Extremely small twist elastic constants in lyotropic nematic liquid crystals
Artikel i vetenskaplig tidskrift, 2020

Recent measurements of the elastic constants in lyotropic chromonic liquid crystals (LCLCs) have revealed an anomalously small twist elastic constant compared to the splay and bend constants. Interestingly, measurements of the elastic constants in the micellar lyotropic liquid crystals (LLCs) that are formed by surfactants, by far the most ubiquitous and studied class of LLCs, are extremely rare and report only the ratios of elastic constants and do not include the twist elastic constant. By means of light scattering, this study presents absolute values of the elastic constants and their corresponding viscosities for the nematic phase of a standard LLC composed of disk-shaped micelles. Very different elastic moduli are found. While the splay elastic constant is in the typical range of 1.5 pN as is true in general for thermotropic nematics, the twist elastic constant is found to be one order of magnitude smaller (0.30 pN) and almost two orders of magnitude smaller than the bend elastic constant (21 pN). These results demonstrate that a small twist elastic constant is not restricted to the special case of LCLCs, but is true for LLCs in general. The reason for this extremely small twist elastic constant very likely originates with the flexibility of the assemblies that are the building blocks of both micellar and chromonic lyotropic liquid crystals.

nematic liquid crystals

chirality

lyotropic liquid crystals

light scattering

elasticity

Författare

C. F. Dietrich

Universität Stuttgart

Peter J. Collings

University of Pennsylvania

Swarthmore College

Thomas Sottmann

Universität Stuttgart

Per Rudquist

Chalmers, Mikroteknologi och nanovetenskap (MC2), Elektronikmaterial och system

F. Giesselmann

Universität Stuttgart

Proceedings of the National Academy of Sciences of the United States of America

0027-8424 (ISSN) 1091-6490 (eISSN)

Vol. 117 44 27238-27244

Ämneskategorier

Oorganisk kemi

Fysikalisk kemi

Annan materialteknik

DOI

10.1073/pnas.1922275117

PubMed

33067393

Mer information

Senast uppdaterat

2020-11-24