Intermediate Radical Termination Theory in Elucidation of RAFT Kinetics and Comparison to Experimental Data

In current work a comprehensive mechanism based on intermediate radical termination theory is assumed for RAFT polymerization of styrene over cumyl dithiobenzoate as RAFT agent. Rate constants for addition (ka) and fragmentation reactions (kf) are set to 6×106 and 5×104 respectively, which lead to an equilibrium constant value of K = ka/kf = 1.2 x 102. Moment equations method was used to model this mechanism and the results were compared to experimental data to verify modeling. The effects of changing RAFT agent concentration on conversion, molecular weight and polydispersity index of the final product were investigated through the modeling. According to the results, the likelihood of living polymerization increases with raising RAFT agent concentration which leads to linearity of conversion and molecular weight curves and therefore lowering the polydispersity index and narrowing the molecular weight distribution.