Solvent effects on morphologies of hollow silica nanoparticles prepared by poly-acrylic acid template method

This paper describes effects of alcohol solvents on size and silica shell microstructure of hollow silica nanoparticles (HSNPs) prepared with ammonium polyacrylate (APA) templates. The various solvents were prepared by changing volume ratio of mixed 1-propanol, 1-butanol, and 1-pentanol against ethanol, and the investigation was based on the octanol/water partition coefficients (log Pow). The log Pow strongly affected the morphologies of the formed APA templates. When the log Pow was higher than 0.250, a precipitate was formed. For the log Pow lower than 0.250, the template was obtained, and its diameter became larger with increasing the log Pow, depending also on the water solubility of APA in alcohol solvents. In addition, the silica shell became rough in alcohol solvents with higher log Pow because the template contained a large amount of aqueous solution with catalyst. Therefore, the morphologies of the HSNPs could be controlled by the alcohol solvents.