Abstract/Summary

Nanoparticle characteristics, including their size, are governed by the reagents employed and the reaction parameters. Here, we systemically vary the catalyst, oxygen content, temperature and solvent to modify the size and zeta potential of thiolated organosilica nanoparticles. Particles were synthesized by self-condensation of 3-mercaptopropyltrimethoxysilane (MPTS) in a range of organic solvents in contact with oxygen, with NaOH and other catalysts. Particle size increased with increasing reaction temperature (70 ± 1 nm at 50 °C; 50 ± 1 nm at room temperature) but decreased when air was bubbled through the reaction mixture compared to no bubbling. Significant decrease in particle size was seen with increasing the dielectric constant of the solvent and with increasing catalyst concentration; from these we provide empirical equations that can be used to design particle sizes by manipulating the dielectric constant of the solvent (or co-solvents) or by varying NaOH catalyst concentration when DMSO is the selected solvent.