Morphology and Structural Color in Coaxial Electrospun Liquid Crystal Fibers

Abstract

Functional fibers with core–shell architecture hold promises for applications ranging from smart textiles to advanced stimuli-sensors. The performance of these materials is dictated by the structural uniformity and molecular alignment of the inner core, and there has been limited progress in developing experimental guidelines for producing uniform and stable fibers, mainly due to the difficulty in nondestructive visualization of the internal core morphology. Despite the advancements in coaxial liquid crystal (LC) fibers, still there remains a need for a systematic nondestructive characterization of microscopic and macroscopic core morphology. In this study, we address this gap by introducing a strategic methodology that establishes LC fiber electrospinning techniques by utilizing LCs as optically anisotropic and self-reporting core materials. The intrinsic birefringence of the LC exhibits as vivid interference colors under polarized light microscopy, enabling direct visualization of the core uniformity. The observed morphological transitions are further rationalized by the Plateau–Rayleigh instability (PRI) model, providing a theoretical basis for understanding fiber formation dynamics. Based on this diagnostic capability, we systematically established a regime map for categorizing the morphological evolution of the fibers as a function of processing parameters. Furthermore, we demonstrate structural color induced by a cholesteric liquid crystal (CLC) phase so that the coaxial fibers can serve as a macroscopic quality control indicator with the naked eye. The methodology and findings presented here can offer practical guidelines for the fabrication of stable core–shell fibers with microscopic and macroscopic quality control.