The Lyotropic Analog of the Polar SmC* Phase

Abstract

Only six years ago, the first clear-cut example of a ferroelectric, lyotropic liquid crystal was discovered. Since then, ongoing investigations in this new research field provided numerous instances of the missing pieces to complete the formerly blank picture of the lyotropic smectic C* (SmC*) phase. In this review we wanted to combine these new results and put them into a wider historical and scientific context. We start by giving an introduction about characteristic features of the well-known thermotropic SmC* phase and why it is so difficult to find a lyotropic equivalent of this fascinating phase. After discussing early examples of achiral lyotropic and swollen SmC phases, we recap the discovery of the first lyotropic SmC* phase. The molecular features necessary for its formation and its properties are analyzed. We place special emphasis on discussing the long-range orientational order of the tilt direction and the corresponding chirality effects. By comparing these exceptional features with thermotropic and swollen SmC* phases, we aim to improve not only the understanding of the lyotropic SmC* phase, but also of the relationship between thermotropic and lyotropic systems in general.

Origin of the Monolayer and Bilayer Arrangement in Smectic A and C Mesophases and Nematic Cybotactic Domains: The Case Study of Benzyloxy-Terminated Isoxazole Liquid Crystals

“…2 The tilted lamellar lyotropic mesophase, equivalent to the thermotropic SmC mesophase, is rare to be found, and until 2013, a few examples had been reported in the literature. 3 The true lyotropic SmC mesophase was first reported by Schafheutle and Finkelmann in 1988 4 and later by Giesselmann and co-workers in 2013. 5 For smectic-type TLCs, a lamellar organization assumes a wide variety of molecular positional arrangements whose ordering can be reached by short-range and long-range molecular correlations.…”

“…In a particular circumstance where the ordered alkyl chain takes action, the additional lamellar mesophase L b is assigned . The tilted lamellar lyotropic mesophase, equivalent to the thermotropic SmC mesophase, is rare to be found, and until 2013, a few examples had been reported in the literature . The true lyotropic SmC mesophase was first reported by Schafheutle and Finkelmann in 1988 and later by Giesselmann and co-workers in 2013 …”

Current Topics in Ionic Liquid Crystals

“…In this long‐known and well investigated class of liquid crystals, lamellar α‐phases (L α , the lyotropic counterpart to SmA) and hexagonal phases (H 1 , the lyotropic counterpart to thermotropic Col h ) are the most common and widespread phases. The first example of a lyotropic nematic phase however was not discovered before 1978 [24] and lyotropic equivalents to SmC‐type phases are even more rare [25–27] …”

Novel Trends in Lyotropic Liquid Crystals

“…Lastly, it should be mentioned that the electroclinic effect could also be verified for the orthogonal chiral L α * phase [141], which very much resembles that of the SmA* phase of thermotropics. Other amphiphilic molecules with a similar behavior have been synthesized since [142], and a detailed account of this topic can be found in the review of Reference [143]. The aspect of a conceptual transfer relating to physical properties and structures between thermotropic and lyotropic liquid crystals is certainly a very novel approach and opens up a whole field of future research in lyotropic liquid crystals.…”