A triethyl-ammonium functionalized 4-nitro-4 0 -alkoxy azobenzene mesogen with a 10-carbon spacer (azo10Q, a ' 'surfactomesogen' ') was complexed in equimolar proportions to a variety of oppositely charged polyelectrolytes, and studied by differential scanning calorimetry (DSC), polarizing optical microscopy, and X-ray diffraction. The complexation generates a single-layer smectic A mesophase over a very wide temperature range from a surfactomesogen that, alone, melts directly to the isotropic phase. The clearing temperatures, ranging from 130 to 190 8C and generally higher than the melting point of azo10Q, are dependent on the nature of the polyelectrolyte as well as its molecular weight. In contrast, a prominent glass transition near ambient temperature appears to be independent of molecular weight, but varies somewhat with the type of polyelectrolyte. A second T g -like transition of much lower intensity is detectable at higher temperatures (generally above 100 8C), and, with literature support, is tentatively attributed to nanophase separation involving sublayer planes in the lamellar packing structure. A series of nonequimolar complexes was also investigated, and it was found that, with decreasing azo10Q content, the clearing temperature viewed by DSC decreases rapidly in intensity (and somewhat in temperature) and then disappears although birefringence remains, whereas the lower glass transition increases rapidly in temperature to finally merge with the upper one.

No abstract

The aim of this work was to determine the structural characteristics of the condensed tannins isolated from the aqueous extract of black spruce (Picea mariana Mill) bark. This is the first report on the structural characterization of condensed tannins from black spruce bark. The condensed tannins from the hot water extract prepared from Picea mariana bark were isolated by column chromatography on Sephadex LH-20 media. In this study, UV-visible and 13 C-NMR spectroscopic techniques, along with pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and liquid chromatogramphy analyses were applied to determine the structural characteristics of black spruce bark tannins. We have confirmed for the first time the presence of methoxylated Brings in the flavanol units of condensed tannins from black spruce bark, which could be regarded as further contribution to the chemotaxonomy of the genus Picea. The methoxylation of Norway spruce bark condensed tannins have been demonstrated previously.

sciences et inge ´nierie des macromole ´cules, Faculte ´des sciences et de ge ´nie, UniVersite ´LaVal, Que ´bec, Que ´bec, Canada G1K 7P4

X-ray diffraction, scanning electron microscopy (SEM), and solid-state cross-polarization magic-angle-spinning (CP/MAS) (13)C-NMR spectroscopy were applied to determine changes over time in the morphology and crystallinity of lime wood (Tilia cordata Miller) generated by the soft-rot fungi. Wood samples were inoculated with Trichoderma viride Pers for various durations up to 84 days. Structural and morphological modifications were assessed by comparing the structural features of decayed lime wood samples with references. Significant morphology changes such as defibration or small cavities were clearly observed on the SEM micrographs of lime wood samples exposed to fungi. Following the deconvolution process of the diffraction patterns, the degree of crystallinity, apparent lateral crystallite size, the proportion of crystallite interior chains, and the cellulose fraction have been determined. It was found that all crystallographic data vary with the duration of exposure to fungi. The degree of crystallinity and cellulose fraction tend to decrease, whereas the apparent lateral crystallite size and the proportion of crystallite interior chains increase with prolonged biodegradation processes. The most relevant signals in CP/MAS (13)C-NMR spectra were assigned according to literature data. The differences observed were discussed in terms of lignin and cellulose composition: by fixing the lignin reference signal intensity, the cellulose and hemicelluloses moieties showed a relative decrease compared to the lignin signals in decayed wood.