Water-based eco-friendly fabrication of physicochemically crosslinked and highly wettable PU-rich electrospun PU/PEO nanofiber composites with exceptional chemical and thermal stability

Abstract

Electrospun nanofiber composites derived from polyurethane (PU) or polyethylene oxide (PEO) have demonstrated astonishing usability in various domestic and industrial sectors. Indeed, the composites of PU and PEO present potential for multifaceted applicability in various fields. However, there are very few reports on electrospun PU/PEO nanofiber composites thus far owing to their low wettability and poor thermal and chemical stability. In addition, their preparation often requires toxic organic solvents. Herein, for the very first time, we developed a water-mediated approach for the preparation of PU-rich hydrophilic PU/PEO nanofiber composites with excellent chemical and thermal stability. Carbodiimide (CL, R–NCN–R) was employed as a green crosslinker, and a simple thermal crosslinking technique was developed. The mass ratio of PU/PEO/CL and the electrospinning parameters were optimized in detail. The crystalline nature and stability of the composites were investigated by SEM, FT-IR, XRD, TGA, and DSC analyses. The results confirmed the high chemical stability of the PU/PEO nanofibers in various organic and aqueous media. The thermal stability of the composites was found to be excellent (T_g, up to 283 °C), and the water contact angle (WCA) test revealed its hydrophilic nature. Surface roughness and phase separation in the nanofiber composites were studied by AFM and TEM analysis. A physical and chemical crosslinking mechanism has been proposed based on the results. Overall, the environmentally friendly approach, cost-effectiveness, excellent stability, high wettability, and swelling behaviour suggest that the PU/PEO nanofiber composites developed in this study would be a preferable option in the filtration sector and biomedical and energy (battery separator) fields.