The creation of long-lasting glassy columnar discotic liquid crystals using 'dimeric' discogens

Citation
N. Boden et al., The creation of long-lasting glassy columnar discotic liquid crystals using 'dimeric' discogens, J MAT CHEM, 9(7), 1999, pp. 1391-1402
Citations number
39
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science","Material Science & Engineering
Journal title
JOURNAL OF MATERIALS CHEMISTRY
ISSN journal
0959-9428 → ACNP
Volume
9
Issue
7
Year of publication
1999
Pages
1391 - 1402
Database
ISI
SICI code
0959-9428(199907)9:7<1391:TCOLGC>2.0.ZU;2-U
Abstract
'Dimeric' discogens have been synthesised which have two triphenylene nucle i, each of which bears five beta-OC6H13 substituents, which are linked thro ugh the remaining beta positions by a flexible O (CH2)(n)O polymethylene ch ain (n = 3-16). Calculations show that the minimum chain length for bridgin g between columns in the Col(h) phase of these compounds is O (CH2)(7)O. It was found that only those dimers for which n>7 formed a Col(h) phase. This mesophase can be supercooled into a metastable glass which is relatively h ard and in which the columnar order and orientation is retained. These glas ses revert to the crystalline state within a few hours but we have shown th at longer-lasting Col(h) glasses can be engineered through introducing an e xtra degree of disorder into the glass by making the 'dimers' subtly unsymm etrical. These 'dimers' either have differently substituted triphenylene ri ngs at the two ends of the linking chain or an amide group within the chain itself. They give Col(h) aligned glasses which last for months at room tem perature.