Dependence of Molecular Weight of Grafting Polymer on Dispersibility of TiO2 Particles in Poly(dimethylsiloxane)

Abstract The effect of the molecular weight of the grafting polymer (a derivative of poly(dimethylsiloxane)) on the dispersibility of TiO 2 particles coated with SiO 2 in poly(dimethylsiloxane) has been investigated. It has been found that there exists an optimal molecular weight for their dispersibility determined from the time dependence of the turbidity of suspensions. The pair interaction energy, which was assumed to be the sum of van der Waals interaction energy, entropic repulsive energy, and bridging adsorption energy through the grafting polymer, was calculated. Comparison of the experimental and calculated results suggested the following. In the dispersion system containing particles grafted with small-molecular-weight ( 3780) polymer, the bridging adsorption is chiefly responsible for the aggregation. It was concluded that these results lead to the presence of the optimal molecular weight of the grafting polymer in the dispersibility.