DOCSLIB.ORG

Atom Transfer Radical Polymerization in Aqueous Dispersed Media

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Atom Transfer Radical Polymerization in Aqueous Dispersed Media Cent. Eur. J. Chem. • 7(4) • 2009 • 657–674 DOI: 10.2478/s11532-009-0092-1 Central European Journal of Chemistry Atom transfer radical polymerization in aqueous dispersed media Invited review Ke Min, Krzysztof Matyjaszewski* Center for Macromolecular Engineering, Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh PA 15213 Received 1 June 2009; Accepted 3 August 2009 Abstract: During the last decade, atom transfer radical polymerization (ATRP) received significant attention due to its exceptional capability of synthesizing polymers with pre-determined molecular weight, well-defined molecular architectures and various functionalities. It is economically and environmentally attractive to adopt ATRP to aqueous dispersed media, although the process is challenging. This review summarizes recent developments of conducting ATRP in aqueous dispersed media. The issues related to retaining “controlled/living” character as well as colloidal stability during the polymerization have to be considered. Better understanding the ATRP mechanism and development of new initiation techniques, such as activators generated by electron transfer (AGET) significantly facilitated ATRP in aqueous systems. This review covers the most important progress of ATRP in dispersed media from 1998 to 2009, including miniemulsion, microemulsion, emulsion, suspension and dispersed polymerization. Keywords: ATRP • Controlled radical polymerization • Dispersed media • Emulsion © Versita Warsaw and Springer-Verlag Berlin Heidelberg. 1. Introduction and scope of the media, preferably with water as the continuous phase. review Aqueous dispersed media are commonly recognized as a diverse and benign means for conducting industrial It has been a long-standing goal in polymer chemistry scale polymerization. The use of water as the dispersion to develop a process that combines the robustness medium is environmentally friendly, as compared to of radical polymerization with precise control over using volatile organic solvents. The presence of water all aspects of polymer structure, a feature typical for also allows excellent heat dissipation during the course living anionic polymerization. This is the reason why of polymerization. The low viscosity of the dispersed controlled/living radical polymerization (CRP) procedures medium allows access to high weight fractions of immediately received a large attention since their debut polymer not readily accessible in solution or bulk [1-5]. In the past two decades, various CRP techniques, polymerizations. Additionally, ease of mixing of raw especially nitroxide mediated polymerization (NMP) materials and handling of the final products (latex) lead [6,7], atom transfer radical polymerization (ATRP) to simple scale-up production of aqueous dispersion [8-11] and degenerative transfer systems [12] such as polymerization [15]. During the polymerization, radicals reversible addition-fragmentation chain transfer (RAFT) are compartmentalized within the dispersed phase and polymerization [13,14], have been introduced, defined hence they cannot terminate with radicals located in and refined. different loci. This compartmentalization effect results As a consequence of the improved understanding of in a higher polymerization rate and a higher molecular homogeneous CRP systems, increasing attention was weight in free radical emulsion polymerization than those paid towards development of CRP in heterogeneous achieved in solution/bulk [16,17]. It has been more than * E-mail: [email protected] 657 Atom transfer radical polymerization in aqueous dispersed media half a century since free radical polymerizations were first [4,8]. Mechanistically, ATRP originates from a widely applied to aqueous dispersed media. Commercialization used organic reaction known as atom transfer radical of CRP will likely benefit from the use of aqueous addition (ATRA) [26,27]. In this synthetic organic dispersed media. chemistry technique, a halogen atom is transferred Many challenges were encountered when chemists homolytically from a dormant halide species to a initially attempted to conduct a CRP in aqueous dispersed transition metal complex, forming a free radical which media. Because of the multi-component nature of the reacts with an unsaturated molecule and is quickly procedures required for CRP, as well as the complex and irreversibly deactivated by a back-transfer of the nature of aqueous dispersed media, simply adding halogen atom from the transition metal complex to the a reagent that can adopt CRP from a bulk or solution organic radical species. Compared to ATRA, ATRP polymerization to an aqueous dispersed polymerization requires a system in which the formed deactivated procedure, resulted in a loss of many of the desirable species can be reactivated to allow further monomer features of both processes. Observed problems addition and hence controlled chain growth. Selection included decreased colloidal stability, a wide particle of a suitable catalyst enables the system to establish a size distribution, loss of control over polymerization, and dynamic equilibrium between propagating chains and low initiation efficiency. In addition, each CRP method dormant chains, as well as to assure fast initiation, has its own set of unique features. A strategy that had reduction of the contribution of the inevitable radical- proven successful in one type of CRP processes has radical termination reactions which ultimately results in not been necessarily efficient for another CRP method. the controlled/“living” character of the polymerization In short, implementing CRP in dispersed media requires [28]. In an ATRP, the catalyst is usually a transition careful consideration of every aspect of the mechanism metal complex, in which the ligand plays a critical role of each process. in determining the reactivity of the catalyst complex Despite all these challenges, remarkable progress [10,29-34]. In addition, the ligand also strongly influences has been achieved in understanding the specific the solubility of the complex, and consequently the requirements and hence application of CRP to aqueous concentration of activators and deactivators in the dispersed media in the recent five years. Several exciting reaction medium [18,35-40]. and innovative developments have been reported that Compared with other controlled living radical successfully allow application of CRPs in aqueous polymerization methods, such as NMP and RAFT dispersions. The progress in this field has been covered polymerization, ATRP provides a simple pathway to in several recently published reviews [15,18-25]. polymers with well defined chain-end functionality [41]. Advances in NMP and RAFT systems have primarily It is also the most efficient methods for synthesis of progressed with respect to a better understanding of how polymers with complex architectures, such as block the particular “mediating” chemistry behaves in a multi- copolymers, star polymers and graft copolymers phase environment. In contrast, ATRP has undergone a [42,43]. ATRP is also well-known for its capability of series of significant improvements in its basic chemistry, synthesizing low molecular weight polymers. In addition particularly with regards to how the polymerization is surface modification is relatively simple using ATRP initiated, that have facilitated and, in some instances, since it is only necessary to pre-modify the surface been driven by its adaptation to aqueous dispersions. with an alkyl halide based ATRP initiators which can This mini-review will discuss the recent progress on be easily introduced to the surfaces of most substrates the application of ATRP to aqueous dispersed media [44-46]. Furthermore, a significant advantage of ATRP and summarize the exploration of the fundamental is that all necessary components are commercially mechanism of ATRP that has played a significant role in available [4,47]. advancing this field and greatly benefited the on-going research. 2.2. Polymerizations in aqueous dispersed media Polymerizations in aqueous dispersed media are 2. Background on ATRP and aqueous the most widely used methods for preparation of dispersed media colloidal particles with a variety of sizes. This process usually occurs in a bi-phasic system, with water as 2.1. ATRP the continuous phase and monomer/polymer in the ATRP was first reported in 1995 and has emerged form of a fine dispersion in water. The terminology of as one of the most powerful synthetic techniques various aqueous dispersed polymerization systems for preparation of well-defined polymeric materials adopted here is employed by most polymer chemists, 658 K. Min, K. Matyjaszewski Scheme 1. Polymerizations in various aqueous dispersed media. and the terms “suspension”, „emulsion”, “miniemulsion”, are sometimes used. Initially, most of the monomer is “microemulsion”, “dispersion” and “precipitation” are present in the form of 1-10 μm or larger droplets. A small clearly distinguished on the basis of the following four percentage of the monomer also exists in the form of criteria: 1) initial state of the polymerization mixture; surfactant-solubilized micelles, with size ca. 5-10 nm, 2) kinetics of polymerization; 3) mechanism of particle and molecularly dissolved in water, depending on the formation; and 4) size of the final polymer particles nature and concentration of the monomer and emulsifier. [48]. It is noteworthy that the complexity of aqueous During the polymerization, particles are formed in the dispersed polymerizations has resulted in ambiguities,
Load more

Recommended publications
  • Controlled/Living Radical Polymerization in Aqueous Media: Homogeneous and Heterogeneous Systems
    Prog. Polym. Sci. 26 =2001) 2083±2134 www.elsevier.com/locate/ppolysci Controlled/living radical polymerization in aqueous media: homogeneous and heterogeneous systems Jian Qiua, Bernadette Charleuxb,*, KrzysztofMatyjaszewski a aDepartment of Chemistry, Center for Macromolecular Engineering, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA bLaboratoire de Chimie MacromoleÂculaire, Unite Mixte associeÂe au CNRS, UMR 7610, Universite Pierre et Marie Curie, Tour 44, 1er eÂtage, 4, Place Jussieu, 75252 Paris cedex 05, France Received 27 July 2001; accepted 30 August 2001 Abstract Controlled/living radical polymerizations carried out in the presence ofwater have been examined. These aqueous systems include both the homogeneous solutions and the various heterogeneous media, namely disper- sion, suspension, emulsion and miniemulsion. Among them, the most common methods allowing control ofthe radical polymerization, such as nitroxide-mediated polymerization, atom transfer radical polymerization and reversible transfer, are presented in detail. q 2001 Elsevier Science Ltd. All rights reserved. Keywords: Aqueous solution; Suspension; Emulsion; Miniemulsion; Nitroxide; Atom transfer radical polymerization; Reversible transfer; Reversible addition-fragmentation transfer Contents 1. Introduction ..................................................................2084 2. General aspects ofconventional radical polymerization in aqueous media .....................2089 2.1. Homogeneous polymerization .................................................2089
    [Show full text]
  • Effects of Solvent Treatment and High-Pressure Homogenization Process on Dispersion Properties of Palygorskite
    Powder Technology 235 (2013) 652–660 Contents lists available at SciVerse ScienceDirect Powder Technology journal homepage: www.elsevier.com/locate/powtec Effects of solvent treatment and high-pressure homogenization process on dispersion properties of palygorskite Jixiang Xu a,b, Wenbo Wang a,c, Aiqin Wang a,c,⁎ a Center of Eco-material and Green Chemistry, Lanzhou Institute of Chemical Physics, Chinese Academy of Science, Lanzhou 730000, China b Graduate University of the Chinese Academy of Science, Beijing 100049, China c R&D Center of Xuyi Palygorskite Applied Technology, Lanzhou Institute of Chemical Physics, Chinese Academy of Science, Xuyi 211700, China article info abstract Article history: Dispersion of natural palygorskite in distilled water, methanol, ethanol, isopropanol, dimethyl formamide, Received 12 September 2012 and dimethyl sulfoxide was carried out using high-pressure homogenization. The effects of solvent parame- Received in revised form 20 September 2012 ters on the microstructure, morphology and colloidal properties of palygorskite were investigated in detail. Accepted 19 November 2012 Elemental analysis, infrared spectroscopy (IR) and thermogravimetric analysis (TGA) confirmed that some Available online 27 November 2012 solvent molecules were encapsulated within the tunnels of palygorskite. The efficiency of the homogeniza- tion process to disperse palygorskite aggregates was closely correlated to the solvent parameters, particularly Keywords: Palygorskite solvent vapor pressure and viscosity. A well disaggregated palygorskite was obtained after dispersing in di- Dispersion methyl sulfoxide. It was also confirmed that colloidal stability and suspension viscosity were affected by Solvents the solvent nature. A more stable suspension with higher viscosity of 2364 mPa s was obtained by dispersing Homogenization palygorskite in isopropanol.
    [Show full text]
  • Chemical Physics of Colloid Systems and Interfaces: 5. Hydrodynamic
    Published as Chapter 5 in "Handbook of Surface and Colloid Chemistry" Second Expanded and Updated Edition; K. S. Birdi, Ed.; CRC Press, New York, 2002. CHEMICAL PHYSICS OF COLLOID SYSTEMS AND INTERFACES Authors: Peter A. Kralchevsky, Krassimir D. Danov, and Nikolai D. Denkov Laboratory of Chemical Physics and Engineering, Faculty of Chemistry, University of Sofia, Sofia 1164, Bulgaria CONTENTS 5.5 HYDRODYNAMIC INTERACTIONS IN DISPERSIONS 106 5.5.1 Basic Equations. Lubrication Approximation 5.5.2 Interaction Between Particles of Tangentially Immobile Surfaces 5.5.2.1 Taylor and Reynolds Equations, and Influence of the Particle Shape 5.5.2.2 Interactions Among Non-Deformable Particles at Large Distances 5.5.2.3 Stages of Thinning of a Liquid Film 5.5.2.4 Dependence of Emulsion Stability on the Droplet Size 5.5.3 Effect of Surface Mobility 5.5.3.1 Diffusive and Convective Fluxes at an Interface; Marangoni Effect 5.5.3.2 Fluid Particles and Films of Tangentially Mobile Surfaces 5.5.3.3 Bancroft Rule for Emulsions 5.5.3.4 Demulsification and Defoaming 5.5.4 Interactions in Non-Preequilibrated Emulsions 5.5.4.1 Surfactant Transfer from Continuous to Disperse Phase (Cyclic Dimpling) 5.5.4.2 Surfactant Transfer form Disperse to Continuous Phase (Osmotic Swelling) 5.5.4.3 Equilibration of Two Droplets Across a Thin Film 5.5.5 Hydrodynamic Interaction of a Particle with an Interface 5.5.5.1 Particle of Immobile Surface Interacting with a Solid Wall 5.5.5.2 Fluid Particles of Mobile Surfaces 5.5.6 Bulk Rheology of Dispersions 5.6 KINETICS OF COAGULATION 5.6.1 Irreversible Coagulation 5.6.2 Reversible Coagulation 5.6.3 Kinetics of Simultaneous Flocculation and Coalescence in Emulsions 5.5.
    [Show full text]
  • UCLA Electronic Theses and Dissertations
    UCLA UCLA Electronic Theses and Dissertations Title Quantitative Video-Tracking Electrophoresis and Refractometry of Nanoemulsions Permalink https://escholarship.org/uc/item/6gt035zv Author Zhu, Xiaoming Publication Date 2013 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California UNIVERSITY OF CALIFORNIA Los Angeles Quantitative Video-Tracking Electrophoresis and Refractometry of Nanoemulsions A dissertation submitted in partial satisfaction of the requirements for the degree Doctor of Philosophy in Chemistry by Xiaoming Zhu 2013 © Copyright by Xiaoming Zhu 2013 ABSTRACT OF THE DISSERTATION Quantitative Video-Tracking Electrophoresis and Refractometry of Nanoemulsions by Xiaoming Zhu Doctor of Philosophy in Chemistry University of California, Los Angeles, 2013 Professor Thomas G. Mason, Chair New kinds of nano-scale objects have led to immense advancements in fundamental science, medicine, and industry. As the development and application of novel nano-materials accelerates, it is vital to create effective, widely applicable, and inexpensive techniques for separating, purifying and characterizing nanoparticles and nanodroplets. In this thesis, we make two advances that rely on optical properties, specifically refractive index and scattering, of nanoparticles and nanoemulsions. We show that the droplet volume fraction φ and surfactant concentration C of a silicone oil-in-water nanoemulsion can be simultaneously determined by diluting the nanoemulsion with pure water, measuring its refractive index n using an Abbé refractometer, and fitting the result using a prediction for n that treats the nanoemulsion as an effective medium. This method can be used for accurate, non-destructive, and rapid determination of nanoemulsion compositions over a relatively wide range. Additionally, we demonstrate a quantitative method for performing real-time optical video tracking gel electrophoresis of nanoparticles and nanoemulsions in a passivated agarose gel.
    [Show full text]
  • Polymer Chemistry Accepted Manuscript
    Polymer Chemistry Accepted Manuscript This is an Accepted Manuscript, which has been through the Royal Society of Chemistry peer review process and has been accepted for publication. Accepted Manuscripts are published online shortly after acceptance, before technical editing, formatting and proof reading. Using this free service, authors can make their results available to the community, in citable form, before we publish the edited article. We will replace this Accepted Manuscript with the edited and formatted Advance Article as soon as it is available. You can find more information about Accepted Manuscripts in the Information for Authors. Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal’s standard Terms & Conditions and the Ethical guidelines still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains. www.rsc.org/polymers Page 1 of 69 Polymer Chemistry Latex routes to graphene-based nanocomposites Elodie Bourgeat-Lami, a* Jenny Faucheu, b* Amélie Noël a, b a Université de Lyon, Univ. Lyon 1, CPE Lyon, CNRS, UMR 5265, Laboratoire de Chimie, Catalyse, Polymères et Procédés (C2P2), LCPP group, 43, Bd. du 11 Novembre 1918, F- Manuscript 69616 Villeurbanne, France b Ecole Nationale Supérieure des Mines, SMS-EMSE, CNRS : UMR 5307, LGF, 158 cours Fauriel, 42023 Saint Etienne, France Accepted Chemistry Polymer 1 Polymer Chemistry Page 2 of 69 Abstract This review article describes recent advances in the elaboration of graphene-based colloidal nanocomposites through the use of graphene or graphene oxide in heterophase polymerization systems.
    [Show full text]
  • Photopolymerization in Dispersed Systems
    PHOTOPOLYMERIZATION IN DISPERSED SYSTEMS Florent Jasinski,a Per B. Zetterlund,a André M. Braun,b Abraham Chemtobc, d* a Centre for Advanced Macromolecular Design (CAMD), School of Chemical Engineering, University of New South Wales, Sydney, NSW 2052, Australia. b Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany c Université de Haute-Alsace, CNRS, IS2M UMR7361, F-68100 Mulhouse, France d Université de Strasbourg, France * To whom correspondence should be addressed: E-mail: [email protected]; Fax: +33 389 60 87 99 ; Tel: +33 389 60 88 34 Abstract Zero-VOC technologies combining ecological and economic efficiency are destined to occupy a growing place in the polymer economy. Today, Polymerization in dispersed systems and Photopolymerization are the two major key players. The hybrid technology based on photopolymerization in dispersed systems has emerged as the next technological frontier, not only to make processes even more efficient and eco-friendly, but also to expand the range of polymer products and properties. This review summarizes the current knowledge in research relevant to this field in an exhaustive way. Firstly, fundamentals of photoinitiated polymerization in dispersed systems are given to show the favourable context for developing this emerging technology, its specific features as well as the distinctive equipment and materials necessary for its implementation. Secondly, a state-of-the-art and critical review is provided according to the seven main processing methods in dispersed systems: emulsion, microemulsion, miniemulsion, dispersion, precipitation, suspension, and aerosol. Keywords: photopolymerization, emulsion, miniemulsion, dispersion, suspension, aerosol 1 Table of contents LIST OF SYMBOLS AND ABBREVIATIONS ................................................................................................. 3 1. INTRODUCTION ............................................................................................................................... 5 2.
    [Show full text]
  • Colloids • Three Primary Types of Mixtures - a Solution, Colloid and Suspension
    Colloids • Three primary types of mixtures - a solution, colloid and suspension. • A colloid is a solution - Particle remain evenly distributed throughout the solution. • Colloidal dispersions - substances remain dispersed and do not settle. • The substance being dispersed - the dispersed phase, • The substance in which it is dispersed - the continuous phase or dispersion medium. Particles in a colloid are larger than most simple molecules and scatter light (Tyndall effect). Preparation of Colloidal Systems A colloidal system can be produced by distributing particles throughout a dispersion medium. • Dispersion methods: by breaking down larger particles. For example, paint pigments are produced by dispersing large particles by grinding in special mills. • Condensation methods: growth from smaller units, such as molecules or ions. For example, clouds form when water molecules condense and form very small droplets. Classification of Colloids Based on the Nature of Interaction Between Dispersed Phase and Dispersion Medium Hydrophilic colloids: ❑ These are water-loving colloids. ❑ The colloid particles are attracted to the water. ❑ They are also known as reversible sols. ❑ Examples include Agar, gelatin, pectin, etc. Hydrophobic colloids: ❑ These are the opposite in nature to hydrophilic colloids. ❑ The colloid particles are repelled by water. ❑ They are also called irreversible sols. ❑ Examples include Gold sols, clay particles, etc Based on Type of Particles of Dispersed Phase Multimolecular Colloids: • Formed as a result of the aggregation of a large number of atoms or small molecules (having diameters of less than 1 nm) of the dispersed media. • The dispersed particles are held together by Van der Val forces Example: Gold sol, Sulphur sol. Macromolecular Colloids: • Colloids formed from macromolecules.
    [Show full text]
  • Solid/Liquid Dispersions in Drilling and Production Fluides Chargés En Forage Et Production Pétrolière
    Oil & Gas Science and Technology – Rev. IFP, Vol. 59 (2004), No. 1, pp. 11-21 Copyright © 2004, Institut français du pétrole Dossier Solid/Liquid Dispersions in Drilling and Production Fluides chargés en forage et production pétrolière Solid/Liquid Dispersions in Drilling and Production Y. Peysson1 1 Institut français du pétrole, 1 et 4, avenue de Bois-Préau, 92852 Rueil-Malmaison Cedex - France e-mail: [email protected] Résumé — Fluides chargés en forage et production pétrolière — Pour atteindre les nouveaux gisements de pétrole, l’industrie pétrolière met en place des forages et des schémas de production de plus en plus complexes. Les puits de forage sont maintenant fortement déviés, horizontaux, multidrains, situés en offshore très profond, etc. Les forages déviés dépassent aujourd’hui les 10 km de déport et les puits forés en offshore explorent des sites où les profondeurs d’eau approchent les 3 km ! Les techniques de forage et de production utilisées exigent une maîtrise de plus en plus grande des paramètres mis en jeu et notamment la maîtrise des propriétés de nombreux fluides chargés. Ces fluides sont des dispersions plus ou moins concentrées de particules solides dans un fluide porteur. Ils se retrouvent fréquemment dans l’industrie pétrolière (fluides de forage, ciments, dispersion d’hydrates dans les effluents, venue de sables avec les fluides de réservoir, gravel pack, slurries de déblais, etc.). Ces milieux divisés solide/liquide peuvent avoir des propriétés particulières parfois à la frontière entre le solide et le liquide : contrainte seuil, propriété rhéofluidifiante, etc. La description de leurs propriétés n’est pas aisée et nécessite d’aborder de nombreuses thématiques scientifiques : rhéologie, chimie et physicochimie, hydrodynamique, thermodynamique, etc.
    [Show full text]
  • Solid/Liquid Dispersions in Drilling and Production Fluides Chargés En Forage Et Production Pétrolière
    Oil & Gas Science and Technology – Rev. IFP, Vol. 59 (2004), No. 1, pp. 11-21 Copyright © 2004, Institut français du pétrole Dossier Solid/Liquid Dispersions in Drilling and Production Fluides chargés en forage et production pétrolière Solid/Liquid Dispersions in Drilling and Production Y. Peysson1 1 Institut français du pétrole, 1 et 4, avenue de Bois-Préau, 92852 Rueil-Malmaison Cedex - France e-mail: [email protected] Résumé — Fluides chargés en forage et production pétrolière — Pour atteindre les nouveaux gisements de pétrole, l’industrie pétrolière met en place des forages et des schémas de production de plus en plus complexes. Les puits de forage sont maintenant fortement déviés, horizontaux, multidrains, situés en offshore très profond, etc. Les forages déviés dépassent aujourd’hui les 10 km de déport et les puits forés en offshore explorent des sites où les profondeurs d’eau approchent les 3 km ! Les techniques de forage et de production utilisées exigent une maîtrise de plus en plus grande des paramètres mis en jeu et notamment la maîtrise des propriétés de nombreux fluides chargés. Ces fluides sont des dispersions plus ou moins concentrées de particules solides dans un fluide porteur. Ils se retrouvent fréquemment dans l’industrie pétrolière (fluides de forage, ciments, dispersion d’hydrates dans les effluents, venue de sables avec les fluides de réservoir, gravel pack, slurries de déblais, etc.). Ces milieux divisés solide/liquide peuvent avoir des propriétés particulières parfois à la frontière entre le solide et le liquide : contrainte seuil, propriété rhéofluidifiante, etc. La description de leurs propriétés n’est pas aisée et nécessite d’aborder de nombreuses thématiques scientifiques : rhéologie, chimie et physicochimie, hydrodynamique, thermodynamique, etc.
    [Show full text]
  • Capillary-Based Microfluidic Sample Confinement for Studying Dynamic Cell Behaviour
    Capillary-based microfluidic sample confinement for studying dynamic cell behaviour Amin Hassanzadeh-Barforoushi A thesis in fulfilment of the requirements for the degree of Doctor of Philosophy University of New South Wales School of Mechanical and Manufacturing Engineering March 2019 Thesis/Dissertation Sheet Surname/Family Name : Hassanzadeh-Barforoushi Given Name/s : Amin Abbreviation for degree as give in the University calendar : PhD Faculty : Engineering School : Mechanical and Manufacturing Engineering Capillary-based microfluidic sample confinement for studying dynamic cell Thesis Title : behaviour Abstract 350 words maximum: (PLEASE TYPE) Cells in the body are in constant interaction with their surrounding environment. These interactions lead to creation of a variety of biophysical and biochemical events such as cell migration, neurite outgrowth and single cell protein secretion. In order to study these complex events, cells should be positioned in accurate spatial locations. This thesis is focused on application of microfluidics in studying cell dynamics based on a new capillary sample confinement approach. The main contributions of this thesis are the fundamentals of capillary-based trapping of biological samples (Chapter 3), microfluidic stamping method for studying cellular migration in patterned co-culture (Chapter 4), microfluidic cell and protein patterning for studying preferential neurite outgrowth dynamics (Chapter 5), and static droplet array for single cell trapping and long-term monitoring (Chapter 6). Using numerical simulation, liquid-air interface movement in a microchannel with different geometries is investigated. For hydrophobic channels, it is found that the slope of the channel geometry can be used to manipulate interface velocity and acceleration. Based on this understanding, microchannel junction geometry for liquid compartmentalization was proposed.
    [Show full text]
  • Optical Properties of Terrestrial Clouds
    1 Optical properties of terrestrial clouds Institute of Environmental Physics, University of Bremen P. O. Box 330440, D-28334 Bremen, Germany and Institute of Physics, 70 Skarina Avenue, Minsk 220072,Belarus [email protected] Abstract The aim of this review is to consider optical characteristics of terrestrial clouds. Both single and multiple light scattering properties of water clouds are studied. The numerous results discussed can be used for solutions both inverse and direct problems of the cloud optics. 2 CONTENTS 1.Introduction 2.Microphysical characteristics of clouds 2.1 Water clouds 2.1.1 Particle size distribution 2.1.2 Concentration of droplets 2.1.3 Refractive index of liquid water and ice 2.2 Ice clouds 3. Local optical characteristics of cloudy media 3.1 Water clouds 3.1.1 Extinction coefficient 3.1.2 Absorption coefficient 3.1.3 Phase function 3.1.4 Asymmetry parameter 3.2 Ice clouds 3.2.1 Extinction coefficient 3.2.2 Absorption coefficient 3.2.3 Phase function 3.2.4 Asymmetry parameter 4. Global optical characteristics of cloudy media 4.1 Visible range 4.2 Near-infrared range 4.3 The total reflectance 5. Satellite remote sensing of cloudy media 5.1 Optical thickness 5.2 The size of particles 5.3 The thermodynamic phase 5.4 The cloud height and cover 5.5 The remote sensing of ice clouds 6. Radiative transfer in inhomogeneous clouds 6.1 Vertical inhomogenity 6.2 Horizontal inhomogenity 7. Conclusion 8. Acknowledgements 9. References 3 1. Introduction Water, ice, and mixed clouds are major regulators of solar fluxes in the Earth atmosphere(Kondratyev and Binenko, 1984; Liou, 1992).
    [Show full text]
  • AGET ATRP Approach
    materials Article Experimental Investigation of Methyl Methacrylate in Stirred Batch Emulsion Reactor: AGET ATRP Approach Mohammed Awad , Thomas Duever and Ramdhane Dhib * Department of Chemical Engineering, Ryerson University, 350 Victoria Street, Toronto, ON M5B 2K3, Canada; [email protected] (M.A.); [email protected] (T.D.) * Correspondence: [email protected] Received: 30 October 2020; Accepted: 16 December 2020; Published: 18 December 2020 Abstract: This study examines the ab initio emulsion atom transfer radical polymerization (ATRP) initiated by an eco-friendly reducing agent to produce poly(methyl methacrylate) (PMMA) polymer with controlled characteristics in a 2 L stirred batch reactor. The effect of the reaction temperature, surfactant concentration, monomer to water ratio, and stirring speed was thoroughly investigated. The results showed that PMMA coagulation becomes quite severe at a certain temperature threshold. However, the coagulation could be avoided at mild reaction temperature, since the outcomes showed that loading more surfactant to the system under high mixing speed has balanced the polymer mixture and yielded high monomer conversion. The PMMA product was analyzed by gravimetry and GPC measurements and after 5 h of polymerization at a reaction temperature of 50 ◦C, monomer conversion of 64.1% was obtained, and PMMA polymer samples produced had an average molar mass of 4.5 kg/mol and a polydispersity index of 1.17. The structure of the PMMA polymer was successfully proved by FTIR and nuclear magnetic resonance (NMR) spectroscopy. The results confirm the living feature of MMA AGET ATRP in emulsion medium and recommend further investigation for other types of surfactant. Keywords: AGET ATRP; ascorbic acid; batch reactor; MMA; two-step emulsion 1.
    [Show full text]