A kind of smart gold nanoparticle–hydrogel composite with tunable thermo-switchable electrical properties

Abstract

A well-dispersed gold nanoparticle–poly-N-isopropylacrylamide (PNIPAm) hydrogel composite with thermo-switchable electrical properties was prepared by the co-polymerization of Au nanoparticles with attached vinyl groups with NIPAm. The Au nanoparticles and the composite are characterized by TEM, UV-Vis, FTIR, and NMR. At the same time, the electrical conductivity, cyclic voltammetry and constant-pontential technique were used to demonstrate the electrical properties of the composite. It was found that the electrical properties of the composite show a tunable property with changing temperature and the electrical conductivity changes by two orders of magnitude at the transition temperature (T_tran). The T_tran of the composite can be adjusted from 0 °C to 40 °C by changing the concentration of Au nanoparticles, the degree of cross-linking or the composition of composite. The change in electrical properties is reversible in a heating and cooling cycle.