Self-Assembly of Unusually Stable Thermotropic Network Phases by Cellobiose-Based Guerbet Glycolipids

Abstract

Bicontinuous thermotropic liquid crystal (LC) materials, e.g., double gyroid (DG) phases, have garnered significant attention due to the potential utility of their 3D network structures in wide-ranging applications. However, the utility of these materials is significantly constrained by the lack of robust molecular design rules for shape-filling amphiphiles that spontaneously adopt the saddle curvatures required to access these useful supramolecular assemblies. Toward this aim, we synthesized anomerically pure Guerbet-type glycolipids bearing cellobiose head groups and branched alkyl tails and studied their thermotropic LC selfassembly. Using a combination of differential scanning calorimetry, polarized optical microscopy, and small-angle X-ray scattering, our studies demonstrate that Guerbet cellobiosides exhibit a strong propensity to self-assemble into DG morphologies over wide thermotropic phase windows. The stabilities of these assemblies sensitively depend on the branched alkyl tail structure and the anomeric configuration of the glycolipid in a previously unrecognized manner. Complementary molecular simulations furnish detailed insights into the observed self-assembly characteristics, thus unveiling molecular motifs that foster network phase selfassembly that will enable future designs and applications of network LC materials.

Tuning the Complex Spherical Phase of Sugar-Based Block Co-Oligomer via Single-Monomer-Mediated Composition Variation

“…The distinctive chemical structure of glycolipids, characterized by a hydrophilic saccharide moiety and short alkyl chains, could serve as a valuable clue for designing a high-χ/low- N BCO capable of self-assembling into well-ordered nanostructures. While much of the research of glycolipids has focused on their lyotropic phase behavior in aqueous environments, − the thermotropic phase behavior has also received attention. − Glycolipids form periodic nanostructures in a liquid crystalline state between the melting point of the alkyl chain and the clearing temperature. The hydrogen bonding interactions between the glucose units are crucial in determining the type and thermal stability of the structures formed.…”