Molecular tilt near nanoparticles in the smectic-A phase of a de Vries liquid-crystalline compound

We show how the inclusions of the nanoparticles or the clusters of nanoparticles in the liquid-crystalline smectic-A phase lead to layer deformations and may create a tilt in their vicinity, thus inducing locally a smectic-A-smectic-C transition. We have studied a freestanding film of "de Vries" compound, which exhibits the smectic-A-smectic-C transition without layer shrinkage, mixed with functionalized gold nanoparticles. The tilt induced by nanoparticle clusters, which decorate the edge dislocations, has been observed in the smectic-A phase. The tilt of liquid-crystal molecules near nanoparticles is a consequence of interaction of liquid-crystalline molecules with the surface of nanoparticles. The observed tilt may prove the concept of existence of a disordered tilt in the smectic-A phase of de Vries compounds. The tilt distribution near nanoparticles is discussed using both the smectic-A elasticity and local smectic-A-smectic-C transition.