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首页 Synthesis and applications of hyperbranched poly…

Synthesis and applications of hyperbranched polymers.pdf

Synthesis and applications of h…

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2013-02-27 0人阅读 举报 0 0 暂无简介

简介:本文档为《Synthesis and applications of hyperbranched polymerspdf》,可适用于工程科技领域

AbstrThThisshortekeyadvancestpertymodifi�Keywords:HyperbranchedpolymerDendrimerStepgrowthpolycondensationSelfcondensingvinylpolymerisationMultiTheABroutetohyperbranchedpolymersGraft�onto’andgraft�from’approachestohyperbranchedpolymers:ropoljEUROPEANPOLYMERJOURNAL*CorrespondingauthorTel:faxContentsHyperbranchedpolymers––backgroundSynthesisofhyperbranchedpolymersStepgrowthpolycondensationsPolyphenylenesPolyestersPolyamidesPolycarbonatesPolyureasandpolyurethanesPolyethersMiscellaneouspolymersSelfcondensingvinylpolymerisationofAB�monomersPolystyrenesPoly(methacrylate)sandpoly(acrylate)sMultibranchingringopeningpolymerisationoflatentABxmonomersPolyaminesPolyethersPolyestersAlternativeroutestowardsthesynthesisofhyperbranchedpolymersbranchingringopeningpolymerisationEmdoi:cationsandinhighvaluetechnologiesElsevierLtdAllrightsreservedaila$hathavebeenmadeintheapplicationofthesehyperbranchedmaterialsintheareasofmaterialproAvailableonlineMarchactedevelopmentofhyperbranchedpolymersisarapidlyexpandingfieldintheareaofmacromolecularsciencereviewhighlightssomeofthenotableexamplesinthesynthesisofhyperbranchedpolymersandsomeofthReceivedNovemberreceivedinrevisedformJanuaryacceptedFebruarySchoolofChemistry,TheUniversityofReading,Whiteknights,Berkshire,ReadingRGAD,UKCRYates,WHayes*SynthesisandapplicationsofhyperbranchedpolymersReviewEuropeanPolymerJournal()–wwwelseviercomlocateeuddress:wchayesreadingacuk(WHayes)seefrontmatter�ElsevierLtdAllrightsreservedjeurpolymjPhysicalpropertiesofhyperbranchedpolymersApplicationsofhyperbranchedpolymersBulkapplicationsofhyperbranchedpolymersSpecialistapplicationsofhyperbranchedpolymersConclusionReferencesHyperbranchedpolymers––backgroundHyperbranchedpolymersarearelativelynewclassofmacromoleculeswhichhavegainedsignificantattentionfrombothacademiaandindustrysinceFlory’sseminaltheoreticalreportinThepolymerisationofABxmonomers(wherexP)togeneratehighlytermsofmolecularweightcharacteristicsandtheirbranchingfactors,Severalmethodscanbeusedtosynthesisehyperbranchedpolymersfromanoniterativepolymerisationprocedure,includingtheselfcondensationofABmonomers,Consequently,thepolymersthusgeneratedexhibitanirregulararchitecturewithincompletebranchpointsdispersedthroughouttheInitiationBCCCBCBCBBSchemCRYates,WHayesEuropeanPolymerJournal()–C=PolymericLinkageABCWhereBTerminalGroupseBBCBBCABMonomerBCCBBBCBBCCBLinearUnitsAACbranchedsolublepolymerswasdescribedinthistheoreticaltreatmentandresultedinaninterestinbranchedpolymersandcomparisonoftheirrelativepropertieswithlinearanalogues,althoughthemajorityofearlyhyperbranchedpolymerstudies–wasfocuseduponthesynthesisofdendrimersTheseperfectlybranchedhyperbranchedmacromoleculeshavebeensynthesisedviaiterativesyntheticapproachesHowever,themainpracticaldisadvantagesofdendrimersarethatthesesynthesesarebothlabourandpurificationintensiveAsaconsequence,moreefficientroutestothegenerationofbranchedpolymersthatarelessreliantuponcomplexmultistepsyntheticprocedureshavebeeninvestigatedleadingtotheformationof�irregular’hyperbranchedpolymersTheseirregularbranchedpolymers,incontrasttodendrimers,arepolydispersesystemsbothinBSchematicrepresentationofahyperbranchedpolymercostructure,incomparisontotheirperfectdendriticanalogues(Scheme)Althoughthetheoreticalrationaleforbranchedpolymersynthesiswasproposedin,thefirstsynthesisofbranchedsystemswasreportedbyV€ogtleandcoworkersinThissynthesisinvolvedtheuseofaliphaticaminebasedABmonomerstoform�cascade’polymersthatcouldbeutilisedasmolecularcavitiesinthecomplexationofionicguestsThispioneeringstudyledtothesynthesisofmolecularreceptorsviaarepetitivereactionofamineswithacrylonitrile,followedbyreductionofthenitrilegroupstotheaminesThissequencewithacrylonitrileaffordedlengthened�cascade’moleculesV€ogtleutilisedthissyntheticstrategytogeneratebranchedandcyclicpolyazacompoundswithincreasinggrowingcavitysizeCBBCCCBranchPointsnstructedbythehomopolymerisationofABtypemonomersThesynthesisofhyperbranchedpolymerscanberationalisedintothreemainstrategies:(i)stepgrowthpolycondensationofABxandABmonomers,(ii)selfcondensingvinylpolymerisationofAB�monomersand(iii)multibranchingringopeningpolymerisationoflatentABxmonomersUtilisingthesepolymerisationstrategies,awidevarietyofhyperbranchedarchitectureshavebeensynthesisedsuccessfully,includingpolyesters,polyamides,polycarbonatesandpolyurethanesHyperbranchedpolymershavebeenutilisedinapplicationsinvariousfieldsrangingfromadditivestocoatingsandinmoreadvancedtechnologiessuchassensors,highloadingsupportsincombinatorialchemistrystudiesandhomogeneouscatalystsInthisshortreviewnotableexamplesofhyperbranchedpolymersarehighlightedinadditiontoanoutlineofsomeoftheapplicationsthathavebeeninvestigatedtodateHowever,theobjectiveofthisarticleisnottoprovideacomprehensivecoverageofthisrapidlyexpandingfieldandthereaderisdirectedtoseveralexcellentreviewsandbooksthathavebeentionTheprimaryadvantageofthisapproachisthatnormalstepgrowthpolymerisationcharacteristicsaremayoftenoccurwhichrenderspurificationofthedesiredproductsmoreproblematic,and(ii)undesirablesidereactionssuchascrosslinkingcanoccurinthepolymerisationprocessTheprerequisiteofthisapproachisthattheABxmonomersemployedhavetobesynthesisedpriortopolymerisationandthisefforthasproventobeadistinctdisadvantagebasedsimplyuponcommercialgroundsThestepgrowthpolycondensationroutehadbeenutilisedextensivelyinthesynthesisofadiverserangeofhyperbranchedsystemsasmanyfunctionalitiesaretoleratedPolyphenylenesTheinnovativeworkofV€ogtleledtothesynthesisofthefirstmacromolecularhyperbranchedpolyphenylenesystemthatwasreportedinbyKimandWebster,(Scheme)Thesynthesisinvolvedtheuseoftransitionmetalcatalysedreactionstogeneratethedesiredpolyphenyleneviatwocomplementaryaryl–arylcouplingreactionsEitherofthereactionsequencesusedemployedthesamemonomer,either,,tribromoorBrBr()i()CRYates,WHayesEuropeanPolymerJournal()–obeyed––themaindrawbacksare,however:(i)gelationXXXB(OH)XXMgXXXX=BrorClRouteARouteB)BuLi)B(OCH))HMgPdNpublishedinrecenttimes,,SynthesisofhyperbranchedpolymersStepgrowthpolycondensationsThisstrategyinvolvesthepolymerisationofABx(wherexP)monomersviaaonesteppolycondensaSchemeSynthesisofahyperbranchedpolyphenyleneutilisingtransXBrBrBrBrtrichlorobenzeneRouteAinvolvedmultipleSuzukicrosscouplingsoftheboronicacidderivative,whilstRouteBproceededviatheformationofaGrignardderivativeandsubsequentuseofanickelmediatedKumadatypecrosscouplingThehyperbranchedpolyphenyleneproducedbytheSuzukicrosscouplingpossessedamolecularweightandpolydispersityofand,respectively––however,RouteBaffordedhyperbranchedmaterialsfeaturingmuchlowermolecularweights()thatwerealsomorepolydisperseinnature(–)ThesehyperbranchedpolyphenylenesexhibitedgoodthermalstabilitiesandwereBrBrBrBrBritionmetalmediatedpolymerisationofABmonomers,solubleinawiderangeoforganicsolventsOnblendingthehyperbranchedpolyphenyleneswithpolystyrenethethermalstabilityofthepolystyrenewasimproved,asthemeltviscosityincreasedthreefoldasaconsequenceofthermalchaintransferThesehyperbranchedpolyphenylenescouldthereforebeenvisagedasthermalstabilitymodifiersM€ullenandMorgenrothhavereportedanalternativeapproachinthesynthesisofstructurallyrelatedhyperbranchedpolyaromaticsystemsinvolvingaDiels–AldercyclisationstrategyThesehyperbranchedpolyaromaticmaterialswereobtainedviathepolymerisationoftheABmonomer,,bis(triisopropylsilylethynylphenyl),diphenylcyclopenta,dienonewithtetrabutylammoniumfluorideindiphenyletherThehyperbranchedpolyphenylenesobtainedpossessedmolecularweightsintherangeof–withpolydispersitiesrangingfromto,dependinguponthereactiontimeandmonomerconcentrationThehyperbranchedpolymersexhibitedgoodthermalstabilityandweresolubleinawiderangeoforganicsynthesisofarelatedhyperbranchedpolyesterThispolymerwassynthesisedfrom,bis(trimethylsiloxy)benzoylchlorideastheABmonomer,(Scheme)inthepresenceorabsenceofacatalyst,suchastrimethylaminehydrochlorideorN,Ndimethylformamide(DMF)ThesehyperbranchedpolyesterswereobtainedwithmolecularweightsrangingfromtowithpolydispersitiesrangingfromtoAsinthecaseofthepolyphenylenes,thesehyperbranchedpolyesterspossessedbothgoodthermalstabilitiesandexcellentsolubilitycharacteristicsincommonorganicsolventsInanalternativeapproach,Feastetalcarriedoutstudiesonthepolymerisationof(hydroxyalkoxy)isophthalates(Fig)toaffordalkyl–arylpolyestersWhentheABmonomerswereheatedbetweenand�Cinthepresenceofatransesterificationcatalyst,stepgrowthpolymerisationofthedesiredhyperbranchedpolyestersoccurredwiththeeliminationofmethanolasthemainbyproductItwasobservedthatasthealkylenechainlengthwasvariedthepolymerisationcharacteristicswereaffectedInthecaseofn¼,boththemolecularweightandpolydispersityofthepolyHOOOHBmOOHnMeOCMeOCn=Fig(Hydroxyalkoxy)isophthalateABmonomersemCRYates,WHayesEuropeanPolymerJournal()–byKricheldorfandcoworkersFr�echetandcoworkersadoptedasimilarapproachinintheHOOHHOOMeSiOOSiMeClOHO∆TMeClEtNSOClClSchemeSynthesisofahyperbranchedpolyesterfromtheAsolventssuchastolueneandwereenvisagedasidealcandidatesforadvancedcoatingsystemsPolyestersNumerousexamplesofhyperbranchedpolyesters,botharomaticandaliphaticinnature,havebeenreportedintheliteraturefeaturingtheuseofawiderangeofABxmonomertypesThefirstbranchedpolyestersystemwassynthesisedbyeitherbulkorsolutionpolymerisationof,bis(trimethylsiloxy)benzoylchloridegroupsarehydrolysedtohydroxylfunctionalitiesOHOOOOOOOOOOOOOOHOOOOOHOOOOOOOOHOOOOOOHOOHOHOOOOHOonomerbis(trimethylsiloxy)benzoylchloridewheretheTMSployedinthesynthesisofhyperbranchedpolyestersmerincreasedwithincreasingreactiontimes,butwhenthealkylenechainlengthwasincreased(n>),theincreaseinmolecularweightwithmonomerconversionwasnolongerobservedInthesecases,themolecularweightincreaseduntilamaximumwasreached,afterwhichitremainedconstantandnofurthergrowthwasapparent,whichisaconsequenceofdeactivationorlossoftheAfunctionalityontheABmonomeremployedInasimilarstudy,Moureyandcoworkersinvestigatedthesynthesisofanacidchloridefunctionalisedhyperbranchedpolyesterinaonepotapproach(Scheme)Thisrouteprovedtobeefficientinthesynthesisofbranchedpolyestersthatweresolubleincommonorganicsolvents,suchastetrahydrofuran(THF)anddichloromethaneTheformationofaliphatichyperbranchedpolyestershasalsobeenstudiedextensivelyAnotablesynthesisinthisareaisthereactionofthecoremolecule(ethyl(hydroxymethyl),propanediol)andtheABmonomer,bis(hydroxymethyl)propionicacid(bisMPA)toaffordhyperbranchedaliphaticpolyesters(Scheme)Acoremoleculewasutilisedinordertoaidcontrolofthepolycondensation,indeedwhenthepolymerisationswerecarriedoutinabsenceofthecoremoiety,insolublecrosslinkedpolymericmaterialswereobtainedTheesterificationwasperformedinthebulkusinganacidcatalystandthehyperbranchedmaterialsobtainedpossessedhighmolecularweightsrangingfromtoBlencoweetalhavepublishedrecentlyarigidhyperbranchedpolyesterthatwassynthesisedusingcouplingreagentssuchas,dicyclohexylcarbodiimide(DCC)and,diisopropylcarbodiimide(DIC)withtheABmonomer,bis(hydroxypropynyl)benzoicacidThecouplingreagentactivatedtheacidiccomponentoftheABmonomer,whichtheninturnreactedwiththeacetylenicalcoholofanadjacentABmonomerunitThesepolymerisationswerecarriedoutsuccessfullyatroomtemperaturetoaffordhyperbranchedpolyesterswithmolecularweightsrangingfromtoandpolydispersitiesofand,respectivelySurprisingly,theseextremelyrigidunsaturatedpolyestersthusproducedexhibitedgoodsolubilitiesinsolventssuchasTHFOHOOHOOHTMSClOTMSOOTMSOOTMSOTMSOClOClSOClcatDMFi)MeNHClii)THFMeOHOOOOCRYates,WHayesEuropeanPolymerJournal()–ROROOROOOORRR=OSiMe,OHR=Cl,OMeSchemeSynthesisofanacidchloridefunctionalisedhyperbranOOOOOOOOROOOOOOOROOROOROOOOROOOOOORORRRRRchedpolyesterinaonepotpolymerisationprocedureHOHOOOOHOHOOCRYates,WHayesEuropeanPolymerJournal()–OHOHOHHOOHOHOH°CHOOOHOHOOHOHOOOOOHOHOOOHOHOHOPolyamidesIngeneral,therearetwodirectsyntheticapproachestowardshyperbranchedpolyamides:(i)lowtemperaturecondensationofaminesandacidchlorides,and(ii)thedirectpolycondensationbetweenaminesandcarboxylicacidsinthepresenceofcondensationreagentsBothoftheserouteshavebeenappliedsuccessfullytoconstructhyperbranchedpolyamidesThesynthesisreportedbyKimininvolvedthereactionofanaromaticABmonomer,andABmonomersinalowtemperaturecondensationapproach(Scheme)ThepolyamidesobtainedviathismethodweresolubleonlyinamidetypesolventssuchasN,Ndimethylacetamide(DMAC),DMFandNmethylpyrrolidinone(NMP)andthislimitedsolubilitymayrestricttheuseandprocessingofthesesystemsThemolecularweightsandpolydispersitiesofthehyperbranchedpolyaromaticamideswereintherangeof–and–,respectivelyanditwasobservedthatwhendissolvedinDMFaggregateswereformedFurthermore,asthemolecularweightsofthesehyperbranchedpolyamidesexceededinterestinglyotropicliquidcrystallinecharacteristicswereexhibitedFeastandcoworkersinvestigated,,analternativeapproachintheformationofaliphaticpolyamidesTheapproachusedentailedtheuseSchemeSynthesisofahyperbranchedaliphaticpolyesterfrombis(MOOOOOOOOHOOOOOOHOOOHOHOOOHOOHOOHOOOOOHOOHOOHOHOOOOOOHOOOOOHOOOOHHOOOOOOOOOOOOHOHOOOHOHHOOOOOOOOHOHOOOHHOOHOOOOHOOOOOOHOOOOOHOOOHOHOOOOOOHOHOHOHOOofNacryloyla,xdiaminoalkanehydrochloride(Scheme)whichwassynthesisedbyadirectprotectiondeprotectionsequenceandwaspolymerisedsubsequentlyviaaMichaeladditionprocesswhenthereactiontemperaturewasraisedto�CThesehyperbranchedpolyamidespossessedinterestingviscositycharacteristics––asthemolecularweightofthepolymerincreasedtheintrinsicviscositydecreasedInaddition,thehydrochloridesaltsofthesepolyamidesweresolubleinwaterandmethanol,butwereinsolubleinorganicmediaasthefreebasesandcouldthereforebeutilisedaswatersolublepolyelectrolytesPolycarbonatesPolycarbonateshavefoundextensiveuseasengineeringthermoplasticmaterialsasaconsequenceofthecombinationofexcellentmechanicalandphysicalpropertiesToexpandandimproveuponthesewellunderstoodphysicalproperties,branchedpolycarbonatestructureshavebeensynthesise

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Synthesis and applications of hyperbranched polymers

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