Preparation of pH-sensitive polyacrylic acid hollow microspheres and their release properties

The pH-sensitive polyacrylic acid (PAA) microspheres with a hollow structure are prepared via Pickering polymerization of acrylonitrile using diethanolamine-adipic acid modified silica nanoparticles as a stabilizer followed by hydrolysis in the presence of sodium hydroxide. The morphology and chemical structure of PAA hollow microspheres are investigated by scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) spectroscopy. The swelling of polymer hollow particles is observed by confocal microscopy. As a kind of functional material, the pH-sensitive PAA hollow microspheres can be used to load and release the substances. The release rates of the dye from PAA hollow microspheres are greatly dependent on pH value with sunset yellow (SSY) as a model molecule. It is proven that the release properties of PAA hollow microspheres can be well controlled via tuning the pH values.