A small-angle X-ray scattering study of nanoparticle assembly in an aligned nematic liquid crystal

Abstract

The assembly of colloidal particles in a nematic liquid crystal has been investigated using small-angle X-ray scattering. The structure and orientation of nanoparticle assemblies in bulk samples of aligned nematic liquid crystal have been determined. The method offers some advantages over optical microscopy, which is usually restricted to investigations of thin cells and micron-sized particles. The scattering from chains of particles has been calculated, and comparison with experimental results has shown that suspensions of 48 and 105 nm diameter silica nanoparticles formed highly ordered structures perpendicular to the liquid crystal director, consistent with quadrupolar defect-induced assembly.

Keywords:

• small-angle X-ray scattering
• alignment
• defects
• liquid crystal
• nanoparticles

Acknowledgements

We are grateful to Diamond (experiment SM8982) for beamtime and Dr Olga Shebanova for her assistance during the experiment. We also thank Natasha Bennett for her assistance in performing the scanning electron microscopy measurements.