Kinetic Study on Nitroxide-Mediated Free Radical Polymerization of tert-Butyl Acrylate

The kinetics of nitroxide-mediated free radical polymerization of tert-butyl acrylate (tBA) was studied. It was demonstrated that the polymerization rate can be increased by addition of a proper amount of a radical initiator, dicumyl peroxide (DCP), without causing any appreciable broadening of the polydispersity. The use of di-tert-butyl nitroxide (DBN) allowed the controlled polymerization of tBA to proceed at a lower temperature than the polymerization controlled by a TEMPO (2,2,6,6-tetramethylpiperidinyl-1-oxy) derivative, which was conducted by Georges et al. [Macromolecules 1996, 29, 8993]. The pseudo-first-order activation rate constant k_act of the poly(tBA)-DBN adduct was also determined by the GPC curve-resolution method to be 1.0 × 10^-3 s^-1 at 120°C, which indicates that the adduct experiences activation-deactivation cycles frequently enough to afford a low polydispersity. Nevertheless, the polydispersity markedly increased and the rate of polymerization decreased at later stages of polymerization due to the decomposition of the alkoxyamine and the subsequent hydrogen transfer.