Cellulose nanofibrils reinforced films without chemical modification, hydrophobic, high elongation, and foldability

Cellulose nanofibrils (CNF) films are generally regarded as promising alternatives for non-biodegradable plastics films. However, the shortcomings of high hydrophilic performance, low elongation and poor folding endurance continue to pose challenges in commercial application. In the present study, we established controllable reflectance CNF films by applying a facile and scalable poly (butylene adipate-co-terephthalate) (PBAT)/SiO 2 nanoparticles (NPs) reinforced strategy in a free chemical modification manner. CNF/PBAT films have the favorable combination of hydrophobicity, elongation and folding endurance. The results reveal a significant improvement in the hydrophobic properties of CNF/PBAT films (water contact angle >80°), as well as a 3 times improvement in folding resistance (1210 cycles), a 3.7 times improvement in tensile strength (89.8 MPa) and controlled reflectance properties. Additionally, we examined the hiding power and color difference of the CNF/PBAT films, and explored the underlying principle for the enhanced hydrophobicity, folding resistance, elongation and reflectance. Finally, the CNF/PBAT films exhibited stable comprehensive performance after we applied the films in drinking straws. The present study provides a facile strategy to prepare hydrophobic, folding resistant, reinforced and reflectance-controlled CNF films and could promote industrial use in the fields of glass film, beverage appliances, packaging, and flexible electronic devices. • Increasing the layer spacing and porosity of CNF films by mixing with SiO2. • Mechanical, elongation, folding and reflectance properties of prepared composite improved markedly. • CNF/PBAT films display a controlled adjustment in reflectance, hiding power, and color difference. • CNF/PBAT films provide stability for packaging, electronics and other advanced applications.