Surface modification of cellulose nanofibers by oxidative polymerization of tannic acid/ethanediamine and their polyvinylalcohol composites

Abstract This paper reported a facile and green method for surface functionalization of cellulose nanofiber (CNF) by oxidative polymerization of tannic acid (TA) and ethanediamine. The modified CNF (T‐CNF) was then used as filler for constructing polyvinylalcohol (PVA) composites. Experimental results suggested that the surface polar groups on CNF were increased after modification. The abundant surface polar groups allowed the homogeneous dispersion of T‐CNF in PVA matrix, and the formation of hydrogen bonds between fillers and matrix. This interfacial interaction and the high aspect ratio of T‐CNF have restricted the thermal mobility of polymer chains and increased the glass transition temperature and melting temperature of PVA. Tensile test suggested the good mechanical properties of composites, and the reinforcement effect of T‐CNF on PVA was better than that of un‐modified CNF. The good free radical scavenging ability of polymerized TA also improved the thermal stability of composites and endowed the composites with good antioxidant property. The T‐CNF/PVA composites with improved properties hold great promising applications in fields such as packaging, adhesive and coating. This work is expected to provide alternative and green approach for the surface modification of CNF and the preparation of multifunctional CNF composites with good properties.