Simultaneous toughening and strengthening of chitin-based composites via tensile-induced orientation and hydrogen bond reconstruction.

Chitin, an abundant, biodegradable, and biocompatible polysaccharide, is one of the most ideal eco-friendly alternatives to petroleum-based plastics. However, the applications of chitin-based materials are hindered by their low processability and brittleness induced by strong hydrogen bonds. Herein, a tensile-induced orientation and hydrogen bond reconstruction strategy was developed to fabricate a chitin nanowhiskers/poly(vinyl alcohol) composite film with high strength and toughness. After stretching and hydrogen bond reconstruction, the tensile strength and elongation at break of the composite film increased from 38.6 to 115.2 MPa and 9.37% to 40.7%, respectively. Furthermore, strengthening and toughening mechanisms were also studied, which were attributed to the effects of the intra-layer orientation and interlayer sliding, respectively.