Fourier transform infrared spectroscopy

About: Fourier transform infrared spectroscopy is a research topic. Over the lifetime, 48250 publications have been published within this topic receiving 1134369 citations.

Synthesis of New Polyaniline/Nanotube Composites Using Ultrasonically Initiated Emulsion Polymerization

Abstract: Ultrasonically initiated, in situ emulsion polymerization was used to prepare multiwalled carbon nanotube/polyaniline composites (MWNTs/PANI). Transmission electron microscopy (TEM) showed that the nanotubes were coated with a PANI layer, with the thickness of this coating varying with the content of carbon nanotubes and polymerization conditions. Whereas polyaniline/carbon nanotube composite particles prepared by the conventional stirring method have a highly structured, nodular morphology, ultrasonic initiation leads to long, thin, polymer-wrapped tubes. In the case of ultrasonically initiated in situ emulsion polymerization, Fourier transform infrared (FTIR) spectra suggested that site-selective interactions between the quinoid ring of the PANI and the MWNTs facilitate charge-transfer between the two components. In such composites, CNT improved the polymer properties, such as thermal stability, as determined by thermogravimetric analysis and conductivity measured using the four-probe method.

Photocatalytic properties of phosphor-doped titania nanoparticles

Abstract: Phosphor-doped titania nanoparticles in an anatase phase were prepared by a simple modified sol–gel method with hypophosphorous acid as a precursor. The resulting materials were characterized by differential thermal analysis-thermogravimetry (DTA-TG), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), nitrogen physical adsorption at 77 K, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), FT-IR pyridine adsorption spectroscopy, and UV–vis spectroscopy. It was found that the phosphor-doped species could significantly increase the surface area of the materials, and consequently gave them a higher content of surface hydroxyl groups. Moreover, the phosphor-doping improved the thermal stability of titania and decreased the phase transformation of anatase to rutile to a certain extent. UV–vis spectra proved that the modification by phosphor shifted the absorption edge of titania to the visible region, making it an effective photocatalyst in visible light. This was demonstrated by the degradation of MB and 4CP under visible-light (>400 nm) irradiation. The excellent photocatalytic activity of phosphor-doped titania compared with pure titania could be explained by its high surface area and small crystallite size.

Fourier Transform Raman and Fourier Transform Infrared Spectroscopy Studies of Silk Fibroin

Abstract: The chemical and conformational structures of Bombyx mori silk were studied with the complementary techniques of Fourier transform Raman spectroscopy and Fourier transform infrared spectroscopy. The Fourier trans- form Raman spectrum of silk showed strong bands for the photosensitive aromatic amino acids tyrosine, tryptophan, and phenylalanine. Intensive UV/ozone irradiation reduced the Raman intensities of the amide III band and the tyrosine signals due to peptide chain scission of the silk polymer and the photochemical changes in the tyrosine residues on the silk molecules. However, the Raman spectroscopy changes for tryptophan were less clearly defined because of peak overlapping with other amino acid signals and the low concentration of tryptophan. The Fourier transform infrared (attenuated total reflectance) technique, coupled with sec- ond-derivative spectroscopy analysis, demonstrated a de- crease in the crystallinity degree and tyrosine content of UV/ozone-irradiated silk, as indicated by changes in the Fourier transform infrared bands of amide III doublet and tyrosine signals. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1999 -2004, 2005

Structural and electronic transitions in polyaniline: A Fourier transform infrared spectroscopic study

Abstract: Fourier transform infrared (FTIR) spectroscopic studies are carried out on different, potentiometric well defined oxidation states of polyaniline in aqueous acidic and organic electrolytes. During the oxidation process ring structures transform from benzenoid into quinoid states. The fully reduced state of polyaniline shows differences in the anion contents in acidic and organic electrolytes. The 400 mV vs saturated calomel electrode (SCE) oxidized state has the maximum number of the intercalated anions in aqueous acidic media in accordance with supporting potentiometric titration experiments. This conducting form of polyaniline shows similar FTIR spectra in organic as well as in acidic media. For the oxidized state at 800 mV vs SCE, a deintercalation of anions in aqueous acidic, or further intercalation in organic electrolyte is observed. Beyond 800 mV vs SCE, polyaniline shows degradation processes in aqueous acidic media which are found to proceed via formation of benzoquinone‐like structures and finally result in a complete dissolution of the polymer.