Illumination-Induced Solute Uptake in Liquid Crystal Droplets: The Role of 5CB Excimers

This study investigates the phenomenon of solute uptake into liquid crystal (LC) droplets, illuminated under UV light, focusing on the role of 4-cyano-4'-pentylbiphenyl (5CB) excimer formation in this process. Our experiments reveal that upon UV irradiation solute molecules, including surfactants and dyes, are actively drawn into the LC phase, forming distinctive assemblies within the droplets. Contrary to previous assumptions that the uptake was driven by the direct photoreactivity of the solutes, we found that the 5CB excimer state plays a critical role for this phenomenon. This state, identifiable through its photoluminescence yet invisible to conventional UV/vis absorption spectroscopy, correlates strongly with the molecular assembly process inside of the droplets. Notably, this mechanism operates across a broad spectrum of solute molecules, from simple surfactants like sodium dodecyl sulfate (SDS) to complex dyes, demonstrating the generality of the excimer-induced solute uptake. The excimer's role is pivotal, facilitating solute incorporation without reliance on their inherent light-absorbing properties. This insight not only advances our understanding of LC behavior under light irradiation but also opens new avenues for designing light-responsive materials.