Several rodlike 4,4‘‘-bis(decyloxy)-p-terphenyl derivatives incorporating nonionic hydrophilic groups in the lateral 2‘-position (2-oxa-4,5-dihydroxypentyl, 2,5-dioxa-7,8-dihydroxyoctyl, 2,5,8-trioxa-10,11-dihydroxyundecyl, and 2,5,8,11-tetraoxa-13,14-tetradecyl groups) and 2‘-(2-oxa-4,5-dihydroxypentyl)-4,4‘‘-diundecyl-p-terphenyl form well-ordered thin films when spread at the air−water interface. One observes two sharp breaks in the pressure/area isotherms separated by a large plateau. The first break occurs at an area of ca. 0.90 nm2/molecule, an area which corresponds to a side-on arrangement of the terphenyl units at the interface. The plateau corresponds to a first-order phase transition. The surface pressure related to this transition significantly rises with an increasing number of oxyethylene units in the hydrophilic lateral groups. Brewster angle microscopic investigations indicate the formation of fluid domains in this region. In some cases these domains coalesce to a homogenous layer. The surface potential is nearly constant in the region of the plateau, which can be explained by a defined collapse due to the formation of a triple layer consisting of a bilayer on top of the monolayer.

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We demonstrate new fluorophore-labelled materials based on acrylamide and on oligo(ethylene glycol) (OEG) bearing thermoresponsive polymers for sensing purposes and investigate their thermally induced solubility transitions. It is found that the emission properties of the polarity-sensitive (solvatochromic) naphthalimide derivative attached to three different thermoresponsive polymers are highly specific to the exact chemical structure of the macromolecule. While the dye emits very weakly below the LCST when incorporated into poly(N-isopropylacrylamide) (pNIPAm) or into a polyacrylate backbone bearing only short OEG side chains, it is strongly emissive in polymethacrylates with longer OEG side chains.Heating of the aqueous solutions above their cloud point provokes an abrupt increase of the fluorescence intensity of the labelled pNIPAm, whereas the emission properties of the dye are rather unaffected as OEG-based polyacrylates and methacrylates undergo phase transition. Correlated with laser light scattering studies, these findings are ascribed to the different degrees of pre-aggregation of the chains at low temperatures and to the extent of dehydration that the phase transition evokes. It is concluded that although the temperature-triggered changes in the macroscopic absorption characteristics, related to large-scale alterations of the polymer chain conformation and aggregation, are well detectable and similar for these LCST-type polymers, the micro-environment provided to the dye within each polymer network differs substantially. Considering sensing applications, this finding is of great importance since the temperature-regulated fluorescence response of the polymer depends more on the macromolecular architecture than the type of reporter fluorophore.

Two 2,4-diamino-6-phenyl-1,3,5-triazines carrying either one or two alkoxy chains at the phenyl substituent have been investigated in binary mixtures with two-chain partially fluorinated benzoic acids. Equimolar compositions of the complementary molecular species form discrete hydrogen-bonded dimeric supermolecules. The dimers organize to infinite ribbons of parallel aligned H-bonded polar aromatic cores that are separated by mixed aliphatic/fluorinated regions. The cross-sectional shape of the ribbon aggregates and, therefore, the two-dimensional lattice symmetries of the ribbon phases, rectangular or oblique, are defined by the number of alkoxy chains of the triazine component. Docking of 2 or 3 equiv of the semiperfluorinated benzoic acids to the diaminotriazine core leads to H-bonded aggregates with a circular cross-sectional shape and, consequently, to the formation of columnar phases on a two-dimensional hexagonal lattice.

mosphere. The graphite cathode of 10 mm diameter was placed horizontally facing the composite anode of 6.15 mm diameter. The latter had a 3.2 mm diameter hole drilled 25 mm filled with a mixture of graphite (Graphit, fein gepulvert reinst, Merck, Germany) and Si powder in the atomic ratio 1:1.The experiments were repeated with and without the addition of 0.03 at.-% of Fe powder to the anode. During arc-discharge evaporation of the graphite/ silicon composite anode a hard cylindrical deposit (the core deposit) grows at the end of the graphitic cathode. Additionally a soot-like deposit is formed around the core deposit of the cathode, here called the collaret deposit. Samples for TEM examination were prepared from the core deposit as well as from the collaret deposit. The deposits were diluted in chloroform, sonicated for 5 min and dropped on a TEM Cu grid (300 mesh) with holey carbon film.The characterization of the samples was performed using TEM, HRTEM, electron diffraction, and analytical electron microscopy using EELS.TEM was carried out with a JEM 2000FX (JEOL, Japan), using an acceleration voltage of 200 kV, HRTEM was carried out with a JEM 4000EX (JEOL, Japan), using an acceleration voltage of 400 kV, and EELS was carried out with a PEELS 666 (Gatan, USA) on a dedicated STEM VG HB 501 UX (Vacuum Generators, UK) operating with a cold field emission gun at 100 kV acceleration voltage. All EELS data were acquired and processed using the EL/P 3.0 software (Gatan, USA). Pure Si and SiC powder samples prepared for electron microscopy in the same way as the arc discharge products were characterized by EELS in order to get reference spectra acquired under comparable conditions.The Si-L edges were acquired with an energy dispersion of 0.1 eV, a convergence angle of 10 mrad and a collector angle of 6.5 mrad. For the measurement of the Si-K edge the gun-lens was less excited to get a sufficient electron intensity at energy losses of about 1800 eV; the energy dispersion was adjusted at 1.0 eV. The Si-K edges were measured with a convergence angle of 10 mrad and a collector angle of 13 mrad.The energy location of the Si-L and the C-K edges was calibrated using zero-loss spectra acquired before the measurements. As a result the error of the energy location is less than ±0.2 eV. A deconvolution of the low-loss spectra was performed to remove the effect of sample thickness on the ELNES of the spectra.