Formation of cellulose nanofiber sponge via in-situ deacetylation of immersion-electrospun cellulose acetate at the hexane/aqueous sodium hydroxide interface

Immersion electrospinning (I-ESP) is a solution-based technique that produces polymer nanofibers through solvent-nonsolvent exchange in a liquid medium. In this study, cellulose-rich nanofiber assemblies with a sponge-like, loosely interconnected fibrous morphology were obtained via I-ESP of cellulose acetate (CA) in a hexane/aqueous NaOH dual-bath system combined with in-situ deacetylation. CA nanofibers were first formed at the hexane/water interface, where the applied electric field facilitated nanofiber assembly even at relatively low voltage. Replacing water with aqueous NaOH enabled partial deacetylation of CA as the fibers contacted the alkaline phase during deposition. The stability of the spinning process was strongly influenced by the NaOH concentration. A moderate concentration (0.1 M) enabled stable fiber formation, whereas a higher concentration (1.0 M) resulted in rapid hydrolysis and unstable fiber deposition. ATR-FTIR analysis confirmed mild in-situ deacetylation through the reduction of acetyl and ester-related peaks. These results demonstrate a simple approach for producing cellulose-rich nanofiber assemblies through I-ESP without a separate post-treatment step.