Electrospun poly(vinylidene fluoride) (PVDF) nanofibers
were collected
on aluminum foil across a 10 mm gap. Scanning electron microscopy
(SEM) images showed that fibers in the gap were macroscopically aligned
and those off the gap were macroscopically randomly aligned. Polarized
Fourier transform infrared (FTIR) spectra and single fiber selected
area electron diffraction (SAED) patterns demonstrated that fibers
deposited in the gap were highly aligned at the molecular level with
the polymer backbones oriented along the fiber axis.
SAED patterns of fibers deposited off the gap were also oriented at
the molecular level, but the degree of orientation was lower.
A series of pyrene/phenanthrene‐fused furan derivatives (1–8) were synthesized by a simple condensation reaction between pyrene‐4,5‐diketone/phenanthrenequinone and substituted phenol/naphthol in the presence of trifluoromethanesulfonic acid in 1,2‐dichlorobenzene heated at reflux. The formed compounds can emit strong blue light in organic solvents. Additionally, the self‐assembly behaviors of two of the compounds (3 and 5) were studied through re‐precipitation method and the resulting nanostructures were characterized by UV/Vis, fluorescence spectra, and field‐emission scanning electron microscopy (FESEM). The findings showed that the shape and size of compounds 3 and 5 could be tuned by the ratio of THF and hexadecyl trimethyl ammonium bromide (CTAB) solution in water.
Electrospun poly(vinylidene fluoride) (PVDF) nanofibers were collected on aluminum foil across a gap with widths that varied in size from 2 to 10 mm. Scanning electron microscopy (SEM) images on fiber bundles showed that in all cases, fibers in the gap were macroscopically aligned across the gap. However, single fiber selected area electron diffraction (SAED) patterns and polarized Fourier Transform Infrared (FTIR) spectra demonstrated that fibers deposited across the gap were also highly aligned at the molecular level with the polymer backbones oriented along the fiber axis and that the extent of molecular orientation increased with the gap width. A possible explanation for this observation is based on the repulsion of similarly charged nanofibers and the simultaneous attraction of these fibers to the oppositely charged gap edges. This provides a plausible model for understanding the deposition kinetics and subsequent molecular orientation as a function of gap size when electrospinning using this method of fiber collection.
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