Highly Transparent, Self-Reinforced, and Hydrophobic Cellulose Acetate Films Fabricated Based on Thermal Stretching and Surface Engineering

Abstract

Imparting cellulose acetate with surface hydrophobicity and self-cleaning function without sacrificing its high transparency and mechanical robustness is a great challenge. In this work, we report a highly transparent, self-reinforced, and hydrophobic cellulose diacetate (CDA) film, prepared by the combination of non-solvent-induced phase separation, uniaxial thermal stretching, and slippery liquid injection (LI). Results indicate that the surface-modified CDA films have hydrophobicity, with the water contact angle (WCA) increasing from ∼58.2 to 105–109°. Meanwhile, by adjusting the draw ratio, the sliding of liquid on the film surface and the WCA hysteresis are effectively improved, especially the sliding angle of CDA-LI-1.7-200 film decreases from 30.5° (for the unmodified CDA film) to 9.4°. Notably, uniaxial stretching provides enhanced mechanical strength for this antifouling CDA film, with up to 60.2% increase in tensile strength (from 37.2 to 59.6 MPa). Meanwhile, it is noted that the modified CDA film also has excellent transparency (≥92%), even slightly higher than that of the unmodified CDA film (∼91.5%). In addition, the surface-modified CDA films show excellent anti-scratching performance and maintain good liquid repellency even after several cycles of severe scratching. The work would provide guidance for the facile preparation of high-performance and multifunctional CDA films.