Silver Nanoparticles Engineered Polystyrene-Poly(N-isopropylmethacrylamide-acrylic acid) Core Shell Hybrid Polymer Microgels for Catalytic Reduction of Congo Red

Polystyrene-poly(N-isopropylmethacrylamide-acrylic acid) [pSty-p(NIpmam-AC)] core shell microgels loaded with silver nanoparticles (NPs) as a recyclable catalyst for rapid reduction of Congo Red (CR) dye in aqueous medium is reported for the first time. Catalytic activity of Ag-pSty-p(NIpmam-AC) core shell composite microgels is measured by adopting the reduction of CR as a benchmark reaction. Restriction of Ag NPs in single layered p(NIpmam-AC) shell of Ag-pSty-p(NIpmam-AC) core shell composite microgels enhances the diffusion of reactants to access the Ag NPs, surface during reaction with respect to previously reported core shell and homogenous composite microgels, and thus enhances the rate of CR reduction. The solid nonresponsive pSty core induces easy recyclability in core shell composite microgel catalysts. The effect of different reaction parameters such as amount of catalyst, concentration of NaBH4 and CR on the reaction completion time for CR reduction, as well as on the value of apparent rate constant (k(app)), is also studied by keeping all other parameters constant, separately. Reduction efficiency of Ag-pSty-p(NIpmam-AC) catalyst is also measured under different reaction conditions for the reduction of CR. A slight decrease in the percentage activity of Ag-pSty-p(NIpmam-AC) catalyst is observed for up to four cycles for CR reduction. The reported Ag-pSty-p(NIpmam-AC) composite microgel catalysts can be used to degrade other pollutants.