Preparation Of Tailor Made Functional Polymers By Anionic Living Polymerization

This book presents these important facts: a) The mechanism of anionic polymerization, a more than 50-year challenge in polymer chemistry, has now become better understood; b) Precise synthesis of many polymers with novel architectures (triblock, multi-block, graft, exact graft, comb, cyclic, many armed stars with multi-components, dendrimer-like hyper-branched, and their structural mixed (co)polymers, etc.) have been advanced significantly; c) Based on such polymers, new morphological and self-organizing nano-objects and supra molecular assemblies have been created and widely studied and are considered nanodevices in the fields of nano science and technology; d) New high-tech and industrial applications for polymeric materials synthesized by anionic polymerization have been proposed. These remarkable developments have taken place in the last 15 years. Anionic polymerization continues to be the only truly living polymerization system (100 % termination free under appropriate conditions) and consequently the only one with unique capabilities in the synthesis of well-defined (i.e., precisely controlled molecular weight, nearly mono-disperse molecular weight distribution, structural and compositional homogeneity) complex macromolecular architectures. This book, with contributions from the world’s leading specialists, will be useful for all researchers, including students, working in universities, in research organizations, and in industry.

Over the years the field of anionic polymerization has attracted numerous outstanding scientists, and today it still is being pursued by many researchers all over the world. The exciting discovery of termination-less polymerization processes and living polymers culminating in the development of narrow molecular weight polymers, star polymers, and tailor-made block and graft copolymers, contributed immensely to the rapid expansion of polymer science. Areas of active research in anionic polymerization presently include the structure of ion pairs and their role in regulating polymer structure, ring opening polymerization of heterocyclic monomers, synthesis of well-defined block and graft copolymers including the application of macromers in such systems, telechelic polymers with functional end groups, and other topics. New developments in the organic chemistry of carbanions such as dipolar carbanions impinge on the field of anionic polymerization. More sophisticated characterization techniques have been instrumental in obtaining better correlations between the structure of polymers and that of intermediates leading to their formation. This book contains the proceedings of the international symposium on "Recent Advances in Anionic Polymerization and Related Processes" which was held at the 1986 spring meeting of the American Chemical Society. It was the first Polymer Division-sponsored meeting exclusively devoted to anionic polymerization since the Houston ACS meeting in the spring of 1980. The proceedings of that meeting were published in the book "Anionic Polymerization", ACS Symposium Series No. 166, edited by Dr. J. E. McGrath.

"The synthesis of homopolymers and block copolymers containing metal coordinating ligands is an important area of research due to the potential applications of these polymers in the fields of optics, electronics, and photonics. Specifically, the terpyridine group is very useful, since it can act as a tridentate chelating ligand due to its strategically positioned, three nitrogen atoms. This allows it to form strong complexes with a variety of transition metal ions. The hydroxyl functionality is another important group due to numerous applications of well-defined hydroxyl-functionalized polymers. They can react with other functional groups on other polymers for chain extension, branching, or crosslinking. They can also be used as macroinitiators for the polymerization of other monomers such as lactide and lactone. Alkyllithium-initiated, living anionic polymerization offers excellent control over molecular weight and molecular weight distribution. The absence of termination and chain transfer steps makes these systems ideally suited for the preparation of chain-end functionalized polymers by the reaction of the living chain ends with appropriate monomers or terminating agents. A recently reported general anionic functionalization method was used to create well-defined terpyridine and hydroxyl end-functionalized polymers. In the first step, living polymeric organolithium compounds were reacted with silyl chlorides to form the corresponding silyl hydride-functionalized polymers. Then, these polymers were reacted with substituted alkenes in the presence of a hydrosilation catalyst to form the corresponding functionalized polymers. A new method was also developed, based on similar chemistry, to prepare an in-chain functionalized diblock copolymer where a variety of functional groups can be placed directly at the interface of the two blocks. This method was used to prepare both in-chain hydroxyl- and terpyridine-functionalized polystyrene-b-polyisoprene copolymers. Lewis bases effect dramatic changes in microstructure, initiation rates, propagation rates and monomer reactivity ratios for alkyllithium-initiated polymerizations of vinyl monomers in hydrocarbon solution. The stability of polymeric organolithium compounds and the mechanism of decomposition in the presence of various stoichiometric equivalents of tetrahydrofuran in benzene solutions were studied due the importance of THF as an additive."--Abstract.

This book presents these important facts: a) The mechanism of anionic polymerization, a more than 50-year challenge in polymer chemistry, has now become better understood; b) Precise synthesis of many polymers with novel architectures (triblock, multi-block, graft, exact graft, comb, cyclic, many armed stars with multi-components, dendrimer-like hyper-branched, and their structural mixed (co)polymers, etc.) have been advanced significantly; c) Based on such polymers, new morphological and self-organizing nano-objects and supramolecular assemblies have been created and widely studied and are considered nanodevices in the fields of nanoscience and technology; d) New high-tech and industrial applications for polymeric materials synthesized by anionic polymerization have been proposed. These remarkable developments have taken place in the last 15 years. Anionic polymerization continues to be the only truly living polymerization system (100 % termination free under appropriate conditions) and consequently the only one with unique capabilities in the synthesis of well-defined (i.e., precisely controlled molecular weight, nearly mono-disperse molecular weight distribution, structural and compositional homogeneity) complex macromolecular architectures. This book, with contributions from the world's leading specialists, will be useful for all researchers, including students, working in universities, in research organizations, and in industry.

Numerous applications require specific properties at polymer surfaces that differ from the bulk, while retaining the advantageous properties of the bulk polymer. In this thesis, we describe work aimed at producing a series of multi-end functionalized polystyrene and polyisoprene additives with a wide range of molecular weights, carrying 1 to 3 fluoroalkyl groups that have been prepared by end capping the living chain ends of polymers prepared via anionic polymerization reactions. The resulting polymers have a well-defined structure with interesting surface modifying properties. We have also carried out hydrogenation of end functionalized polyisoprene to form poly(ethylene-alt-propylene) with the same functional group. The resulting polymers have been used as additives in an attempt to render the surface of polymer films hydrophobic/lipophobic and we have characterized these polymer films using static contact angle measurements with water as the main contact fluid. We have systematically studied the effect of additive molecular weight, concentration and annealing conditions on the surface properties. It has been discovered that these additives undergo rapid adsorption to a surface or interface and significantly enhance surface properties. In addition, to support the contact angles results, elastic recoil detection analysis (ERDA) and Rutherford backscattering analysis (RBS) have been carried out to acquire further quantitative evidence of surface segregation.

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.

The International Symposium on Ionic Polymerization (IP'99) was held in Kyoto, Japan, July 1999. It was sponsored by IUPAC, the Chemical Society of Japan, the Society of Polymer Science, Japan, the Society of Synthetic Organic Chemistry, Japan and the Japan Chemical Innovation Institute. The research areas covered were directed at the traditional fields of cationic, anionic and ring-opening polymerization, as well as polymer synthesis, including radical, metal catalyzed, and enzymatic polymerization, plus polycondensation and new polymer architecture. The papers in this volume of Macromolecular Symposia cover a broad range of topics illustrative of the symposium.

Novel methods for the synthesis of chain-end and in-chain functionalized polymers, as well as star polymers, were developed using anionic polymerization techniques. A new mechanism for the reaction of polymeric organolithium compounds with thiiranes has been found. The reaction of poly(styryl)lithium and poly(butadienyl)lithium with propylene sulfide and ethylene sulfide was investigated in hydrocarbon solution for the preparation of thiol-functional polymers. It was found by MALDI-TOF mass spectral analysis of the reaction products that the reaction proceeded by attack of the anion on the methylene carbon atom of the thiirane ring followed by ring opening to form the thiol-functionalized polymer. The reaction of poly(styryl)lithium with trimethylene sulfide did not produce the corresponding thiol-functionalized polymer; the resulting methyl-terminated polymer was formed by attack of the anion on the sulfur atom followed by ring opening to form a primary carbanion. A new method for synthesis of alkoxysilyl-functionalized polymers was developed. Using a general functionalization methodology based on the hydrosilation of vinyltrimethoxysilane with [omega]-silyl hydride-functionalized polystyrene, alkoxysilyl-functionalized polystyrene was obtained in high yield (83 %). The main side product was vinylsilane-functionalized polymer. A small amount of dimer (approximately 2 %) was formed from the hydrosilation reaction of silyl hydride-functionalized polymer and vinylsilane-functionalized polymer. Star polymers with an average number of 6.8 arms were obtained by reacting poly(styryl)lithium with 6.6 equivalents of vinyldimethylchlorosilane in benzene at 30 °C. It was found that, in benzene at 30 °C, vinyldimethylchlorosilane is an efficient linking agent for the preparation of well-defined star-branched polymers. In contrast, the reaction of poly(styryl)lithium with 5 equivalents of vinyldimethylchlorosilane in THF at -78 °C produced vinylsilane-functionalized polymer in high yield (> 93 %). Poly(styryl)lithium was reacted with 2.5 equivalents of vinyldimethylethoxysilane; reaction occurred exclusively by the addition of the living anion to the vinyl group. In-chain, dihydroxyl-functionalized polystyrene was prepared by reaction of poly(styryl)lithium and 1,3-butadiene diepoxide. The hydroxyl functionalities were activated with potassium naphthalenide. Addition of ethylene oxide monomer yielded the corresponding heteroarm polystyrene/poly(ethylene oxide) stars. Two commercially available triepoxides, N,N-diglycidyl-4-glycidyloxyaniline and Tactix 742, were used to prepare the corresponding 3-armed stars in high yield.

"The objective of this work was to anionically synthesize well-defined polymers having functional groups either at the chain-end or along the polymer chain. General functionalization methods (GFM) were used for synthesizing both kinds of polymers. Chain-end functionalized polymers were synthesized by terminating the anionically synthesized, living polymer chains using chlorodimethylsilane. Hydrosilation reactions were then done between the silyl-hydride groups at the chain-ends and the double bonds of commercially available substituted alkenes. This produced a range of well-defined polymers having the desired functional groups at the chain ends. In-chain functionalized polymers were synthesized by anionically polymerizing a silyl-hydride functionalized styrene monomer: (4-vinylphenyl)dimethylsilane. Polymerizations were done at room temperature in hydrocarbon solvents to produce well-defined polymers. Functional groups were then introduced into the polymer chains by use of hydrosilation reactions done post-polymerization. The functionalized polymers produced were characterized using SEC, 1H and 13C NMR, FTIR, MALDI TOF mass spectrometry and DSC. The monomer reactivity ratios in the copolymerization of styrene with (4-vinylphenyl)dimethylsilane were also measured. A series of copolymerizations was done with different molar ratios of styrene(S) and (4-vinylphenyl)dimethylsilane(Si). Three different methods were used to determine the values of the monomer reactivity ratios: Fineman-Ross, Kelen-Tudos and Error-In-Variable (EVM) methods. The average values of the two monomer reactivity ratios obtained were: r(Si) =0.16 and r(S) = 1.74. From these values it was observed that in the copolymerization of styrene with (4-vinylphenyl)dimethylsilane, the second monomer was preferentially incorporated into the polymer chain. Also, r(Si)r(S) = 0.27, which shows that the copolymer has a tendency to have an alternating structure. Amino acid-functionalized polymers (biohybrids) were synthesized by using a simple and efficient, three-step method. The first step was to make a copolymer of styrene with (4-vinylphenyl)dimethylsilane, followed by introduction of amine functional groups into the polymer chain, suing a hydrosilation reactions between the silyl-hydride units in the copolymer chain and the double bond of allyl amine. The third step was a condensation reaction between these amine functional groups on the copolymer chain and the carboxyl group on N-carbobenzyloxy-phenylalanine (a protected amino acid). Although this method has been used to incorporate a particular amino acid onto the polymer chain, it maybe possible to extend this procedure to introduce virtually any amino acid or peptide group into the polymer chain. Finally a thermoplastic elastomer (TPE) was synthesized using the monomer (4-vinylphenyl)dimethylsilane. The first block of this TPE was a copolymer block of styrene with (4-vinylphenyl)dimethylsilane, followed by a polyisoprene block and finally another copolymer block of styrene and (4-vinylphenyl)dimethylsilane. This polymer was characterized using SEC, 1H and 13C NMR, FTIR, DSC, DMTA, TEM and tensile testing. It was seen to exhibit properties similar to those of a regular styrene-diene-styrene TPE. However, the silyl-hydride units introduced into this polymer chain can be easily converted to different functional groups using hydrosilation reactions. Introduction of such functional groups would be helpful in tailoring the properties of the TPE."--Abstract.