Functionalization of Single-Walled Carbon Nanotubes with Poly(methyl methacrylate) by Emulsion Polymerization

Covalent grafting of acrylate-functionalized single-walled carbon nanotubes (SWCNTs) with poly(methyl methacrylate) was accomplished by emulsion polymerization using sodium dodecylbenzene sulfonate (SDBS) as an emulsifying agent. The acrylate-functionalized SWCNTs with polymerizable vinyl groups on their surfaces were prepared by a reaction sequence involving oxidation, hydroxylation, and vinylation reactions. The as-prepared acrylate-functionalized SWCNTs were then dispersed in water in the presence of SDBS, resulting in the exfoliation of SWCNTs into small bundles of approximately 2−6 tubes and the simultaneous formation of SWCNT micelles. Subsequent addition of methyl methacrylate resulted in its absorption into the SWCNT micelles due to the interactions between the monomer and the nanotube surface. Grafting copolymerization of methyl methacrylate with the vinyl groups on the SWCNT surface was subsequently performed in the micelles to produce poly(methyl methacrylate)-functionalized SWCNTs. Thermogravimetric analysis indicated that the average polymer content in the functionalized SWCNTs ranged from 42 to 63 wt %, depending on the time of monomer pre-emulsion.