Polyvinylidene fluoride (PVDF)/cellulose nanocrystal (CNC) nanocomposite fiber and triboelectric textile sensors

Polyvinylidene fluoride (PVDF)/cellulose nanocrystal (CNC) nanocomposite fibers are prepared by dry-jet wet spinning at the CNC concentrations of 0, 1, and 3 wt%, followed by mechanical stretching up to the draw ratio (DR) of 8. The structure analysis results show that the strong interaction between PVDF and CNC leads to good mechanical properties and high β phase fraction (Fβ) that is beneficial for its application as a smart textile. The chain conformational variation of PVDF is analyzed as a function of processing condition, exhibiting that the tensile properties and Fβ of all the fibers are enhanced as the polymeric chains are extended with increasing DR. Among various fibers, the nanocomposite fiber containing 1 wt% CNC possesses the highest tensile strength of 298 MPa, tensile modulus of 3.3 GPa, and Fβ of 69.1% at a DR of 8. However, at a high CNC loading of 3 wt%, the tensile properties are decreased, which may be due to the defect structure evolution by CNC aggregation. In order to demonstrate the feasibility as a smart textile, triboelectric textile sensors are fabricated via cross-stitching and conventional weaving, resulting in a good pressure sensing capability over a broad range of 0.98–98 kPa.