Optically transparent super-hydrophobic thin film fabricated by reusable polyurethane-acrylate (PUA) mold. (4th January 2018)

• Record Type: Journal Article
• Authors: Park, J-S; Park, J-H; Lee, D-W
• Is Part Of: Journal of micromechanics and microengineering. Volume 28:Number 2(2018:Feb.)
• Publication Date: 2018-01-04
• Subjects: super-hydrophobic -- polydimethylsiloxane -- UV curable PUA -- artificial lotus leaf -- nano-silica; Microelectromechanical systems -- Periodicals; Micromechanics -- Periodicals; 621.38105
• DOI: 10.1088/1361-6439/aa9f04
• Languages: English
• ISSNs: 0960-1317

Abstract

Abstract: In this paper, we describe a simple manufacturing method for producing an optically transparent super-hydrophobic polymer thin film using a reusable photo-curable polymer mold. Soluble photoresist (PR) molds were prepared with under-exposed and under-baked processes, which created unique hierarchical micro/nano structures. The reverse phase of the PR mold was replicated on the surface of polydimethylsiloxane (PDMS) substrates. The unique patterns on the replicated PDMS molds were successfully transferred back to the UV curable polyurethane-acrylate (PUA) using a laboratory-made UV exposure system. Continuous production of the super-hydrophobic PDMS thin film was demonstrated using the reusable PUA mold. In addition, hydrophobic nano-silica powder was sprayed onto the micro/nano structured PDMS surfaces to further improve hydrophobicity. The fabricated PDMS thin films with hierarchical surface texturing showed a water contact angle ⩾150°. Excellent optical transmittance within the range of visible light of wavelengths between 400–800 nm was experimentally confirmed using a spectrophotometer. High efficiency of the super-hydrophobic PDMS film in optical transparency was also confirmed using solar panels. The fabricated PUA molds are very suitable for use in roll-to-roll or roll-to-plate systems which allow continuous production of super-hydrophobic thin films with an excellent optical transparency.