Hybrid electrospun nonwovens from chitosan/cellulose acetate

Co-mixtures of chitosan (CS) and cellulose acetate (CA) were electrospun into fibrous webs from a binary co-solvent containing 70:30 trifluoroacetic acid (TFA): methylene chloride (DCM). Fibrous webs were produced from CS/CA in ratios (wt%) of 20:80, 40:60, 50:50 and 60:40. As determined by SEM analysis, 12% polymer solutions of CS/CA 60:40 produced structures with uniform bead free fibre morphologies with an average fibre diameter of 458 nm. FTIR-spectroscopy confirmed the presence of CS in the as-spun fibres in the form of chitosan-amine trifluoroacetate salts (NH ₃ ⁺CF ₃COO ^-). Uniform mixing of the CS and CA components was confirmed by DSC analyses. Alkaline neutralisation of the chitosan amine salts was explored as a means of increasing wet stability. The as-spun fibres were found to be relatively unstable in aqueous medium due to the solubility of the chitosan amine salts. Alkaline post-neutralisation was evaluated as means of minimising weight loss and maximising retention of fibrous structure.