The purpose of this study is to understand the solubility and spinnability of cellulose acetate (CA) and its electrospinning behaviour in different solvents. As the process of electrospinning and the corresponding fibre propertiesare primarily governed by the solvents used, a systematic study of the selection of solvent systems using the solubility parameters of Hildebrand and Hansen along with a Teas chart for a particular polymer is essential for the better optimization of the process. It appeared from the Teas chart that higher dispersion force ($f_d$) and lower hydrogen bonding force ($f_h$) areconvenient for both the solubility and spinnability of CA in single solvent of acetone and binary solvent of 2:1 acetone/$N$,$N$ dimethylacetamide(DMAc). The viscosity of the solutions escalated with increasing concentration of CA due to polymer chain entanglement which in turn favoured fibre formation. Among the solvent systems used in this work, field emission scanning electron microscopy arrayed the electrospun CA fibres using pure acetone as a solvent produced both cylindricaland ribbon-shaped fibres of a diameter of 1 $\mu$m, whereas CA in 2:1 acetone/DMAc yielded smooth bead-free cylindricalfibres of diameter in the range of 250–350 nm and CA in 3:1 acetic acid/water formed fibres with beads. Rheological analysis showed that fibre formation improved with increasing viscosity of CA solution. Electrical conductivity measurement of the CA solutions depicted that with an increase in CA concentration, fibre diameters were increased, whereas the conductivitydecreased. Also, attenuated total reflectance–Fourier transform infrared spectroscopy confirmed the major peaks of CA for all the electrospun samples.

The aim of this study is to correlate the solubility and electrospinnability of gelatin in different organic solvent systems. Teas graph was employed using the Hansen parameters in this systematic study to map the solvents that dissolve and enable the electrospinning of gelatin. It was found that in some cases, the solvent dissolved gelatin but the solution was not spinnable. Increasing the hydrogen bonding force ($f_h$) assisted in the electrospinning of the gelatin solution. Higher dispersion force ($f_d$) improves the electrospinnability at lower concentration of gelatin. The viscosity of the solution of pure acetic acid (AA) is higher than the binary solution of 3:1 AA/water and 3:1 AA/ tetrahydrofuran (THF) for the same concentration of gelatin; the higher viscosity enhanced the electrospinning properties. Interestingly, field-emission scanning electron microscopy arrayed that the effect of increasing the concentration of gelatin in the pure AA system resulted in the formation of thicker fibres, however, it induced the formation of uniform fibres in the 3:1 AA/water system, whereas beaded morphology was obtained when lower concentration of gelatin was used. The fibres obtained from electrospinning the solution of 3:1 AA/THF resulted in the formation of thicker and non-uniform fibres due to the low electrical conductivity as well as the high volatility of the solution. Attenuated total reflectance-Fourier transform infrared spectroscopy portrayed all the major peaks of gelatin in the electrospun fibres. However, widening of the Amide-A peak of gelatin was observed when the solvent system of formic acid and 3:1 AA/THF were used. Thermal study of the fibre mats depicts that the binary solvent system using AA is more suitable to obtain nanofibres with more analogous structure to pristine gelatin. The electrospun samples of gelatin in the different solvent systems did not exhibit any cytotoxity on the HeLa cell line. Teas graph can be used as a quick solvent selection tool to prepare electrospinning solutions of gelatin blended with synthetic polymers to obtain nanofibres for biomedical applications.