Synthesis and characterization of PNM@IAM core-shell microgels through inverse emulsion polymerization and its application for heavy metal ions capture

Abstract

In this study, thermo and pH-sensitive multifunctional poly (N-isopropylacrylamide-co- N,N’-methylenebisacrylamide, Poly(NIPAAm-co-MBA) - (N-4-amino-2-methylene-4-oxobutanoic acid, IAM) named as (PNM@IAM) core-shell microgels are synthesized by inverse microemulsion polymerization technique using two monomers, N-isopropylacrylamide (NIPAAm) and N-4-amino-2-methylene-4-oxobutanoic acid (IAM). The formation of the microgels are confirmed by 1H nuclear magnetic resonance (1H NMR) and attenuated total reflection fourier transform infrared (ATR-FTIR) spectra. The light transmittance study shows that the microgels prepared at different concentrations and pHs exhibit different physical properties. The phase transition temperature is increased with the addition of IAM. Dynamic light scattering (DLS) analysis reveals that the swelling of the microgels at basic environment is due to the deprotonation of the weak acid groups in IAM. The metal ion chelating test shows that the core-shell PNM@IAM could effectively absorb metal ions in highly basic environment. The absorption and release of heavy metal ions from aqueous solution could be controlled by adjusting the pH of the reaction environment.