Dilute solution behavior and chain-stiffness of a chiral mesogen-jackted liquid crystal polymer

A series of optically active mesogen-jacketed liquid crystal polymers with narrow polydispersities (P-1 - P-6) were studied by a combination of static and dynamic laser light scattering techniques and viscosity measurements in THF at 25°C. It is found that THF is a good solvent for the polymers studied. The dependences of the intrinsic viscosity [η] and root mean-square radius of gyration 〈R _g ²〉 _z ^1/2 of the polymers on weight-average molecular weight M̄ _w are [η] = (2.75 ± 0.05) × 10 ^-3 M̄ _w ^{0.78 ± 0.02} and 〈R _g ²〉 _z ^1/2 = (1.53 ± 0.04) × 10 ^-2 M̄ _w ^{0.60 ± 0.01}, respectively, in THF at 25°C. According to Bohdanecky-Bushin's method based on Yamakawa-Fujii- Yoshizaki's theory for worm-like chain cylinders, the molar mass per unit contour length M _L and the persistence length q were estimated to be (29.8 ± 1.0) × 10 ² nm and (15.4 ± 3.0) nm, respectively. The values of the exponent α of Mark-Houwink-Sakurada equation and q indicate that these liquid crystal polymers of the side-chain type have an extended conformation in dilute solutions as most main-chain liquid crystal polymers.