Factors Affecting the Redispersibility of Organosilica Sols Prepared by a Modification of Silica Particles with a Polyol-Based Polymer

Organosilica sols which were redispersible in nonpolar or less polar organic solvents were prepared by a chemical modification of the silica surface with a polyol-based coupling polymer; the redispersibility was then examined in terms of the molecular weight of the coupling polymer, charged coupling polymer/silica (mmol g−1) (P/S) ratio, and the size of modified silica particles. Fractionated coupling polymers with an Mw/Mn of 2.0—2.8 were used. The charged P/S ratio was a leading factor for the redispersibility. The redispersibility was achieved when the charged P/S ratio exceeded approximately 0.3 mmol g−1, using coupling polymers of various molecular weights. The particle size of the modified silica decreased along with an increase in the charged P/S ratio and the reaction time. The presence of a free polymer was not essential for the redispersibility when the saturation of the silica surface with the coupling polymer was nearly completed.