The optimization campaign yielded 89 data points containing information on the final monomer mole fractions in the feed (𝑓) as well as the final monomer mole fractions in the terpolymer (𝐹). Using these data points, one can calculate the ternary reactivity ratios 𝑟 𝑖𝑗 by setting up a system of Ordinary Differential Equations (ODEs). In this analysis, we modelled the terpolymerization via the Terminal Model 5 , which treats the chemical reactivity of the propagating chain as dependent only on the identity of the monomer unit at the growing end, and the monomer that it will react with. Therefore, in a ternary system, chemical equations describing the propagation can be written down in the general form: