Preparation of breathable and superhydrophobic coating film via spray coating in combination with vapor-induced phase separation

Abstract

Abstract Breathable and superhydrophobic coating film has been successfully prepared in one step by combining spraying technique and non-solvent vapor induced phase separation. Namely, solution of an inexpensive commercially available thermoplastic elastomer, i.e., a star-shaped triblock copolymer of poly (styrene- block -butadiene- block -styrene), was sprayed in an ethanol vapor atmosphere. The sprayed tiny droplets of the polymer solution facilitated the solvent evaporation and the non-solvent condensation, resulting in their fast phase separation and solidification. After complete evaporation of the solvent in a few minutes, a porous and superhydrophobic coating film was thus obtained, with a nanometer to micrometer inter-connected nodular morphology. In order to improve the superhydrophobicity and strengthen the coating film, inorganic nanoparticles of SiO 2 have been added into the polymer solution for spraying fabrication. The obtained coating films were thermally treated to further improve their mechanical properties for practical application. The contact angle, the sliding angle and the abrasion tests results proved all previous methods effective. Moreover, water-vapor permeation through the coating film was checked to indicate its breath ability. Therefore, this paper provides a practical method for the preparation of porous and superhydrophobic coating films, which may have great promise in microfiltration and textile industry.