1.1 Basic Polymer Chemistry 1.2 Polymer Nomenclature

 Polymers are the largest class of soft materials: over  Polymer = 100 billion pounds of polymers made in US each year  Monomer =  Classification systems  Polymer =

 Typical physical state?  Mechanisms of chain growth  Oligomer =

 Typical physical state?  Polymerization =

1.3 Polymer Synthesis 1.4 Chain Growth Polymerization  Two synthetic methods  Addition polymerization  Chain growth/addition polymerization  One molecule adds to another with no net loss of atoms (high atom economy)  Individual steps are typically rapid (msec, sec)  Discrete steps

 Step growth polymerization

 Propagation rate >> termination rate  What happens if the reaction runs longer? Do the chains get longer? Do you just get more chains?

1 1.5 Chain Growth Polymerization 1.6 Monomers for Chain Growth  Addition polymerization  Polymers form by…  What’s in the polymerization mixture?  Defining features

 Useful monomers for chain growth CH3 Cl CH2 CH CH CH Monomer Polymer H2C H2C H2C H2C ethylenepropylene styrene vinyl chloride nCH2 CH (CH2 CH)n X X O N X X C O O-CH3 CH2 O CH3 C HC C nCH2 CH (CH2 CH O)n CH C CH CH CH O H2C H2C 3 H2C H2C vinyl acetate methyl methacrylate butadiene acrylonitrile

1.7 Chain Growth Polymerization 2.1 Radical Polymerization

 Mechanisms to link monomers together  Three steps to radical polymerization  Radical  Initiation  Cationic (1) RO OR 2RO  Anionic  Transition metal catalysis (2) RO + H2C CH RO CH2 CH R R  Propagation

RO CH2 CH + H2C CH RO CH2 CH CH2 CH R R R R

 Termination

2 2.2 Radical Polymerization 2.3 Radical Polymerization

Initiation Propagation  Termination  Radical Coupling

polystyrene RO CH RO CH CH RO CH CH H2C CH2 H2C CH2 CH2 styrene  Head attacks the tail of the next monomer  What defines the “head”?  Why would RO• attack the tail preferentially?  Disproportionation (H abstraction) Initiation Propagation Cl Cl Cl Cl Cl

RO CH RO CH CH RO CH CH polyvinylchloride H2C CH2 H2C CH2 CH2 vinyl chloride  Propagation continues until …

2.4 Radical Polymerization 2.5 Radical Polymerization

 Chain transfer  Another “termination” mechanism  “back-biting”

CH CH2 2 C H CH CH 4 9 CH CH2 2 CH2 CH2 CH CH2 CH2 H CH2 CH2 CH2 CH3

 This is a prominent type of branch. Why would this be so?

3 2.6 Radical Polymerization 2.7 Radical Polymerization

 Another termination process (chloroalkanes)  Monomers for radical polymerization

RO (CH CH) CH CH Cl RO (CH2 CH)n CH2 CH + CCl4 2 n 2 F Cl Cl R R R R CH C + CCl3 2 F C CH F Cl H2C C H2C H2C CCl3 + CH2 CH Cl3CCH2 CH R R ethylene F 1,1-dichloroethylene vinylchloride 1,1,2,2-tetrafluoroethylene

N CH2 O OCH3 HC C C C CH CH CH CH3 H C H2C H2C 2 H2C acrylonitrile 1,3-butadiene styrene methylmethacrylate

2.8 Radical Diene Polymerization 2.9 Radical Polymerization

Reaction:  Accounts for about ½ of all commercial polymerization nCH CH CH CH (CH CH CH CH ) 2 2 2 2 n  What polymer structure forms when propylene is 1,3-butadiene polybutadiene subjected to a radical process? Mechanism:

(1) ROOR 2RO

(2) RO + CH2 CH CH CH2 RO CH2 CH CH CH2  Ethylene forms high molecular weight polymer but only under extreme conditions – why? (3) RO CH2 CH CH CH2 +CH2 CH CH CH2

RO CH2 CH CH CH2 CH2 CH CH CH2  Product is highly branched (where do the branches then (3), (3), (3), etc. come from?)

 Is it possible to make linear PE?

4 3.1 Cationic Polymerization 3.2 Anionic Polymerization  Initiating and propagating species are cations  Initiator and propagating species are anions  Monomer attributes?

 Cationic polymerization of isobutene (2-methylpropene) Initiation Propagation Initiation Propagation

CH3 CH3 CH3 H CH polystyrene C CH3 H C CH3 C 3 R CH R CH CH R CH CH H2C CH2 H2C CH CH Chain H2C 2 H2C 2 CH2 styrene isobutene or isobutylene titibtermination by loss of H+ CN CN CN CN CN Propagation What forms? R R CH R CH CH CH CH polyacrylonitrile CH3 CH3 H C H3C CH3 H2C CH2 2 CH2 CH2 polyisobutylene H C C CH3 C CH3 acrylonitrile H C CH2 CH2 2

3.3 Anionic Polymerization 3.4 Living Polymerization  Monomer attributes?  What’s a “living polymer”?

 Other example of monomers?

 Chain termination

H O R CH CH CH 2 R CH CH CH + OH H CH2 CH2 n CH2 CH2 CH2 n CH2

polystyrene

5 4.1 Copolymers 4.2 Copolymers

 Random copolymers  ABS = acrylonitrile-butadiene-styrene terpolymer

CH2 CH + CH2 CH CH CH2 +CH2 CH CN

 SBR (styrene-butadiene rubber)

CH2 CH CH2 CH CH CH2 CH2 CH

nCH2 CH CN

+ > nCH2 CH CH CH2

 Control the amount of each monomer that ends up CH CH CH CH CH CH CH CH CH CH 2 2 2 2 2 in the polymer?

4.3 Copolymers 4.4 Block Copolymers  Block copolymers

Polystyrene  MhiMechanism an d process Polybutadiene

Polybutadiene framework held together (cross-linked) by clusters of polystyrene  Styrene-butadiene block copolymer

SSSSSBBBSSSSSBB

6 4.5 Copolymers 5.1 Metal Catalyzed Polymerization  Graft copolymers Coordination and Insertion

M = Cr, Ti, Zr, Hf, V, Fe, Co, Ni, Pd, Cu

 Styrene-butadiene graft copolymer H2C  Styrene polymerization off polybutadiene backbone CH2 L L L CH2CH3 CH2CH3 CH2 CH CH CH CH2 CH CH CH CH2 CH CH CH2 CH2CH3 M M M CH CH CH2 CH 2 2 C 2 CH2 C L L L H2 CH CH H2 H2C CH2 CH2 CH CH

 Could you graft polybutadiene off a polystyrene backbone?

5.2 Ziegler-Natta Catalysis 5.3 Ziegler-Natta Catalysis Chain Growth – Polyethylene (Polyethene) Chain Growth – Polypropylene (Polypropene)

H2C H2C Cl Cl CH2 Cl CH3 CH2CH3 CH2CH3 Cl Cl C CH2CH3 Cl H CH2CH3 CH2CH3 Ti Ti Ti CH2CH3 CH2 CH Ti Ti Ti C 2 CH CH2 C H CH Cl Cl Cl H2 C H2 C C CH3 H C Cl Cl Cl H2 2 CH3 H2 CH3 H2C

H C H2 2 CH2CH3 H H2C CH2CH3 C H C 2 Cl C 2 C H C C H Cl Cl CH 2 CH 2 CH CH Cl 3 H2 2 CH CH C 2 3 CH Ti Ti CH 3 H Ti 3 Ti CH2CH3 CH2 CH2 C Cl CH2 H2C CH Cl H2 Cl Cl H2C HC CH3

CH3

7 5.4 Ziegler-Natta Catalysis 5.5 Metal Complex Catalysis Chain Termination with Hydrogen  For polypropylene, the metal center can direct the

H C H C 2 Polymer chain growth – MACROGALLERIA H2 2 Polymer C C C H C Cl 2 C H2 C H2 Cl  If one orientation is preferred …. then one polymer H2 H2 Ti H Ti stttructure i s pref erred d( (ittiisotactic) H Cl H H Cl HCH3 HCH3 H CH3 H CH3 H CH3 isotactic: C C C C C H CH2 CH2 CH2 CH2 CH2 CH2 Cl CH2CH2 H Ti CH H2C Polymer CH3 HCH3 H H CH3 3 HCHH 3 H2C Cl C atactic: C C C C C C H2 H2 CH2 CH2 CH2 CH2 CH2 CH2

H2C H2 CH H CH CH3 H H CH CH3 H Cl C Cl CH2 3 H 3 3

CH2 syndiotactic: C C C C C Ti Ti CH CH CH CH H H CH2 CH2 2 2 2 2 Cl Cl

5.6 Polyethylene (PE) Types 5.7 Ziegler-Natta Catalysis

Density (g/cc)  Used to make a variety of polymers HDPE 0.94 - 0.97  HDPE = high density polyethylene High Density PE Formed by…

Properties LLDPE 0.915 - 0.94 Linear Low Density PE H CH 2 CH2CH3 H2C LDPE 0.90 - 0.93 CH2 CH2 n Low Density PE

8 5.8 Ziegler-Natta Catalysis 5.9 Ziegler-Natta Catalysis

 LLDPE = linear low density polyethylene  LLDPE = linear low density polyethylene  mechanism H2C  How are branches introduced? CHR

Cl Cl Cl CH2CH3 CH2CH3  How is the branch length changed? CH2CH3 Ti Ti Ti CH2 CH C 2 Cl Cl C Cl H2 H2  How are the number and location of branches CH2 controlled? H2C

H2 H2C CH2CH3 C H C H Cl C 2 CH H Cl CH2 CH2 CH2CH3 2 CHR CH2CH3 H2C Ti R Ti CH2 CH CH2 CH C 2 n Cl Cl H2 R CH2 H2C

5.10 ROMP Catalysis 6.1 Step Growth Polymerization  Often referred to as condensation polymerization  Metathesis L L L L M CHR L M CHR CHR  No free radical or ions are necessary L M +  Reactive functional groups H C CHR H2C CHR CHR 2 CH2

 Ring Opening Metathesis Polymerization  Polymer grows in multiple directions L L L  1:1 stoichiometry of functional groups L M CH2 L M CH2 L M  A—A + B—B  A—A-B—B-A—A-B—B

New bonds formed during L L L step growth polymerization L M L M L M

9 6.2 Step Growth Polymerization 6.3 Step Growth Polymerization  Often referred to as condensation polymerization  Polymerization mixture contains wide distribution of  Atom efficient? slowly growing oligomers O O H H -H O n HO C (CH ) C OH +Nn (CH ) N 2 2 4 2 6 Polyamide H H adipic acid hexamethylenediamine (HMDA) diacid + diamine

O O O C (CH ) C NH (CH ) NH 2 4 2 6 n C nylon 6,6  Reactions between functional groups N H O O Amide (acid and amine) O -H2O n HO C C OH + n HO CH2 CH2 OH Ester (acid and alcohol) C Polyester O Carbonate (alcohol and acid dichloride) terephthalic acid ethylene glycol diacid + dialcohol Urethane (alcohol and isocyanate) O O O C C OCH2 CH2 O O C n O N C H O O poly(ethylene terephthalate)

6.4 Polyamides 6.5 Nylon Nomenclature  First synthetic polyamide was  Double-numbered: 6,6 or 6,10 poly(hexamethyleneadipamide), now called nylon 6,6  First number =  Reactants?  Second number =

 Mechanism?  Single-numbered: 4 or 6 or 12 O O H H -H O  Number = n HO C (CH ) C OH +Nn (CH ) N 2 2 4 2 6  H H

adipic acid (C6) hexamethylenediamine (C6)

O O C (CH ) C NH (CH ) NH 2 4 2 6 n nylon 6,6 molecular weight = 10,000-25,000 n = 40-110

10 6.6 Two Routes to Polyesters 6.7 Esterification Mechanism  Polyester mechanism O O O O O OH + -H2O H n HO C C OH + n HO CH2 CH2 OH HO C C OH HO C C + HO CH2 CH2 OH high  OH terephthalic acid ethylene glycol

O O O OH H O OH -H2O C C OCH2 CH2 O HO C C OCH2 CH2 OH HO C C OCH2 CH2 OH

n OH OH2

O OH O O -H+ O O HO C C O CH2 CH2 OH HO C C O CH2 CH2 OH -2n CH3OH n CH3OC C OCH3 + 2n HO CH2 CH2 OH low   LeChatlier’s Principle dimethyl terephthalate (DMT) O O

C C OCH2 CH2 O n

6.8 Dendrimer 6.9 Polycarbonates  Polycarbonates are strong, clear plastics  Carbonate = diester of carbonic acid  Optical market (DVD, CD’s)

CH3 O -HCl n HO C OH + n Cl C Cl

CH3 phosgene dialcohol + bisphenol A dichloride CH3 O

(O C OC)n

CH3

11 7.1 Thermoset Polymers 7.2 Thermoset Polymers  Linear polymers are typically thermoplastic  Thermoset polymers are cross-linked  Soften or melt when heated  Can dissolve ((galthough sometimes with difficult y) in solvents  Chemistry to form the polymer takes place in the polymerization reactor  Can be melted and shaped (molded) into finished articles without further chemistry  Chemistry to form the polymer takes place duringg(g) formation (molding) of the final article  Thermoplastics are a collection of individual  The polymer “sets-up” or hardens within the mold chains

7.3 Polyurethane 7.4 Polyurethane  Reaction of an isocyanate and an alcohol yields  Poly(propylene glycol) is formed by base a urethane catalyzed ring opening of propylene oxide with propylene glycol (diol)

 Reaction of a diisocyanate and a diol (like polypropylene glycol) gives polyurethane

12 7.5 Polyurethane 7.6 Polyurethane  Reaction of polypropylene glycol (diol) and  Reaction of a triol and toluenediisocyanate toluenediisocyanate gives linear polyurethane yields a rigid cross-linked polyurethane O

CH2O C NH CH3

NCO CH2OH O

C2H5 C CH2OH + O C N CH3 C2H5 CCH2OCNH CH3

CH2OH NCO O NCO trimethylolpropane TDI CH2OCNH CH3

N C O

CH3 CH3

CH2O (CH2 CH O)n CH2 CH OH

CH2OH CH3 CH3 CH3 Urethane linkage KOH CHOH + 3n CH2 CH CHO (CH2 CH O)n CH2 CH OH CH2OH O CH3 CH3 glycerol propylene oxide CH2O(CH2 CH O)n CH2 CH OH

7.7 Phenol-Formaldehyde Polymers 7.8 Two Component Epoxy Resins  Leo Baekeland discovered the polymerization 1. Low molecular weight polymer with epoxy end groups of formaldehyde and phenol to give phenolic 2. Curing agent resins  Ethylenediamine reacts with epoxy end groups on  Primarily used as a wood adhesive lllihtllow molecular weight polymer O O

OH NH2 CH2 CH2 NH2 + CH2 CH X CH CH2 CH CH2 CH2 CH2 2

OH HO OH OH OH OH HO CH N CH2 CH X CH CH2 N CH2 CH2 N CH2 CH X CH CH2 N CH2 CH2 2 CH2 CH2 CH OH CH OH CH OH CH2 2 X X CH CH OH CH OH CH2 2 bakelite  CH2 CH2 N N

13