Fabrication of a high-transparency self-cleaning coating from recycled EVA waste combined with modified SiO₂

The utilization of discarded EVA plastic to fabricate superhydrophobic coatings aligns with the principles of sustainable technology and paves a new way for the repurposing of waste EVA. • The coating boasts >98% transmittance and a >155° water contact angle. It exhibits excellent stability under UV, high-temperature, and water impingement conditions, and its short curing time makes it highly promising for practical use. • Incorporating EVA repairs coating defects, reduces porosity, and significantly enhances optical transparency. The withdrawal speed in dip-coating determines the coating thickness: faster speed leads to thicker coating, with optical properties showing clear thickness dependence. Ethylene-vinyl acetate (EVA) copolymers are extensively utilized as encapsulation materials in photovoltaics owing to their excellent adhesion, high transparency, and weathering resistance. However, efficient recycling pathways for the strip-shaped waste generated during industrial-scale manufacturing remain limited. Herein, we devised a novel recycling strategy to fabricate a highly transparent and superhydrophobic self-cleaning coating by incorporating waste EVA and hexamethyldisilazane (HMDS)-modified SiO₂ nanoparticles via a simple dip-coating process. The resultant coating exhibited outstanding superhydrophobicity, with a water contact angle exceeding 155° and a sliding angle below 2°, while maintaining exceptional visible-light transmittance of over 98%. Systematic microstructural analyses revealed that the quantity and size distribution of defects, along with the film thickness, were the primary factors governing optical performance, whereas surface roughness played a comparatively minor role. The coating thickness could be precisely controlled by adjusting the lift speed during dip-coating, and complete curing was achieved within 2 min. This work not only provides an effective recycling pathway for waste EVA but also demonstrates considerable potential for applications requiring both high transparency and self-cleaning functionality, such as solar panel covers and architectural glazing. Download: Download high-res image (207KB) Download: Download full-size image