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1、.pubs.acs.org/MacromoleculesNovelGrapheneUHMWPENanocompositesPreparedbyPolymerizationFillingUsingSingle-SiteCatalystsSupportedonFunctionalizedGrapheneNanosheetDispersionsMarkusStürzel,*,†FabianKempe,†YiThomann,†StefanMark,‡MarkusEnders,‡andRolfMülhaupt*,†FreiburgMaterialsResea
2、rchCenter(FMF)andInstituteforMacromolecularChemistry,UniversityofFreiburg,Stefan-Meier-Str.31,D-79098Freiburg,GermanyAnorganisch-ChemischesInstitut,UniversityofHeidelberg,ImNeuenheimerFeld270,D-69120Heidelberg,GermanyABSTRACT:Novelfamiliesofultrahigh-molecular-weightpolyethy-len
3、e(UHMWPE)nanocomposites,containinguniformlydispersed,functionalizedgraphene(FG)nanosheets,werepreparedbymeansofthepolymerizationfillingtechnique(PFT).Unparalleledbyanyothercarbonandboehmitenanocomposites,FG/UHMWPEexhibitedanunusualsimultaneousimprovementinstffness,elongationatbre
4、ak,andeffectivenucleationofpolyethylenecrystallizationatonly1wt%FGcontent.FGnanosheetsareultrathinwithathicknessofonlyonecarbonatomandlateraldimensionsofseveralmicrometers.OwingtothepresenceofsurfacehydroxylgroupsontheFG,singleFG/methylaluminoxane(MAO)nanosheetscanbeeffectivelyd
5、ispersedinn-heptane,thusenablingimmobilizationofanMAO-activatedchromium(Cr1)single-sitecatalystonFG.Incontrasttonanometer-scalecarbonblack(CB),multiwallcarbonnanotubes(CNT),graphite,andnanoboehmite,whichfailedtoformstabledispersions,FG/MAO/Cr1affordedthehighestcatalystactivities
6、andexcellentmorphologicalcontrol.Inpolymerizationfilling,theintegrationofananoparticledispersionintothepolymerizationprocesseliminatedtheneedforspecialsafetyandhandlingprecautionstypicallyrequiredbyconventionalcompoundingofnanoparticleswithultralowbulkdensities...INTRODUCTIONUltr
7、ahigh-molecular-weightpolyethylene(UHMWPE),withmolarweightsexceeding1million,iswell-knownforitsultrahightoughnesscombinedwithhighabrasionresistance,verylowfrictioncoeffcient,lowmoistureuptake,andexcellentchemicalstability.1Sheets,parts,andfibersareproducedfromUHMWPE.Applicationsr
8、angefromwear-resistanttransportbeltsandsupertou