Facile synthesis of micron-size Janus particles by one-pot suspension polymerization and their functional modification

The design and fabrication of micron-size Janus particles (JPs) with new structures and properties are still great challenges although various methods have been used to synthesize nano-size JPs. Therefore, it is of great significance to develop a high-efficiency preparation and facile functionalization technology for micron-size JPs. Herein, we developed a facile one-pot suspension polymerization to synthesize micron-size JPs which can be easily further functionalized for the first time. The key of this method is to use an amphiphilic block copolymer prepared by atom transfer radical polymerization (ATRP) as the macromolecular surfactant (MS). On the one hand, within a certain hydrophile-lipophile balance (HLB) range, the reversed micelles in the oil phase were used to absorb water and expand, then aggregate and fuse, and finally phase separate from the oil phase to form JPs. On the other hand, the MS prepared by ATRP has an initiating group at the MS chain end, which is exposed on one side on the surface of the JPs, so that the facile functionalization of the JPs can be further realized by the ATRP strategy.