Molecular dynamics simulations of liquid crystal molecules at an air-water interface

Molecular dynamics simulations were done for terminally alkyl and alkoxy substituted azobenzene liquid crystal (LC) molecules at an air-water interface using realistic (LC and water) molecular models. The simulation result were compared with those of a corresponding amphiphilic modification, i.e. terminal omega-carboxyalkoxy substituted azobenzene. Comparison with a LC with a different mesogen core, phenylpyrimidine, was also made. The interaction energetics were found to be more or less similar both in the alkyl and alkoxy terminated azobenzene and its amphiphilic modification, i.e. cohesive energy dominated over adhesive energy. In contrast, a large difference was found between alkyl and alkoxy terminated azobenzene and phenylpyrimidine LCs; cohesive and adhesive energy contributions were competitive in the latter molecule.