简介：Thechaindynamicsofapairofdiblockpoly(styrene-b-butadiene)(PS210-b-PB960)andtriblockpoly(styrene-b-butadiene-b-styrene)(PS200-b-PB1815-b-PS200)copolymersinbothdiluteandsemidilutetoluenesolutionshasbeencomparativelystudiedbydynamiclaserlightscattering.Asexpected,themutualdiffusionofindividualchainchangesintoafastcooperativediffusionofthechainsegments('blobs')betweentwoneighboringentanglementpointsforboththecopolymersasthesolutionchangesfromdilutetosemidilute.Furtherincreasesoftheconcentrationleadtoasecondslowrelaxationmode.Forthetriblockchains,thereexistsanadditionalmiddlerelaxationbetweenthefastandtheslowmodes.with0.33＜α＜0.44,muchsmallerthan0.75predictedor0.72observedforlinearhomopolymerchainsingoodsolvent.ItimpliesthatthesolventqualityoftolueneforPBmightnotbeasgoodasthatforPS.Duetosuchadifferenceinsolubility,itisreasonabletospeculatethatthePBandPSblocksaretransientlysegregatedinsemidilutesolution.TherelaxationofthesetransientPBandPSricherdomainsleadstotheobservedslowrelaxation.Suchaspeculationissupportedbytheappearanceofanadditionalslowrelaxationmodeinthestudyofpolyisoprene-b-polystyrene-b-polyisopreneinsemidilutesolutionincyclohexane,anon-selectivesolvent,inwhichwealternatedthesolubilitydifferencebyavariationofthesolutiontemperature.