Dual grafting strategy via Schiff base cross-linking for durable antibacterial and uvioresistant starch-based...

In the face of the environmental crisis stemming from petrochemical plastics, there is an urgent need to search biodegradable packaging film. Starch emerges as an ideal alternative owing to eco-friendliness and renewability. Based on time, temperature, pH and molar ratio, salicylaldehyde starch (SCS) and aminated poly (vinyl alcohol) (APVA) with optimal grafting rates are successfully synthesized. Subsequently, starch-based films (SCSP) are fabricated via controllable dual-grafting strategy and Schiff base cross-linking. Because of the presence of modified APVA, the SCSP film has high tensile strength (≥ 20.5 MPa) and elongation at break (≥ 38.3 %). The incorporation of Schiff base group endows films with exceptional UV resistance (≥ 99 %) and sustained sterilization for up to 30 days. Meanwhile, excellent compatibility and gas barrier properties of films prevent bananas from browning for 120 h under ultraviolet irradiation, and extend the shelf life of strawberries by up to 7 days. In particular, the film is virtually biodegradable in soil after 35 days and exhibits high biosafety with cell viability of over 83.2 %, which presents a controllable and simplified modification strategy for starch, and opens up the possibility of alleviating the pollution caused by petrochemical plastics.