| Abstract
| - A core−shell hybrid nanostructure, possessing a hard backbone of multiwalled carbonnanotube (MWNT) and a soft shell of brushlike polystyrene (PS), was successfully prepared by in situatom transfer radical polymerization (ATRP), using Cu(I)Br/N,N,N‘,N‘‘,N‘‘-pentmethyldiethylenetriamine(PMDETA) as the catalyst, at 100 °C in diphenyl ether solution. The molecular weight of PS was wellcontrolled, as was the thickness of the shell layer. TEM images of the samples provided direct evidencefor the formation of a core−shell structure, i.e., the MWNT coated with polymer layer. FTIR, 1H NMR,SEM, and TGA were used to determine the chemical structure, morphology, and the grafted PS quantitiesof the resulting products. To further establish the covalent linkage between PS and MWNT moieties, theresulting PS-functionalized MWNTs were defunctionalized by hydrolysis or by thermal decomposition.Comparative studies, based on TEM and SEM images between the PS-functionalized and chemicallydefunctionalized MWNT samples, also revealed the covalent coating character. GPC analysis showedthat the number-average molecular weight (Mn) of the grafted PS chains ranged from 5000 to 11 000with a relatively broad polydispersity index (PDI, ca. 1.77−3.57). Further copolymerization of tert-butylacrylate (tBA) with the PS-linked MWNTs as initiators was realized, illustrating that (1) the PS speciesis still “living” although the lower controllability of PDI and (2) acrylate-type monomers can becopolymerized with styrene-type ones on the sidewalls of the MWNT. We believe that achieving thesehybrid objectives, on the basis of such simple grafting, will pave the way for the design, fabrication,optimization, and eventual application of more functional carbon nanotube-related nanomaterials.
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