Adhesion strength and superhydrophobicity of polyurethane/organoclay nanocomposite coatings

Substrate adhesion was investigated experimentally for superhydrophobic coatings fabricated from polyurethane modified with waterborne perfluoroalkyl methacrylic copolymer and a (fatty amine/amino-silane surface modified) montmorillonite clay nanofiller. The superhydrophobic coatings were obtained by spray casting precursor solutions onto aluminum surfaces. Upon thermosetting, initial static water contact angles exceeding 160 degrees and contact angle hysteresis values below 8 degrees were measured, yielding antiwetting and self-cleaning characteristics. Adhesion strength was then characterized with a 90 degrees tape testing method and was analyzed with respect to changes in surface morphology via electron microscopy as well as changes in wettability. The coating remained adhered to the substrate after repeated adhesion testing with 38-50 N/m tape (one of the strongest available), showing higher adhesion than any superhydrophobic coating reported to the author's knowledge. Superhydrophobic performance was also shown to be retained even after repeated tape testing. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012