Poly(Methacrylate)s of Cage Silsesquioxanes With Hydrogen Bonding Networks Toward Optically Transparent Films

ABSTRACT Polyhedral oligomeric silsesquioxane (POSS), a cage silsesquioxane, is a versatile building block for the design of organic–inorganic hybrid materials. Numerous POSS‐tethered copolymers have been developed to enhance the properties of commercial polymers. In contrast, homopolymers that incorporate POSS units into their side chains are rare because of the intrinsically high crystallinity of POSS, which often results in brittle and turbid polymer films. In this study, we propose a novel molecular design strategy for obtaining homogeneous and optically transparent POSS‐based poly (methacrylate) films. The key structural feature is the introduction of hydrogen bonding (HB) sites such as urethane and urea groups. These intra‐ and/or inter‐molecular HB networks effectively suppress the crystallization of POSS moieties. The thermal and mechanical properties of the resulting materials are significantly influenced by the nature of the HB sites.