Robust and versatile superhydrophobic cellulose-based composite film with superior UV shielding and heat-barrier performances for sustainable packaging.

Replacing single-use plastic delivery bags (SPDBs) with cellulose-based materials is an effective strategy to reduce environmental pollution. However, the inherent hydrophilicity and ultralow mechanical strength of cellulose materials limit its development. In this study, zinc oxide (ZnO)-cellulose composite films were successfully prepared through "two-step strategy" of lotus leaves structure simulation, including deposition of micro-nano ZnO particles and stearic acid (STA) modification. Well-dispersed micro-nano ZnO particles with stick-like structure were anchored in the ZnO-cellulose composite film prepared at 90 °C (CF-90). Due to the special structural design and strong interaction between the cellulose and micro-nano ZnO particles, the CF-90 showed higher mechanical property (a 47.8 % improvement in the tensile strength). Impressively, CF-90 also exhibited great UV shielding properties with larger UPF value of 1603.98 and superhigh heat-barrier performance. Moreover, CF-90 obtained excellent superhydrophobicity with a water contact angle of 163.6° by further modification. Consequently, the versatile cellulose-based material bringing a dawn on application of sustainable packaging materials for express delivery industry.