Thermoresponsive poly(N-vinylcaprolactam) nanocomposite hydrogels containing graphene were successfully prepared by frontal polymerization. High concentration of graphene (5.0 mg/mL) was obtained by direct graphite sonication in the self-same liquid monomer, thus avoiding any chemical manipulation and obtaining real graphene as nanofiller instead of one of its more or less oxidized derivative, which is what generally reported in published reports. Furthermore, the corresponding nanocomposites were obtained without using any solvent to be eventually removed. The materials were fully characterized by RAMAN, SEM, and TEM, and their swelling behavior and rheological properties were investigated. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012