Vinyl polymerization. LXXIII. Polymerization and copolymerization of bornyl or isobornyl methacrylate

A study of the radical polymerization and copolymerization of bornyl (endo‐bornyl) methacrylate (BMA) or isobornyl (exo‐bornyl) methacrylate (IBMA) with styrene has been made at 50–70°C. BMA polymerized faster than IBMA, and the polymer obtained from BMA (PBMA) was higher in molecular weight than that from IBMA (PIBMA). From the results of the detailed kinetic investigation, it was found that the values of activation energy, activation entropy, and Q and e for BMA were nearly the same as those for methyl methacrylate (MMA), but those for IBMA differed somewhat in activation entropy and Q value from those for MMA. It was also found that PIBMA could be easily acetolyzed to give an atactic polymethacrylic acid, while PBMA was stable to acetolysis as well as PMMA. Accordingly, it might be concluded that endobornyl group in BMA showed the same electric and steric effects on the rate and the reactivity for radical polymerization to methyl group in MMA, while the exo‐bornyl group showed a somewhat increased steric effect.