The influence of electrospinning parameters and solvent selection on the morphology and diameter of polyimide nanofibers

Polyimide (PI) fibers display excellent thermal and mechanical performance; they have been recently investigated to fabricate hydrophobic membranes (mats) for high-performance applications. We studied the effect of electrospinning processing parameters and solvent selection on the morphology and the diameter of PI fibers. 11 different solvents and 22 solvent systems able to dissolve PI were located in a Teas graph with the aim of building the solubility-electrospinnability map for this material. PI solutions prepared with various solvents were electrospun at different electrospinning process parameters according to a 34–1 fractional factorial design of experiments. Polymer concentration and applied voltage were the most significant factors to create thin and uniform fibers. More homogeneous fibers and reproducible electrospinning process were obtained by using polymer concentrations above 15 wt%. However, all solutions showed different morphological evolution according to the solvents used. Based on the solubility–spinnability region settled for this PI, non-woven mats were obtained with rough surface fiber morphology and high water contact angle, suitable for applications such as hydrophobic membranes for oil-water separation.