All-biomass-based eco-friendly waterproof coating for paper-based green packaging

Abstract

Waterproof coating is necessary for paper-based packaging materials, especially as a plastic substitute in single-use applications. Currently, most paper-based packaging employs hazardous fluorocarbon coatings or other petroleum-based additives, which has caused a lot of concerns over safety. Herein, a novel edible waterproof coating was fabricated by a beeswax-in-water Pickering emulsion using hemicellulose-grafted-lauric acid (H-LA) micelles as nano-stabilizers. The fully biomass-based waterproof coating agent presented a uniform and stable water dispersion with a droplet size of around 1 μm. And compared with conventional surfactants, H-LA micelles stabilized at the oil–water interfaces and formed Pickering emulsions with enhanced stability. The Pickering emulsion was then applied as a coating of paper. The coated paper exhibited excellent water-resistance with a water contact angle of 130 ± 2.89° and an effective waterproof time of up to 6 h. The coated paper also showed good moisture barrier properties; the water vapor transmission rate was lower than 5.05 g mm m⁻² day⁻¹. Moreover, the waterproof coating was non-toxic, environmentally friendly and biocompatible, and could completely biodegrade in soil within 2 months. This work may provide an alternative solution for safe, cost-effective and sustainable paper-based packaging materials to replace traditional disposable plastics.