A stacked polymer film for robust superhydrophobic fabrics

A robust superhydrophobic fabric was achieved by depositing a stacked polymer film composed of a poly(1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane) (p(V4D4)) layer and a poly(1H,1H,2H,2H-perfluorodecylacrylate) (p(PFDA)) layer. The polymer film was deposited by initiated chemical vapor deposition (iCVD), a solventless process that allows conformal coating of the stacked polymer film on various micro-structured substrates. The two polymeric layers most likely formed a covalent bonding at their interface, and thus the stacked polymer film was characterized by both strong hydrophobicity and enhanced mechanical robustness originated from highly cross-linked p(V4D4) and p(PFDA). The surface topography of superhydrophobic coating was systematically tunable by controlling the operating parameters of iCVD process and a hierarchical structure was obtained by a simple one-step iCVD process. The film was also highly transparent in the wavelength range from 380 nm to 780 nm. Fabrics coated with this stacked polymer film displayed chemical robustness even after exposure to different chemicals including acetone, toluene, H2SO4, and KOH. The fabric also maintained its water repellency even after 20 000 cycles of the abrasion test and after 75 cycles of the laundry test.