INVESTIGATION OF DYNAMIC ORIENTATION PROCESS OF NEMATIC LIQUID-CRYSTALS TRIGGERED BY CONFORMATIONAL CHANGE OF SURFACE MONOLAYER

We developed a measuring system that measures both capacitance and tra nsmittance of a liquid crystal(LC) cell simultaneously. We then studie d the dynamic orientation process of nematic LC molecules between two- photochromic command surfaces. The command surfaces consist of a polym er monolayer bearing azobenzene side chains and they are deposited on glass substrate coated with indium-tin-oxide by using the Langmuir-Blo dgett technique. The capacitance of LC cells increased and decreased a lternately due to orientation transition in LC molecules by irradiatin g ultraviolet(UV) and visible light, respectively. Similarly, with the alternating irradiation of UV and visible lights, the transmittance o f the LC cell changed periodically. Mean tilt angles of LC molecules u nder irradiation of UV and visible lights were evaluated from the resu lts of capacitance and transmittance. It was found that the transient transmittance response was delayed to the transient capacitance under the UV irradiation. This result corresponds to that the LC molecules i n homeotropic mode tend to remain the optical alignment.