Coaxial electrospinning with ethanol aqueous solution for preparing high quality Zein nanofibers

A modified coaxial electrospinning process is developed for producing thinner zein nanofibers. With ethanol aqueous solutions as sheath fluids, high quality zein nanofibers have been successfully generated using the modified process. Electron scanning microscope results demonstrate that the nanofibers have better quality than those produced by a single fluid electrospinning in terms of nanofiber diameters and their distributions. The former has an average diameter of 1230 +/- 340 nm while the later 420 +/- 140 nm under a sheath-to-core flow rate ratio of 0.267. The mechanism is proposed that an appropriate ethanol aqueous solution surrounding the core zein jet helps to retain it in a fluid state to experience a longer time and more stable electrical drawing, with little adverse influence on the zein chain entanglements in the core fluid jets and thus its electrospinnability. The modified coaxial electrospinning process described here extends the capability of electrospinning process and opens a new way to obtain thinner nanofibers of macromolecules with fine structural uniformity.