In this study, electrospun immiscible blend fibers of poly(vinylidene fluoride) (PVDF)/polysulfone (PSF) were prepared. Due to the strong shearing during electrospinning, cocontinuous fibers of PVDF in the PSF matrix were obtained despite the minor composition of PVDF (5-30 wt.%) in the blend. After annealing these electrospun blend fibers above the melting temperature of PVDF (170 degrees C) and the glass transition temperature of PSF (185 degrees C), nanosized droplets (primarily 200-300 nm) of PVDF were developed inside the PSF matrix from the breaking up of PVDF nanofibers because of the Plateau Rayleigh instability. Fractionated crystallization occurred in these PVDF nanodroplets with the heterogeneously nucleated crystallization in the range of 105-135 degrees C and the homogeneous nucleation at 55-60 degrees C. The mechanism of homogeneous nucleation was confirmed by the study of crystallization kinetics using differential scanning calorimetry. Only the nonpolar alpha-phase was observed by wide-angle X-ray diffraction despite of the homogeneously nucleated crystallization at a high supercooling in these PVDF nanodroplets. This study leads to a conclusion that nanoconfined crystallization at a moderate crystallization rate is less important than the local electric field to induce the ferroelectric phases of PVDF. (C) 2012 Elsevier Ltd. All rights reserved.

• Journal: Polymer
• Volume: 53
• Issue: 20
• Pages: 4472-4480
• ISSN: 0032-3861
• DOI: 10.1016/j.polymer.2012.08.014
• Year: 2012
• Number:
• Type: