Synthesis and properties of liquid crystalline polyacetylene derivatives

We have synthesized mono-substituted acetylenes with a liquid crystalline group and then poylmerized them with Ziegler-Natta and metathesis catalyts. The liquid crystalline group in the side chain of the polymer is composed of a cyclohexylphenoxy (PCH) or biphenoxy (BP) moiety as a mesogenic core, a methylene chain [-(CH2)3-] as a spacer, and an alkyl chain as a terminal group. The polymers are abbreviated as PPCHn03A (n = 2, 3, 5 ∼ 8) or PBP503A. All polymers exhibited a fan-shaped texture in the polarizing microscope that is characteristic to smectic liquid crystalline phase, consistent with DSC measurements. Spectroscopic characterizations were carried out by means of IR, UV-VIS, 1H- and 13C-NMR, as well as evaluations of molecular weights by GPC and electrical conductivities upon iodine doping before and after magnetically forced alignment.