Effects of Dilution, Polarization Ratio, and Energy Transfer on Photoalignment of Liquid Crystals Using Coumarin-Containing Polymer Films

Journal Article · Tue May 27 00:00:00 EDT 2008 · Macromolecules

DOI:https://doi.org/10.1021/ma702809g· OSTI ID:928744

Orientation of a nematic liquid crystal, E-7, was investigated using coumarin-containing polymethacrylates to elucidate the roles played by the dilution of coumarin and the polarization ratio of irradiation. Dilution of coumarin by inert moieties had adverse effects on a nematic cell’s number density of disclinations and its orientational order parameter in the parallel but not the perpendicular regime. In addition, both dilution of coumarin and a decreasing polarization ratio resulted in a lower extent of coumarin dimerization at crossover, Xc. The significantly reduced Xc in a homopolymer comprising triphenylamine and coumarin was attributed to the dilution of coumarin and the diminished polarization ratio caused by competing absorption with simultaneous triplet energy transfer from triphenylamine to coumarin moieties.

• Research Organization: Univ. of Rochester, NY (United States). Lab. for Laser Energetics
• Sponsoring Organization: USDOE
• DOE Contract Number: FC52-08NA28302
• OSTI ID: 928744
• Report Number(s): DOE/NA/28302-830; 2008-31; 1802
• Journal Information: Macromolecules, Vol. 41
• Country of Publication: United States
• Language: English