Role of Cellulose Nanofiber Surface Functionalization in the Interfacial Interactions of Pectin-Based Nanocomposites

Abstract Functionalized nanocellulose has been strategically employed in biobased materials to overcome intrinsic limitations by modulating the interfacial interactions and broadening their application potential. In this study, pectin-based nanocomposites were prepared by incorporating pristine, TEMPO-mediated oxidized, or EPTMAC-cationized cellulose nanofibers (CNFs), and the influence of these surface functionalization strategies on interfacial interactions and macroscopic properties was investigated. Chemical functionalization significantly influenced the supramolecular forces within the nanocomposites and their interfacial dynamics with the polyelectrolyte matrix, particularly at the highest tested loading (10 wt %). Crystallinity, morphology, mechanical performance, thermal stability, and water affinity were all influenced by CNF surface chemistry. Films containing oxidized CNFs showed higher surface hydrophobicity, indicating stronger structural organization and reduced availability of hydrophilic groups. In contrast, cationic CNFs resulted in lower mechanical resistance and thermal stability. The observed behaviors indicate that interfacial interactions in the nanocomposites arise from the combined contributions of electrostatic interactions, chemical functionality, steric effects, and structural organization. Overall, the results demonstrate that CNF surface chemistry serves as a tunable design parameter for tailoring nanocomposite performance, contributing to the development of materials aligned with circular economy principles.