ON THE PREPARATION OF ORGANOSILICON MU-SPHERES - A POLYCONDENSATION IN MU-EMULSION

Polycondensation of methyltrimethoxysilane in the presence of the surf actant benzethonium chloride yields strictly spherical organosilicon m icronetworks of controlled size in the range of 3 nm less than or equa l to R less than or equal to 15 nm with R the particle radius. After a short induction period the size of the particle increases linearly wi th the cube root of added monomer volume which proves the number of gr owing nuclei to be constant with time or conversion, whereas the mecha nism controlling the number of growing nuclei remains unclear. In many respects the polycondensation resembles a condensation in mu-emulsion although the surface are per surfactant molecule (headgroup area) is shown to decrease with decreasing particle size, a fact which is not y et understood. The particle density in solution is only about one-thir d of the dry particle density which means that the mu-network is consi derably swollen in solution.