Abstract
The influence of the total monomers concentration and of the copolymerization solvent on the reactivity ratio, r~1~, of methyl methacrylate (MMA) (M~1~) ω‐(p‐vinylbenzyl ether) macromonomer of poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO–VBE) (M~2~) monomer pair was investigated. For two different molecular weights of PPO‐VBE macromonomers: M~n~ = 15,200 and M~n~ = 5,100, the determined reactivity ratio, r~1~, decreases with the increase in macromonomer concentration. Therefore the reactivity of the macromonomer, 1/r~1~, follows the opposite trend. The influence of monomers concentration on r~1~ is higher for higher molecular weight macromonomers. The nature of polymerization solvent also affects the value of reactivity ratio, r~1~. Micelle formation was demonstrated by ^1^H‐NMR spectroscopy performed on the resulting graft copolymers in different solvent mixtures. An attempt to explain the observed concentration and solvent effects based on the partition of comonomer concentrations between the bulk of solvent and around the growing chain is presented. Based on this explanation, the determined r~1~ represents a product of the partition coefficient, k, and the true reactivity ratio, r~1~^0^.