Ultra-long MWCNTs highly oriented in electrospun PVDF/MWCNT composite nanofibers with enhanced β phase

We report aligned polyvinylidene fluoride (PVDF)/multiwalled carbon nanotube (MWCNT) composite nanofibers, in which micrometer-long MWCNTs were highly oriented within the PVDF nanofiber matrix and thus the β-phase formation was enhanced. The PVDF/MWCNT composite nanofibers were successfully fabricated via far-field electrospinning at a low injection rate of 0.1 mL h⁻¹. In this work, we propose a method to eliminate defects and excess amorphous carbon in order to visualize and capture high-resolution images of MWCNTs within the nanofibers using transmission electron microscopy (TEM). The TEM studies show that the MWCNTs were embedded within the nanofiber matrix and oriented parallel to the fiber axis. Moreover, the α- to β-phase transformation was led by both the electrospinning process and electrostatic interactions between the highly oriented MWCNTs and the PVDF chains, and the β-phase content was found to be 86.6% (at 0.1 wt% MWCNT), as verified using wide angle X-ray diffraction patterns.