Salt effects on the phase behavior, structure, and rheology of chromonic liquid crystals

Andrei F. Kostko, Bani H. Cipriano, Olga A. Pinchuk, Lior Ziserman, Mikhail A. Anisimov, Dganit Danino, Srinivasa R. Raghavan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

69 Scopus citations

Abstract

Chromonic liquid crystals are formed by the addition of aromatic molecules such as disodium chromoglycate (cromolyn) to water. In this study, we investigate the addition of salts to the lyotropic nematic phase of cromolyn aqueous solutions. The addition of sodium and potassium salts shifts the isotropic-nematic phase boundary upward by more than 10°C, so that samples that were isotropic at room temperature are transformed into nematic phases. Salt effects are predominantly dictated by the cation, not the anion, and appear to differ based on cation size. In contrast to small, hydrated cations like sodium, large, weakly hydrated cations such as tetraethylammonium and tetrabutylammonium shift the phase boundary downward, thus stabilizing the isotropic phase at the expense of the nematic one. The phase behavior results are highly correlated with viscosity measurements, with an upward shift in the phase boundary correlating with an increase in solution viscosity and vice versa. We also probe the microstructure in cromolyn-salt solutions, both indirectly by small-angle neutron scattering (SANS) and directly by cryo-transmission electron microscopy (cryo-TEM). The cryo-TEM images show the presence of rodlike aggregates that possibly undergo a higher order aggregation into bundles in the presence of salt.

Original languageEnglish
Pages (from-to)19126-19133
Number of pages8
JournalJournal of Physical Chemistry B
Volume109
Issue number41
DOIs
StatePublished - 20 Oct 2005
Externally publishedYes

Fingerprint Dive into the research topics of 'Salt effects on the phase behavior, structure, and rheology of chromonic liquid crystals'. Together they form a unique fingerprint.

Cite this