Effect of surfactant and oil type on the solution synthesis of nanosized silica

We have investigated the effects of using two different oils, cyclohexane and chloroform, and two different surfactants, nonylphenyl pentaethylene glycol (NP-5) and dimethyldodecylamine oxide (DDAO) in a modified Stِber process for synthesizing silica colloids. Mean particle size was affected by both the oil and the surfactant used, and a significant interaction was also observed between these two factors: DDAO produced larger particles in cyclohexane, and NP-5 produced larger particles in chloroform. Water-to-surfactant and water-to-silicate ratios, as well as volume of oil added, were also observed to affect mean particle size. Only the volume of added oil was determined to affect the size dispersity of particles, with the use of a smaller volume of oil leading to a lower dispersity in particle size.