Vortex fluidic mediated one-step fabrication of polyvinyl alcohol hydrogel films with tunable surface morphologies and enhanced self-healing properties

Previous strategies for controlling the surface morphologies of polyvinyl alcohol (PVA)-based hydrogels, including freeze-drying and electrospinning, require a post-treatment process, which can affect the final textures and properties of the hydrogels. Of particular interest, it is almost impossible to control the surface morphology during the formation of PVA hydrogels using these approaches. The strategy reported in this study used the novel vortex fluidic device (VFD) technology, which for the first time provided an opportunity for one-step fabrication of PVA hydrogel films. PVA hydrogels with different surface morphologies could be readily fabricated using a VFD. By also reducing the cross-linking agent concentration, a self-healing gel with enhanced fracture stress (60% greater than that of traditionally made hydrogel) was achieved. Interestingly, the associated self-healing property remained unchanged during the 260-s mechanical testing performed with the strain rate of 5% s⁻¹. The VFD can effectively tune the surface morphologies of the PVA-based hydrogels and their associated properties, particularly the self-healing property.