Influence of Smectic Liquid Crystallinity on Lamellar Microdomain Structure in a Main-Chain Liquid Crystal Block Copolymer Fiber

The microlamellar and smectic liquid crystal (LC) structures of a block copolymer of a main-chain LC polyester connected at both ends with poly(ethyl methacrylate) are investigated by fiber X-ray scattering. In the as-spun fiber, the lamellae are parallel to the fiber axis, while the smectic layers are perpendicular to it. Annealing the as-spun fiber at a temperature higher than the isotropization temperature (T-i) of the LC segment preserves the lamellae, but the LC structure disappears. Further annealing the fiber at T < T-i improves the lamellar stacking coherence and aligns the smectic layers parallel to the lamellae. In contrast, annealing the as-spun fiber at T < T-i conserves the smectic layers and arranges the lamellae in parallel to the smectic layers. Thus, the liquid crystallinity affects the lamellar ordering and orientation. [GRAPHICS] .