Balancing performance and eco-friendliness: Esterified cellulose nanofiber films for next-generation food Packaging

Biodegradable cellulose-based materials promise an alternative to conventional plastics, yet combining high performance with environmental sustainability is challenging. Here, we introduce cellulose nanofiber (CNF) films esterified with short-chain fatty acids, systematically optimizing chain length to boost barrier properties while retaining biodegradability. Esterification increased tensile strength by ~30 MPa through hydrophobic interactions, reduced the water vapor transmission rate over 200-fold, and decreased the oxygen transmission rate nearly six-fold compared to petroleum-based materials. Furthermore, the films were optimized for spray coating, enabling uniform deposition and scalability. Notably, they fully decomposed within 16 weeks under composting conditions. We hypothesize that the degree of esterification and fatty acid chain length govern the balance between barrier performance and biodegradability, as validated through structural, mechanical, and barrier analyses. These findings demonstrate a rational design strategy for functionalized CNFs, advancing high-performance, biodegradable materials for next-generation sustainable applications, including food packaging.