Structure of multi-component colloidal lattices at oil-water interfaces.

We have successfully assembled two-component S-PS/AS-PS (sulfate-treated polystyrene/aldehyde sulfate-treated polystyrene) and three-component S-PS/AS-PS/C-PS (sulfate-treated polystyrene/aldehyde sulfate-treated polystyrene/carboxylate-treated polystyrene) colloidal lattices at poly(dimethylsiloxane)-water interfaces. The colloidal particles assemble into long-range-ordered structure and oscillate around their equilibrium positions. Different types of particles distribute randomly in the lattice with no obvious phase separation. In the two-component colloidal lattices, the S-PS particles form mostly sixfold lattice sites, whereas the AS-PS particles largely form fivefold defect sites. The calculated attractive capillary force is stronger for the AS-PS particles, which likely explains their tendency to aggregate compared to the S-PS particles. In addition, we have performed total force calculation and extrapolated the surface charge densities of the particles in the oil phase.