Synthesis and characterization of graphene sheets grafted with linear triblock copolymers based on methacrylate ester
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Two different linear triblock polymer-grafted graphene sheets (GSs) had been synthesized by chemical surface modification reaction. The linear terpolymers PtBMA101-b-PGMA19-b-PSt100 and PtBMA127-b-PHEMA21-b-PDMAEMA132 had been synthesized by reversible addition–fragmentation chain transfer process and with their narrow polydispersity index M w/M n of 1.25 and 1.33, respectively. The results of FTIR showed that the characteristic peak area of hydroxyl in the PtBMA127-g-GS-g-PDMAEMA132 was less than that of the graphite oxide (GO), while the signal of the aromatic ring at 710 cm−1 (from 750 to 690 cm−1) displayed in the PtBMA101-g-GS-g-PSt100. The ratio of the intensities (I D/I G) for the GSs in Raman spectra was markedly increased compared with that of the pristine GO. Both illuminated that the two different terpolymers had taken chemically covalent graft on the surface of the GO. The polymer grafting efficiency in the composite GSs was 44 and 42 mass% determined by thermogravimetry for PtBMA127-g-GS-g-PDMAEMA132 and PtBMA101-g-GS-g-PSt100, respectively. Friedman’s analysis showed that the apparent activation energies of the PtBMA101-g-GS-g-PSt100 were higher than those of the PtBMA127-g-GS-g-PDMAEMA132 during the thermal decomposition, because of the existence of the benzene ring for the former. The results from rheological analysis showed that the amphiphilic GSs solutions both displayed an obvious pseudoplastic fluid behavior, the existence of benzene ring in the amphiphilic PtBMA101-g-GS-g-PSt100 made the flowability of solution even worse than that of the amphiphilic PtBMA127-g-GS-g-PDMAEMA132 solution according to the same content of the GSs, and meanwhile, the flexible polymer arms of the PtBMA and PDMAEMA made the viscosity more sensitive to the shear rate for the PtBMA127-g-GS-g-PDMAEMA132.
KeywordsRAFT Linear triblock copolymer Graphene Thermogravimetry Friedman analysis
B.L. gratefully acknowledges the financial support from the National Natural Science Foundation of China (Grant No. 21204012) and the Guangdong Natural Science Foundation (Grant No. S2012040007981).
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