On Polyethylene Oxide – Polyvinylidene Fluoride Blends and their Nanofibers*

Blends of polyethylene oxide (PEO) – Polyvinylidene Fluoride (PVDF) were obtained by using three different procedures: PEO-PVDF(I) blends are obtained by dispersing PEO within deionized water, followed by the addition of the micron-sized PVDF powder and homogenization by sonication. PEO-PVDF(II) blends were obtained by dispersing separately PEO in water and PVDF in acetone and subsequent mixture of the two solutions. PEO-PVDF (III) bends were obtained by dispersing both PEO and PVDF in acetone and then mixing the two solutions. Films of PEO-PVDF were obtained by evaporating the solvent in a vacuum oven at 60 °C. Solutions of PEO-PVDF, containing various amounts of polymer were used to obtain mats of PEO-PVDF(I), (II), and (III) blends via force spinning. The glass transition of PEO is about -50 °C and of PVDF is about – 35 °C. Hence, weak interactions between these macromolecular chains may convert PEO-PDMS into a compatible blend, with a single glass transition temperature. DSC investigations confirmed the interactions between PEO and PVDF chains. Additionally, DSC provided information about the melting and crystallization process, where the melting of PEO is about 65 °C and the melting of PVDF is about 175 ^oC.

Electron microscopy photos complemented by elemental analysis provided information about the morphology of PEO-PVDF films and mats with emphasize on the distribution of F atoms. The stretching of the polymer solution during the force spinning is expected to result into an enhanced alignment of PVDF chains within mats. X – Ray diffraction, Raman and FTIR spectroscopy focused on the similarities and differences between PEO-PVDF films and mats. The effect of the solvent’s nature on the morphology of PEO-PVDF blends will be discussed in detail.

Acknowledgments: We acknowledge the financial support for this research by National Science Foundation PREM Grant DMR 2122178.