Structure and morphology of liquid‐crystalline polymers

Abstract

Liquid‐crystalline phases are characterized by structures intermediate between a three‐dimensionally ordered crystal and a disordered fluid. Polymers with liquid‐crystalline structures can be obtained from specific monomers containing mesogenic groups with a tendency to form liquid‐crystalline phases. These mesogenic groups are either incorporated into the main chain or attached to a chain as side groups. In both cases liquid‐crystalline structures, and also enantiotropic liquid‐crystalline phases, have been reported. Smectic polymers are characterized by layered structures with long‐range order in the direction of the layer normal and two‐dimensional short‐range order within the layers. The nematic polymers are characterized by a preferred direction on a microscopic scale and short‐range positional order of the centers of mass of the mesogenic groups. Thermal and textural properties are similar to the corresponding properties of low molecular weight liquid crystals.

Nematic Polymers and Related Structures

“…Blumstein et al [52] considered .their polymer nematic when t$e X-ray reflection at small angles was diffuse. Perplies et al [74, 811 found a peak in the small angles of the X-ray diffractogram when the polymerization was carried out in the nematic state: Later the same group [82] pointed out that the structure of the polymer did not depend on the state where it had been prepared. Similar structure of polymers in a homologous series were found in polymers independent of the presence or absence of nematic state of the monomer [58].…”

Synthesis and characterization of fluorinated poly(azomethine ether)s from new core-fluorinated azomethine-containing monomers

“…However, it is well known that molecular reorientation in LC polymers depends on a previous heat treatment (thermal history) and, therefore, in some cases, the endothermic melting peaks can be found only after a proper annealing of a polymer. [39][40][41] Polarization microscopy techniques allowed investigation of LC phases after long-term relaxation of the materials and achieving of the equilibrium in them. Figure 4 displays representative polarization microscopy images recorded for a higher molecular weight polymer (PAME-IV) showing a well-pronounced thermotropic LC behavior typical for all polymers under study.…”

A review on polyaniline composites: Synthesis, characterization, and applications

“…Polymers were considered as electronically insulating materials [ 3 ] because of presence of covalent bonds in saturated carbon skeleton. [ 4 ] Shirakawa et al [ 5 ] found electric conductivity in polyacetylene, this was an astonishing invention in 1977 which gave a new dimension to the discovery of the polymers. Alan Heeger also suggested that this conductivity can be increased by oxidative doping.…”