Evidence of surface segregation in the organization of metallic nanoparticles dispersed in a cholesteric liquid crystal

Platinum nanoparticles dispersed in a cholesteric liquid crystal can form periodic ribbons which mimic the well-known fingerprint texture. The distance between ribbons is directly correlated to the helical pitch and therefore to the molecular chirality. Here we show how the particles are organized in volume by transmission electron microscopy investigations of cross-sections. A selective segregation takes place at the periphery of the anisotropic film and the particle ordering is localized close to the film-air interface. Potential applications of these results to build periodic ribbon-like patterns of nanoparticles on various substrates are emphasized.