Photochemistry of Liquid-Crystalline Polymers
Polymers and High Performance Materials
Several aspects of the photophysics and photochemistry of liquid crystalline polymers containing aryl cinnamate and stilbene chromophores are reported. UV-VIS spectra of these materials in various phases in thin films are perturbed relative to spectra in solution. These perturbations are attributed to chromophore aggregation that is dependent on the phase type. Fluorescence and fluorescence excitation spectra of a stilbene polyester show the presence of emissive aggregates. The photochemical reactions of these materials are also dependent on phase. In polyarylcinnamates the ratio of 'dimer' or 'dimer like' to photo-Fries photoproducts depends both on temperature (phase type) and wavelength of irradiation. 'Dimer' or 'dimer like' products are formed preferentially under conditions where chromophore association and/or excitation is maximized. In the stilbenes a photocycloaddition is observed that is photoreversible at elevated temperature. Parallel studies are reported on small molecule model compounds.
ACS Symposium Series
Cozad, R. A.,
Griffin, A. C.,
Hoyle, C. E.,
Varma, S. S.,
(1994). Photochemistry of Liquid-Crystalline Polymers. ACS Symposium Series, 579, 13-26.
Available at: http://aquila.usm.edu/fac_pubs/7162