Development of superhydrophobic textiles via polyvinylidene fluoride phase separation in one-step process

The purpose of this study was to develop a polyester fabric having superhydrophobicity and piezoelectric properties that could be formed in a one-step process. Using a method of non-solvent induced phase separation and immersion precipitation, polyvinylidene fluoride (PVDF) was applied to polyester fabrics, to reduce the surface energy and form hierarchical roughness with micro- and nano-scale structures, and the surface morphology, chemical composition, surface wettability, piezoelectric properties, and breathability of the produced fabric were investigated. When the polyester fabric was coated with only the PVDF solution, a hydrophobic surface with micro-scale roughness was obtained. However, when the fabric was coated with the PVDF solution and subsequently immersed in an n-octyl alcohol bath, nano-scale surface roughness was formed with spherulites of diameter 600 to 870 nm. The specimen coated with 40 mg/ml PVDF solution and subsequently immersed in an n-octyl alcohol bath exhibited a water contact angle of 159.9°, a water shedding angle of 6.3°, and improved water vapor transmission, but did not demonstrate piezoelectric properties. This study is meaningful in that a superhydrophobic and breathable textile, with reduced surface energy and nano-scale surface roughness, was formed in a one-step process by phase separation of PVDF.