Preparation and properties of polypyrrole-based thermosensitive gels
PNIPAM/CS composite thermosensitive gels were synthesized by using N-isopropyl acrylamide(NIPAM)and chitosan(CS)through the soap-free emulsion polymerization.PNIPAM/CS gels exhibit obvious thermal sensitivity with the volume phase transition temperature(VPTT)at 38.5 ℃.Subsequently,the photoresponsive polypyrrole(PPy)layer was grown on the surface of PNIPAM/CS by the in-situ adsorption method,resulting in PNIPAM/CS@PPy nanogels.PNIPAM/CS@PPy nanogels are spherical with a size range of 100 to 200 nm.When the temperature increases from 20 to 42 ℃,the nanogels show an obvious reduction of hydrodynamic size from 250 nm to 140 nm,indicating the volume shrinkage driven by temperature change.The results verify that the nanogels have strong absorbance in the near-infrared light region and show strong photothermal effects under irradiation of 808 nm laser,and the temperature elevation increases with gel concentrations.PNIPAM/CS@PPy nanogels have potential applications in thermosensitive drug release and photothermal therapy.
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