Thermoresponsive graphene oxide-PNIPAM nanocomposites with controllable grafting polymer chains via moderate in situ SET-LRP

In this study, we report a mild and efficient strategy for growing thermosensitive polymers directly from the surface of exfoliated graphene oxide (GO). Exfoliated GO sheets were sequentially subject to the epoxide ring-opening reaction with tris(hydroxymethyl) aminomethane (TRIS) to increase the amount of reactive sites, the esterification with 2-bromo-2-methylpropionyl bromide to introduce the Br-containing initiating groups, and the surface-initiated single electron transferliving radical polymerization of N-isopropylacrylamide (NIPAM) to tune the molecular weights of grafted polymers. All these reactions were performed at ambient temperature without losing any other oxygen-containing functionality on GO. The resulting TRIS-GO-PNIPAM nanocomposites still maintain the separated single layers in dispersion, and the dispersibilities in organic solvents are significantly improved. Meanwhile, the aqueous dispersion of TRIS-GO-PNIPAM shows reversible temperature switching self-assembly and disassembly behavior at about 40 degrees C. Such smart graphene-based hybrid materials are promising for applications in nanoelectronics, sensors, and microfluidic switches. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012