Termination and Transfer Kinetics of Sodium Acrylate Polymerization in Aqueous Solution

Rate coefficients of termination and backbiting of secondary chain-end radicals (SPRs) and of propagation of tertiary midchain radicals (MCRs) have been measured for 20 wt % sodium acrylate (NaA), i.e., fully ionized acrylic acid, in aqueous solution at temperatures from 0 to 60 degrees C. Highly time-resolved SPR and MCR concentration vs time traces, measured after applying an intense laser pulse at t = 0, were analyzed via PREDICI simulation. Cross- and homotermination of MCRs have no major impact on the kinetics. The termination rate coefficient of SPRs in dilute solution of NaA is by more than 1 order of magnitude below the associated value of nonionized AA. The reduction of backbiting rate coefficient upon full ionization is close to the one associated with enhancing the concentration of nonionized AA from 10 to 50 wt %.