In situ formation of copper nanoparticles in a p(NIPAM-VAA-AAm) terpolymer microgel that retains the swelling behavior of microgels

Abstract

Abstract Copper nanoparticles (CuNPs) are formed inside a microgel assembly by an in situ reduction method, confirmed by changes observed in the absorption spectra of CuNPs at different pH values. The presence of CuNPs has been also confirmed by X-ray diffraction (XRD) studies. The terpolymer microgel p(N-isopropylacrylamide-vinyl acetic acid-acrylamide) (p[NIPAM-VAA-AAm]), which is reported for the first time, was synthesized by free radical emulsion polymerization of a temperature-sensitive NIPAM monomer, pH sensitive VAA monomer and a hydrophilic AAm monomer. The effect of temperature below and above the pKa of VAA and the effect of pH at 20°C in the absence and presence of CuNPs on the hydrodynamic radius of microgel was studied. Size of microgel particles is a function of temperature due to the presence of NIPAM, and a function of pH due to the presence of VAA. The presence of CuNPs has little or no effect on the size of microgels by varying pH, which allows these gels to retain their properties with added benefits of CuNPs for possible drug delivery applications.