Quaternized cellulose nanofibril paper coatings for sustainable packaging with improved barrier and antibacterial performance

Abstract

Abstract Quaternized cellulose nanofibrils (quaternized CNFs) with different cationic group contents were prepared and applied as multilayer paper coatings to develop sustainable antibacterial and barrier materials. Increasing the cationic group content (160–660 µmol/g) reduced CED viscosity and yield stress, indicating weakened network structures and reduced interfibrillar interactions These rheological changes improved coating flow and layer uniformity, leading to denser coating layers with enhanced air barrier performance and water resistance. Antibacterial tests revealed clear contact-active antibacterial activity against Gram-positive bacteria, which increased with cationic group content and coating layer number, likely because the immobilized quaternary ammonium groups more effectively interacted with the exposed negatively charged cell membrane. In contrast, antibacterial performance against Gram-negative bacteria remained limited, likely due to the protective outer membrane. Within the investigated range, a maximum cationic group content of approximately 660 µmol/g was sufficient for Gram-positive bacteria, whereas higher contents may be required for effective activity against Gram-negative bacteria.