Molecular ordering of the discotic liquid crystal HAT6 confined in mesoporous solids

Publikationstyp
Journal Article
Date Issued
2014-06-05
Sprache
English
Author(s)
Calus, Sylwia  
Kityk, Andriy V.  
Huber, Patrick  orcid-logo
Institut
Werkstoffphysik und -technologie M-22  
TORE-URI
http://hdl.handle.net/11420/12791
Journal
Microporous and mesoporous materials  
Volume
197
Start Page
26
End Page
32
Citation
Microporous and Mesoporous Materials 197 (): 26-32 (2014-01-01)
Publisher DOI
10.1016/j.micromeso.2014.05.036
Scopus ID
2-s2.0-84903833993
Publisher
Elsevier
An optical polarimetry study of the orientational order of a discotic liquid crystal (DLC), 2,3,6,7,10,11-hexakis(hexyloxy)triphenylene (HAT6), confined into parallel-aligned cylindrical nanochannels of mesoporous alumina, silica, and silicon membranes as a function of temperature and channel radius (3.4-21.0 nm) is presented. In contrast to the bulk state, the birefringence resulting from the confined discotic liquid crystal, exhibits a continuous temperature evolution and is positive indicating a dominating face-on (homeotropic) type molecular ordering with respect to the channel walls. Pronounced hysteresis effects observed in the experiment are traced to different nucleation sites of the low-temperature phase upon cooling and the high-temperature phase upon heating. Deviations from the Gibbs-Thomson scaling of the phase transition temperature for channel diameters below 10 nm are traced to splay distortions of the confined liquid crystal.
Subjects
Columnar discotics
Nanocomposites
Porous alumina
Porous silica
Porous silicon
DDC Class
530: Physik
600: Technik
More Funding Information
This work has been supported by the Polish National Science Centre (NCN) under the Project “Molecular Structure and Dynamics of Liquid Crystals Based Nanocomposites” (Decision No. DEC-2012/05/B/ST3/02782) and by the German Research Foundation (DFG) by Grant No. Hu850/3-1.