Dynamics of ethyl cellulose nanoparticle self-assembly at the interface of a nematic liquid crystal droplet

Design and fabrication of many next-generation liquid crystal (LC)-based devices rely on nematic LC domains in the form of drops or emulsions. In addition to surfactants, solid nanoparticles may be used to stabilize LC-in-water Pickering emulsions, possibly adding new dimensions to device functionality. In this work we quantitatively study the adsorption of ethyl cellulose (EC) nanoparticles, as a colloid model system, on the 4-cyano-4'-pentylbiphenyl (5CB)-water interface via a series of dynamic interfacial tension measurements. It is found that the planar alignment of 5CB molecules at the interface with water is unaffected by particle adsorption, but a significant reduction of the interfacial tension over time occurs. It is also found that adsorption of EC nanoparticles to the LC-water interface is irreversible and results in close hexagonal packing. This study demonstrates a systematic approach to quantitatively investigate the effect of nanoparticles on the stabilization of LC emulsions.