i,i , for termination of two radicals of chain length i are determined as a function of chain length by single-pulse PLP in conjunction with electron paramagnetic resonance spectroscopy (SP-PLP-EPR). The as-obtained data that allow for modeling PnMA polymerization kinetics and product properties at moderate degrees of monomer conversion are compared with reported data for several other alkyl methacrylates. A distinct family behavior of this group of monomers is seen.

Electron paramagnetic resonance (EPR) spectra of the ensemble of growing macroradicals are recorded during the radical copolymerization of styrene-d8 and methyl methacrylate (MMA) for various comonomer compositions and subsequently modeled by MATLAB in combination with EasySpin simulations. Fully deuterated styrene-d8 is used to simplify the EPR spectra and to allow a clear assignment of the EPR-signals to the two different terminal units. By that approach, the macroradical fraction having styrene-d8 as terminal unit, 𝚽 s , could directly be determined from the copolymerization spectra without concentration calibration. The so-obtained 𝚽 s values could not be described by the penultimate model using the literature-reported set of reactivity ratios. Consequently, 𝚽 s, the copolymer composition, and the overall propagation rate coefficient are adjusted in small steps simultaneously using Excel arriving at a new and more reliable set of reactivity ratios for the copolymerization of styrene and MMA.

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