Nanocellulose-reinforced semi-refined carrageenan biofilms: Surface modification and characterization for sustainable...

Growing environmental concerns over petroleum-based plastics have intensified research into bio-based packaging materials from renewable marine resources. This study reports the fabrication and comprehensive characterization of nanostructured biofilms produced from semi-refined carrageenan (SRC) extracted from red seaweed, reinforced with cellulose nanofibers (CNF) to address the inherent limitations of seaweed-based films, including poor mechanical strength and moisture sensitivity. SRC retaining residual cellulose was combined with varying CNF loadings (0-7 wt%) to enhance structural integrity and moisture-related barrier potential. Surface modification using triethoxymethylsilane (TEMS) was applied to further improve hydrophobicity by reducing surface hydroxyl groups and enhancing interfacial compatibility. The optimized TEMS-modified SRC biofilms containing 5 % CNF exhibited a remarkable tensile strength of 45.37 MPa, a tensile modulus of 931.22 MPa, and a water contact angle of 83.73°, representing a significant increase in tensile strength and hydrophobicity compared to unmodified films. Thermal analysis revealed enhanced thermal stability with higher char formation at elevated temperatures. These enhancements result from improved intermolecular interactions between CNF and the SRC matrix, coupled with effective silane coupling that reduces water affinity and increases film compactness. The synergistic effects of CNF reinforcement and surface silanization demonstrate a promising strategy for developing robust, thermally stable, and hydrophobic biofilms as sustainable alternatives for eco-friendly packaging application.