Formation of core/shell ultrafine fibers of PVDF/PC by electrospinning via introduction of PMMA or BTEAC

Core/shell structured ultrafine fibers of poly(vinylidene fluoride) (PVDF)/polycarbonate (PC) were prepared by electrospinning their dispersions in a mixed solvent of N,N-dimethylformamide and tetrahydrofuran. The morphology of the obtained fibers viewed under a scanning electron microscope and a transmission electron microscope could be adjusted via introduction of poly(methyl methacrylate) (PMMA) or triethylammonium chloride (BTEAC). The viscosity of the dispersions increased with the increasing amount of PMMA in the range of 10-15 wt%, while the diameter of the dispersive spheral phase in the dispersions decreased. A proper amount of PMMA could decrease the resistance of the dispersive phase transformation in PVDF/PC dispersions, so that the uniform fibrous morphology and distinct core/shell structure were easily formed in the electrospun fibers. Because of the significant increase of the conductivity of the PVDF/PC dispersion, addition of 2 wt% BTEAC could also promote formation of the core/shell structure of electrospun PVDF/PC ultrafine fibers. Comparison between electrospun fibers of PVDF/PC, PVDF/PC/PMMA and PVDF/PC with BTEAC etched by chloroform showed that the core/shell structure of PVDF/PC with BTEAC was in the highest quality.