Quaterpolymeric microgel stabilized cuprous oxide nanoparticles in catalytic reduction of methylene blue

This article presents the catalysis of dual hydrophobic monomer-based quaterpolymeric microgel stabilized cuprous oxide (Cu 2 O) nanoparticles in the chemical reduction of the harmful methylene blue (MB) dye. Styrene (St), 2-acrylamido-2-methylpropane sulfonic acid (AMPS), cyclohexyl methacrylate (CHMA), and N-(hydroxymethyl)acrylamide (NHMA) have been used for the fabrication of the microgel through free-radical emulsion polymerization. The two hydrophobic components (St and CHMA) of the microgel have been chosen to increase the stability of the nanoparticles. Among the four monomers, NHMA works as a crosslinker as well. By varying the amounts of Cu 2 O nanoparticles, while keeping the microgel amount constant, three grades of nanocomposites (MG@Cu 2 O-1 to MG@Cu 2 O-3) have been fabricated. The synthesized microgels and the nanocomposites have been characterized by Fourier transform infrared spectroscopy, elemental dispersive X-ray analysis, dynamic light scattering, scanning electron microscopy, transmission electron microscopy, and thermal gravimetric analysis. X-ray diffraction and elemental dispersive X-ray analyses have supported the presence of Cu 2 O nanoparticles in the microgel matrix. Further, the kinetics of the catalytic reduction of MB dye, using NaBH 4 as reducing agent, have been studied under different concentrations of the nanocomposite and the reducing agent. The MG@Cu 2 O nanocomposites have shown superior stability and reusability for several cycles, by maintaining a significant catalytic efficiency with minimal activity drop. It has been observed that the catalytic efficiency increased with higher NaBH 4 concentrations.