Synthesis and characterization of ferroelectric side chain liquid crystal polymers bearing banana-shaped chiral mesogens

A series of ferroelectric liquid crystal polymers having banana-shaped side chain mesogens were synthesized through photo-polymerization of epoxide mo iety. 2,5-disubstituted-thiophene sub-unit was used in synthesizing the ban ana-shaped monomers. These liquid crystal compounds were characterized by N MR, differential scanning calorimetry (DSC) and optical polarized microscop y (POM). Mesomorphism was investigated as a function of spacer units. All t he synthesized low molar mass banana-shaped compounds exhibit smectic blue phase, but chiral smectic C phase could be observed only on compounds havin g longer spacer. The clearing temperature of low molar mass compounds fluct uated a little when spacer length varies. All polymers exhibit cholesteric mesophase and an observable glass transition. These liquid crystalline comp ounds reveal strong photoluminescence at visible region (lambda(max) = 475 nm for M9EPX) and have potential use in polarized organic light emitting di ode materials.