Crystal and Pseudo-Crystal Phases in Main Chain Mesogenic Homo- and Copolymers with Flexible Spacers

Some packing principles of polymers containing rigid and flexible segments are presented, as revealed by X-ray diffraction of crystal phases. Two types of conformationally disordered crystal states are recognized: (a) with "layered" disorder (quasi-2-dimensional) and (b) with “occluded” disorder (3-dimensional). In both cases the flexible spacer is non-crystalline, which is ascribed to the mismatch in cross-sectional areas of the spacer and the mesogen. The relative ease of crystallization of random copolymers containing spacers of varying length is attributed to their miscibility in the disordered layers.