Effects of feeding mode on synthesis of polyalkylsilsesquioxane emulsion and latex properties

Abstract

A stable polyalkylsilsesquioxane emulsion was prepared by batch and semi-continuous emulsion polymerization of methyl triethoxysilane (MTES) and n-propyltrimethoxysilane (PTMS). The influence of different feeding modes on the emulsion particle size and morphology structure was investigated by dynamic laser scattering (DLS), transmission electron microscopy (TEM), scanning electron microscopy (SEM). The results indicated that the particle sizes of the polyalkylsilsesquioxane emulsion increased and finally tended to be constant with the extension of reaction time. The latex particle size distribution index (PDI) decreased with the extension of reaction time. The particle size prepared by the batch method was larger than that by the semi-continuous method, while the PDI was smaller. The actual solid content of the emulsion was 15.6% (by batch) and 15.5% (by semi-continuous) when the monomer mass fraction was 30% in the total system. The polymerization stability and storage stability of the emulsions prepared by the two methods are good. The morphologies of latex particles prepared by the two methods were spherical. There was a core–shell structure. There were some similar crystal structures in the molecular chain of polyalkylsilsesquioxane prepared with alkyltrialkoxysilane. The thermal degradation weightlessness peak of the polymer in a nitrogen atmosphere was at 450–600 °C, while in air atmosphere it was at 250–300 °C. The final residues were 68% in nitrogen, 65.1% in air atmosphere.