【正文】 hydroxyl groups on the FG, single FG/methylaluminoxane (MAO) nanosheets can b由于表面羥基上的FG存在下，單FG /甲基鋁氧烷（MAO）的納米片可以effectively dispersed in n heptane, thus enabling immobilization of an MAOactivated chromium (Cr1) singlesite catalyst on F有效地分散在 正庚烷，從而使一個被MAO活化的鉻（CR1）上的FG單活性中心催化劑固定化。 Unparalleled by any other 與其他carbon and boehmite nanoposites, FG/UHMWPE exhibited碳和水軟鋁石納米復合材料相比，F(xiàn)G / UHMWPE unusual simultaneous improvement in stiffness, elongation at break, and在剛性上表現(xiàn)出不尋常的同步提高，斷裂伸長率， effective nucleation of polyethylene crystallization at only 1 wt % FG聚乙烯結晶僅為1％（重量）。. . . .. . Novel Graphene UHMWPE Nanoposites Prepared byPolymerization Filling Using SingleSite Catalysts Supported onFunctionalized Graphene Nanosheet DispersionsMarkus Stu?rzel,*,? Fabian Kempe,? Yi Thomann,? Stefan Mark,? Markus Enders,? and Rolf Mu?lhaupt*,?Freiburg Materials Research Center (FMF) and Institute for Macromolecular Chemistry, University of Freiburg, StefanMeierStr.31, D79098 Freiburg, GermanyAnorganischChemisches Institut, University of Heidelberg, Im Neuenheimer Feld 270, D69120 Heidelberg, GermanyABSTRACT: Novel families of ultrahighmolecularweight polyethylene (UHMWPE) nanoposites, containing uniformly dispersed,functionalized graphene (FG) nanosheets, were prepared by means ofthe polymerization ?lling technique (PFT). Unparalleled by any othercarbon and boehmite nanoposites, FG/UHMWPE exhibited anunusual simultaneous improvement in stffness, elongation at break, andeffective nucleation of polyethylene crystallization at only 1 wt % FGcontent. FG nanosheets are ultrathinwith a thickness of only one carbon atom and lateral dimensions of several micrometers.Owing to the presence of surface hydroxyl groups on the FG, single FG/methylaluminoxane (MAO) nanosheets can beeffectively dispersed in nheptane, thus enabling immobilization of an MAOactivated chromium (Cr1) singlesite catalyst on FG.In contrast to nanometerscale carbon black (CB), multiwall carbon nanotubes (CNT), graphite, and nanoboehmite, which failedto form stable dispersions, FG/MAO/Cr1 afforded the highest catalyst activities and excellent morphological control. Inpolymerization ?lling, the integration of a nanoparticle dispersion into the polymerization process eliminated the need for specialsafety and handling precautions typically required by conventional pounding of nanoparticles with ultralow bulk densities. 學習好幫手INTRODUCTIONUltrahighmolecularweight polyethylene (UHMWPE), withmolar weights exceeding 1 million, is wellknown for itsultrahigh toughness bined with high abrasion resistance,very low friction coeffcient, low moisture uptake, and excellentchemical Sheets, parts, and ?bers are produced fromUHMWPE. Applications range from wearresistant transportbelts and supertough engineering plastics to biomaterials,implants for use in hip, knee, and spine replacements,ultrastrength gelspun UHMWPE fabrics for waterrepellantropes, cutresistant gloves, and bulletproof body Formany applications it is highly desirable to improve theUHMWPE crystallization rate, toughness/stiffness balance,and especially the electrical as well as thermal conductivitybecause UHMWPE is a thermal and electrical insulator.Provided that effective dispersion is achieved, anisotropicnanoparticles can signi?cantly improve polyole?n perform UHMWPE nano and microposites with carbonblack, graphite,4 and multiwall carbon nanotubes (MWCNT),5processed by means of pression molding, have beendeveloped to improve electrical conductivity. It should be notedthat dry powder blending with nanoparticles requires specialsafety precautions and handling procedures to preventemissions, dust explosions, and health hazards resulting fromnanoparticle inhalation or adsorption. A recent advanceintroduced electrostatic spraying of graphene nanoplatelet(GNP) suspensions with an average thickness of 6?8 nmand a speci?c surface area of 120?150 m2/g. Such GNP stackscontaining more than 60 graphene nanosheets produce169。 2012 American Chemical SocietyUHMWPE/GNP nanoposite ?lms that exhibit substantially improved fracture toughness and tensile strength at a verylow GNP content of only wt %.6 In conventionalapproaches toward UHMWPE nanoposites, graphiteoxide (GO) and chemically reduced GO were dispersed indiluents such as ethanol and then spraycoated onto UHMWPEpowder prior to pression For optimizing the material properties it is of great interest toimplement nano?ller dispersion directly into ethylene polymerization to bene?t from the low viscosity of the liquidpolymerization media, thus preventing emission of nanoparticles at the same time. Catalytic polymerization in thepresence of ?llers (“insitu polymerization”) is used extensivelyto produce conventional thermoplastic polyole?n poundswith very high ?ller content. In polymerization?lling processes,the ?llers are used as catalyst supports to enable matrix growthdirectly from the nano?ller surface. Progress in the polymerization?lling technique (PFT) for polyole?ns has beenreviewed by Dubois and ?10 Singlesite catalysttechnology offers exciting new opportunities for tailoring ole?npolymerization11 and PFT processes by designing bothmolecular polyole?n architectures and polyole?n particlemorphologies. PFT affords polyole?n nanoposites withsigni?cantly improved CNT dispersion and electrical conductivity, thus enabling effective electromagnetic shielding ofReceived: July 4, 2012Revised: August 13, 2012Published: August 30, 2012| Macromolecules 2012, 45, 6878?6887??■6878在功能化石墨烯納米片分散體上采用可支持的單中心催化劑通過聚合填充制備新型石墨烯超高分子量聚乙烯納米復合材料ABSTRACT: Novel families of ultrahighmolecularweight polyethy摘要：制備含有均勻分散func