MOLECULAR-ORIENTATION AT RUBBED POLYIMIDE SURFACES DETERMINED WITH X-RAY-ABSORPTION SPECTROSCOPY - RELEVANCE FOR LIQUID-CRYSTAL ALIGNMENT

Authors
WEISS K WOLL C BOHM E FIEBRANZ B FORSTMANN G PENG B SCHEUMANN V JOHANNSMANN D
Citation
K. Weiss et al., MOLECULAR-ORIENTATION AT RUBBED POLYIMIDE SURFACES DETERMINED WITH X-RAY-ABSORPTION SPECTROSCOPY - RELEVANCE FOR LIQUID-CRYSTAL ALIGNMENT, Macromolecules, 31(6), 1998, pp. 1930-1936
Citations number
43
Categorie Soggetti
Polymer Sciences
Journal title
Macromolecules → ACNP
ISSN journal
00249297
Volume
31
Issue
6
Year of publication
1998
Pages
1930 - 1936
Database
ISI
SICI code
0024-9297(1998)31:6<1930:MARPSD>2.0.ZU;2-S
Abstract
The molecular orientation at the surface of polyimide (PI) alignment l ayers used for liquid crystal displays has been determined using X-ray absorption spectroscopy (NEXAFS). The second moments of the orientati on distribution function obtained from a detailed analysis reveal that , upon rubbing, the PI substrates develop biaxiality and an inclinatio n of a few degrees. For a nematic liquid crystal (LC) in contact with these alignment layers, the pretilt angle was determined and revealed a weak correlation with buffing strength.