The study of surface free energy and wettability of liquid crystal alignment layers

• Main Authors: Chih-hung Lu, 盧志宏
• Other Authors: Wen-Jun Zheng
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/q2rsfj

碩士 === 國立中山大學 === 光電工程研究所 === 96 === In the present studies we investigated the effects of mechanical rubbing on the surface characteristics of polymer liquid crystal alignment layers. Contact angles of water droplets in contacted with the rubbed polyimide were measured using a surface tension meter, and the surface free energy of the polymer thin films were evaluated. We found that the contact angle of water and surface free energy on rubbed polyimide is anisotropic, and rubbing caused decrease in surface free energy and wettability of the polyimide surface. It was also seen that the contact angle hysteresis and the surface free energy measured in the direction parallel to the rubbing direction is smaller than that in the direction anti-parallel to the rubbing direction. We found that when the pile impression of the velvet fibers is 0.3 mm and the cumulative number of rub is 3 times, the contact angle hysteresis in direction parallel or anti-parallel to the rubbing direction will to be close. Be suitable choosing rubbing conditions, the SSFLCs without zigzag defects was produced. The pretilt angle and the response time of liquid crystal increased with the cumulative number.