Fabrication of pH-responsive microcapsules by precipitation polymerization on calcium carbonate templates

A simple and fast method was developed to fabricate pH-responsive microcapsules. After the copolymerization of N-isopropylacrylamide (NIPAAm), methacrylic acid (MAA), and a crosslinker, poly(ethylene glycol) diacrylate, at 65 degrees C in the presence of sacrificial CaCO3 microparticles, hollow microcapsules were acquired by template removal. A higher temperature and the presence of MAA/NIPAAm were found to be critical factors for the successful fabrication of the microcapsules. The entire fabrication step was simple, fast, and easy to scale up. The microcapsules were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. The pH responsiveness of the microcapsules was confirmed by confocal laser scanning microscopy and -potential analysis. Together with the fastness and simplicity of the fabrication process, this kind of pH-responsive microcapsule holds potential for drug- and gene-delivery systems. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013