Construction of an interpenetrating polymer network in situ to develop multifunctional cellulose nanofiber-enhanced films with superior mechanical performances

The development of biodegradable films with enhanced mechanical performance is of great importance for environmental concerns. Inspired by the unique multiple hydrogen bonding of spider silk, in this work, we developed a tough polyvinyl alcohol (PVA)-based, TEMPO-oxidized cellulose nanofibers (TOCNF)-enhanced film with outstanding stretchability, mechanical strength, fatigue resistance, and biodegradability by constructing an interpenetrating polymer network (IPN) with abundant hydrogen bonds via a combination of in situ radical-crosslinking and solvent casting method. The film incorporated 1 wt% of TOCNF, namely P/A-TCF1, exhibits excellent biodegradability, outstanding elongation (470 %), significant toughness (143 MJ/m 3 ), healable efficiency (90 %) and high tensile strength (45 MPa), surpassing the performance of a vast of commercially-available films. Importantly, the P/A-TCF1 film can withstand 5000 actual 180° folds without causing any structural damage, and the tensile strength remains almost 90 % of its original value. This strategy provides a novel approach for exploring exceptional fold-resistant films.