Macromolecular order

Lyotropic polymeric LC, formed by dissolving two aromatic polyamides in concentrated sulphuric acid, have been studied using variable-director 13C NMR experiments.324 The experimental line shapes at different angles w.r.t the external field were used to extract macromolecular order and dynamic in these ordered fluids. An interesting application of lyotropic LC is for the chiral discrimination of R- and S-enantiomers, and has recently been demonstrated by Courtieu and co-workers.325 The idea was to include a chiral compound 1-deutero-l-phenylethanol in a chiral cage (e.g., /1-cyclodextrin) which was dissolved and oriented by the nematic mean field in a cromolyn-water system. Proton-decoupled 2H NMR spectrum clearly showed the quad-rupolar splittings of the R- and S-enantiomers. The technique is applicable to water-soluble solutes. 

The examples represented here have demonstrated our increasing ability to design and to manipulate ever larger supramolecular systems and merge concepts from supramolecular and polymer chemistry. Yet we are still far Irom approaching the perfection and versatility and, most important, the functionality of biomolecules and their superstructures. Like in biology, macromolecules and the competition between macromolecular order and disorder will play a dominant role in the preparation of functional molecular devices and nanoscopic objects. 

The increased interest in thermotropic wholly aromatic LC polyesters is related above all to their commercial applications. Their ability to exist as anisotropic melts, combined with high molding and extrusion characteristics, allows very easy processing of these materials into various pats and articles. The fundamental aspect of this interest is associated with the fact that, with these polymers, it is possible to examine the effect of chain stiffness and of the influence of regular chain structure on evolution of macromolecular order in polymers on the whole. 

What are the most likely modes of degradation of conductivity, macromolecular order and other related properties of CPs on heating What do they tell you with regard to design and synthesis of thermally stable CPs ... 

MACROMOLECULAR ORDER AND CONFORMATION IN THE SOLID AND NEMATIC PHASES OF SEMI-RIGID POLYMERS AND POLYMER-MONOMER MIXTURES—NMR STUDY... 

The characterization of quasi-equilibrium macromolecular order and conformation in these systems, as well as the dynamics of cooperative chain orientation in samples subjected to external forces are of paramount importance for the understanding of their macroscopic properties. In this work we pursue previous efforts along these lines and present the main results of a proton and deuterium nuclear magnetic resonance (NMR) study of molecular order and chain conformation, and their temperature... 

Peptides represent yet another family of intervening materials that provide a probe for conformational effects. Because peptides can aggregate as helices or as sheets, they produce a macromolecular order comparable to that of liquid crystals. Dipole effects in helical peptides are additive, so that a macroscopic dipole from the C- to the N-end of the peptide (or vice versa) can enhance or oppose the pulsed PET. 

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