Enhanced chromonic stacking assisted by a hydrogel network

Abstract

We report that the stacking order in lyotropic chromonic liquid crystal (LCLC) Sunset Yellow FCF (SSY) is enhanced when incorporated into a cationic hydrogel via the ionic bonds. The chromonic-incorporated gel is initially opaque but transparent and shows a birefringence at high temperatures. The stacking correlation length at room temperature (≈25 °C) is as large as 5.97 nm, corresponding to about 18 molecules in a single stack, and the stacking energy is found to be 7.96 k_BT. Both values are larger than those in a normal SSY solution with the respective concentration (≈1 M).

Keywords:

• Lyotropic chromonic liquid crystals (LCLCs)
• sunset yellow FCF (SSY)
• ionic hydrogels
• chromonic aggregates
• correlation length
• stacking energy

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors thank S. Arai, Y. Ohgi for their help with DSC measurements. K.V.L. acknowledges Prof. Jian Ping Gong (Hokkaido University) for fruitful discussions at Haneda airport. K.V.L. also thanks H. Nguyen for helpful advice. This work was partially supported by Japan Society for the Promotion of Science KAKENHI (Grant No. JP18K14094).