Preparation and characterization of thermo-, pH-, and magnetic-field-responsive organic/inorganic hybrid microgels based on poly(ethylene glycol)

Nanocomposite microgels are a new class of intelligent materials because of their fast response time, large surface area, and so on. In this study, we demonstrate a new kind of multiple stimulus-responsive organic/inorganic hybrid microgels by combining dual stimuli-responsive poly(2-(2-methoxyethoxy)ethyl methacrylate-co-oligo(ethylene glycol)methacrylate-co-acrylic acid) (PMOA) microgels with magnetic attapulgite/Fe3O4 (AT-Fe3O4) nanoparticles. AT-Fe3O4 nanoparticles were introduced into the dual-responsive (temperature and pH) PMOA microgels network by in situ polymerization. The responsive behaviors, microstructures, and the interaction between AT-Fe3O4 and PMOA microgels matrix of the prepared microgels were systematically characterized using field emission scanning electron microscopy, particle size and Zeta potential analyzer, vibrating sample magnetometer, and Fourier transform infrared spectroscopy. The results showed that the AT-Fe3O4 nanoparticles dispersed well in the microgel matrix, and the nanoparticles could be stably present in PMOA without phase separation because of the hydrogen bond (H-bond) interactions between AT-Fe3O4 nanoparticles and PMOA matrix. In addition, the multifunctional AT-Fe3O4/PMOA nanocomposite microgels had both temperature/pH sensitivity and magnetic functionality.