IMAGE: This figure shows the emulsion interfacial polymerization mechanism for producing Janus particles.
Credit: Dr. FAN Junbing

An article entitled “A general strategy to synthesize chemically and topologically anisotropic Janus particles” was recently published in the journal Science Advances.  Researchers from the Technical Institute of Physics and Chemistry of the Chinese Academy of Sciences recently developed a general emulsion interfacial polymerization approach to synthesizing a large variety of Janus particles with controllable topological and chemical anisotropy.   With this technique the researchers produced a particle nucleus inside oil droplets and the particle nucleus naturally moves toward the oil/water interface.  The  general emulsion interfacial polymerization approach, overcomes the limitation of surface tension.  Surface tension usually leads to the production of spherical particles , posing a challenge for fine-tuning the topology and chemistry of particles.


The researchers’ emulsion polymerization approach can produce Janus particles with anisotropic topologies and amphiphilicity (Fig.2 above).  The strategy produced approximately 5 g of uniform Janus particles in one batch, providing an effective way to synthesize Janus particles on a large scale.   Their emulsion interfacial polymerization strategy can be used for polymerizing various vinyl monomers, including positively charged, neutrally charged and negatively charged ones, greatly enriching the community of Janus particles.  The large scale production creates new opportunities in a wide variety of applications, ranging from the environment to health, especially in those involving oil-water separation and biological detection.


The “God particle” is the nickname of a subatomic particle called the Higgs boson. While different subatomic particles are responsible for giving matter different properties, the Higgs boson, or “God particle,” is believed to be the particle which gives mass to matter.  Janus particles are named after the Roman god Janus, who had two faces. The particles are asymmetrical and contain different chemical groups on their various surfaces. From a chemical point of view, it is not easy to make particles of this kind, as the chemical groups in a solution have a tendency to spread uniformly across a surface, rather than settle conveniently on one half of the particle.