Fabrication of Ionic Cellulose Nanofiber Composites by Electrospinning Cellulose Microfibril-Gel-Dispersions in Poly(vinyl Alcohol) Solution

In this study, we propose a fabrication method to obtain composites of poly(vinyl alcohol) (PVA)/ionic cellulose nanofibers, in which a fiber structure is manipulated through a reconstruction of 2,2,6,6-tetramethyl-piperidinyl-1-oxyl radical (TEMPO)-oxidized cellulose nanofiber (TCNF) or the carboxymethyl cellulose nanofiber (CMCNF) heterogeneous microfibril gels using electrospinning method. The key concept is to assemble nanofibers from thin few-nanometer-scale width cellulose nanofibers (microfibrils) to thicker several-hundred-nanometer-scale width cellulose nanofibers by electrospinning insoluble microfibril-gel-dispersion in PVA solution. In the case of CMCNF, nanofibers with less-fused structures were successfully reconstructed via electrospinning. Energy-dispersive X-ray spectroscopy revealed that sodium ions exist in the fibers, where they function as counter ions of carboxylate groups of polyelectrolyte moiety of CMCNF. Thus, the obtained composites do contain both ionic cellulose nanofibers and PVA. The proposed fabrication route can be used to fabricate composites as nonwoven fabrics of polyelectrolyte nanofibers. These natural polymer based ionic fabrics will be widely useful to propose low-environmental-impact polymer actuators and active sensing elements involving the ion transport phenomena.