Continuous Synthesis of Star-Shaped Block Copolymers through Successive Photocontrolled O-ATRP in Flow Tube Reactors

In this work, star-shaped block copolymers are prepared in flow tube reactors made of Teflon at room temperature via photocontrolled organocatalyzed atom transfer radical polymerization (O-ATRP) by a core-first strategy. 1,2,3,5-Tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN), which has a strong reduction potential, is used as the organic photocatalyst. Methyl methacrylate (MMA) is selected as the monomer to establish the first block, and the polymerization rate constant of MMA in the flow reactor is 1.44 times higher than that in the batch reactor. Meanwhile, the activity and spatiotemporal control of the polymerization are validated by kinetics investigation and photo on/off experiments. In addition, in situ chain extension of the freshly prepared poly(methyl methacrylate) (PMMA) in a flow manner is achieved by secondary tandem connection of multiple microtubes using a metering pump, and star-shaped block copolymers with different block ratios can be prepared in continuous flow reactors by setting different retention times. This method simplifies the operation process while improving efficiency, which is conducive to scaling up production.