The global push to reduce plastic waste has intensified interest in paper as a sustainable packaging material. Derived from renewable plant fibers, paper is biodegradable, recyclable, and widely available. However, its intrinsic porosity and hydrophilicity result in poor resistance to water and oil, severely limiting its use in food and consumer packaging. Conventional solutions, such as fluorinated coatings or polyethylene laminates, improve barrier properties but undermine recyclability and introduce environmental concerns.
In a study now available in Journal of Bioresources and Bioproducts, researchers present a new coating strategy that addresses these long-standing challenges by integrating biodegradable components into a lignin nanoparticle–stabilized Pickering emulsion. The approach leverages the amphiphilic nature of lignin nanoparticles to stabilize an oil-in-water emulsion composed of polyvinyl alcohol (PVA) and stearic acid (SA), forming a multifunctional coating that enhances paper performance without sacrificing environmental compatibility.
In the reported system, PVA serves as a hydrophilic, film-forming polymer in the aqueous phase, providing mechanical reinforcement and oil resistance through a dense hydrogen-bonded network. Stearic acid, a naturally derived fatty acid, acts as the hydrophobic oil phase, imparting water repellency. Lignin nanoparticles, prepared through a solvent-exchange self-assembly process, irreversibly adsorb at the oil–water interface, stabilizing the emulsion without synthetic surfactants. This Pickering emulsion design enables the uniform dispersion of hydrophobic components within a water-based coating system.
When applied to paper substrates, the emulsion forms a continuous and compact coating layer that seals surface pores and creates a synergistic barrier against both water and oil. The coated paper exhibits a water contact angle exceeding 110°, a Cobb 60 value below 18 g/m², and a Kit oil resistance rating above 9/12—levels comparable to those of commercially used plastic-coated papers. At the same time, tensile strength and wet strength are significantly improved, allowing the paper to maintain structural integrity even after prolonged water exposure.
Beyond barrier and mechanical performance, the study places strong emphasis on end-of-life considerations. Unlike conventional plastic-coated papers, the reported coating can be removed through a simple hot-water repulping process. During recycling, PVA dissolves, stearic acid melts and disperses, and lignin nanoparticles are released, enabling clean recovery of cellulose fibers without degrading recycled paper quality. Soil burial tests further demonstrate that the coated paper fully degrades within approximately 120 days, while polyethylene films show no observable degradation under identical conditions.
The coated paper also demonstrates functional advantages in food preservation. Packaging tests using fruits such as bayberries, grapes, and cherry tomatoes show that the coating effectively reduces moisture loss by lowering water vapor transmission, extending freshness compared with uncoated paper. These results suggest potential applications in fresh produce and food packaging, where moisture control is critical.
By combining biomass-derived materials with Pickering emulsion technology, the reported strategy provides a scalable and environmentally benign route to high-performance paper packaging. While further optimization is needed—particularly in simplifying lignin nanoparticle production and improving gas barrier properties—the work illustrates how renewable nanomaterials can help bridge the performance gap between paper and plastics. As regulatory pressure and consumer demand continue to drive the transition toward sustainable packaging, such multifunctional, recyclable coatings may play a key role in enabling paper to replace plastics in demanding applications.
Journal of Bioresources and Bioproducts
Experimental study
Not applicable
Lignin Nanoparticle Stabilized Pickering Emulsion Coating for Fabricating Water- and Oil-Proof, Biodegradable, and Recyclable Paper
27-Jan-2026