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Influence of Chain Stiffness and Preparation Methods on the Efficiency of Polyimide Alignment Layers for Liquid Crystal Orientation

Title data

Neuber, Christian ; Giesa, Reiner ; Schmidt, Hans-Werner:
Influence of Chain Stiffness and Preparation Methods on the Efficiency of Polyimide Alignment Layers for Liquid Crystal Orientation.
In: Molecular Crystals and Liquid Crystals. Vol. 461 (2006) Issue 1 . - pp. 83-99.
ISSN 1563-5287
DOI: https://doi.org/10.1080/15421400601091359

Official URL: Volltext

Project information

Project financing: Deutsche Forschungsgemeinschaft

Abstract in another language

In this work the influences of chain stiffness, solution concentration, and preparation methods on the formation and efficiency of highly oriented polyimide alignment layers are investigated. To quantify the performance of the alignment layers in liquid-crystalline (LC) cells, the orientation of a calamitic bis-azo dye in a lowmolecular-
weight nematic LC guest-host mixture was employed. The degree of orientation was quantified by measuring the dichroic ratio (DRUV) of the dye with polarized UV spectroscopy. Alignment layers were prepared from precursors of 15 polyimide polymers with different chain stiffnesses. Additionally, the effect of polymer
solution concentration, denoted as low (approx. 2wt%) and high (50 wt%), and orientation techniques (casting and shearing) were systematically investigated.
Cells assembled with buffed polyimide alignment layers originating from Q2 1.5 wt% solutions in NMP of a rigid para-linked poly(amic ethyl ester) precursor 20
polymer resulted in a very high DRUV of 15. This value can be compared to values obtained with commercially available flexible polyimide layers, which had a DRUV of only 8. Pretilt angles of selected cells were also measured and were found to be in the range of 0.7 to 5.1 .

Further data

Item Type: Article in a journal
Refereed: Yes
Institutions of the University: Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Macromolecular Chemistry I
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Macromolecular Chemistry I > Chair Macromolecular Chemistry I - Univ.-Prof. Dr. Hans-Werner Schmidt
Profile Fields
Profile Fields > Advanced Fields
Profile Fields > Advanced Fields > Polymer and Colloid Science
Profile Fields > Advanced Fields > Advanced Materials
Research Institutions
Research Institutions > Research Centres
Research Institutions > Research Centres > Bayreuth Institute of Macromolecular Research - BIMF
Research Institutions > Collaborative Research Centers, Research Unit
Research Institutions > Collaborative Research Centers, Research Unit > SFB 481 Komplexe Makromolekül- und Hybridsysteme in inneren und äußeren Feldern
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 540 Chemistry
Date Deposited: 30 Jun 2015 07:49
Last Modified: 10 Mar 2016 09:25
URI: https://eref.uni-bayreuth.de/id/eprint/1359