(546e) Droplet Impact-Induced Chemical Release from Liquid Crystal Films

Thermotropic liquid crystals (LCs) are a highly promising class of anisotropic liquids, displaying a remarkably diverse range of colloidal and interfacial phenomena with unprecedented complexities and functionalities. For example, LC films submerged in water have demonstrated the ability to optically respond to chemicals or external fields and release chemicals following an LC phase transition. These earlier findings lead us to hypothesize that the inherent stimuli-responsiveness of LCs can facilitate the creation of a new type of functional surfaces, which can programmably feed chemicals to droplets. Recently, we developed a porous LC polymeric network to stabilize LC films against water droplet-induced dewetting, enabling chemical release to water droplets on an LC surface platform (without droplet pinning) through various environmental cues, such as thermal, optical, and chemical stimuli.

In this study, we introduce a novel chemical release method using droplet impact. Our preliminary results have indicated that the release of chemicals pre-encapsulated in the LC film strongly depends on the Weber number of the impacting droplet. Specifically, at room temperature, the chemical release from the nematic phase 5CB LC film only occurs above a threshold Weber number, while no release is observed below this threshold. Overall, the progress reported in this study provides design principles for novel stimuli-responsive chemical release, presenting an opportunity to achieve unprecedented levels of controllability and responsiveness for use in additive manufacturing.