title: Simple and cost-effective fabrication of highly flexible, transparent superhydrophobic films with hierarchical surface design.
abstract: Optical transparency and mechanical flexibility are both of great importance for significantly expanding the applicability of superhydrophobic surfaces. Such features make it possible for functional surfaces to be applied to various glass-based products with different curvatures. In this work, we report on the simple and potentially cost-effective fabrication of highly flexible and transparent superhydrophobic films based on hierarchical surface design. The hierarchical surface morphology was easily fabricated by the simple transfer of a porous alumina membrane to the top surface of UV-imprinted polymeric micropillar arrays and subsequent chemical treatments. Through optimization of the hierarchical surface design, the resultant superhydrophobic films showed superior surface wetting properties (with a static contact angle of >170° and contact angle hysteresis of <3.5°) in the Cassie-Baxter wetting regime, considerable dynamic water repellency (with perfect bouncing of a water droplet dropped from an impact height of 30 mm), and good optical transparency (>82% at 550 nm wavelength). The superhydrophobic films were also experimentally found to be robust without significant degradation in the superhydrophobicity, even under repetitive bending and pressing for up to 2000 cycles. Finally, the practical usability of the proposed superhydorphobic films was clearly demonstrated by examining the antiwetting performance in real time while pouring water on the film and submerging the film in water.
authors: Department of Nano Fusion Technology and BK21 Plus Nano Convergence Technology Division, and ‡Department of Cogno-Mechatronics Engineering, Pusan National University , Busan 609-735, Republic of Korea.
authors: Tae-Hyun
authors: TH
authors: Kim
authors: Sung-Hun
authors: SH
authors: Ha
authors: Nam-Su
authors: NS
authors: Jang
authors: Jeonghyo
authors: J
authors: Kim
authors: Ji Hoon
authors: JH
authors: Kim
authors: Jong-Kweon
authors: JK
authors: Park
authors: Deug-Woo
authors: DW
authors: Lee
authors: Jaebeom
authors: J
authors: Lee
authors: Soo-Hyung
authors: SH
authors: Kim
authors: Jong-Man
authors: JM
authors: Kim
keywords: cost-effective fabrication; hierarchical surface design; mechanical flexibility; optical transparency; superhydrophobic film