Colloidal science has long been intrigued by the prospect of self-assembly of materials. The
orientational order of the rod-shaped molecules within nematic liquid crystals (LCs) gives them
particularly strong potential as colloidal hosts due to the interactions between the LC and colloidal
particles at surfaces between the two. Depending on the boundary conditions (BCs) at these surfaces,
a variety of topological defects can arise, creating particles which affect a uniform LC field
similarly to how electrostatic multipoles affect a uniform electric field. However, although elastic
dipoles, quadrupoles, and hexadecapoles have all been previously reported, no such examples of
octupoles have been created thus far. Here we show that glycerol droplets doped with specific concentrations
of certain surfactants can be dispersed within both 4-Cyano-40-pentylbiphenyl (5CB)
and ZLI-2806 nematic liquid crystals to reliably produce elastic octupoles containing one “boojum”
and one “Saturn ring” topological defect. The resulting elastic multipole has mixed BCs and
is an intermediate state in the transition from completely planar BCs in the elastic quadrupole with
boojums and the completely homeotropic BCs in the elastic dipole with a hedgehog defect. The
results from this work provide an additional building block in colloidal self-assembly.
