Variations in the elastic constants of a fulgide-doped liquid crystal system

被引:6
作者
Allinson, H
Gleeson, HF
机构
[1] Department of Physics and Astronomy, Schuster Laboratory, University of Manchester, Manchester
[2] Centre for Self Organised Molecular Systems (SOMS), University of Leeds, Leeds
关键词
D O I
10.1039/jm9950502139
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The dye material thiophene fulgide was doped into the nematic liquid crystal E7 to a low concentration (2% m/m) to form a photochromic guest-host mixture. The photochromic thiophene fulgide has a thermally stable UV-induced isomer; the isomerism induces changes to the steric, dipolar and electronic conjugation properties of the species. The bend and splay elastic constants of this novel photochromic guest-host mixture have been determined and compared with the properties of the undoped liquid crystal. The bend elastic constant was determined from the threshold magnetic field of the Freedericksz transition measured optically, whilst the splay elastic constant was found from the variation of birefringence at fields above this threshold field. Both elastic constants of the guest-host mixture were observed to be approximately 10% lower than those of pure E7 at equivalent reduced temperatures. However, irradiation of the photochromic material within the guest-host mixture causing isomerism of the guest did not change the elastic constants of the bulk system. The reproducibility of these results is considered indicating an interesting alignment degradation phenomenon relating to the lecithin surface treatment used.
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收藏
页码:2139 / 2144
页数:6
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