Bioinspired Strong, Tough, and Biodegradable Poly(Vinyl Alcohol) and its Applications as Substrates for Humidity Sensors

Biodegradable polymeric materials with high strength and outstanding toughness are necessary for real-world applications in the fields of electronics, electrics, and packaging. Unfortunately, such performance portfolios in polymers remain challenging to achieve due to their different governing mechanisms. Inspired by the hydrogen-bond (H-bond) cross-linking structure of spider silk, herein, strong and tough poly(vinyl alcohol) (PVA) composites with beta-cyclodextrin as a cross-linker are developed. Benefiting from the H-bond cross-linking effect, the addition of 1.0 wt% of beta-cyclodextrin enables PVA to achieve a high tensile strength of 136.5 MPa, and a high elastic modulus of 3.0 GPa, in combination with a good toughness of 82.1 MJ m(-3). In addition, the presence of beta-cyclodextrin improves the biodegradability of PVA composite by decreasing its crystalline size. Furthermore, PVA/beta-cyclodextrin composite combined with MXene has great potential as a sensor material for humidity and strain detection. This proof-of-concept opens numerous opportunities to create strong, tough, and biodegradable polymers for packing and sensing applications.