Control size distribution of hollow silica nanoparticles by viscosity of emulsion template

This paper describes the effect of the viscosity of the template on the sol-gel synthesis which is useful to rapidly form the shell structure of hollow silica nanoparticles (HSNPs) and control the HSNP sizes. The Poly acrylic acid/ammonia aqueous solution (PAA/NH3) acts as the templates for the silica coating performs in ethanol, which are subsequently removed by water to obtain the HSNPs. The influence of the template viscosity on the silica coating and the morphology of the HSNPs were studied using four kinds of PAAs with different molecular weights (MWs), such as 5000, 25,000,50,000 and 250,000. It was found that the viscosity of the PAA/NH3 templates increased with the increasing MW PM. Unfortunately, the highest molecular weight of PM (250,000) used in this study hardly formed templates because of its highly excessive viscosity. The ultra-small HSNPs could be successfully synthesized using PAA(50,000) as the template along with a high TEOS conversion ratio (95%) and a shorter reaction time (2 h). Moreover, the decreasing MW PM provided a large size HSNP with a low TEOS conversion. (C) 2016 Elsevier B.V. All rights reserved.