Repeatable replication method with liquid infiltration to fabricate robust, flexible, and transparent, anti-reflective superhydrophobic polymer films on a large scale

Flexible superhydrophobic films that can be adapted to any target object for practical applications have drawn much attention in recent years. In this paper, we propose a simple method to fabricating highly flexible superhydrophobic polydimethylsiloxane (PDMS) films, via a repeatable replication and nondestructive detachment from a superhydrophobic aluminum mold. Due to the hierarchical surface structures and intrinsic hydrophobicity of PDMS, the fabricated films exhibited superior water repellency without any further modifications using low surface energy materials. Moreover, these water repellent films exhibited excellent mechanical durability and flexibility without losing the anti-wetting property under harsh conditions. The use of a robust superhydrophobic mold and the easy detachment of the film using a solution with a low surface tension allow for the clean release of large-area replicas without any damages to the mold. This enables the repeated fabrication of superhydrophobic PDMS films without the deterioration of their wettability using a single mold. Furthermore, the superhydrophobic PDMS film exhibited an efficient anti-reflection property and high transparency, which allows an enhanced light collection and efficiency when applied to solar cells. Consequently, this simple and inexpensive method is appropriate for diverse applications that require films with superior mechanical and optical properties, and a special wetting behavior.