Controlling topological defects and liquid crystal (LC) phases in three dimensions (3D) is of particular interest to the generation of blue phases and other topologically structured materials, which will lead to possibly disruptive display technologies. However, it has been experimentally challenging to realize the 3D topology. Here, we investigate formation of 3D geometries of smectic-A (SmA) LCs guided by nanoparticle assembly and the underlying substrate. When the surface chemistry and substrate geometry (here 1D channels) promoted planar alignment of LC molecules, hexagonal arrays of toric focal conic domains (TFCDs) were formed due to competing effects of planar anchoring at the LC/substrate interface and homeotropic anchoring at the LC/air interface. When the silica nanoparticle surface was functionalized by fluorosilane, they spontaneously phase separated from the SmA LCs and aggregated only in the TFCDs at the LC/air interface, which in turn altered the LC anchoring to planar conditions in these regions. In contrast, unmodified silica particles were found embedded within LC layers, breaking the ordered symmetry of SmA film. By imposing nanoparticles with variable surface chemistry, we added new dimensions to control geometries of smectic LCs in 3D, which could shed new light on ways to engineer functional complex structures.

3D topology of smectic liquid crystals guided by nanoparticle assembly and a patterned substrate

245th National Meeting (2013)

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