Synthesis of Polystyrene and Silica Gel Polymer Hybrids Utilizing Ionic Interactions

We investigated the synthesis of nanometer scale homogeneous polystyrene and silica gel polymer hybrids utilizing ionic interactions. The partially sulfonated polystyrene (10 mol %) was used as a starting organic polymer and (3-aminopropyl)trimethoxysilane (APTMOS) was used as a countercation as well as the precursor to the inorganic phase. The content of silica gel was controlled by the further addition of tetramethoxysilane (TMOS). The level of dispersity of the organic and the inorganic phase was found to be dependent on the amounts of APTMOS. When more than 0.5 mol equiv of APTMOS in relation to the sulfonic acid groups was incorporated in the sol−gel reaction mixture of TMOS and the polystyrene sulfonic acid, the obtained polymer hybrids became optically transparent. The homogeneity of the polymer hybrids was also found to be strongly dependent on the type of solvents. Polar solvents such as dimethyl sulfoxide yielded transparent hybrids while tetrahydrofuran or N,N -dimethylformamide caused the phase separation of the two elements. The homogeneity of the polymer hybrids was examined by scanning electron microscopy, transmission electron microscopy and nitrogen porosimetry studies. All of these results support the nanometer scale dispersion of each phase. The morphological study on the polymer hybrids was also conducted using dynamic mechanical analysis, which suggested the increase in cross-linking between the organic phases with the increase in APTMOS.