X-ray Diffraction Study of Intermolecular Interactions in Cholesteryl Ester-Substituted Cyclosiloxanes

Abstract

The mesophase structure of a series of sixteen cholesterol-based liquid crystalline materials based on cyclosiloxane backbones is examined. The co-existence of two layer types (full and partial interdigitation of cholesterol mesogens) in the mesophase is examined as a function of ring size, composition, and spacer length. The relative X-ray intensities from each layer type are discussed as a function of these variables. An increase in the ring size and cholesterol composition, and a decrease in the spacer group all result in more partially interdigitated packing. Molecular modeling calculations performed on the mesogens and macromolecules examine relative differences in the orientational relationships and flexibility of mesogens.

Key Words:

• Liquid crystal
• cholesterol
• interdigitation
• X-ray difraction
• cyclic siloxane
• molecular modeling