Liquid crystalline side-group block copolymers with triblock structure: Investigations on the influence of the block arrangement on the morphology and the LC-phase behavior

Abstract

Liquid crystalline triblock copolymers with LC inner block and amorphous outer blocks have been synthesized by “living” anionic polymerization and investigated using DSC, TEM, and small‐angle x‐ray diffraction. All samples of poly[styrene‐block‐2‐(3‐cholesteryloxycarbonyloxy) ethyl methacrylate‐block‐styrene] (PS‐b‐PChEMA‐b‐PS) show liquid crystalline behavior and phase separation between the blocks. Compared to triblock copolymers with PS inner block (PChEMA‐b‐PS‐b‐PChEMA) and diblock copolymers (PS‐b‐PChEMA) the LC block copolymers with PS outer blocks have the same properties. The LC behavior and the morphology do not depend on the block arrangement; they are only influenced by the volume fractions of the blocks. Those samples in which the liquid crystalline subphase is not continuous (spheres) only a nematic phase was found, whereas in all samples with a continuous liquid crystalline subphase, the smectic A phase of the homopolymer was observed. © 1996 John Wiley & Sons, Inc.

Liquid crystalline block and graft copolymers

“…The most extensive and conclusive studies on the interaction between the morphology displayed by the phase separation between the polymer blocks and the LC phase structure displayed by the LC component(s) were performed by Fischer and Poser on polystyrene/poly[2-(3-cholesteryl-oxycarbony1oxy)ethyl methacrylate] (PS/PChEMA) block copolymers [48,[52][53][54]. Therefore, 32 samples with different composition, block arrangement (AB, ABA and BAB-structures) and molecular weight were synthesized.…”

Morphology of side chain liquid crystalline block copolymer thin films and effects of thermal annealing

“…Because of the large interfacial area of the thin film, the orientation of the domains depends greatly upon the relative surface energies of the blocks 7–10. The incorporation of a liquid crystalline (LC) component into a block copolymer system can have significant effects upon the self‐assembly behavior and domain orientation for both bulk materials11–18 and thin films 9, 19, 20. Additionally, liquid crystalline polymers (LCP) are of particular interest as they can allow for the introduction of responsive elements into the system, for example, thermo‐, chemo‐, electro‐, or photo‐responsive 21…”