Silanization of sepiolite nanoparticles: effect of reaction conditions on surface charge and the colloidal stability of particles

The purpose of this paper is to investigate the influence of the silanization reaction conditions on surface charge and the colloidal stability of modified particles. Surface modification of nanoparticles was performed using acidic and basic silanization methods. Methacryloxypropyltrimethoxysilane (γ–MPS) was used as silane coupling agent. The silanization reaction was performed in the following conditions: (i) acidic ethanol-water solution with a pH of 5 and (ii) basic cyclohexane with a pH of 9. Zeta Potential analyses were applied to study the surface charge of sepiolite nanoparticles. The colloidal stability of the modified nanoparticles was investigated using a separation analyzer. The results revealed that the basic condition resulted in higher silanization efficiency. The higher hydrophobicity of the silanized nanoparticles decreased their dispersion stability in ethanol.