Periodic Grating‐like Patterns Induced by Self‐Assembly of Gelator Fibres in Nematic Gels

Abstract

Periodic orientation patterns occurring in nematic gels, revealed by optical and scanning electron microscopy, are found to be formed by spontaneous self-assembly of fibrous aggregates of a low-molecular-weight organogelator in an aligned thermotropic liquid crystal (LC). Self-organization into periodic structures is also reflected in a calorimetric study, which shows the occurrence of three thermoreversible states, namely, isotropic liquid, nematic and nematic gel. The segregation and self-assembly of the fibrous aggregates leading to pattern formation are attributed to the highly polar LC and to hydrogen bonding between gelator molecules, as shown by X-ray diffraction and vibrational spectroscopy. This study aims to investigate in detail the effect of the chemical nature and alignment of an anisotropic solvent on the morphology of the gelator fibres and the resulting gelation process. The periodic organization of LC-rich and fibre-rich regions can also provide a way to obtain templates for positioning nanoparticle arrays in an LC matrix, which can lead to novel devices.

Thermally tunable selective formation of self-assembled fibers into two orthogonal directions in oriented liquid-crystalline smectic templates

“…3 Anisotropic aggregation of gelators in LC templates results in macroscopic alignment of functional self-assembled fibers. [20][21][22]29,30,[36][37][38][39] The LC fields also allow the formation of complicated fibrous structures such as loop-like fibers 40 or gradually twisted aligned fibers. 20 Therefore, the self-assembled composites of liquid crystals and gelators are versatile and advantageous approaches for the construction of complex fibrous structures.…”