Synthesis And Characterization Of Polymandelide And Lactide Methacrylate Block Copolymers

Author : Ali Ekrem Müftüoğlu
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (85 download)

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Download or read book Synthesis and Characterization of Various Macromolecular Architectures by Using Combined Controlled and Photoinitiated Polymerization Methods written by Ali Ekrem Müftüoğlu and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced polymeric materials with specialized properties are of great interest. Block and graft copolymers are the most demanded advanced materials since they display combined physical and mechanical properties. Because of their diverse macromolecular structures, they may possess novel characteristics required for many high-tech applications. Therefore, engineering macromolecular architectures is one of the major goals in polymer chemistry. Controlled polymerization methods appear to be the most powerful and versatile tools in achieving this goal. in the present work, macromolecular chains of various chemical compositions were ~ assembled in original topologies by combination of Atom Transfer Radical Polymerization (ATRP) or Ring-opening Polymerization (ROP) with photoinduced radical or radical promoted cationic polymerizations. These macromolecular architectures involve block, graft, block-graft, and brush type copolymers as well as miktoarm star copolymers and hyper-branched polymers... For this purpose, end-chain, mid-chain or side-chain mono- or bi- amino- or N;N- dimethylamino- functional precursor polymers were prepared either by A TRP or ROP. Subsequently, these prepolymers served as macromolecular co-initiators in photoinduced radical or promoted cationic polymerizations. For the preparation of diblock copolymers, N,N-dimethylaniline end-functional polystyrenes (PSt) with well-defined structures and low polydispersities were synthesized by A TRP of styrene in bulk at 11 O0C using 4-( dimethylamino )benzyl 4- (bromomethyl) benzoate as initiator in conjunction with a cuprous complex, Cu(I)Br/bipyridine. These polym'ers were further used in block copolymerization with methyl methacrylate (MMA) and cyclohexene oxide (CHO) via photoinduced radical and radical promoted cationic polymerization routes, respectively, as represented by (1) and (2). in the former case, macroradical generation was achieved with benzophenone sensitizer by photoexcitation followed by hydrogen abstraction from amino end groups. A visible light initiating system has been utilized in the radical promoted cationic polymerization of CHO. The system involves a xanthene dye (Erythrosin B) as the sensitizer, an aromatic N;N-dimethylamino group and diphenyl iodonium hexafluorophosphate as the radical source and radical oxidizer, respectively. While pure block copolymers were obtained in the free radical route, the free radical promoted cationic polymerization yielded both block and homopolymers...