We investigated the effects of ion beam (IB) irradiation and rubbing on the directional behavior and alignment mechanism of liquid crystals (LCs) on polyimide (PI) surfaces. We found that the LC direction follows the IB irradiation alignment direction on the PI surface regardless of whether the irradiation occurs before or after rubbing. We assumed that the LC direction depends strongly on the C-O bonds created from C=O bonds on the PI surface broken by IB irradiation and conducted an investigation of the chemical bonding state of the PI surface by x-ray photoelectron spectroscopy.
Bibliographical noteFunding Information:
This research was supported by the MKE (Ministry of Knowledge Economy), Korea under the ITRC (Information Technology Research Center) Support program supervised by the IITA (Institute of Information Technology Advancement) (Grant No. IITA-2008-C1090-0801-0018). FIG. 1. Four types of alignment method on the PI surface used in this experiment: (a) IB irradiation after rubbing, (b) rubbing after IB irradiation, (c) rubbing alone, and (d) IB irradiation alone. FIG. 2. Microphotograph of LCs on the PI surfaces subjected to the two types alignment methods (under crossed nichols): (a) IB irradiation after rubbing and (b) rubbing after IB irradiation. FIG. 3. Transmittance as a function of incident angle on the PI surface for the two alignment methods to measure the pretilt angle: (a) IB irradiation after rubbing and (b) rubbing after IB irradiation. FIG. 4. V - T characteristics of the TN cells on the PI surface for (a) IB irradiation after rubbing and (b) rubbing after IB irradiation. FIG. 5. XPS spectra for the C1s of the PI (SE-7492) surface for (a) rubbing, (b) IB irradiation after rubbing, (c) IB irradiation, and (d) rubbing after IB irradiation.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)