Development of a novel pressure sensing material based on polypyrrole-coated electrospun poly(vinylidene fluoride) fibers

• Polypyrrole-coated electrospun poly(vinylidene fluoride) fibers were obtained.
• The composites were prepared by in situ oxidative polymerization on electrospun PVDF.
• The electrical conductivity was enhanced by increasing the pyrrole content.
• The composites exhibited variation in the electrical conductivity under pressure.

Conductive polypyrrole-coated poly(vinylidene fluoride) (PVDF/PPy) fibers with diameters ranging from 500 nm to 1 μm were prepared through pyrrole (Py) oxidative polymerization on electrospun PVDF membrane. The influence of polymerization conditions on structures and properties of PVDF/PPy composites were investigated. The electrical conductivity and PPy content enhanced significantly with increasing Py concentration due to the conducting polymer layer formation that completely coated the PVDF fiber surfaces. The effect of dynamic load on electrical conductivity of PVDF/PPy composites has been registered. The maximum electrical sensitivity was observed for the composites containing 50 wt.% of PPy content, for which the relative conductivity increases around 40-fold with applied compressive stress. This behavior can be explained by the fact that during compressive stress, the contact between PVDF/PPy fibers increases to form new conducting pathways and, hence, the relative conductivity of the polymer composites enhances significantly. It was also observed that the electrical conductivity is almost the same as its previous value after the loading being released. The PVDF/PPy composite properties produced by the method described in this study have showed interesting possibilities for pressure sensor developments.

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