Fabrication of complex microcapsules containing poly(allylamine)-g-poly(N-isopropylacrylamide) and their thermal responsivity

Complex microcapsules containing thermo-responsive poly(allylamine)-g-poly(N-isopropylacrylamide) (PAH-g-PNIPAAm) were fabricated by adsorbing one layer of PAH-g-PNIPAAm onto CaCO3 microparticles doped with poly(styrene sulfonate) sodium salt (PSS), followed by dissolution of the CaCO3 particles. The complex capsules were characterized by confocal microscopy, scanning electron microscopy, transmission electron microscopy and atomic force microscopy. The existence of PAH-g-PNIPAAm in the complex microcapsules was confirmed by FTIR spectroscopy, and its thermo-responsive property was studied by 1H NMR. The capsules showed different morphologies when dried at 25 and 50 °C, as well as enhanced stability at 40 °C in alkaline solution due to the additional hydrophobic interaction.