Enhancing the Durability and Mechanical Performance of Superhydrophilic Coatings through Organic–Inorganic Hybrid Nanoparticles

Abstract

Superhydrophilic coatings are prominent in various industries, including automotive, and consumer electronics. However, challenges persist in terms of mechanical performance and durability. This study focuses on the development of organic–inorganic hybrid nanoparticles for superhydrophilic coatings that exhibit exceptional thermomechanical stability and long-term durability. Employing green chemistry, polyethylene glycols (PEGs) are grafted onto silica nanoparticles, controlling the PEG molecular weight from 200 to 1000 to systematically investigate its impact on coating characteristics. Additionally, the intriguing phenomenon of phase separation facilitated by a polyurethane binder and its effects on both morphology and hydrophilicity is investigated. All hybrid coatings consistently exhibit remarkable superhydrophilicity, with contact angles consistently below 10°, the lowest being 1.4°. Longer PEG chains played a pivotal role in enhancing the thermal stability of the grafted PEG shell within the hybrid nanoparticles, achieving a maximum enhancement in decomposition temperature of 150 °C. Furthermore, the PEG shell substantially improves strain durability, with SiO₂-PEG 1000–50% exhibiting outstanding transmittance retention of 100% without any cracks even under a 100% tensile strain. SiO₂-PEG 200 emerged as the champion in maintaining superhydrophilicity throughout a 20-day long-term durability assessment. Moreover, the research has unveiled the intricate degradation mechanism responsible for the decline in hydrophilicity in these hybrid coatings.