Structurally engineered cellulose-based mulch film with enhanced hydrophobicity and strength for green agriculture

Conventional low-density polyethylene (LDPE) mulch films have caused serious white pollution, driving the need for sustainable alternatives. Biodegradable cellulose paper mulch has shown great potential, yet its practical use remains limited by excessive water absorption and poor mechanical strength. To overcome these drawbacks, a sandwich-like multilayer structure was innovatively constructed by successively coating cationic starch (S) and 3-aminopropyl triethoxysilane (APTES) onto cellulose substrates, followed by glyoxal-mediated cross-linking (CSGA). CS acted as an interfacial adhesive via hydrogen bonding and electrostatic interaction, while APTES introduced hydrophobic silane moieties through Schiff base and acetal linkages. Compared to pristine cellulose paper, the resultant composite film (CS₃GA₅) exhibited a significant improvement in dry tensile strength (26.8 MPa) and wet tensile strength (5.2 MPa), with a water contact angle increased from 16° to 128°, and a reduced swelling ratio from 123 % to 62 %. Additionally, the seed germination rate under CS₃GA₅ was 82 %, comparable to that of commercial LDPE mulch. The CS₃GA₅ film also demonstrated complete biodegradability within 56 days in natural soil, aligning with crop growth cycles. This work presents a facile and scalable approach for fabricating high-performance biodegradable mulch films, offering a promising solution for microplastics pollution.