Synthesis of bimetallic nanoparticles loaded on to PNIPAM hybrid microgel and their catalytic activity

This study was designed to preparecarboxyl-functionalized poly (N-isopropylacrylamide) PNIPAM microgels having excellent catalytic properties.Recently, researchers are trying to fabricate cost effective and efficient hybrid catalytic materials for the synthesis of nitrogenous compounds along with enhanced optical properties. For the same motive, synthesis of carboxyl-functionalized PNIPAM microgels was performed by using polymerization of soap-free emulsion of N-isopropyl acrylamide, which is NIPAM along with acrylic acid (AA). The thiol group was introduced through the imide bond mediated by carbodiimide, between carboxyl-functionalized microgels through carboxyl group and aminoethanethiol (AET). Copper, Palladium and Cu/Pd nanoparticles were incorporated successfully into thiol-functionalized PNIPAM microgels through metals thiol linkage. The synthesized microgels and hybrid encompassing metallic nanoparticles were characterized in detail by using Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron (XPS) and Fourier transformed infrared spectroscopy for structural interpretation. The thermal properties of the pure and hybrid microgels were inspected by TG analysis. The prepared nanocomposites PNIPAM-Cu, PNIPAM-Pd and PNIPAM-Cu/Pd exhibited decent catalytic properties for the degradation of 4-Nitrophenol and methylene blue, but the bimetallic Cu/Pd have remarkable catalytic properties. The catalytic reaction followed pseudo-first-order reaction with rate constants 0.223 min⁻¹, 0.173 min⁻¹ for 4-Nitrophenol and methylene blue in that order. In this study,we were able to establish that Cu/Pd hybrid is an efficient catalyst for 4-Nitrophenol and methylene blue as compared to its atomic analogue.