Tuning the Thermal Transition of Poly(N-isopropylacrylamide) Based Core-Shell Composite Nanoparticles

The focus of this work is to synthesize thermo-responsive composite core-shell nanoparticles using Pickering emulsion polymerization and, more importantly, to tune the transition temperature of these nanoparticles. The synthesized polystyrene/poly(N-isopropylacrylamide) (PNIPAAm)-silica core-shell nanoparticles are temperature-sensitive with a transition near 32 degrees C in pure water. An increase of the N-isopropylacrylamide monomer enhances the degree of transition. In addition, the transition temperature of the composite core-shell nanoparticles can be tuned using facile approaches, such as by incorporating a crosslinker or co-monomer during the synthesis, or adding a surfactant or co-solvent to the media. The work also suggests that tunability of the transition temperature of these composite nanoparticles follows similar mechanisms as those at the macroscopic scale.