Wen Bing, Kim Jong-Hyun, Yokoyama Hiroshi, Rosenblatt Charles
Department of Physics, Case Western Reserve University, Cleveland, OH 44106-7079, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2002 Oct;66(4 Pt 1):041502. doi: 10.1103/PhysRevE.66.041502. Epub 2002 Oct 21.
A spatially varying herringbone pattern with an easy axis alternating in angle between 0 and psi and having a period of 200 nm was scribed into a polyimide-coated substrate. The depression of the nematic-isotropic transition temperature for a nematic layer at the patterned surface relative to its value at a uniformly rubbed surface was investigated as a function of psi for 15 < psi < 88 degrees. It was found that the depression of the transition temperature increases with psi, up to approximately 7 mK at psi=88 degrees. A simple model was developed that includes not only elasticity, but also anchoring effects at the polyimide. The model, which is used to calculate the thickness of the nematic layer, indicates that anchoring-rather than elastic-effects play the dominant role in the depression of the layer's transition temperature.
在涂有聚酰亚胺的基底上刻划出一种空间变化的人字形图案，其易轴在0到ψ之间交替变化，周期为200纳米。研究了图案化表面处向列相层的向列-各向同性转变温度相对于均匀摩擦表面处该温度值的降低情况，作为15°<ψ<88°时ψ的函数。结果发现，转变温度的降低随ψ的增加而增加，在ψ = 88°时高达约7 mK。建立了一个简单的模型，该模型不仅包括弹性，还包括聚酰亚胺处的锚定效应。用于计算向列相层厚度的该模型表明，锚定效应而非弹性效应在层转变温度的降低中起主导作用。
