Synthesis of a novel graphene-based gold nanocomposite using PVEIM-: B -PNIPAM as a stabilizer and its thermosensitivity for the catalytic reduction of 4-nitrophenol

A cationic block copolymer of poly(1-vinyl-3-ethylimidazolium bromide) and poly(N-isopropylacrylamide), abbreviated as PVEIM-b-PNIPAM, is used as a thermo-switch and a stabilizer to fabricate a novel thermo-sensitive graphene-gold nanocomposite via electrostatic interactions, one-pot in situ growth, and chemical reduction. The morphology, chemical structure, and thermosensitivity of the nanocomposite are systematically characterized, which manifests that the PVEIM-b-PNIPAM stabilizer leads to uniformly distributed gold nanoparticles (GNPs) on the surface of reduced graphene oxide (RGO). The new nanocomposite has good dispersibility and high catalytic activity for the reduction of 4-nitrophenol. In addition, the phase transition of this nanocomposite can be reversibly modulated by temperature in water, which results in significantly different catalytic activities depending on the temperature. This thermo-sensitive nanocomposite may be applied as a thermo-switch material for heterogeneous catalysis, sensors, smart material devices etc.