Effect of electrospinning parameters on the morphology of polyurethane nanofibers and their shape memory behaviors

Introduction: We investigated the effect of various electrospinning parameters on the morphology and average diameter of shape memory polyurethane (PU) nanofibers. The shape memory performance of an electrospun PU nanofiber mat was also studied. Methods: The examined parameters included solution concentration (16–22 wt%), applied voltage (8–10 kV), feed rate (0.8–1.2 mL/h), needle-to-collector distance (18–20 cm), and solvent mixture (N,N-dimethylformamide (DMF), DMF/chloroform, and DMF/ethyl acetate). The morphology of electrospun PU nanofibers was observed using a scanning electron microscope. The shape memory properties of the electrospun PU nanofiber mat obtained at the optimal parameters were investigated using a thermomechanical cyclic testing program. Results: Bead-free nanofibers with an average diameter of 600 nm were obtained using a 20 wt% PU solution in DMF, an applied voltage of 10 kV, a feed rate of 1.0 mL/h, and a needle-to-collector distance of 20 cm. Using DMF/chloroform and DMF/ethyl acetate as solvents, uniform PU nanofibers were obtained at a PU concentration of 16 wt%. The electrospun PU nanofiber mat exhibited excellent shape memory properties, achieving shape recovery ratios and shape fixity ratios exceeding 90%. Conclusions: A PU nanofiber mat was successfully fabricated by electrospinning and is considered a potential material for shape memory applications.