Steroid-Based Liquid Crystalline Polymers: Responsive and Biocompatible Materials of the Future

Steroid-based liquid crystal polymers and co-polymers have come a long way, with new and significant advances being made every year. This paper reviews some of the recent key developments in steroid-based liquid crystal polymers and co-polymers. It covers the structure–property relationship between cholesterol and sterol-based compounds and their corresponding polymers, and the influence of chemical structure and synthesis conditions on the liquid crystalline behaviour. An overview of the nature of self-assembly of these materials in solvents and through polymerisation is given. The role of liquid crystalline properties in the applications of these materials, in the creation of nano-objects, drug delivery and biomedicine and photonic and electronic devices, is discussed.

Synthesis and Properties of Maleic Acid Cholesteryl Monoester–Citric Acid Triester

A new maleic acid cholesteryl monoester–citric acid trimester (MACM-CAT) containing three cholesterol units has been synthesised successfully. The structure was characterised by a series of spectroscopic methods and thermal analysis including polarising optical microscopy. The results showed that MACM-CAT displayed a triangular-like ordered layered structure and exhibited a good liquid crystalline behaviour. The introduction of sodium citrate onto cholesterol units is favourable for the formation of hydrogen bonds of MACM-CAT and improvement of the stability. More importantly, the study provides a novel route for the synthesis of liquid crystalline materials.

Photoinduced Reorientation in Thin Films of a Nematic Liquid Crystalline Polymer Anchored to Interfaces and Enhancement Using Small Liquid Crystalline Molecules

The photoinduced reorientation of the side-chain mesogens in nematic liquid crystalline (LC) polymer thin films triggered by the axis-selective photo-Fries rearrangements of side-chain phenyl benzoate moieties is studied to understand the regulation of the anisotropic nanostructures supported by LC polymers. The influence of the substrate surface in anchoring the side-chain mesogens near the interfaces is examined by comparing the reorientation of 30- and 120-nm-thick films. Irradiation with linearly polarized ultraviolet (UV) light and subsequent annealing causes the side-chain mesogen reorientation to align perpendicular to the electric field of the incident UV light. The inplane order in the 30-nm-thick films is lower than that in the 120-nm ones. On the other hand, the annealing period required for mesogen alignment is independent of the film thickness. It is suggested that the substrate surfaces anchor the LC mesogens to fix their orientation, rather than slowing down the reorientational motion. In addition, it is demonstrated that small LC molecules miscible with the nematic LC polymer enhance photoinduced reorientation through cooperative molecular interaction with the side-chain mesogens, remarkably accelerating the orientation and improving the inplane order of the unidirectionally aligned mesogens.

Self-organization of cholesterol-side-chain liquid crystalline polymers by tailoring the main chain structure and flexible spacer length

Liquid crystal polymers with cholesterol side-chains formed different smectic A phases under the influence of the main-chain structure and flexible spacer length.