Poly­(glycidyloxypropyl)­silsesquioxane (PGPS) was successfully synthesized by hydrolysis and polycondensation using the nitrogen flow method. A poly­(3-(2,3-dihydroxypropoxypropyl)­silsesquioxane) (PSQ-OH) film was prepared via two routes. In route A, PSQ-OH was prepared by the hydrolysis of the epoxy group of PGPS in an aqueous hydrochloric acid (HCl)/tetrahydrofuran solution, affording a diol group; then, PSQ-OH was coated on a glass substrate and heated. The antifogging performance of the PSQ-OH film was evaluated in terms of water uptake (WU) and scratch resistance. The obtained PSQ-OH film exhibited a low WU of 5% and a scratch resistance of 1.6. In route B, PGPS was coated on a glass substrate and immersed in a 0.5 mol/L aqueous sulfuric acid solution for 1–15 h at room temperature, producing a diol group. The solid-state 13C nuclear magnetic resonance spectrum indicated that the epoxy group was completely hydrolyzed after immersion for 15 h. The WU of the PSQ-OH film prepared via route B increased from 5 to 19% with the increase in the immersion time and was higher than that of the PSQ-OH film prepared via route A. The PSQ-OH film on a glass substrate retained transparency under water vapor exposure at 60 °C. The PSQ-OH film prepared via route B exhibited a high scratch resistance of 2.7–3.6, similar to that of a poly­(3-(2-aminoethylaminopropyl)­silsesquioxane) film. The scratch resistance of the PSQ-OH film was 5–7 times higher than that of the poly­(vinyl alcohol) film. The PSQ-OH film was uniform with no pinholes and cracks. The PSQ-OH film was transparent and colorless and exhibited a high transmittance of >90% in the wavelength range of 400–800 nm. Overall, the prepared PSQ-OH film exhibits good antifogging, transparency, and mechanical properties.

To investigate the effect of introducing a hydrophilic and flexible tetraethylene glycol chain into a polysilsesquioxane (PSQ) antifogging film, a poly[3-(2,3-dihydroxypropoxypropyl)-co-tetraethylene glycol]silsesquioxane (PSQ-Diol/EG) film was prepared via the sol−gel reaction of 3-glycidyloxypropyltrimethoxy s i l a n e ( G P T M S ) a n d t e t r a e t h y l e n e g l y c o l b i s -(triethoxysilylpropyl)ether (BTESP-EG). Their antifogging property, mechanical property, and durability were investigated. First, poly(glycidyloxypropyl-co-tetraethylene glycol)silsesquioxane (PSQ-Gly/EG) was synthesized via the sol−gel reaction of GPTMS and BTESP-EG. Thereafter, to prepare the PSQ-Diol/ EG film, PSQ-Gly/EG was coated onto a glass substrate, and the ring-opening reaction of epoxy groups was conducted by immersing the film in a 0.5 mol/L H 2 SO 4 solution. The PSQ-Diol/EG films exhibited a water uptake (WU) of 15−19%, similar to that of the poly[3-(2,3-dihydroxypropoxypropyl)]silsesquioxane (PSQ-OH) film (12−19%). The transparency of the PSQ-Diol/ EG film was maintained even after exposure to water vapor because of the absorption of water by the PSQ-Diol/EG film. The PSQ-Diol/EG film exhibited a high scratch resistance of 2.4−3.5 determined by nanoindentation, comparable to that of the PSQ-OH film (2.7−3.6). In the durability test, the WU of the PSQ-OH film slightly decreased during repetitive changes in the relative humidity (RH) between 95 and 20% at 30 °C, and cracks were formed on the surface after leaving the film to stand at a high RH of 95% at 50 °C. Contrarily, the PSQ-Diol/EG film did not exhibit a decrease in WU and crack formation on the surface under the same conditions. The introduction of hydrophilic and flexible tetraethylene glycol chains into the PSQ antifogging film was effective in improving the durability while maintaining the antifogging property and mechanical strength. The polycondensation reaction of residual silanol groups observed for the PSQ-OH film was probably suppressed in the PSQ-Diol/EG film because of the space effect of the tetraethylene glycol units keeping the silanol groups away from each other.

A poly [3-(2-aminoethylamino)propyl]silsesquioxane (PAEAPS) film was immersed in 0.5 mol/L hydrogen chloride (HCl) methanolic solution and a poly [3-(2aminoethylamino)propyl]silsesquioxane hydrochloride (PAEAPS-Cl) film containing the amine hydrochloride salt was prepared for the development of high-performance antifogging materials based on polysilsesquioxane. The PAEAPS-Cl film exhibited a higher water uptake (WU) of 29% and scratch resistance of 4.3 estimated by a nanoindenter than the PAEAPS film (WU = 22% and scratch resistance = 3.2). The introduction of the amine hydrochloride salt structure increased the antifogging properties and surface hardness. 29 Si solid-state nuclear magnetic resonance (NMR) spectra indicated that the structure of the siloxane network in the PAEAPS film drastically changed upon hydrolysis by amino groups after exposure to water vapor at 40 °C and 95% relative humidity for 1 h. In the PAEAPS-Cl film, the cleavage of the siloxane network was prevented by the introduction of the amine hydrochloride salt as the neutral group, but the amine hydrochloride salt sometimes induced the morphological change of the PAEAPS-Cl film because of strong hydration and cracks and dimples were observed after exposure to water vapor at 40 °C and 95% relative humidity for 1 h. The poly[3-(2-aminoethylamino)propyl-co-methyl]silsesquioxane hydrochloride (P(AEAP-co-Me)S-Cl) film was prepared by the hydrolysis and polycondensation of 3-(2-aminoethylaminopropyl)triethoxysilane and methyltriethoxysilane, followed by immersion in 0.5 mol/L HCl methanolic solution. The obtained P(AEAP-co-Me)S-Cl film exhibited a WU of 17%, lower than those of the PAEAPS and PAEAPS-Cl films, but cracks and dimples were not observed in the P(AEAP-co-Me)S-Cl film even after exposure to water vapor at 40 °C and 95% relative humidity for 1 h. Furthermore, the introduction of the amine hydrochloride salt structure did not decrease transparency and the PAEAPS-Cl and P(AEAP-co-Me)S-Cl films showed high transparency, similar to the PAEAPS film.