Ferroelectric liquid crystalline conducting polymers — synthesis and properties of polyacetylene derivatives with chiroptical liquid crystalline groups

We have synthesized chiroptical liquid crystalline (LC) polyacetylene derivatives to develop the first ferroelectric LC conducting polymers. The LC side chain of the polymer consists of a chiral alkoxy or alkoxycarbonyl moiety as a terminal group, a biphenyl moiety as a mesogenic core, and a trimethylene or decamethylene segment as a spacer. Polymerizations were carried out using a metathesis catalyst of MoCl5-SnPh4 or a rhodium-based catalyst of [Rh(NBD)Cl]2- NEt3. The monomer and the corresponding polymer showed the same sign in circular dichroism (CD) spectra, indicating that the optical configuration of the monomer is maintained in the polymer. Measurements of differential scanning calorimeter and polarizing optical microscope showed that the polymer, PBP9 *003A prepared with Mo-based catalyst, has a chiral smectic C (Sc*) phase responsible for the ferroelectric liquid crystal.