Continuous-flow RAFT copolymerization of styrene and maleic anhydride: acceleration of reaction and effect of polymerization conditions on reaction kinetics

Reversible addition-fragmentation chain transfer radical polymerization of styrene and maleic anhydride was successfully performed in continuous-flow microreactor. Results of the structural characterization showed that the obtained styrene-maleic anhydride (SMA) copolymers possessed controlled molecular weight, low dispersity and alternating structures. Subsequently, effects of the polymerization conditions, including reaction pressure, temperature, feed flowrate and tube length, on the polymerization kinetics and molecular structure of the SMA copolymers were investigated in detail. It was found that the reaction rate was increased as the reaction temperature increased within certain limits, as well as the feed flowrate due to the increased mass and heat transfer efficiency. Besides, first-order kinetics of the polymerization was observed when the reaction times were adjusted by only changing the tube length. Good stability was exhibited when the reaction conducted continuously for 10 h. This approach can reduce the reaction time significantly from several hours to about half an hour.