Eur. Phys. J. E (2022) 45: 63
https://doi.org/10.1140/epje/s10189-022-00217-y

Regular Article - Soft Matter

Impact of random-field-type disorder on nematic liquid crystalline structures

¹ Jožef Stefan Institute, Jamova cesta 39, 1000, Ljubljana, Slovenia
² Jožef Stefan International Postgraduate School, Jamova cesta 39, 1000, Ljubljana, Slovenia
³ Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška cesta 160, 2000, Maribor, Slovenia

^a aleksander.zidansek@mps.si

Received: 22 May 2022
Accepted: 4 July 2022
Published online: 25 July 2022

Abstract

We study bicomponent systems where one component represents a liquid crystalline (LC) phase, and the other component randomly perturbs the LC order. Such systems can serve as a testbed to systematically analyse the impact of qualitatively different types of random-type sources of perturbation on the orientational and/or translational order. This mini-review presents typical representatives of such systems, where orientational and translational order is probed in nematic and smectic A LCs, respectively. As a source of perturbation, we consider either different porous matrices (control-pore glass, aerogels) or aerosil nanoparticles, which can form in LCs' different fractal-like network organizations. In such complex systems, LC ordering fingerprints the interplay among LC elastic forces, interfacial forces, and randomness. The resulting LC behaviour could be characterised by either long-range, quasi long-range, or short-range order. We demonstrate under which conditions random-field-like phenomena or interfacial effects dominate. However, these effects are relatively strongly entangled in most experimental systems, and individual impacts cannot be precisely identified.