Functionalization of Graphene Oxide Towards Thermo-Sensitive Nanocomposites via Moderate In Situ SET-LRP

A mild and efficient strategy is presented for growing thermo-sensitive polymers directly from the surface of exfoliated graphene oxide (GO). This method involves the covalent attachment of Br-containing initiating groups onto the surface of GO sheets followed by in situ growing poly[poly(ethylene glycol) ethyl ether methacrylate] (PPEGEEMA) via single-electron-transfer living radical polymerization (SET-LRP). Considering the lack of reactive functional groups on the surface of GO, exfoliated GO sheets were subjected to an epoxide ring opening reaction with tris(hydroxymethyl) aminomethane (TRIS) at room temperature. The initiating groups were grafted onto TRIS-GO sheets by treating hydroxyls with 2-bromo-2-methylpropionyl bromide at room temperature. PPEGEEMA chains were synthesized by in situ SET-LRP using CuBr/Me6TREN as catalytic system at 40 degrees C in H2O/THF. The resulting materials were characterized using a range of testing techniques and it was proved that polymer chains were successfully introduced to the surface of GO sheets. After grafting with PPEGEEMA, the modified GO sheets still maintained the separated single layers and the dispersibility was significantly improved. This TRIS-GO-PPEGEEMA hybrid material shows reversible self-assembly and deassembly in water by switching temperature at about 34 degrees C. Such smart graphene-based materials promise important potential applications in thermally responsive nanodevices and microfluidic switches. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 4747-4755, 2011