Control of liquid crystal alignment by polyimide surface modification using atomic force microscopy
作者:
A. J. Pidduck,
S. D. Haslam,
G. P. Bryan-Brown,
R. Bannister,
I. D. Kitely,
期刊:
Applied Physics Letters
(AIP Available online 1997)
卷期:
Volume 71,
issue 20
页码: 2907-2909
ISSN:0003-6951
年代: 1997
DOI:10.1063/1.120212
出版商: AIP
数据来源: AIP
摘要:
Atomic force microscopy (AFM) has been used to modify a polyimide surface to give controlled liquid crystal (LC) alignment, and to examine the modification produced. Strong LC azimuthal anchoring was observed typically for normal forces>300 nNand line densities>5 &mgr;m−1,and optically diffracting LC elements were fabricated by repeatedly overpatterning the same area along different directions. Atomic force microscopy images showed little sign of topographic modification such as grooving, whereas lateral force images showed locally increased friction. Estimated contact pressures, 0.08–0.3 GPa, suggest shear-yielding occurs within a surface layer, causing polymer chain alignment. The AFM micromechanical interaction is compared with that occurring during the conventional cloth-rubbing LC alignment process.
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