Photogeneration of high pretilt angles of nematic liquid crystals by azobenzene-containing polymer films

A vertically aligned (VA) type of nematic liquid-crystal (LC) cell was explored using photoirradiated thin films of a polymethacrylate with mesogenic moieties of 4-trifluoromethoxyazobenzene as side chains. Optical anisotropy was generated by slantwise irradiation of films of the polymer with nonpolarized ultraviolet light, followed by annealing treatment to enhance the photodichroism which displayed thermal stability. The photoirradiated films brought about high pretilt angles of the LC so that a VA-type LC cell was fabricated. The cell exhibited electro-optical properties with excellent optical quality on applying voltages even after heating at 100 degrees C for several hours. (C) 1999 American Institute of Physics. [S0003-6951(99)04317-X].