ABSTRACT
Fluorescing 5,10,15,20-terakis(1-methyl-4-pyridinio)porphyrin tetra(p-toluenesulfonate) (TMPyP)-embedded and -coated polyvinyl alcohol (PVA) nanofibers were fabricated by using the electrospinning technique. To improve nonpolar solvent solubility of TMPyP/PVA nanofibers, tetraethyl orthosilicate (TEOS) was used as a cross-linking agent. UV-vis spectroscopy showed a strong Q band and two relatively weak Soret bands from the TMPyP/PVA nanofibers, and revealed that the TMPyP molecules were homogeneously loaded to the fibers. Scanning electron microscopy revealed that the electrospun nanofibers had ultrafine structures with an average diameter of ca. 250 nm. X-ray photoelectron spectroscopy confirmed the compositional structure of TMPyP/PVA/TEOS nanofibers and revealed the relative coverage of TMPyP molecules on the surface of TMPyP-embedded and TMPyP-coated PVA/TEOS fibers. For the comparison of the acid vapor sensitivity, TMPyP-embedded PVA/TEOS films, and TMPyP-embedded PVA/TEOS fibers, TMPyP-coated PVA/TEOS fibers were exposed to 1N nitric-acid vapor for 20-60 seconds. Fluorescence microscopy revealed that TMPyP-coated PVA/TEOS nanofibers exhibited better acid-sensing capability than TMPyP-embedded PVA/TEOS nanofibers and films.
Subject(s)
Nanofibers/chemistry , Nanotechnology/methods , Nitric Acid/analysis , Polyvinyl Alcohol/chemistry , Porphyrins/chemistry , Fluorescent Dyes/chemical synthesis , Fluorescent Dyes/chemistry , Gases/analysis , Microscopy, Electron, Scanning , Microscopy, Fluorescence , Nanofibers/ultrastructure , Particle Size , Photoelectron Spectroscopy , Spectroscopy, Fourier Transform InfraredABSTRACT
We have fabricated fluorescing polystyrene/dicyanopyrazine-linked porphyrin (PS/4-TDCPP) nanofibers using the electrospinning technique. UV-vis spectroscopy shows a strong Soret band and two relatively weak Q bands from the PS/4-TDCPP films and fibers, and reveals that the 4-TDCPP molecules are homogeneously dispersed in the films and fibers. Scanning electron microscopy (SEM) reveals the effect of solvent and collecting distance on the morphology of the electro-spun PS/4-TDCPP fibers. Fibers spun from a 50% dimethlyformamide (DMF), 50% methylethylketone (MEK) solution have ultra-fine structures with an average diameter of 300 nm. In the case of fibers from pure DMF and DMF:MEK (1:3) solutions, beads are formed along the length of the fibers. Variation of the collecting distance from 20 to 30 cm does not induce significant differences in the morphology of the electro-spun PS/4-TDCPP fibers. However, at a collecting distance of 15 cm, many beads are formed along the fibers. Acid-sensing capability of the PS/4-TDCPP fibers is demonstrated by fluorescence microscopy.
