Preparation and characterization of poly(N-isoproylacrylamide-co-dimethylaminoethyl methacrylate) microgels and their composites of gold nanoparticles

Abstract

This work reports the crosslinkage of N-Isopropylacrylamide (NIPAM) and N, N-dimethylaminoethyl methacrylate (DMAEMA) in water using N, N’- methylene-bis(acrylamide) (BIS) as crosslinker. The particle size, volume phase transition temperature (VPTT), swelling and deswelling behaviors of the obtained poly(NIPAM-co-DMAEMA) microgels were studied at different temperature and pH using dynamic light scattering (DLS) technique. Additionally, investigation of particle size and VPTT of the microgels was done by altering the content ratio of DMAEMA monomer. The prepared microgels were used as a nanoreactor for the synthesis of gold nanoparticles (Au-NPs) using sodium borohydride (NaBH4) as reducing agent. The in situ synthesized Au-NPs were characterized and visualized by UV–vis Spectroscopy and TEM analysis, respectively. Optical properties of poly(NIPAM-co-DMAEMA)/Au-NPs composite were studied by changing the concentration of gold(III) chloride trihydrate (HAuCl4·3H2O), sodium borohydride (NaBH4) and temperature of the system. The prepared microgel composite were used as a catalyst for the reduction of toxic 4-nitrophenol (4-NP) with apparent rate constant (kapp) of 0.336min−1. Catalytic activities of the microgel composite were tuned by making use of thermoresponsive behavior of the microgels. Due to temperature and pH responsive nature of the synthesized microgels they have potential for application in drug delivery and sensory materials.