Theory of nematic ordering driven by hydrogen bonding between rods and solvent molecules

ABSTRACT

A mean-field theory is introduced to describe nematic ($N$) ordering and phase separations in aqueous low-molecular-weight liquid crystalline molecules (or short rodlike molecules). We consider a physical bonding (or a hydrogen bonding) between the rod and solvent (water) molecules. Our theory predicts that the hydrogen bonds between the unlike molecules stabilise the $N$ phase and take place novel phase separations on the temperature-concentration plane. Upon increasing the number of functional groups on the rods, capable of forming the physical bond with the solvent molecule, the stable $N$ phase region is broadened on the phase diagram. We also find a miscibility window of the $N$ phase and closed-loop coexistence curves with upper and lower critical solution temperatures near the $N$ phase.

Graphical abstract

KEYWORDS:

• Aqueous liquid crystals
• hydrogen bonding
• nematic
• closed-loop
• lower critical solution temperature

Disclosure statement

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

Additional information

Funding

This work was supported by JSPS KAKENHI Grant Number 18K03566;Japan Society for the Promotion of Science [18K03566];