Multiple cross-linked cellulosic paper-based waterproof and biodegradable mulch film for "green" agriculture

Biodegradable cellulosic mulch has been demonstrated as the promising alternative to traditional plastic mulch film in agriculture, whereas the highly hydrophilic property and poor wet strength severely restricted their practical application. Herein, a new waterproof dialdehyde cellulose (OR)-polyamide epichlorohydrin (P)-alkyl ketene dimer (A) (OR-P-A) was carefully designed as the green mulch film. The hydrogen bonds and Schiff base reaction between -CHO on dialdehyde cellulose fibers and -NH₂ on PAE reinforced the interfacial interaction of cellulosic fibers. Furthermore, the formed β-keto ester bonds of -OH on cellulose with AKD improved the water resistance of paper fiber. Compared with the pristine cellulose film, the dry and wet tensile strength of OR-P-A₂ were increased to 17 MPa and 3 MPa, respectively. Moreover, the water contact angle was increased from 25° for pristine cellulose film to 124° for OR-P-A₂. In addition, the germination rate of cabbage seeds covered by OR-P-A₂ was similar to that of commercial polyethylene film in practical application. This strategy proposed a novel method to improve the hydrophobicity of cellulose film, which boosting the development of biodegradable mulch film and "green" agriculture.