Polymeric Janus Particles with Hierarchical Structures

Janus colloidal particles with hierarchical structures are generated by phase separation of diblock copolymer polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) and homopolymer poly(methyl methacrylate) (PMMA) binary blends in confined geometry. The dependence of their morphology on the copolymer composition, solvent selectivity, particle size, and polymer/aqueous solution interfacial property was investigated. By varying the particle/aqueous solution interfacial property alternately, the Janus particles exhibited a reversible morphological transformation under solvent-adsorption annealing process. In addition, by introducing 3-n-pentadecyphenol (PDP) which can hydrogen bond with P4VP to form supramolecules, the structure of the Janus particles can be well tuned. Furthermore, due to the complexation of pyridine unit with Au precursor, composite Janus particles with Au nanoparticles selectively incorporated in P4VP microdomains can be easily manipulated.