Amphotropic liquid-crystalline behaviour of glycolipids in amino acid ionic liquids

ABSTRACT

We examined lyotropic liquid-crystalline behaviour of glycolipids (GLs) with a normal alkyl chain or a diacetylene-functionalised alkyl chain in several amino acid ionic liquids (AAILs). It was found that the mixtures of GL and AAIL form various nanosegregated liquid-crystalline phases, such as smectic, bicontinuous cubic and hexagonal columnar phases, depending on the two-component ratio and AAIL species. The observed liquid-crystalline behaviours were summarised as phase diagrams. It is noteworthy that the employment of amino acid anions with superior hydrogen-bonding ability, such as aspartic and glutamic acid anions, gives a phase diagram with a wide liquid-crystalline region. Comparing with a phase diagram obtained for the GL/water mixtures, we gained insights on the similarity/dissimilarity between water and AAILs as self-organisation media of amphiphiles. For the diacetylene-functionalised molecule, UV irradiation was carried out to progress polymerisation. It is of interest that the polymerisation reaction progressed when the glycolipid formed a smectic phase in an AAIL while a reaction progress was not found when it formed a bicontinuous cubic phase in another AAIL. We believe that AAILs have a great potential to be a liquid media not only for amphiphiles but for various functional materials, such as polymers and colloids, to form novel assemblies.

GRAPHICAL ABSTRACT

KEYWORDS:

• Amino acid ionic liquid
• glycolipid
• bicontinuous cubic phase
• gyroid

Acknowledgments

This work was supported by the Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B) (no. 17H03038).

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary materials

Supplementary material can be accessed here.