Acharya B R, Kim J H, Kumar S
Department of Physics, Kent State University, Kent, Ohio 44242, USA.
Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics. 1999 Dec;60(6 Pt A):6841-6. doi: 10.1103/physreve.60.6841.
A material-independent method for determining liquid-crystal (LC) anchoring energy on rubbed polyimide (PI) surfaces has been devised. This method exploits the changes in the easy axis of rubbed PI film induced by exposure to linearly polarized UV (LPUV) light. The distribution of PI chains in a rubbed film is approximated by a Gaussian function and its width determined from the measured rotation of the LC easy axis as a function of exposure time. A quasimicroscopic free energy of the LC-substrate interface is used to model LC anchoring properties. The experimental and calculated values of the azimuthal anchoring energy are in good agreement and found to depend inversely on the width of the distribution function. The measurements of the width of the chain distribution function provide a simple LC material-independent method for determining the LC anchoring properties. With this method, it is also possible to calculate the strength of the interaction between PI chains and LC molecules.
已设计出一种与材料无关的方法，用于确定摩擦聚酰亚胺（PI）表面上的液晶（LC）锚定能。该方法利用了摩擦PI薄膜的易轴因暴露于线偏振紫外（LPUV）光而发生的变化。摩擦薄膜中PI链的分布由高斯函数近似，其宽度根据测量的LC易轴旋转随曝光时间的变化来确定。使用LC-基板界面的准微观自由能来模拟LC锚定特性。方位角锚定能的实验值和计算值吻合良好，且发现其与分布函数的宽度成反比。链分布函数宽度的测量提供了一种简单的与LC材料无关的方法来确定LC锚定特性。使用这种方法，还可以计算PI链与LC分子之间相互作用的强度。
