One-Step Preparation of PVB-SA Green Water- and Oil-Proof Coatings for Food Packaging

The growing demand for sustainable packaging has accentuated the urgent need for high-performance, environmentally friendly coatings. In this study, we proposed a low-cost and industrially applicable one-step dip-coating strategy that integrates poly(vinyl butyral) (PVB) with stearic acid (SA) to construct multifunctional coatings on bamboo fiber paper. PVB established hydrogen bonding with cellulose, forming a dense and continuous film that acted as a robust physical barrier and adhesive matrix. Concurrently, SA molecules interacted with PVB or cellulose through their carboxyl groups, whereas their long alkyl chains self-assembled during curing to generate hierarchical micro/nanostructures, thereby markedly reducing the surface energy. The synergistic interplay between PVB and SA produced a dual-repellent interface, in which PVB ensured film compactness and adhesion, whereas SA imparted pronounced hydrophobic and oleophobic characteristics. As a result, the modified bamboo fiber paper exhibited a high water contact angle of 136.41 ± 1.98°, an oil resistance grade of 12, and a tensile strength of 25.30 MPa─representing a 3.26-fold improvement over the unmodified substrate (7.76 MPa). This strategy demonstrated a facile, economical, and scalable route for producing multifunctional, eco-friendly paper coatings with substantial potential for sustainable food and medical packaging applications.