Equilibrium Constants and Activation Rate Coefficients for Atom Transfer Radical Polymerizations at Pressures up to 2 500 Bar

Abstract

Equilibrium constants, K(ATRP), and activation rate coefficients, k(act), have been measured up to 2 500 bar and used for estimating reaction volumes, Delta V(R), and activation volumes, Delta V(act)(double dagger), respectively. Quantitative analysis of binary copper-ligand-alkyl bromide initiator systems, without monomer being present, has been carried out in a solution of acetonitrile by high-pressure online-FT-NIR/VIS spectroscopic monitoring of the Cu(II) ligand species. The numbers for Delta V(R) and Delta V(act)(double dagger) are close to each other and reflect the characteristics of ligand complexation. Whereas Delta V(R) is almost insensitive to the type of initiator, the absolute K(ATRP) clearly depends on this alkyl bromide species.