Synthesis and properties of liquid crystalline poly(p-phenylene) and poly(p-phenylenevinylene) derivatives

We have synthesized poly(p-phenylene) (PPP) and poly(p-phenylenevinylene) ( PPV) derivatives which are substituted with liquid crystalline (LC) groups as side chains of phenylene rings. The LC group is composed of phenylcycloh exyl (PCH) or cyanobiphenyl (CB) moiety as a mesogenic core and various met hylene spacers of 6-10. All polymers synthesized were fusible and soluble i n organic solvents. PPP derivatives with the CB moiety in the LC substituen t and PPV derivatives with the PCH and CB moieties in the LC substituent ex hibited enantiotropic LC behaviors. The cast film of PPV derivative showed electrical conductivities of 10(-5) and 10(-3) S/cm before and after iodine doping, respectively. The polymer aligned by a rubbing treatment showed a linearly dichromic fluorescence.