Antifogging coatings are crucial for maintaining transparent material visibility. However, conventional water-absorbing polymer coatings often have inferior mechanical properties. Polysilsesquioxane (PSQ) materials derived from sol–gel reactions exhibit high hardness. However, previous attempts to functionalize them with amino groups to improve water absorption resulted in discoloration and insufficient water uptake. We report herein the synthesis of organic–inorganic hybrid coatings based on PSQ functionalized with highly hydrophilic glucose units, aiming to achieve a superior balance among high transparency, mechanical durability, and excellent water absorption. Trialkoxysilane (GlcTES) and dialkoxysilane (GlcDES) monomers bearing glucose units were synthesized and subsequently polymerized via a sol–gel process to produce a sol solution. This was coated onto glass substrates to form hybrid films. The resulting PSQ-GlcT1D0 film, prepared by the homopolymerization of GlcTES, was completely colorless and highly transparent, overcoming the discoloration observed in previously reported amino-functionalized PSQ films. The film also demonstrated excellent mechanical durability, achieving a high pencil hardness of 6H. Furthermore, the coating film exhibited good water absorption, attributed to the abundant hydroxyl groups of the glucose units. Dynamic vapor sorption measurements revealed a high water uptake of 29% for PSQ-GlcT1D0, comparable to that of poly(vinyl alcohol) (PVA), and an even higher uptake of 34% for a copolymer film (PSQ-GlcT1D1). Consequently, these PSQ films displayed transparency and effective antifogging performance. These features were attributed to the high bulk water absorption capacity rather than surface hydrophilicity, as the water contact angle of PSQ-GlcT1D0 was 56°. This work demonstrates that the nanoscale hybridization of a robust PSQ network with glucose units is an exceptional strategy for creating advanced antifogging materials.
Adachi et al. (Tue,) studied this question.