Thermotropic liquid crystalline conjugated polymers, poly(cyclohexylphenoxyacetylenes)-synthesis and properties

A series of poly(cyclohexylphenoxyacetylenes) that are polymers of mono-substituted acetylenes with liquid crystalline group in the side chain have been synthesized to elucidate systematically phase transition behaviors, optical and electrical properties of the polymers. Since the side chain of the polymers consists of cyclohexylphenoxy moiety as a rigid mesogen, a methylene chain as a spacer, and a terminal alkyl group as a flexible moiety, the polymers are abbreviated as PPCHn03A (n = 2, 3, 5, 6, 7 and 8). The polymerizations are carried out using Ziegler-Natta, metathesis and rhodium complex catalysts. Special attention has been paid to the identification of liquid crystalline state of the substituted acetylene monomers and polymers through observation of polarizing optical microscope and DSC measurement. Macroscopic alignment of the polymer due to the external force such as shear stress or magnetic force has been focused in relation to enhancement of electrical conductivity upon iodine doping.