Preparation of cellulose nanofibers coated with poly(vinyl alcohol) crystals and their application in composite films

Abstract

Poly(vinyl alcohol) (PVA) was crystallized from a dilute solution in the presence of cellulose nanofibers (CeNFs). The CeNFs acted as nucleating agents for PVA crystallization, and PVA crystals were grown on the CeNFs' surface. As a result, CeNFs coated with PVA crystals (CeNF/PVA nanocomposite fiber (NCF_(CeNF/PVA))) were successfully obtained. The NCF_(CeNF/PVA) showed good dispersibility in water even after drying. Composite films were prepared using the aforementioned NCF_(CeNF/PVA) and their mechanical properties were measured. Despite the low content of NCF_{(CeNF/PVA=1/5)} (0.1 wt%, corresponding to 1.7 × 10⁻² wt% CeNF), the mechanical properties of the composite films improved in comparison to those of the control samples. This reinforcement effect of the NCF_{(CeNF/PVA=1/5)} was greater than that of pure CeNFs. Surface modification of the NCF was also discussed, and the surface hydrophilicity of the NCF could be controlled depending on the choice of coating crystal.