高分子物理（浙江大学） 1 高分子的链结构 Chain Structure of Polymers-2.pptVIP

高分子的链结构 1.1 高分子结构的特点和分类 1.1.1 高分子的结构特点 1.1.2 高分子的结构层次 1.2 高分子链的近程结构 1.2.1 结构单元的化学组成 Composition of structural unit 聚丁二烯　PB Polybutadiene Only partial non-metal elements in Ⅲ A, ⅣA, ⅤA, ⅥA can form inorganic polymers 1.2.2 分子构造 1.2.3 键接异构 Bond order isomer Regio-selectivity of structural units in polymerization How to determine regio-regularity? 1.2.4 立体异构 Stereoisomerism 三种类型 Stereo-configuration affect polymer properties PS： isotactic PS：crystallizable，Tm=240 ?C ，uneasy to dissolve atactic PS：soft temperature 80 ?C ，soluble in benzene PP： isotactic PP： Tm=175 ?C ，high strength, used as fiber and engineering plastic atactic PP： soft, additive for paving asphalt Is stereoregularity the necessary condition for polymer crystallization? Stereo-isomerism and regio-isomerism may occur simultaneously! 1.2.5 共聚物的序列结构 无规共聚物 (random copolymer) Two or more monomer units distribute along the polymer chain randomly ABAABABBAAABABBAAA The interaction among structural units and the intermolecular interaction are altered. The solution properties, crystallizability and mechanical properties of the copolymer are different from the corresponding homopolymers. For example: PE and PP are plastics, but EP random copolymer is rubber. PTFE(聚四氟乙烯) is a plastics. Molten processing is impossible, but copolymer of tetrafluoroethylene and hexafluoropropylene is a thermoplastic. 嵌段共聚 (block copolymer) AAAAAAAAABBBBBBBBB polyA-b-polyB or poly(A-b-B) SBS (styrene-b-butadiene-b-styrene): prepared by living anionic polymerization SBS： thermoplastic elastomer high temp: can flow and can be processed by injection molding. low temp: like crosslinking rubber (PS chains at both ends are glassy, “physical” crosslinking). 接枝共聚 (graft copolymer) ABS (acrylonitrile-butadiene-styrene): ternary copolymer prepared by combination of random copolymerization and grafting polymerization.