The influence of molecular weight on the reactivity of a vinylbenzyl ether macromonomer of poly(2,6‐dimethyl‐1,4‐phenylene oxide)

The synthesis of a series of vinylbenzyl ether macromonomers of poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO–VBE) with number average molecular weights between 1,000 and 27,000 and narrow molecular weight distribution is presented. The reactivity ratio r 1 was determined for the comonomer pairs methyl methacrylate (MMA) and butyl methacrylate (BMA), respectively ( M 1 ), and PPO–VBE ( M 2 ) over the entire range of molecular weights of the macromonomer. r 1 was determined by the single experiment intergrated equation. Since both the monomer and macromonomer present an induction period, it has been shown that the determination of r 1 from one single point experiment is not correct. Accurate r 1 values can be obtained from one single copolymerization experiment only when the comonomer conversions are determined at several different reaction times. The macromonomer reactivity (1/ r 1 ) increases with its molecular weight up to about 5,000–7,000. Above these values its reactivity decreases. An attempt to explain this behavior based on the kinetic excluded free volume effect is presented.