Cellulose Nanocrystals: Dispersion in Co-Solvent Systems and Effects on Electrospun Polyvinylpyrrolidone Fiber Mats

This study reports a method to achieve dispersion of freeze-dried Cellulose nanocrystals (CNCs) with polyvinylpyrrolidone (PVP) in a water-methanol co-solvent system using purely mechanical means; in this case, magnetic stirring and sonication. During this study, no chemical modifiers or surfactants of any kind were added during the dispersion process as they increase the cost and duration of the manufacturing process for CNC reinforced composites and nanocomposites. The effect of CNC loading (0-20wt% of PVP) and preparation method on solution viscosity, dispersion, and mechanical properties of electrospun PVP/CNC nanocomposite fiber mats were examined. In particular, this study demonstrates that pre-dispersion of the hydrophilic CNCs in pure deionized water before the addition of methanol and PVP is critical to improving dispersion and achieving greater homogeneity of the system. All samples were examined for birefringence by polarized light microscopy, which was correlated to the level of CNC dispersion within the polymer matrix. The effect of CNC loading on the mechanical properties of the composite mats was investigated via tensile testing. Humidity was identified as an important factor affecting the PVP nanofiber morphology and strength, though its effects were not characterized in this study.