Synthesis of poly(methylsilsesquioxane-co-dimethylsiloxane) liquids and deep-ultraviolet transparent elastic resins through co-solvent-free water-rich hydrolytic polycondensation of organoalkoxysilanes

A co-solvent-free hydrolytic polycondensation of mono- and dimethylmethoxysilanes at high H 2 O/Si ratios (≳10) gave methylsilsesquioxane-rich (80 mol%) liquids heat-curable to stiff, tough, and deep-UV transparent resins showing full elastic recovery.