Search results for " Infrared Spectroscopy"
showing 10 items of 438 documents
Hyper-reticulated calixarene polymers: a new example of entirely synthetic nanosponge materials
2018
New calixarene-based nanosponges (CaNSs), i.e., hyper-reticulated polymers constituted by calixarene monomer units joined by means of bis(1,2,3-trialzolyl)alkyl linkers, were synthesized, characterized and subjected to preliminary tests to assess their supramolecular absorption abilities towards a set of suitable organic guests, selected as pollutant models. The synthesis was accomplished by means of a CuAAC reaction between a tetrakis(propargyloxy)calix[4]arene and an alkyl diazide. The formation of the polymeric network was assessed by means of FTIR and 13C{1H} CP-MAS solid-state NMR techniques, whereas morphological characterization was provided by SEM microghaphy. The materials were pro…
Polyaminoazide mixtures for the synthesis of pH-responsive calixarene nanosponges
2019
Two mixtures of polyaminoazides were synthesized by a nucleophilic displacement strategy providing no separation of the components. The mixtures were adequately characterized by means of combined HR-ESIMS, FTIR and NMR techniques and, despite their complexity, they were successfully used to accomplish the subsequent preparation of pH-sensitive calixarene hyper-reticulated nanosponge materials. The desired responsivity to pH variations of the nanosponges obtained was verified by means of absorption tests on a set of organic pollutant model molecules.
Corrigendum to “ATR-FTIR and XRD quantification of solid mixtures using the asymptotic constant ratio (ACR) methods. Application to geological sample…
2020
Solid state electrochemical behavior of organosulfur compounds
2017
Abstract The solid-sate electrochemistry of organosulfur compounds existing in petroleum and its derived matrices is described using the voltammetry of immobilized microparticles methodology. Cyclic and square wave voltammogrammetric responses of sulfur compounds responsible of aging of asphalt pavements, namely, thiophenes, disulfides, sulfides, sulfoxides and sulfones were determined at compound-modified graphite electrodes in contact with 0.10 M H2SO4. The electrochemical oxidation/reduction products were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy with energy dispersion x-ray detection (SEM-EDX) couple…
Electropolymerization of N-methylanthranilic acid and spectroelectrochemical characterization of the formed film
2009
Abstract The electropolymerization of N-methylanthranilic acid (NMAA) is reported in this paper. The monomer is substituted both at ortho- and N-position and, to the best of our knowledge, it has not been previously electropolymerized. Electropolymerization of NMAA was done on glassy carbon and optically transparent (indium) tin oxide electrodes. The obtained films, which are probably of an oligomeric nature (oligoNMMA), were characterized with cyclic voltammetry (CV), in situ UV–vis and Raman spectroscopy, ex situ FTIR spectroscopy and scanning electron microscopy (SEM). Our results show that NMAA can be electropolymerized as thin films in 1.0 M HClO4, but the oxidation and reduction peak …
In-situ polymerization of polyaniline in radiation functionalized polypropylene films
2015
Abstract In-situ generation of a nanodispersed conductive polymer within a polypropylene matrix has been pursued in order to obtain flexible, conductive films. Radiation grafting of acrylic acid to polypropylene (PP) has been applied to insert carboxyl functionalities on PP. The radiation-grafted films have been further derivatized with a variety of diamines and used as substrates for in-situ chemical oxidative polymerization of polyaniline (PANI). PANI grows as a thin skin from the surface of the film as well as an interpenetrated network in its interiors. Evidence of chemical attachment of PANI to PP has been sought by performing FTIR and XPS analyses after extraction of the unbound polym…
Analytical evaluation of polyunsaturated fatty acids degradation during thermal oxidation of edible oils by Fourier transform infrared spectroscopy
1998
The oxidative deterioration of polyunsaturated fatty acids (PUFAs) in culinary oils and fats during episodes of heating associated with normal usage (80-300 degrees C, 20-40 min) has been monitored by Fourier transform infrared spectroscopy (FTIR). The thermal oxidation of PUFAs is a free radical chain reaction, in which hydroperoxides are generally recognized as the primary major products. Hydroperoxides of PUFAs are easily decomposed into a very complex mixture of secondary products with the decrease in unsaturation. The oxidative advance of PUFAs during heating was studied by the determination of unsaturation percentage at different temperatures and heating times. Oils frequently used in…
Fast proton conduction in hydrogen bonded microheterogeneous systems: Bis(2-ethylhexyl)phosphoric acid/N-methyl formamide liquid mixtures
2009
Structural and dynamical properties of bis(2-ethylhexyl)phosphoric acid (HDEHP)/N-methyl formamide (NMF) liquid mixtures in the whole composition range have been investigated by Fourier Transform Infrared spectroscopy (FT-IR), X-rays Diffraction (XRD), and AC complex impedance spectroscopy. Driven by hydrogen bond interactions among HDEHP PO(4)H group and NMF CO and NH groups, and also by steric effects among the HDEHP alkyl chains, the system microstructure is mainly characterized by the coexistence of spatially separated hydrophilic and hydrophobic nanodomains showing local organization and short-range order. The evolution of this structural feature with system composition has been highli…
A Study by Spectroelectrochemical FTIR and Density Functional Theory Calculations of the Reversible Complexing Ability of an Electroactive Tetrathiaf…
2006
We report on the study of the electrochemically targeted complexation/expulsion of a metal cation (Ba2+) by a crown ether tetra(thiomethyl)tetrathiafulvalene derivative (crown-TTM-TTF). Real time, in situ FTIR spectroelectrochemistry was used to obtain spectroscopic evidence of this electrochemically triggered phenomenon. Density functional theory calculations allowed the spectral information collected to be assigned. Both experimental and theoretical results clearly show that neutral crown-TTM-TTF complexes well Ba2+. Complexation is evidenced by a significant downshift of the frequency corresponding to the asymmetric stretching of the C-O-C ether groups. Concerning the cation crown-TTM-TT…
Covalently bonded layer-by-layer assembly of multifunctional thin films based on activated esters.
2009
We demonstrate that chemically stable, multifunctional polymer thin films can be obtained using the layer-by-layer (LbL) deposition based on covalent bonds between adsorbing chains. Poly(pentafluorophenyl-4-vinylbenzoate) (P1) or poly(pentafluorophenylacrylate) (P2) polymers were assembled with poly(allyl amine) (PAAm) to yield LbL multilayer films through amide bond formation by the reaction between activated esters of P1 or P2 and amine groups in PAAm, which was quantitatively monitored by Fourier transform infrared spectroscopy (FT-IR). It was found that the difference in the solubility of P1 and P2 against ethanol, which was used as the solvent for PAAm, during the LbL deposition yields…