Ultra-flexibility, robust waterproof and breathability of polyvinylidene fluoride membrane blended silver nitrate for electronic skin substrate

Abstract

Flexibility, waterproof and breathability of substrates are the key issues restricting the application of electronic skin. Composite nanofibrous membranes (CNFMs) as substrates of electronic skin are prepared from polyvinylidene fluoride and silver nitrate blended solution by electrospinning technique. The microstructure and performances of the CNFMs are characterized by scanning electron microscopy, x-ray diffraction, capillary pore size analyzer, gravimetric method, water vapor permeability tester, optical contact angle tester, water permeability tester, intelligent electronic strength tester, hand-held electronic thickness meter and seveneasy conductivity meter. The results indicate that with the introduction of silver nitrate, the waterproof and breathability of CNFMs are balanced and optimized. The moisture permeability increases by 22%–69% from 2915.9 g · m−2 · 24 h−1 of pristine nanofibrous membrane (PNFM) to 3801.2–4151.5 g · m−2 · 24 h−1 of CNFMs and the hydraulic pressure decreases from 23.4 kPa to 21.6–16.5 kPa. However, the change of contact angle is irregular, which depends on the presence of like lotus-leaf-papillae morphology on fiber surface. The tensile strength of CNFMs decreases greatly and the elongation increases by 3–8 times from 7.7% of PNFM to 25.1%–63.2% of the CNFMs. The improvement of CNFMs flexibility is attributed to the hierarchical roughness of nanofiber surface, the unlock bonding between fibers and various combination forms of silver particles in CNFMs. Thus it was suitable to be applied as the substrate of electronic skin.