Atom transfer radical polymerization of isobornyl acrylate: A kinetic modeling study

A detailed kinetic modeling study of the atom transfer radical polymerization (ATRP) of isobornyl acrylate (iBoA) is presented. This study combines a detailed reaction scheme with a systematic approach to account for diffusional limitations. Calculated values for diffusion coefficients and the Williams-Landel-Ferry parameters for poly(iBoA) are based on rheological measurements. A good agreement with experimental data is obtained for the polymerization rate, average chain length, and polydispersity index in conditions ranging from 323 to 348 K for targeted chain lengths varying from 50 to 100 and initial activator/deactivator concentrations between 10-50/0-2.5 mol m^-3. In these conditions, βC-scission reactions are insignificant and backbiting reactions result in a slight decrease of the polymerization rate and level of control at high conversions only. Termination is subject to diffusional limitations during the whole ATRP, while diffusional limitations on deactivation cannot be neglected at higher conversion. Diffusional limitations are shown to be codetermined by the evolution of the chain length distribution of both the end-chain and mid-chain macromolecular species.