Microstructure and tacticity in radical copolymerization II Stereochemical configuration of styrene‐methyl methacrylate copolymers synthesized in solution

Abstract

The composition and stereochemical configuration of methyl methacrylate‐styrene copolymers obtained in benzene, chlorobenzene and benzonitrile has been evaluated by 1H‐NMR spectroscopy. The methyl methacrylate centered triad fractions in the copolymers have been calculated on the basis of the previously reported methoxy signal assignments. The results obtained are discussed taking into consideration the variation in the polarity of solvents; they make it possible to state that the presence of solvents not only affects the kinetic parameters but also changes the composition and the stereochemical configuration of monomer sequences in the copolymers.

Solvent effects on the free-radical copolymerization of styrene with butyl acrylate. I. Monomer reactivity ratios

“…In addition to Ito and Otsu's work,1 solvent effects on the free‐radical copolymerization of S/MMA have been reported by Bonta et al4 and by our group 5, 6. Our results subsequently were reanalyzed in publications by Davis7 and by Klumperman and O'Driscoll 8.…”

“…As has been previously stated, in the copolymerization of S/MMA, a decrease of the apparent reactivity ratio of S and an increase of the apparent reactivity ratio of MMA with the increase of the solvent polarity were observed 5. Furthermore, Davis7 reanalyzed the microstructure data previously published6 for this system and claimed that the bootstrap model was operative in the copolymerization of S/MMA in benzene, chlorobenzene, and benzonitrile. Considering that the bootstrap model holds in both systems (S/BA and S/MMA) and also considering the structural similarity between BA and MMA and the quite similar dipole moment of both monomers (MMA = 1.67 D, BA = 1.93 D), we compared the different influences of the solvents in their behavior.…”