Recent Progresson Preparation of Amphiphilic Janus particles

Janus comes from the Roman mythology of the double god. In his Nobel Prize acceptance speech in 1991, De Gennes first proposed the concept of Janus particles, which is used to describe two sides of the same particle having different chemical composition and/or morphological structure. Janus particle surfaces can have different hydrophilic and hydrophobic properties at the same time. Similar to traditional molecular surfactants, Janus particles can spontaneously adsorb onto the fluid interface, thus effectively stabilizing the multiphase system (emulsion or foam). Janus particles of various forms can be obtained according to different preparation processes. The organic polymer Janus particles mainly include spherical, disk, column and hollow shape. Due to the asymmetry of morphology and chemical composition of Janus particles, the conventional methods for preparing uniformly modified particles, such as suspension polymerization and emulsion polymerization, cannot be generally adopted. Over the past two decades, many methods for the preparation of Janus particles have been developed, including interface protection modification, phase separation and self-assembly of block copolymer.