Transparent and Chemically Durable Polyurethane Acrylate Film for Protective Encapsulation of Flexible Electronics

The demand for lightweight, flexible, and transparent encapsulation materials is rapidly increasing with the advancement of flexible and wearable electronics. Yet, achieving a unified balance among mechanical flexibility, optical clarity, and chemical robustness within a single polymer remains difficult. In this work, a compositionally tunable vinyl-terminated silicon-containing polyurethane acrylate (PUA) system was developed by adjusting the polycarbonate diol (PCDL) content to implement the barrier. Then, the PUA-B film was synthesized by copolymerizing PUA and butyl acrylate (BA); this design enabled the fabrication of highly transparent and mechanically resilient films that retained their optical and structural integrity after repeated folding and friction (100 cycles). The optimized PUA-B film exhibited outstanding resistance to acids, alkalis, and solvents, and effectively protected metallic and electrochemical devices from corrosion and failure in harsh environments (for 4 h). These results highlight a design principle for engineering multifunctional polyurethane-based films that combine elasticity, transparency, and environmental endurance, advancing their potential use in next-generation encapsulation and protection of flexible electronic systems.