DESIGN OF MOLECULAR ARCHITECTURES FOR POLYMERIC MESOPHASE FORMATION

Based on the tendency of low molar mass liquid crystals composed of extended mesogens symmetrically disubstituted with long n-alkoxy substituents to exhibit smectic C mesophases, we have proposed that SCLCPs with laterally attached (vs. terminally attached) mesogens offer an ideal architecture for obtaining s(C)* mesophases. In particular, mesogens that typically form the desirable s(C)*-n phase sequence can be laterally attached to the polymer backbone through a chiral spacer, which should result in high values of spontaneous polarization. Not only are we using mesogens which exhibit s(C)*-n phase sequences, we are also attempting to induce smectic layering into systems which typically form nematic mesophases by using immiscible hydrocarbon/fluorocarbon components and electron-donor-acceptor interactions. Thus far, the thermotropic behavior of poly{5-[[[2',5'-bis[(3''-fluoro-4''-dimethoxyphenyl)ethynyl]benzyl]oxy]carbonyl]bicyclo[2.2.1]hept-2-ene}s and poly{5-[[[2',5'-bis[(3''-fluoro-4''-methoxybenzoyl)oxy]benzyl]oxy]carbonyl]bicyclo[2.2.1]hept-2-ene}s correspond to that of their low molar mass analogs. Preliminary results demonstrate that smectic layering is successfully induced in 2,5-bis[(4'-n-alkoxybenzoyl)oxy]toluenes and polynorbornenes with laterally attached 2,5-bis[(4'-n-alkoxybenzoyl)oxy]benzyl mesogens by terminating the n-alkoxy substituents with perfluorinated segments.