Copolymerization of Styrene with Isobutyl Vinyl Ether by Radiation

Abstract

In order to elucidate the reason for the considerable difference in the activation energies for the propagation of styrene and isobutyl vinyl ether (IBVE), radiation-induced copolymerization of styrene with IBVE was carried out in bulk at 0 and 40°C. The obtained copolymerization ratios are (M1=styrene) 0°C r1=0.46±0.05, r2=9±140°C r1=0.20±0.06, r2=11±3 From the temperature dependences of r1 and r2, mutual polymerization rate constants, k12 and k21, and their activation energies, Ep were evaluated assuming both kp and Ep values obtained in bulk polymerizations of styrene and IBVE are constant also in the copolymerization systems studied. It is found that in the reactivity of cation, styrene is greater than IBVE, however, the relation is reversed in relative reactivity of monomer.From the comparison with Ep values in other free cationic polymerization systems, Ep value for IBVE cation is considered to be in some respects extraordinary high, as well as its frequency factor. This is presumably explained in terms of the solvation of IBVE to cation and possibly, resonance stabilization of IBVE cation end.