Metal‐template synthesis of cyclic epoxide–amine oligomers: Uncrosslinked epoxide–amine addition polymers, 47

The addition reaction of 2,2‐bis‐[4‐(2,3‐epoxypropoxy)‐phenyl]‐propane (DGEBA) and preformed complexes of metal ions and disecondary diamines led to a large quantity of cyclic epoxide–amine oligomers. As shown by gel permeation chromatographic analysis, cycles of n = 1, 2, and 3 were formed. Functional epoxide end groups of the prepared oligomers were completely missing in the IR and ¹H NMR and ¹³C NMR spectra. In the fast atom bombardment and matrix‐assisted laser desorption/ionization mass spectra, the molecular ions of the n = 1, 2, 3 cycles of DGEBA and N,N′‐dibenzyl‐5‐oxanonanediamine‐1,9 were detected at m/z = 680, 1361, and 2042. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2047–2052, 2003     

New analysis of the ν5 and 2ν9 bands of HNO3 by infrared and millimeter wave techniques: line positions and intensities

Nitric acid (HNO₃) plays an important role in the Earth’s atmosphere as a reservoir molecule of NO_x species. It has a strong infrared signature at 11 μm which is one of the most commonly used for the infrared retrieval of this species in the atmosphere since this spectral region coincides with an atmospheric window. It is therefore essential to have high quality spectral parameters in this spectral region. The main goal of this work is then to generate as reliable as possible line positions and intensities for the ν₅ and 2ν₉ cold bands centered at 879.1075 and 896.4467 cm⁻¹, respectively. In particular the existing line parameters need improvement in the wings of the 11 μm window in order to retrieve more accurately the CFC-11 (CCl₃F) and CFC-12 (CCl₂F₂) atmospheric species at ∼850 and ∼920 cm⁻¹, respectively. This work is also motivated by theoretical considerations. Very strong resonances couple indeed the 5¹ and 9² rotational levels. In addition the ν₉ mode (OH torsion) is a “large amplitude” motion, and torsional splittings affect both the v₉=2 and the v₅=1 rotational transitions. In the present study, these effects are accounted for simultaneously both for the line position and line intensity calculations. To calculate the line positions the Hamiltonian matrix accounts for the very strong Fermi and the weaker Coriolis interactions linking the 5¹⇔9² rotational levels, and the torsional effects are accounted for within the frame of the IAM (Internal Axis Method) approach. In addition, the v-diagonal blocks involve non-orthorhombic operators together with Watson’s type rotational operators. This means that the z-quantization axis deviates from the a inertial axis for both the 5¹ and 9² vibrational states. The line intensity calculations were performed accounting also for the axis switching effects. As far as the experimental line positions are concerned we have used the millimeter wave data available in the literature [J. Mol. Spectrosc., 175 (1996) 395; J. Mol. Spectrosc., 208 (2001) 121; and references therein], as well as new centimeter wave measurements performed in Kiel and new Fourier transform infrared spectra recorded in Giessen. For the line intensities we have used an extensive set of individual line intensities measured recently [J. Mol. Spectrosc., 218 (2003) 151]. All these experimental data were very satisfactorily reproduced using the theoretical model described above and an improved set of line positions and intensities was generated for the ν₅ and 2ν₉ bands allowing one to better model the HNO₃ absorption in the 11 μm spectral domain.     

Self‐Assembly of Imidazolium‐Based Surfactants in Magnetic Room‐Temperature Ionic Liquids: Binary Mixtures

The phase behaviour of binary mixtures of ionic surfactants (1‐alkyl‐3‐imidazolium chloride, C_nmimCl with n=14, 16 and 18) and imidazolium‐based ionic liquids (1‐alkyl‐3‐methylimidazolium tetrachloroferrate, C_nmimFeCl₄, with n=2 and 4) over a broad temperature range and the complete range of compositions is described. By using many complementary methods including differential scanning calorimetry (DSC), polarised microscopy, small‐angle neutron and X‐ray scattering (SANS/SAXS), and surface tension, the ability of this model system to support self‐assembly is described quantitatively and this behaviour is compared with common water systems. The existence of micelles swollen by the solvent can be deduced from SANS experiments and represent a possible model for aggregates, which has barely been considered for ionic‐liquid systems until now, and can be ascribed to the rather low solvophobicity of the surfactants. Our investigation shows that, in general, C_nmimCl is a rather weak amphiphile in these ionic liquids. The amphiphilic strength increases systematically with the length of the alkyl chain, as seen from the phase behaviour, the critical micelle concentration, and also the level of definition of the aggregates formed.     

The Ethylene Hot Band Spectrum near 3000 cm

A new hot band spectrum of ethylene has been recorded from 2970 to 3015 cm⁻¹at low rotational temperatures in a seeded molecular jet, using vibrational energy transfer from SF₆to C₂H₄. An IR–IR double resonance technique has been applied to pump the lower states and subsequently probe the hot bands. Two new hot bands, ν₁₀+ ν₁₁− ν₁₀and ν₇+ ν₁₁− ν₇, have been found. The weak hot band starting from ν₇has been identified by direct labeling of some rotational levels in the ν₇manifold. High resolution FTIR spectra at ambient and at elevated temperatures have been recorded, too; it has thus become possible to extend the analysis to higher rotational quantum numbers. The previously analyzed ν₉+ ν₁₀level has been reinvestigated and ab-type Coriolis interaction with the nearby ν₇+ ν₁₁state has been observed. Rotational energy levels of ν₇+ ν₁₁and of ν₉+ ν₁₀have been fitted simultaneously, taking into account the local perturbations due to five dark states. From the shift of allK≠ 0 levels to higher frequencies in the ν₁₀+ ν₁₁state, a globala-type Coriolis interaction with ν₈+ 2ν₁₂has been identified.     

Energy loss from internal reflection off metal layers on glass

The reflection characteristics of metal layers are considered for the situation where the electromagnetic radiation is incident from the glass side. Theoretical and measured reflectance values are presented which indicate that for some metals the reflection has a strong dependence on the refractive index of the incident medium.

Some examples are given of recent cases where the above results were an important consideration in the choice of the metallic reflecting material. These results indicate that aluminium should not be automatically considered the best choice for the visible region nor gold for the infra-red.     

Development and characterization of a wettable surface modified aromatic polyethersulphone using glow discharge induced HEMA-graft polymerisation

The aromatic polyethersulphone (PES) is a well known polymer for the preparation of membranes with excellent thermal stability and chemical resistance. The disadvantage of PES-membranes is their hydrophobic character, which in contact with protein containing solutions leads to high protein adsorption and as a consequence to deterioration of membrane properties. In this report the surface modification of PES by means of glow discharge induced grafting of 2-hydroxyethyl methacrylate (HEMA) is described. Graft polymerisation creates a largely wettable layer of poly(2-hydroxyethyl methacrylate) (PHEMA) on the surface of PES. This has been shown by contact angle measurements using the Wilhelmy plate method. Chemical characterization is carried out by means of X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy/attentuated total reflection (FTIR-ATR). The influence of storage conditions on the surface properties of modified PES samples has been investigated after storage in vacuum, water, and air.