Synthesis of nanosilica using acrylic polymers as surface modifiers

Abstract

Preparation and characterization of silica nanoparticles through sol-gel processing using sodium silicate as a precursor were carried out. Amorphous silica was synthesized using sodium silicate and hydrochloric acid by precipitation according to Stőber method. A system of chemical reactions has been developed using two different polymeric anionic surfactants, namely poly(methacrylic acid) (PMAA) and a copolymer of methacrylic acid and 2-ethylhexyl acrylate (PMAA-EHA)(60:40). The synthesized silica particles were characterized by using fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The FTIR analysis confirm that the nanosilica particles surface have been modified with acrylic polymers, forming ester bonds between carboxylic groups of acrylicpolymers and surface silanol groups of nanosilica. TGA studies reveal silica particles modified with polymers showed higher weight loss than unmodified nanosilica due to the decomposition of the acrylic polymer adhered to the silica nanoparticles. The SEM images of unmodified and acrylic polymer modified particles show uniform size distribution and spherical shape.