A deuteron NMR study of axial motion and side chain conformation in the mesophase of discotic liquid crystal main-chain polymers

Liquid‐crystalline perylene oligomers: Synthesis and phase behavior

“…In contrast, the spectrum of 2 shows only a slight reduction of the quadrupolar splitting, which is known from the literature to indicate that the columnar rotation is obstructed, as is also the case for the smectic model compound PO-17d. The reduction of the quadropular splitting detected upon heating 2 within the mesomorphic phase is consistent with smallangle librations around an equilibrium position of the mesogenic units [20]. The immobilization of the a-CD2 group at the urazole ring, caused by oligomer linkage via the benzylic alkyl chains, is particularly remarkable in view of the fact that the packing ofthe alkyl chains is amorphous, as seen by the observation of a diffuse halo around 2 0 = 18' (see Fig.…”

Solid state NMR study of hydrogen bonding, miscibility, and dynamics in multiphase polymer systems

“…NMR spectra are dominated by the nuclear shielding tensor (anisotropic chemical shift), which can be analyzed to yield quantitative information about rotational motions [159]. In polymer science people are particularly interested in the mobility of macromolecular chains, the basic ones being aliphatic.…”

Structure and dynamics of liquid‐crystalline polymers with different molecular architectures

“…In Fig. 9b such spectra are compared for a low molar mass discotic and a polymer discotic [33,34]. At low temperatures in the glassy state, the axial motion is quenched in both cases and one observes the usual Pake type spectrum covering the full spectral width of 250 kHz.…”

“…Thus motional narrowing occurs but the axial motion is indeed restricted. The detailed analysis [34] shows that about 60 % of the discs are involved in large angle rotations around f 45", the remaining 40 % rotate by less then & 10". The introduction of the polymer chain thus causes the axial motion to be ill-defined, where the rotation of different discs is quenched to different degrees.…”