Kinetics and electron spin resonance study of the radical polymerization ofn-butyl acrylate mediated by a nitroxide precursor:C-phenyl-N-tert-butylnitrone

The C-phenyl-N-tert-butylnitrone/azobisisobutyronitrile pair is able to impart control to the radical polymerization of n-butyl acrylate as long as a two-step process is implemented, that is, the prereaction of the nitrone and the initiator in toluene at 85 °C for 4 h followed by the addition and polymerization of n-butyl acrylate at 110 °C. The structure of the in situ formed nitroxide has been established from kinetic and electron spin resonance data. The key parameters (the dissociation rate constant, combination rate constant, and equilibrium constant) that govern the process have been evaluated. The equilibrium constant between the dormant and active species is close to 1.6 × 10−12 mol L−1 at 110 °C. The dissociation rate constant and the activation energy for the CON bond homolysis are 1.9 × 10−3 s−1 and 122 ± 15 kJ mol−1, respectively. The rate constant of recombination between the propagating radical and the nitroxide is as high as 1.2 × 109 L mol−1 s−1. Finally, well-defined poly(n-butyl acrylate)-b-polystyrene block copolymers have been successfully prepared. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6299–6311, 2006