Solution blow co-spinning of cellulose acetate with poly(ethylene oxide). Structure, morphology, and properties of nanofibers

Cellulose acetate (CA) nanofibers are prepared using solution blow co-spinning (SBS) with poly(ethylene oxide) (PEO). The pure CA membranes are obtained by washing water-soluble PEO from the fibrous CA-PEO blend. Nanofibrous membranes are characterized using optical and scanning electron microscopy (SEM), differential scanning calorimetry (DSC), infrared spectroscopy (ATR-FTIR), and surface zeta potential measurements. Thermal transitions from DSC and ATR-FTIR spectra analysis were used to confirm the removal of the PEO. Although the characteristic signals of PEO are not observed by FTIR, an additional thermal step transition in CA nanofibers indicates the embedding of a small amount of PEO (up to 6 wt%). SEM analysis shows that CA-PEO blends are constituted by fibers with mean diameters from 671 to 857 nm (depending on the SBS parameters), while after PEO removal, diameters range from 567 to 605 nm. We propose a new method for staining CA-PEO membranes with iodine solution in absolute ethanol that allows the differentiation of CA and PEO components with an optical microscope. The microscopy results suggest that PEO assists in the spinning by enveloping CA nanofibers, allowing uninterrupted processing. The successful deacetylation to cellulose using an aqueous KOH solution is confirmed with zeta potential measurements and ATR-FTIR.