SEM micrographs of PVDF fibers prepared by electrospinning
from 20 wt.% PVDF solutions in DMF/acetone with
different DMF/acetone ratios are shown in Fig. 2. With the
increase of the DMF/acetone ratio, the average fiber diameter
was decreased while the population and size of beads were
increased, which can be attributed to the higher polarity and
boiling point of DMF over that of acetone [23,26].