Pitch measurements in chiral lyotropic chromonic liquid crystals

ABSTRACT

The recent interest in lyotropic chromonic liquid crystals (LCLCs) has resulted in significant understanding of the assembly behaviour and liquid crystal properties of these water-based systems. On the other hand, there has been much less investigation into chiral LCLCs, which result if the chromonic molecule is chiral or if a chiral dopant is added to the solution. Measurements of the pitch of the LCLC disodium cromoglycate (DSCG) with several chiral dopants using both the Cano wedge and fingerprint texture methods are reported. The results include quantitative measurements of both the pitch and the helical twisting power. The ability of dopants to induce twist in DSCG varies widely, with some having almost no effect, with others producing a pitch approaching 3 and with most displaying an inverse pitch–dopant concentration dependence that is nonlinear at high concentrations.

Graphical Abstract

KEYWORDS:

• Liquid crystals
• lyotropic chromonic
• chromonic
• chiral
• pitch

Acknowledgements

The authors thank Zoey Davidson, Oleg Lavrentovich, Angel Martinez and Mohan Srinivasarao for helpful discussions.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was made possible by partial financial support from the U. S. National Science Foundation through the Materials Research Science and Engineering Center Grant DMR-1120901 to the University of Pennsylvania.