A further inspection of the literature-based r values highlights that for the comonomer pair acrylate-methacrylate most emphasis has been on MMA/n-butyl acrylate (BA) and less on MMA/MA. More in detail, rMMA values between 1.93 and 2.15, and rBA values between 0.31-0.4 have been determined, varying the nature of the solvent and the temperature, and consistent with a tertiary radical being more stable than a secondary one and e.g. the results of Penlidis et al. focusing on terpolymerization between triisopropylsilyl acrylate, MA, and BA.