https://doi.org/10.1140/epje/i2002-10157-2
Original Paper
Deformable tetrahedratic phases: The effects of external fields and flows
1
Advanced Liquid Crystal Technologies, POB 1314, NJ 07902, Summit, USA
2
Max-Planck-Institute for Polymer Research, PO Box 3148, 55021, Mainz, Germany
3
Theoretische Physik III, Universität Bayreuth, 95440, Bayreuth, Germany
* e-mail: cladis@alct.com
We discuss changes in the symmetry and physical properties of an isotropic phase which has initially tetrahedral symmetry characterized by four unit vectors. In its undeformed state, these four vectors are at the tetrahedral angle ($109.47^\circ$) to each other. We find that this optically isotropic phase becomes uniaxial under the influence of an external electric field, ${\bf E}$, resulting in a phase with C 3v symmetry. For an applied simple shear flow, the system becomes biaxial and a time-dependent state with C 1 symmetry arises. We discuss to what extent deformations induced by external forces and flows on this optically isotropic phase, which we call a "deformable tetrahedratic phase", are consistent with observations at the isotropic-B7 transition found recently in compounds composed of banana-shaped molecules and suggest a number of experiments to test the conclusions of this model.
© EDP Sciences, Società Italiana di Fisica, and Springer-Verlag, 2003