The persistent radical effect in nitroxide mediated polymerization: Experimental validity

The free-radical polymerization of styrene has been studied at 123 degreesC in the presence of a betaphosphonylated alkoxyamine (diethyl[(1,1-dimethyl -ethyl)(1-phenylethoxy)amino]-2,2-dimethylpropyl phosphonate) (styryl-DEPN) . The persistent radical effect is undoubtedly observed experimentally unti l the effect of viscosity on the rate constant of termination is no longer negligible. The kinetic laws of the persistent radical effect allow us to c alculate the pseudo equilibrium constant of dissociation/combination betwee n dormant and active species K-polystyryl-DEPN = 6.1 x 10(-9) mol.L-1 at 12 3 degreesC. We have verified the reliability of this constant by computer s imulation in comparison with the experimental data.