First principles modelling of free-radical polymerisation kinetics

Computational quantum chemistry can make valuable contributions to modelling and improving free radical polymerisation. At a microscopic level, it can assist in establishing reaction mechanisms and structure-reactivity trends; at a macroscopic level it can be used in the design and parameterisation of accurate kinetic models for process optimisation and control. This review outlines and critically evaluates various methodological approaches that have been employed in first principles prediction of rate coefficients in free radical polymerisation, examining in turn the choice of chemical model, electronic structure method, solvation modelling and the coupled issues of partition function evaluation and conformational analysis. It is shown that accurate and reliable predictions are possible but only if necessary precautions are taken into account. The practical value of accurate computational modelling of radical polymerisation kinetics is then illustrated through three representative case studies from the literature in which theory has been used to develop accurate kinetic models: free radical copolymerisation kinetics; defect structure formation in radical suspension polymerisation of vinyl chloride; and reversible addition fragmentation chain transfer polymerisation.