Bioinspired poly(vinyl alcohol) films with tunable adhesion and self-healing for biodegradable electronics and beyond

Abstract

Polymers have attracted attention for their use in enabling biodegradable electronics. However, many polymers suitable as substrates either have no adhesion or suffer from weak and unstable adhesion. Addressing this challenge, we report a simple method to achieve tunable adhesion on various surfaces for wide applications. We achieve this by combining poly(vinyl alcohol) (P), dopamine (DA) and citric acid (CA) to produce modified poly(vinyl alcohol) adhesive films. These films are derived from bio-based constituents through an environmentally benign, easily reproducible and scalable fabrication process. They offer strong adhesion to various surfaces, such as stainless steel (138–191 kPa) and Polytetrafluoroethylene (PTFE) (67–93 kPa) and facilitate easy detachment with water. Notably, the modified films showed a better degradation compared to pristine P films under anaerobic conditions. The extent of degradation was characterized both quantitatively and qualitatively. The biokinetic parameters of anaerobic digestion process were estimated using three different kinetic models. It is anticipated that DA and CA molecules penetrate the interplanar distance of P chains as supported by powder X-ray diffraction (XRD) studies, thus, accelerating the degradation process. Additionally, the inclusion of CA enhanced the stability of DA molecules against oxidation, increased the extent of H-bonding and acted as a plasticizer. The addition of DA and CA bestowed the films with self-healing property due to the presence of multiple H-bonds. Tensile experiments revealed that the strength of self-healed samples approached that of pristine samples. The findings of this study hold promise for the development of innovative, biodegradable poly(vinyl alcohol)-based self-healing adhesive films with potential applications across various domains like smart packaging, soft robotics, on-skin electronic tattoos and self-healing electronics.