A study of the electroclinic effect in the smectic A* phase of mixtures with strongly chiral alkoxybiphenyl-phenyl carboxylate dopants |
| |
Authors: | Jaskaran S Kang David A Dunmur Christopher J Booth John W Goodby Kenneth J Toyne |
| |
Institution: |
a Centre for Molecular Materials and Department of Chemistry, The University of Sheffield, Sheffield, United Kingdom
b School of Chemistry, The University of Hull, Hull, United Kingdom |
| |
Abstract: | A detailed investigation has been reported of the electroclinic behaviour in the smectic A* phase of eleven mixtures made up of a commercial achiral smectic C host and strongly chiral alkoxybiphenyl-phenyl carboxylate dopants. A new technique was used to measure the induced tilt angle as a function of electric field and temperature. For all the mixtures, the electroclinic response followed a Curie-Weiss type temperature dependence for measurements performed well away from the smectic A* to smectic C* phase transition temperature. The strength of the electroclinic response was evaluated for each mixture by determining the temperature independent ratio k/a (i.e. the electroclinic coupling susceptibility, k divided by the susceptibility coefficient controlling the induced tilt, a). Analysis of the results showed that k/a of the mixtures was dependent on the type and position of the electronegative or polar substituents that affected the net dipole moment of the chiral dopants. In fact, the value of k/a was largest when fluorine was replaced by hydrogen in the lateral position and at the chiral centre. Furthermore, relatively short alkyl chains (e.g. C6H13) at the chiral centre were preferred to longer ones (e.g. C10H21) for a larger electroclinic response. |
| |
Keywords: | |
本文献已被 InformaWorld 等数据库收录! |
|