Approach to the preparation of temperature-sensitive poly(N-isopropylacrylamide)/polyethylenimine microgel

Abstract

A novel route was developed to the preparation of temperature-sensitive poly(N-isopropylacrylamide)/polyethylenimine (PNIPAM/PEI) microgels by the radical copolymerisation of N-isopropylacrylamide with acryloylated PEI in aqueous media. Here, the acryloylated polyethylenimine (PEI), used as a macromonomer, was synthesised by a dehydration condensation reaction between PEI and acrylic acid. The as-prepared microgels exhibited well-defined core/shell structure with PNIPAM-rich core surrounded by PEI-rich shell. The microgels showed the volume phase transition temperature near physiological temperature, which can be easily regulated by the pH of microgel dispersion.