Fluorine-Free Hydrophobic Coatings with Enhanced Interfacial Adhesion and Synergistic Self-Cleaning Properties

Abstract

Effective antismudge surfaces are in high demand for applications ranging from electronic devices to architectural glass. However, constructing a mechanically robust, fluorine-free and eco-friendly antismudge coating on transparent substrates remains a significant challenge. Herein, we report an organic–inorganic hybrid strategy combining APTES-modified SiO₂ nanoparticles with PDMS-based waterborne polyurethane to coconstruct hierarchical micronano topographies and low-surface-energy interfaces. The optimized coating exhibits a water contact angle of 105°, visible-light transmittance >88%, and outstanding self-cleaning against both low-viscosity liquids like n-tetradecane and high-viscosity contaminants like milk, tea and coffee. Surface energy analysis further confirmed its low-energy nature, with the optimized 10-SKWPU coating showing the lowest surface energy of 22.07 mN/m. Theoretical calculations reveal that modification reduces the SiO₂ bandgap by 14.2%, thereby enhancing interfacial charge transfer and cross-linking density, which underpins the observed robustness and hydrophobicity. This work provides an engineering-feasible route for designing transparent, durable, and eco-friendly antismudge coatings.