Development of a superhydrophobic electrospun poly(vinylidene fluoride) web via plasma etching and water immersion for energy harvesting applications

Smart textiles have been enormously developed recently, but attachment of batteries and low washing resistance are the major challenges in the development of wearable smart textiles. However, piezoelectric materials harvesting energy from mechanical action can be readily integrated with smart textiles and can replace conventional batteries. Therefore, energy harvesters with poly(vinylidene fluoride) (PVDF) were fabricated by the electrospinning process. In addition, simple CF₄ plasma etching followed by water immersion of the electrospun PVDF webs resulted in superhydrophobicity, with a water contact angle of 169.8 ± 1.5°, a water shedding angle of 4.7 ± 1.8°, and self-cleaning properties. This would decrease the number of washing cycles during use and increase the durability of the smart textile. X-ray photoelectron spectroscopy indicated that metals were co-deposited as etch-resisting masks to fabricate a nanostructure during plasma etching and were removed by water immersion. The piezoelectric performance of the superhydrophobic electrospun PVDF web showed a higher peak-to-peak output voltage of 3.50 V than the untreated electrospun PVDF web (2.86 V). Furthermore, the breathability of the superhydrophobic PVDF web was remarkably higher than those of the PVDF film. Therefore, the new flexible electrospun PVDF web with superhydrophobicity and piezoelectricity has significant potential as energy harvesters in wearable smart textiles.