Electrospinning of poly(vinyl pyrrolidone) fibers containing metal oxide nanoparticles under dense CO₂

Electrospinning is an electrostatic process for formation of polymer fibers with nano/microscale diameter from solution. In this study, poly(vinyl pyrrolidone) (PVP) dissolved at 4 wt% concentration in dichloromethane (DCM) containing titanium oxide (TiO₂) nanoparticles was used as polymer feed solution for electrospinning under pressurized carbon dioxide (CO₂) at temperature of 30 °C, pressure of 5 MPa, and applied voltage of 10–14 kV. Scanning electron microscopy (SEM) revealed that the PVP fibers electrospun with and without TiO₂ nanoparticles exhibited the same morphology with hollow structure and average pore diameter of 2–7 μm. Fourier-transform infrared (FT-IR) spectroscopy revealed that the electrospun PVP fibers had properties similar to the PVP starting material. X-ray photoelectron spectroscopy (XPS) revealed that the TiO₂ nanoparticles were present in the residue after thermogravimetric (TG) analysis of electrospun fibers. Graphical Abstract: SEM images of PVP with 25-nm TiO₂ nanoparticles, electrospun at 5 MPa and various applied voltages, exhibiting hollow fiber morphology[Figure not available: see fulltext.].