Preparation of Hydrophilic Polysilsesquioxanes and Their Applications as Water Separation and Antifogging Coating Materials

Polysilsesquioxanes (PSQs) have been extensively studied as typical organic-inorganic hybrid materials that exhibit functionality and processability owing to organic substituents on silicon atoms, while also thermal and mechanical stability attributable to the inorganic siloxane (Si-O-Si) network structure. We describe herein the introduction of hydrophilic substituents into random PSQs to improve properties, such as water permeability and absorption capability, for developing reverse osmosis (RO) membranes for water separation and antifogging coating materials. Previously studied PSQ-based RO membranes generally exhibited low water permeability, although they showed excellent heat and chlorine resistance. Recently, we introduced hydroxy-containing substituents onto the silicon atoms of PSQs, enhancing the water permeability of PSQ-based RO membranes. Scratch-resistant antifogging coating materials are obtained by introducing amino, ammonium, and hydroxy units onto PSQ silicon atoms. The low durability of the initially studied materials was improved through chemical modification of the PSQ structures.