Synthesis and Characterization of Graft Copolymers Poly(isoprene-g-styrene) of High Molecular Weight by a Combination of Anionic Polymerization and Emulsion Polymerization PDF Download
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 9
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Book Description
In this study, high molecular weight "comb-shaped" graft copolymers, poly(isoprene-g-styrene), with polyisoprene as the backbone and polystyrene as side chains, were synthesized via free radical emulsion polymerization by copolymerization of isoprene with a polystyrene macromonomer synthesized using anionic polymerization. A small amount of toluene was used in order to successfully disperse the macromonomer. Both a redox and thermal initiation system were used in the emulsion polymerization, and the latex particle size and distribution were investigated by dynamic light scattering. The structural characteristics of the macromonomer and comb graft copolymers were investigated through use of size exclusion chromatography, spectroscopy, microscopy, thermal analysis, and rheology. While the macromonomer was successfully copolymerized to obtain the desired multigraft copolymers, small amounts of unreacted macromonomer remained in the products, reflecting its reduced reactivity due to steric effects. Nevertheless, the multigraft copolymers obtained were very high in molecular weight (5-12 × 105 g/mol) and up to 10 branches per chain, on average, could be incorporated. A material incorporating 29 wt% polystyrene exhibits a disordered microphase separated morphology and elastomeric properties. As a result, these materials show promise as new, highly tunable, and potentially low cost thermoplastic elastomers.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 9
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Book Description
In this study, high molecular weight "comb-shaped" graft copolymers, poly(isoprene-g-styrene), with polyisoprene as the backbone and polystyrene as side chains, were synthesized via free radical emulsion polymerization by copolymerization of isoprene with a polystyrene macromonomer synthesized using anionic polymerization. A small amount of toluene was used in order to successfully disperse the macromonomer. Both a redox and thermal initiation system were used in the emulsion polymerization, and the latex particle size and distribution were investigated by dynamic light scattering. The structural characteristics of the macromonomer and comb graft copolymers were investigated through use of size exclusion chromatography, spectroscopy, microscopy, thermal analysis, and rheology. While the macromonomer was successfully copolymerized to obtain the desired multigraft copolymers, small amounts of unreacted macromonomer remained in the products, reflecting its reduced reactivity due to steric effects. Nevertheless, the multigraft copolymers obtained were very high in molecular weight (5-12 × 105 g/mol) and up to 10 branches per chain, on average, could be incorporated. A material incorporating 29 wt% polystyrene exhibits a disordered microphase separated morphology and elastomeric properties. As a result, these materials show promise as new, highly tunable, and potentially low cost thermoplastic elastomers.
Author: Nevin Çankaya
Publisher: BoD – Books on Demand
ISBN: 9535134876
Category : Science
Languages : en
Pages : 266
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Book Description
Summary-Book Contents: Your purpose of reading this book is to concentrate on recent developments on elastomers. The articles collected in this book are contributions by invited researchers with a long-standing experience in different research areas. I hope that the material presented here is understandable to a broad audience, not only scientists but also people with many different disciplines. The book contains eleven chapters in two sections: (1) "Mechanical Properties of Elastomers" and (2) "Elastomers for Natural and Medical Applications." The book provides detailed and current reviews in these different areas written by experts in their respective fields. This book will be useful for polymer workers and other scientists alike and will contribute to the training of current and future researchers, academics, PhD students, and other scientists.
Author: Maurice Morton
Publisher: Elsevier
ISBN: 0323158846
Category : Science
Languages : en
Pages : 257
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Book Description
Anionic Polymerization: Principles and Practice describes the unique nature of the anionic mechanism of polymerization. This book is composed of two parts encompassing 11 chapters that cover the aspects of the synthetic possibilities inherent in this system. Part I deals with the various aspects of anionic polymerization mechanism, including the monomers, initiators, solvents, and the involved initiation and propagation reactions. This part also describes the copolymerization and organolithium polymerization reactions of styrene and dienes. Part II explores the applications of anionic polymerization in polymer synthesis. This part specifically tackles the synthesis of narrow molecular weight, branched and a,?-difunctional polymers, and block copolymers. Polymer chemists and researchers who work in the chemical industry and who would wish to utilize the unique features of anionic polymerization in the synthesis of new products will find this book invaluable.
Author: Christopher Michael Hurley
Publisher:
ISBN:
Category : Addition polymerization
Languages : en
Pages : 151
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Book Description
This dissertation explores the synthesis and use of multifunctional anionic polymerization initiators for the purpose of opening the gateway to the synthesis of polymer architectures of greater complexity. First the multifunctional oxyanion initiator generated by reacting poly(4-hydroxystyrene) with sodium hydride was used to synthesize a previously unknown polymer containing an aryl halide functional group. The homopolymer solution self-assembly behavior of poly(4-hydroxystyrene) and the newly synthesized poly (4-(4-bromophenyloxy)styrene) were both investigated. This is followed by the synthesis and characterization of multifunctional alkyne core molecules and random copolymers of polystyrene-co-poly(4-hydroxystyrene) which served as templates for the synthesis of new random copolymers of polystyrene-co-poly(4-(2- propynyloxy)styrene). The newly formed multifunctional alkyne core molecules and alkyne functionalized random copolymers served as polymer backbones in a "grafting to" strategy. Previously prepared azide terminated polymers were grafted to the multifunctional alkyne core molecules and polymer backbones by copper (I) catalyzed alkyne-azide cycloaddition reactions. Lastly, the synthesis of a new hydrocarbon soluble multifunctional initiator was undertaken. The resulting molecule was shown to be an efficient initiator of anionic polymerization in non-polar solvent in the absence of polar additives, necessary in all previous attempts to combat large scale aggregation of such multifunctional initiator. This new initiator will open the way to facile synthesis of well-defined star polymers, star-block copolymers, and more complex polymer architectures.
Author: R. J. Ceresa
Publisher:
ISBN:
Category : Block copolymers
Languages : en
Pages : 224
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Book Description
Author: E. Tsartolia
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: Anbanandam Parthiban
Publisher: John Wiley & Sons
ISBN: 1118860489
Category : Technology & Engineering
Languages : en
Pages : 408
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Book Description
Understanding the reactivity of monomers is crucial in creating copolymers and determining the outcome of copolymerization. Covering the fundamental aspects of polymerization, Synthesis and Applications of Copolymers explores the reactivity of monomers and reaction conditions that ensure that the newly formed polymeric materials exhibit desired properties. Referencing a wide-range of disciplines, the book provides researchers, students, and scientists with the preparation of a diverse variety of copolymers and their recent developments, with a particular focus on copolymerization, crystallization, and techniques like nanoimprinting and micropatterning.
Author: Joseph Paul Kennedy
Publisher: John Wiley & Sons
ISBN:
Category : Science
Languages : en
Pages : 208
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Book Description
Author: Ashok Kakkar
Publisher: Royal Society of Chemistry
ISBN: 1788010426
Category : Technology & Engineering
Languages : en
Pages : 241
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Book Description
The term ‘miktoarm polymers’ refers to asymmetric branched macromolecules, a relatively new entry to the macromolecular field. Recent advances in their synthesis and intriguing supramolecular chemistry in a desired medium has seen a fast expansion of their applications. The composition of miktoarm polymers can be tailored and even pre-defined to allow a desired combination of functions, meaning polymer chemists can have complete control of the overall architecture of these macromolecules. By carefully selecting the composition, they can create supramolecular structures with intriguing properties, particularly for applications in biology. Miktoarm Star Polymers features chapters from experts actively working in this field, and provides the reader with a unique introduction to the fundamental principles of this exciting macromolecular system. Topics covered include the design, synthesis, characterization, self-assembly and applications of miktoarm polymers. The book is an excellent overview and up to date guide to those working in research in polymer chemistry, materials science, and polymers for medical applications.
Author: Mark G. Branch
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Styryl-terminated polystyrene macromonomers have been synthesised by the anionic polymerisation of styrene. Initiation was by sec-butyl lithium; termination involved the addition of diphenylethylene prior to vinyl benzyl chloride. Characterisation of the macromonomers was performed using gel permeation chromatography (GPC) and proton nuclear magnetic resonance spectroscopy (nmr). Novel comb graft copolymers were synthesised by the copolymerisation of the macromonomer with a comonomer. The following comonomers were used: Z-vinylpyridine (Z-VP), 4- vinylpyridine (4-VP) and N-(vinylbenzyl)pyrrolidone (VBP). Graft copolymers were made with a range of compositions by varying the feed ratios of the comonomer to the macromonomer. Reactivity ratios were determined for the different graft copolymer systems and compared to the simple statistical copolymerisation of styrene with comonomer. Characterisation of the graft copolymers was performed using GPC, nmr and membrane osmometry. Micellar dispersions of the comb graft copolymers were prepared in cyclohexane, toluene and methanol. These were subsequently characterised by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Micellar behaviour was related to graft copolymer composition and structure. The graft copolymers were subsequently used as steric stabilisers in dispersion polymerisations of bis-hydroxyethyl terephthalate in high boiling aliphatic hydrocarbon, methyl methacrylate in cyclohexane, vinyl pyridine in toluene/cyclohexane and styrene in methanol. A number of parameters have been investigated including initiator, stabiliser and monomer concentrations. Graft copolymer composition and structure were shown to be important factors for the effective steric stabilisation of polymer particles in conjunction with information on surface coverage data.
