Morphology of Nematic and Smectic Vesicles

TL;DR

This paper presents a theoretical model explaining how internal liquid-crystalline order influences the diverse shapes of vesicles, including nano-fibers, tetrahedral, and ellipsoidal forms, with implications for nano-carrier design.

Contribution

It introduces a minimal theoretical framework for understanding how nematic and smectic order affects vesicle morphology, integrating analytical and numerical methods.

Findings

Identifies low free energy vesicle shapes including nano-fibers, tetrahedral, and ellipsoids.

Shows topological defects influence vesicle morphology.

Highlights potential for designing nano-structures with specific symmetries.

Abstract

Recent experiments on vesicles formed from block copolymers with liquid-crystalline side-chains reveal a rich variety of vesicle morphologies. The additional internal order ("structure") developed by these self-assembled block copolymer vesicles can lead to significantly deformed vesicles as a result of the delicate interplay between two-dimensional ordering and vesicle shape. The inevitable topological defects in structured vesicles of spherical topology also play an essential role in controlling the final vesicle morphology. Here we develop a minimal theoretical model for the morphology of the membrane structure with internal nematic/smectic order. Using both analytic and numerical approaches, we show that the possible low free energy morphologies include nano-size cylindrical micelles (nano-fibers), faceted tetrahedral vesicles, and ellipsoidal vesicles, as well as cylindrical vesicles. The tetrahedral vesicle is a particularly fascinating example of a faceted liquid-crystalline membrane. Faceted liquid vesicles may lead to the design of supra-molecular structures with tetrahedral symmetry and new classes of nano-carriers.