• Bourgerette, Christian
• Mitov, Michel
• Guerville, François De

Abstract

Metallic nanoparticles dispersed in a cholesteric liquid crystal can order in accordance with the helical structure of the chiral phase. Since the liquid crystals we used have a glassy state, the nanostructures may be examined by transmission electron microscopy. The platinum nanoparticles form periodic ribbons which mimic the well-known fingerprint cholesteric texture. The particles do not decorate the pristine texture but create a novel structure with a larger periodicity. The distance between the ribbons is directly correlated to the helical pitch which therefore becomes a simple control parameter to tune the structuring of nanoparticles. Investigations of cross-sections show how the particles are arranged in the volume; a selective segregation proceeds at the periphery of the film and the particle ordering is localized close to the film–air interface. On the fingerprint patterning of nanoparticles, we do an analogy with the positive staining of polymer films with heavy-metal-containing compounds for transmission electron microscopy investigations and we discuss the accumulation of particles in the sites with the highest energy of director distortions.

Topics

• nanoparticle
• impedance spectroscopy
• compound
• phase
• Platinum
• transmission electron microscopy
• texture
• liquid crystal