitation and vacuum drying.

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EN052 ‐ Molar ratio 1:1, 0 °C

Figure LXVIII. 1H‐NMR spectrum of EN052 (copolymerisation of limonene with 2‐mercaptoethyl ether), t=0.

Figure LXIX. 1H‐NMR spectrum of EN052 (copolymerisation of limonene with 2‐mercaptoethyl ether), t=1 h at 0°C.

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Figure LXX. 1H‐NMR spectrum of EN052 (copolymerisation of limonene with 2‐mercaptoethyl ether), t=1 h at 0°C and t=30 min at RT.

Figure LXXI. 1H‐NMR spectrum of EN052 (copolymerisation of limonene with 2‐mercaptoethyl ether), t=1 h at 0°C and t=16 h at RT.

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Figure LXXII. 1H‐NMR spectrum of EN052 (copolymerisation of limonene with 2‐mercaptoethyl ether). Taken after precipitation. Crosslinking of the thiol‐ene polymer with TRIS.

Figure LXXIII. 1H‐NMR spectrum of the used TRIS. 

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Copolymerisation of the thiol‐ene polymer with maleic anhydride.

Figure LXXIV. 1H‐NMR spectrum of EN058 (copolymerisation of EN053 poly(limonene‐co‐2‐mercaptoethyl ether) with maleic anhydride), t=0.

Figure LXXV. 1H‐NMR spectrum of EN058 (copolymerisation of EN053 poly(limonene‐co‐2‐mercaptoethyl ether) with maleic anhydride). Taken after a dose of 2.55 J cm‐2.

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‐‐‐‐‐‐‐‐‐‐References‐‐‐‐‐‐‐‐‐‐

References 1. Zapata, R.B., et al., In situ Fourier transform infrared spectroscopic studies of limonene epoxidation over PW‐Amberlite. Appl. Catal., 2009. 365(1): p. 42‐47.

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