高分子化学浙江大学polymer3FreeRadicalCopolymeriza

Chapter3FreeRadicalCopolymerization,2,1Introduction,Homopolymerizationpolymerizationofonekindofmonomer;Copolymerization(additionpolymerization)polymerizationofmorethanonekindofmonomer;,1.1Concept,Newkindsofcopolymercanbesynthesizedbycopolymerizationofdifferentcombinationofvariousmonomers.Copolymergeneratedfromsamemonomerscanhavedifferentcompositionsandtopologies.,4,Examples,StyreneStyrene+AcrylonitrileStyrene+ButadieneStyrene+Acrylonitrile+Butadiene,PSSANSBRABS,Brittle,transparent,poorsolventtolerationHighimpact,goodsolventtolerationHighelasticityEngineeringplastics,MaleicanhydrideStyrene+maleicanhydride,NopolymerSMA,1.2Typeofcopolymer,alsoobtainedbyothermethods,Normallypreparedbyothermethods,poly(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-propylene)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,1.2Nomenclatureofcopolymer,Keytopicsincopolymerization,-ABABBAABABBAAABABA-,Compositiondistributiontherelativeamountsofeachmonomerunitincorporatedintothecopolymer,A%orB%,Sequencedistributionthewayinwhichthesemonomerunitsarearrangedwithinapolymerchain;AAorAB,8,2.Copolymercomposition,9,EssentialPoint,Thecompositionofacopolymerdoesnotnecessarilymatchthecompositionofthecomonomersusedinthereaction(feedratio投料比).,Ethylene-vinylacetatecopolymervinylacetate%property1020plastic3040adhesive50rubber,10,Possiblepropagationsequencesinfree-radicalcopolymerization,11,assumptionsincopolymerization,therateofthepropagationbechain-length-independent.onlytheterminalunitofthepolymerradicalcanaffectitsreactivitynosidereactions,suchasdepropagation,monomerpartitioning,andvariousformsofcomplexformation,12,Reactionsincopolymerization,13,TheoverallratesofconsumptionofmonomersM1,M2thenfollowtheseexpressions:,ignoretheinitiation,Theexpressionforinstantaneouscopolymercomposition(F1/F2),molarfractionofM1,molarfractionofM2,2.1Copolymercompositionequation,Steady-stateassumption,Mayo-LewisEquation,16,Reactivityratio（竞聚率）,Specialcases:r1=0andr2=0Eachcomonomerpreferstoreactwiththeother.Perfectlyalternatingcopolymer.r11andr21Eachcomonomerpreferstoreactwithothersofitsownkind.Tendencytoformblockcopolymers.r1*r2=1Thereisnopreferenceduetothechainends.Randomincorporationofcomonomers;“Ideal”copolymerization.,Theratioofratecoefficientofhomopolymerizationtocopolymerization,17,Examples,Neithermonomerhomopolymerizesverywell.FormsalmostperfectlyalternatingcopolymerofhighMW.Alternatingcopolymerizationiscommoninfreeradicalreactionswhenonemonomerhaselectronwithdrawinggroupsandtheotherhaselectrondonatinggroups.,18,InfluneceofPolymerizationmechanismonr,St(M1)-MMA(M2)Radical：r1=0.52,r2=0.46;Cationic：r1=10,r2=0.1;Ionic:r1=0.1,r2=6;,19,Copolymerequationintermsofmolefraction,Copolymercompositiondependsonnotonlythemonomerfeed,butthereactivityratioaswell.,20,0,1,r1,r11ork11k12tendtohomo-thancopolymn.,r1k12onlyhomopolymn.,butadiener1=1.39,styrener2=0.78,1.Idealcopolymerization(r1*r2=1),Typicalcopolymercompositioncurves,r11,22,A.r1=r2=1,B.r11,C.r11,r21,azeotropiccopolymerization恒比共聚copolymercompositionequalstomonomerfeed,VDC(偏氯乙烯)-MMA,r1=1.0,r2=1.0Acrylamide(丙烯酰胺)-丙烯酸甘油酯,r1=1.0,r2=1.0Ethylene-VAcr1=1.07,r2=1.08,23,Characteristicsofidealcopolymerization,Thereisnopreferenceduetothechainends.Randomincorporationofcomonomers.Idealcopolymerization,r1*r2=1,2.Alternativecopolymerization(r1=r2=0),Typicalcompositioncurves,Eachcomonomerpreferstoreactwiththeother.Perfectlyalternatingcopolymer.copolymercompositionindependentonmonomerfeed,Ifr2=0andr10,St/MMAinitiatedbyBPO/AlR3,3.Others,Typicalcompositioncurves,r11,block,r1r2=1randomr1=r2=0alternativer11,r21blockormixtureofhomopolymerr11,r21orr1andr21,28,Independentonmonomerconversion,29,2.3Copolymercompositionwithconversion,r11,f1orF1,conversion,r11,30,r11,31,Copolymercompositionwithconversion,Polymerizedmonomer,Monomerbeforepolym.,Monomerafterpolym.,Sincefvarieswithconversion,F1alsovarieswithconversion.Therefore,theaveragecopolymercompositionshouldbeobtainedbyintegration,32,Averagecopolymercomposition,M0=1M,St-MMAf10=0.8,f20=0.2,r1=0.53,r2=0.56,F1=f1=0.484,33,Controllingcopolymercomposition,苯乙烯-反丁烯二酸二乙酯共聚物瞬时组成与转化率的关系(r1=0.30,r2=0.07),Whenthef10isclosetoazeotropicpoint,thecopolymercompositionslightlyvarieswithconversion(90%).Whenthef10isfarfromazeotropicpoint,thecopolymercompositiongreatlyvarieswithconve