Sunday, 12 July 2020

Minority governs the packing: Nanophase segregation or layer roughening?

M. Vijay Kumar, S. Krishna Prasad, D. S. Shankar Rao and P. K. Mukherjee, Langmuir, 30, 4465 (2014)

In this work we demonstrate two important features that arise out of introducing a liquid crystalline (LC) compound into the rotator phase matrix, and the consequent competition between the anisometric segments of the LC moieties, and the aliphatic units. First, we show that the change in the structural character of the mixed medium depends on which of the entities forms the minority concentration: in case of this being the alkane, the two components of the binary system get nanophase segregated, whereas if the LC molecules are in small concentration then the layered structure merely gets roughened without any segregation. The second and more significant result of the calorimetric and Xray experiments, at low LC concentrations, is the induction of a rotator phase that leads to unusual phase sequence, not reported hitherto. Possible scenarios for the molecular arrangement are discussed. A Landau model is also presented that explains some of the observed features.

Posted by S. Krishna Prasad