Boroxy-modified UV dual-cure ladder-like polysiloxane coatings with excellent hardness, UV resistance

Abstract

Protective hard coatings are crucial for the screens of electronic devices; however, conventional polymer coatings often face limitations in hardness, self-cleaning ability, and fingerprint resistance. In this study, we developed a novel UV dual-curable ladder-like polysilsesquioxane (LPSQ) coating, modified with boroxyl groups, to improve its protective performance. LPSQ was synthesized via a sol-gel process using controlled ratios of phenyltrimethoxysilane (PTMS), 3-methacryloxypropyltrimethoxysilane (KH-570), and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (ECTMS). The subsequent modification with 4-vinylphenylboronic acid (4-VPBA) introduced a boroxyl network through thermal dehydration. The resulting LPSQ-co-VPBA coating exhibited exceptional mechanical properties, achieving a pencil hardness of up to 8H and excellent adhesion (Grade 0). Notably, the LPSQ153-co-VPBA coating demonstrated extraordinary hardness of 1.83 GPa. Furthermore, the modified coating exhibited enhanced thermal stability, with its decomposition temperature rising from 200 °C to 350 °C, as well as superior UV shielding (41.2 % increase in absorption) and excellent visible light transmittance. Additionally, the coating displayed remarkable self-cleaning and anti-fingerprint properties, with artificial fingerprint liquid sliding off in just 1 s. These findings underscore the potential of boroxyl-modified LPSQ coatings as high-performance protective materials for next-generation electronic device screens. It offer superior hardness, optical clarity, thermal stability, and self-cleaning properties.