Design and Characterization of Fluorinated Maleimide-Based Hybrid Nanofiber Composites as Potential Separators for High-Temperature Batteries

The development of functional polymeric nanofibers having both superior thermal stability and surface wetting properties simultaneously is a significant research topic in advanced materials engineering. For this purpose, copolymers of 3,5-bis((perfluorophenyl)methoxy)benzyl-4-(2,5-dioxo-2,5-dihydro-1 H-pyrrol-1-yl)benzoate (FMI) with acrylonitrile (AN) and styrene (St) were synthesized via free-radical copolymerization. The molecular weights were determined by gel permeation chromatography (GPC), while structural characterization was conducted via 1H-NMR and Fourier-transform infrared (FT-IR) spectroscopies. Hybrid nanofiber membranes of the synthesized polymers were fabricated via electrospinning. Thermal stability was assessed by thermogravimetric analysis (TGA), which revealed that the incorporation of maleimide groups significantly improved the thermal stability of polyacrylonitrile (PAN) nanofibers. Scanning electron microscopy (SEM) characterization showed a distinct morphological trend that the nanofiber diameter systematically decreased with increasing fluorine content. Furthermore, surface wetting investigations revealed that despite the intrinsic hydrophilicity of the baseline PAN matrix, the integration of fluorinated segments imparted pronounced hydrophobic and oleophobic characteristics to the resulting nanofiber networks.