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Preparation of photochromic poly(vinylidene fluoride-co-hexafluoropropylene) fibers by electrospinning

โœ Scribed by Mao Wang; Sean A. Vail; Amy E. Keirstead; Manuel Marquez; Devens Gust; Antonio A. Garcia


Publisher
Elsevier Science
Year
2009
Tongue
English
Weight
601 KB
Volume
50
Category
Article
ISSN
0032-3861

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โœฆ Synopsis


Photochromic poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) fibers were prepared by electrospinning from a solution of copolymer and ester-functionalized nitrospiropyran (SPEST) molecules. The surface and internal features of the electrospun (ES) fibers were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and wide-angle X-ray diffraction (WAXD). The strong segregation of fluorine-rich groups on the fiber surface, which occurs during and/or after the electrospinning process, is driven by the lower surface tension for fluorine-rich groups and leads to encapsulation of SPEST predominantly near the core of the fibers, as confirmed by both X-ray photoelectron spectroscopy (XPS) and dynamic water contact angle (CA) measurements. The photochromic behavior of the spiropyran is preserved in the polymeric fibers, as confirmed by steadystate absorption and emission spectroscopy. Both isomeric forms of the photochrome in SP-PVDF-co-HFP were emissive, an effect that is thought to be due to the steric and/or electrostatic restrictions on the ring-opening reaction imposed by the fiber.


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