Acrylic Acid and Methacrylic Acid Based Microgel Catalysts for Reduction of 4-Nitrophenol

Abstract

N-isopropylacrylamide (NIPAM) monomer is copolymerized with acrylic acid (AA) and methacrylic acid (MAA) to synthesize poly-N-isopropylacrylamide-acrylic acid) [P(NIPAM-AA)] and poly(N-isopropylacrylamide-methacrylic acid) [P(NIPAM-MAA)] microgels. Both of these microgels possess same mol percentage of monomer and co-monomer. In order to study the influence of nature of co-monomer on size of in-situ synthesized nanoparticles, silver ions are reduced within these microgels under same conditions. The prepared samples are analyzed by Fourier transform infrared microscopy (FTIR), scanning electron microscopy (SEM), dynamic light scattering (DLS) and UV‒Vis spectroscopy. Synthesized hybrid microgels are used as catalysts for reduction of 4-nitrophenol under same conditions to investigate the influence of nature of co-monomer on apparent rate constant (k_app) of catalysis. Effect of various catalyst dosages on value of k_app is also studied. It is observed that value of k_app does not linearly increase with increase in catalyst dosage but it follows a different pattern. The dependences of dosages of both hybrid microgels on k_app are also compared. The effect of dosages of both catalysts on reaction time and catalysis duration is also studied.