Polyelectrolyte-mediated self-assembly of polystyrene nano-spheres into honeycomb-patterned microbeads

Abstract

Honeycomb-patterned polystyrene (PS) microbeads were prepared through the self-assembly of PS nano-spheres induced by solvent evaporation in the presence of a cationic polyelectrolyte – poly(diallyl dimethyl ammonium chloride) (PDAD). Irregular particles were synthesised when the suspension was added with a single anionic electrolyte – sodium dodecyl sulphate (SDS), and large beads without regular patterns were obtained with the addition of both of SDS and PDAD. The building blocks – PS nano-spheres were synthesised by a nano-emulsion method using SDS as the emulsifier. The surfaces of the synthetic PS nano-spheres were negatively charged by sulphate radicals of SDS. The interaction between positively charged PDAD and negatively charged sulphate radicals of PS nano-spheres plays the crucial role in the formation of honeycomb patterns. Also, the honeycomb-patterned PS microbeads have a potential application in acid-sensitive drug delivery system.