High barrier paper coating with dual-crosslinked networks based on cellulose nanofibrils and epoxidized natural
Ziqing Jiang1, Zhexuan Ouyang1, Shuo Zhang1
1Guangdong Provincial Key Laboratory of Food Quality and Safety, College of Food Science, South China Agricultural University, Guangzhou, 510642, China.
Abstract:
The development of sustainable high barrier coatings for paper packaging requires effective alternatives to conventional plastics. This study presents a fully bio-based, dual-crosslinked coating system comprising of cellulose nanofibrils (CNF) and epoxidized natural rubber (ENR) to synergistically enhance barrier properties of paper. The coating fully leverages the inherent hydrophobicity of ENR and the tortuous nanofibrillar network of CNF. A hierarchical crosslinking network was constructed through hydrogen bonding between epoxy groups of ENR and hydroxyl/carboxyl groups of CNF, further reinforced by Fe3+-mediated coordination crosslinking. The optimized coating reduced water vapor transmission rate (WVTR) by 84% (from 3154 to 510 g/m2·24h) and decreased the oil Cobb value by 95% compared to the uncoated paper. A practical demonstration using high-fat spicy strips further illustrated the oil barrier efficacy. Furthermore, under wet conditions, the dual-crosslinked samples retained over 80% of their dry tensile strength, substantially higher than samples relying solely on hydrogen bonding. This work provides a promising strategy for sustainable high barrier coatings in food packaging applications.
