Disulfide Cross-Linked PVA Elastomer Films with Self-Healing and High Dielectric Properties for Flexible Capacitive Pressure Sensors

Poly(vinyl alcohol) (PVA) has been widely used owing to its excellent processability and mechanical strength. However, films formed via strong hydrogen bonding are typically dense and brittle, which limits their practical applicability. Although various strategies have been investigated to overcome this issue, most approaches rely on hydrogel systems that often exhibit low mechanical strength and reduced durability due to solvent evaporation. In this work, a flexible and self-healable PVA-based elastomer film was successfully developed. The film was synthesized by incorporating polyethylene glycol (PEG) and 2,2′-ethylenedioxydiethanethiol (EDDET) into the PVA structure through disulfide covalent bonding. The resulting film exhibited excellent mechanical properties, with a tensile strength of 2.4 ± 0.2 MPa (mean ± SD, n = 5) and an elongation at break of 210 ± 3.2% (mean ± SD, n = 5), as well as a high dielectric constant of 12.4 ± 0.3 (mean ± SD, n = 5) at 105 Hz. When used as the dielectric layer in a capacitive tactile sensor, the film showed high sensitivity and maintained stable performance even after 10,000 cycles of repeated pressure loading. Furthermore, owing to the reversible nature of disulfide bonds, the film demonstrated effective self-healing behavior upon mechanical damage.