A multifunctional soybean protein isolates crosslinked gelatins composite mulch film: Fabrication, characterization, and application

The development of sustainable agriculture has boosted an increase in demand for biodegradable and multifunctional biomass-based mulch films. Herein, a sort of eco-friendly and multifunctional soybean protein isolates crosslinked gelatins (SPI-c-Gel) composite mulch films were elaborately designed through the Schiff base reaction. The formation of physical entanglement and chemical cross-linking between the molecular chains of SPI and Gel could effectively dissipate the loading energy and thereby strengthen the resistance of the composite mulch films to water penetration. Specifically, the maximum tensile strain and tensile stress were observed to increase from 4.05 MPa at 73.3 % for pure SPI film to 14.7 MPa at 151 % for optimized SPI-c-Gel_0.3 mulch film. The swelling rate in water declined from 280 % for pure SPI film to 141 % for SPI-c-Gel_0.3 composite film. Furthermore, the fabricated composite mulch film exhibited satisfied water retention, urea slow-release properties, and biodegradability. The application experiments of SPI-c-Gel_0.3 composite mulch have shown that the seeds grew faster when cabbage seeds were covered by such mulch film during seed germination. Our findings provide a novel strategy for regulating the physical and chemical properties of biopolymer-based multifunctional mulch films, which may be employed to promote the development of sustainable agriculture.