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Infrared Reflection Absorption Spectroscopy (infrared + reflection_absorption_spectroscopy)

Distribution by Scientific Domains
Polymers and Materials Science60%
Chemistry40%

Selected Abstracts

Investigation into the Chemical Reactivity of Plasma-Deposited Perfluorophenyl Methacrylate Using Infrared Reflection Absorption Spectroscopy and Microcantilever Studies

PLASMA PROCESSES AND POLYMERS, Issue S1 2007
Nuria Queralto
Abstract Perfluorophenyl methacrylate (pp-PFM) was plasma-polymerized using low duty cycle conditions to yield a surface rich in active ester groups. The reactivity of this surface towards different primary amines was investigated using infrared reflection absorption spectroscopy (IRRAS) and micromechanical cantilever (MC) sensors. While IRRAS provided information on the chemistry, the MC sensors technique gave insights into volume changes induced by the reactions of the polymer film. We found that the volume change upon reaction was different for each of the amines studied and correlated this to the ability of the amines to diffuse into the polymer matrix. The changes observed can be related to reactions occurring either at the liquid,solid interface or to reactions occurring within the matrix of the polymer and appear to be related to the chemical structure of the amines. [source]

Solid-supported amphiphilic triblock copolymer membranes grafted from gold surface

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2009
Ekaterina Rakhmatullina
Abstract Gold-supported amphiphilic triblock copolymer brushes composed of two hydrophilic poly(2-hydroxyethyl methacrylate) (PHEMA) blocks and a hydrophobic poly(n -butyl methacrylate) (PBMA) middle part were synthesized using a surface-initiated ATRP. Attenuated total reflectance Fourier transform infrared spectroscopy, polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS), ellipsometry, contact angle measurements, and atomic force microscopy were used for the characterization of PHEMA- co -PBMA- co -PHEMA brushes. The PM-IRRAS analysis revealed an increase of the chain tilt toward the gold surface during growth of the individual blocks. We suggest that the orientation of the amphiphilic polymer brushes is influenced by both the chain length and the interchain interactions. Additionally, a detachment of the polymer membranes from the solid support and subsequent gel permeation chromatography analyses allowed us to establish their compositions. We applied block-selective solvents (water and hexane) as well as a good solvent for the whole polymer chain (ethanol) to study the morphology and solvent responsive behavior of the amphiphilic brushes. The presented results could serve as a good starting point for the fabrication of functional solid-supported membranes for biosensing applications. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1,13, 2009 [source]

Investigation into the Chemical Reactivity of Plasma-Deposited Perfluorophenyl Methacrylate Using Infrared Reflection Absorption Spectroscopy and Microcantilever Studies

PLASMA PROCESSES AND POLYMERS, Issue S1 2007
Nuria Queralto
Abstract Perfluorophenyl methacrylate (pp-PFM) was plasma-polymerized using low duty cycle conditions to yield a surface rich in active ester groups. The reactivity of this surface towards different primary amines was investigated using infrared reflection absorption spectroscopy (IRRAS) and micromechanical cantilever (MC) sensors. While IRRAS provided information on the chemistry, the MC sensors technique gave insights into volume changes induced by the reactions of the polymer film. We found that the volume change upon reaction was different for each of the amines studied and correlated this to the ability of the amines to diffuse into the polymer matrix. The changes observed can be related to reactions occurring either at the liquid,solid interface or to reactions occurring within the matrix of the polymer and appear to be related to the chemical structure of the amines. [source]

Mechanistic Insights into Selectivity Control for Heterogeneous Olefin Oxidation: Styrene Oxidation on Au(111)

CHEMISTRY - AN ASIAN JOURNAL, Issue 1 2010

Abstract We demonstrate that intermolecular interactions, controlled by both oxygen and styrene coverage, alter reaction selectivity for styrene oxidation on oxygen-covered Au(111). Several partial oxidation products are formed,styrene oxide, acetophenone, benzoic acid, benzeneacetic acid, and phenylketene,in competition with combustion. The maximum ratio of the yields of styrene oxide to the total CO2 produced is obtained for the maximum styrene coverage for the first two layers (0.28,ML) adsorbed on Au(111) precovered with 0.2,ML of O. Furthermore, our reactivity and infrared studies support a mechanism whereby styrene oxidation proceeds via two oxametallacycle intermediates which, under oxygen-lean conditions, lead to the formation of styrene oxide, acetophenone, and phenylketene. Benzoate, identified on the basis of infrared reflection absorption spectroscopy, is converted into benzoic acid during temperature-programmed reaction. These results demonstrate the ability to tune the epoxidation selectivity using reactant coverages and provide important mechanistic insight into styrene oxidation reactions. [source]

In Situ Characterization of Thermo-Responsive Poly(N -Isopropylacrylamide) Films with Sum-Frequency Generation Spectroscopy

CHEMPHYSCHEM, Issue 7 2010
Volker Kurz
Abstract The thermo-responsive behaviour of thiol modified poly(N -isopropylacrylamide) (pNIPAM) films immobilized on gold are probed by in situ broadband sum-frequency generation (SFG) spectroscopy. The pNIPAM films were prepared by atom transfer radical polymerization (ATRP) using a nitro-biphenyl-thiol (NBT)-SAM on a polycrystalline gold surface as a substrate. Additionally, Raman and infrared reflection absorption spectroscopy (IRRAS) are applied to spin-coated pNIPAM films. Molecular groups involved in the reorientation and disordering of the polymer chains during the LCST (lower critical solution temperature) transition of pNIPAM are identified. The characteristic vibrations of the CH3 groups show a gradual reorientation of the isopropyl groups within the pNIPAM film and instantaneous reorientation of the outermost CH3 groups around 32,°C. [source]