Silica nanocolloids doped polyvinyl alcohol film with enhanced water uptake and ion exchange capacity for water-driven IPMC actuator

Ionic polymer metal composites (IPMCs) are widely used in flexible actuation and sensing. Traditional IPMCs employ the commercial Nafion film as the electrolyte films, suffering from low water uptake (WU), high modulus, and high cost. This study reports a water-resistant polyvinyl alcohol (PVA) electrolyte film with high WU and ion exchange capacity (IEC), using PVA as the matrix, sulfonic SiO2 nanocolloids as the fillers, and glutaraldehyde as the crosslinking agent. Physicochemical tests reveal that the PVA film containing 9 wt% sulfonic SiO2 nanocolloids exhibits better IPMC-related properties when compared to Nafion: 3.92 folds in WU, 1.14 folds in IEC, and 0.238 folds in elastic modulus. After spraying an electrode slurry containing poly(3,4-ethylenedioxythiophene) /poly(styrenesulfonate) dispersed multi-walled carbon nanotubes, the SiO2/PVA film IPMC actuator demonstrated exceptional electromechanical response. Under DC signal, it maintains a steady one-way deflection with a large swelling angle of 48.1 ° and no significant back relaxation. Under AC signals, it generates periodic deflections with outputted displacements up to 8.19 mm for 440 s; after water replenishment, the actuator remains a repeatable and reliable deflection without an evident displacement decay. The SiO2/PVA film IPMC actuator demonstrates outstanding stability and actuation performance, making it suitable for applications in bionic robotics and wearable electronics.