Synthesis and characterization of thermoresponsive and biocompatible core–shell microgels based on N-isopropylacrylamide and carboxymethyl chitosan

The objective of the study is to report thermally sensitive and biocompatible capability core–shell microgels. These core–shell microgels composed of a chemically crosslinked poly(N-isopropylmethacrylamide) (PNIPAM) core and a carboxymethyl chitosan (CMCS) shell were designed and synthesized by seed emulsion polymerization in this work. Due to the excellent biocompatible nature of CMCS, these PNIPAM/CMCS hybrid microgels have good biocompatibility. The chemical component of the PNIPAM/CMCS particles was confirmed by comparing the Fourier-transform infrared spectra (FTIR) of PNIPAM and PNIPAM/CMCS particles. Transmission electron microscopy (TEM) picture shows the core–shell structure of the resulted PNIPAM/CMCS nanocomposite particles. Thermally induced deswelling of PNIPAM/CMCS water dispersions which occurred in the increase of the temperature in the region of the lower critical solution (LCST) was investigated by means of dynamic light scattering (DLS). The thermal study by using differential scanning calorimetry (DSC) revealed that volume-phase transition temperatures of the physical microgel increased first with an increase in CMCS and slightly increased thereafter with a further increase in CMCS.