Interface interactions in hybrid organosilane-nitride films on polymer substrates

Organic-inorganic hybrid coatings are becoming increasingly important due to their unique property combination [1, 2], including high optical transparency, improved scratch and abrasion resistance and excellent weathering, thanks to the synergism between the properties of the organic and inorganic components. The present study focuses on preparation and characterization of hybrid materials based on organosilane-modified silicon nitride films. Most of the studies of silane interaction with inorganic films have been limited to metal oxide surfaces [3, 4]. Transparent, inorganic silicon nitride (SiNx) thin films of various thicknesses were deposited by PECVD on polyimide substrates. A range of organosilanes with different amine functionality, and at different concentrations in ethanol were spin coated on the SiNx films and thermally cured at 80°C for 18 hrs. The silane coated SiNx films were characterized with Rutherford Backscattering Spectrometry (RBS), Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and X-ray Photoelectron Spectroscopy (XPS) with an aim of understanding the interactions between the organic and the inorganic layers. The results show the condensation of the aminosilane in contact with the nitride (hydrolyzed surface) layer. Interface formation mechanisms, including partial dissolution of the nitride and formation of cross-linked polysiloxane layer are also investigated.LT

Stamp-forming of reactive-thermoplastic carbon fibre/PA12 composite sheet

LT

Chelating NHC Ruthenium(II) Complexes as Robust Homogeneous Hydrogenation Catalysts

A series of ruthenium(II) N-heterocyclic carbene chelate complexes were prepd. by using bidentate chelating alkene-carbene, thioether-carbene, carboxylate-carbene and bis-carbene ligands. Metalation of 1-R-3-X-imidazolium salts (1-3, R = Me, X = allyl, MeSCH2CH2; R = mesityl, X = O2CCH2) by either [RuCpCl(PPh2)2] or [RuCl2(cymene)]2 gave the corresponding n-donor-carbene chelates [CpRu(PPh3)[MeSCH2CH2NCN(Me)CH:CH-κS,κC2]][BF4] (6), [CpRu(PPh3)[η2-CH2:CHCH2NCN(Me)CH:CH-κC2]]Y (5a,b, Y = Cl, BF4), [CpRu(PPh3)[O2CCH2NCN(Ar)CH:CH-κO,κC2]] (7, Ar = mesityl), [(η6-cymene)RuCl[η2-CH2:CHCH2NCN(Me)CH:CH-κC2]][BF4] (8), [(η6-cymene)RuCl[MeSCH2CH2NCN(Me)CH:CH-κS,κC2]][BF4] (9), [(η6-cymene)RuCl[O2CCH2NCN(Ar)CH:CH-κO,κC2]] (10). Reaction of 3,3'-diisopropyl-1,1'-methylenebis(imidazolium) diiodide with [RuCl2(arene)]2 gave [(arene)RuCl[iPrNCN(CH:CH)CH2NCN(CH:CH)iPr-κC2,κC2']][PF6] (11, 12, arene = benzene, p-cymene). Rigid coordination of all donor sites was concluded from NMR spectroscopy, and the electronic effects of the donor groups were evaluated by electrochem. analyses. The chelating donor group had a strong influence on the activity of the metal center in styrene hydrogenation reaction. A thioether group or a second NHC donor site essentially deactivates the metal center. Complexes comprising a NHC tethered with an olefin or a carboxylate group showed appreciable activity, though only the carboxylate-functionalized system proved to be a precursor for homogeneous hydrogenation. According to in situ high-pressure NMR analyses, complexes featuring a carboxylate chelating group are remarkably resistant toward reductive elimination even under strongly reducing conditions and may, therefore, be used repeatedly.LCO

Uniaxial strain in graphene by Raman spectroscopy: G peak splitting, Gruneisen parameters, and sample orientation

We uncover the constitutive relation of graphene and probe the physics of its optical phonons by studying its Raman spectrum as a function of uniaxial strain. We find that the doubly degenerate E(2g) optical mode splits in two components: one polarized along the strain and the other perpendicular. This splits the G peak into two bands, which we call G(+) and G(-), by analogy with the effect of curvature on the nanotube G peak. Both peaks redshift with increasing strain and their splitting increases, in excellent agreement with first-principles calculations. Their relative intensities are found to depend on light polarization, which provides a useful tool to probe the graphene crystallographic orientation with respect to the strain. The 2D and 2D(') bands also redshift but do not split for small strains. We study the Gruneisen parameters for the phonons responsible for the G, D, and D(') peaks. These can be used to measure the amount of uniaxial or biaxial strain, providing a fundamental tool for nanoelectronics, where strain monitoring is of paramount importance.THEO

Comportement sismique des spéléothèmes (stalactites et stalagmites)

IMACSG

Deconsolidation in Composite Processing : Comparison of Two Glass Fiber-Polypropylene Systems

LT

Over-compression moulding of thermoplastic composite pultrusions

LT

Pressure drop measurements in Cable-In-Conduit Conductors (CICC) with different layouts

CRPPSP

H5EPTPACH2OH: Synthesis, Relaxometric Characterization and 1H NMR Spectroscopic Studies on the Solution Dynamics of Its LnIII Complexes

The synthesis and characterization of a new metal chelator, 4-(S)-hydroxymethyl-3,6,10-tri(carboxymethyl)-3,6,10-triazadodecanedioic acid (H5EPTPACH2OH), is reported. Protonation constants for the ligand H5EPTPACH2OH and for the previously reported H5EPTPAC16 have been determined by potentiometry, which reveals that both ligands display slightly higher protonation constants relative to that of the ligand DTPA5-. The stability constant for the [Gd(EPTPACH2OH)(H2O)]2- complex has also been determined by potentiometry. The obtained value (log KGdL = 16.7) is two orders of magnitude lower than that for the [Gd(EPTPA)(H2O)]2- complex, which indicates the destabilizing effect of the pendant hydroxymethyl group at the EPTPA backbone. The microscopic protonation scheme has been deduced from the pH dependence of the 1H NMR spectra of both H5EPTPACH2OH and H5EPTPAC16 ligands. The first two protonations occur exclusively at the backbone nitrogen atoms - the first protonation occurs preferentially at the more basic central nitrogen atom. The second proton distributes preferentially between the two terminal nitrogen atoms with the favoring of the trimethylene nitrogen atom over the ethylene nitrogen atom. The LnIII complexes of the ligand H5EPTPACH2OH have been prepared and their solution dynamics studied by 1H NMR spectroscopy. Two sets of resonances of very different intensities from two isomeric complexes have been observed. Relaxometric investigations (17O NMR and 1H NMRD) demonstrate that the [Gd(EPTPACH2OH)(H2O)]2- complex displays an accelerated water-exchange rate (kex = 87.6 × 106 s-1) that is close to the theoretically derived optimal value. However, the kinetic stability of this complex in phosphate-buffered solutions towards Zn2+ transmetallation is quite low, but higher than that of the corresponding methyl derivative.LCI

Hybrid thermoplastic composite beam structures integrating UD tows, stamped fabrics, and injection/compression moulding

LT