高分子化学（浙江大学） polymer3 Free Radical Copolymerization

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1、Chapter3FreeRadicalCopolymerization21IntroductionHomopolymerization——polymerizationofonekindofmonomer;Copolymerization(additionpolymerization)——polymerizationofmorethanonekindofmonomer;1.1ConceptNewkindsofcopolymercanbesynthesizedbycopolymerizationofdifferent

2、combinationofvariousmonomers.Copolymergeneratedfromsamemonomerscanhavedifferentcompositionsandtopologies.4ExamplesStyreneStyrene+AcrylonitrileStyrene+ButadieneStyrene+Acrylonitrile+ButadienePSSANSBRABSBrittle,transparent,poorsolventtolerationHighimpact,goodsol

3、venttolerationHighelasticityEngineeringplasticsMaleicanhydrideStyrene+maleicanhydrideNopolymerSMA1.2TypeofcopolymeralsoobtainedbyothermethodsNormallypreparedbyothermethodspoly(ethylene-co-propylene)乙烯-丙烯共聚物poly(ethylene-r-propylene)乙烯-丙烯无规共聚物poly(ethylene-b-pr

4、opylene)乙烯-丙烯嵌段共聚物poly(ethylene-g-propylene)乙烯-丙烯接枝共聚物poly(ethylene-a-styrene)乙烯-苯乙烯交替共聚物1.2NomenclatureofcopolymerKeytopicsincopolymerization-ABABBAABABBAAABABA-Compositiondistributiontherelativeamountsofeachmonomerunitincorporatedintothecopolymer,A%orB%Seque

5、ncedistributionthewayinwhichthesemonomerunitsarearrangedwithinapolymerchain;AAorAB82.Copolymercomposition9EssentialPointThecompositionofacopolymerdoesnotnecessarilymatchthecompositionofthecomonomersusedinthereaction(feedratio投料比).Ethylene-vinylacetatecopolymer

6、vinylacetate%property10~20plastic30~40adhesive50rubber10Possiblepropagationsequencesinfree-radicalcopolymerization11assumptionsincopolymerizationtherateofthepropagationbechain-length-independent.onlytheterminalunitofthepolymerradicalcanaffectitsreactivitynosi

7、dereactions,suchasdepropagation,monomerpartitioning,andvariousformsofcomplexformation12Reactionsincopolymerization13Theoverallratesofconsumptionofmonomers[M1],[M2]thenfollowtheseexpressions:ignoretheinitiationTheexpressionforinstantaneouscopolymercomposition(F

8、1/F2)molarfractionofM1molarfractionofM22.1CopolymercompositionequationSteady-stateassumptionMayo-LewisEquation16Reactivityratio（竞聚率）Specialcases:r1=0andr2=0Eachcomonomerpreferstore