The Mechanism and Thermodynamic Studies of CMRP: Different Control Mechanisms Demonstrated by CoII(TMP), CoII(salen*), and CoII(acac)2 Mediated Polymerization, and the Correlation of Reduction Potential, Equilibrium Constant, and Control Mechanism

Abstract

The mechanism study of cobalt mediated radical polymerization (CMRP) is performed with CoII(TMP), CoII(salen*), and CoII(acac)2 at 60 °C to demonstrate that the control of vinyl acetate radical polymerization is achieved via a degenerative transfer pathway when CoII(TMP) and CoII(salen*) are used but via a reversible termination process with equilibrium constant (Keq) equal to 1.4 × 106 m−1 when CoII(acac)2 is the mediator. Given by the measured Keq in CMRP with varied cobalt complexes and the reduction potential (E1/2) of the corresponding cobalt complexes, a linear correlation between log(Keq), and E1/2 is found and can be used to estimate the Keq of other CMRP systems. With the enriched database of Keq values, the control mechanisms of CMRP are quantitatively defined by CoII/CoIII equilibrium constant. The connection of reduction potential, equilibrium constant, and control mechanism would contribute to the in‐depth understanding of CMRP process. image