RADICAL POLYMERIZATION REACTIVITY OF DIALKYL ITACONATES AND CHARACTERIZATION OF THEIR POLYMERS

Radical polymerizations and copolymerizations of dialkyl itaconates (DRI) having the same two ester alkyl groups were carried out in the presence of 2,2'-azobisisobutyronitrile as an initiator. The eighteen kinds of DRIs homopolymerized easily to give vinylidene-type polymers having molecular weights of 7000-1 10,000. The polymerization behaviour of DRIs, consisting of diisopropyl, dicyclohexyl and di-tert-butyl esters, was investigated kinetically. The polymerization reactivities of butyl (Bu) esters were found to be in the order: nBu congruent-to iBu > sBu > tBu, contrary to those for dialkyl fumarates (DRF) (nBu congruent-to iBu < sBu < tBu). The ESR spectra due to the propagating radical were observed in the radical polymerization of DRIs at 60-degrees, indicating that the bimolecular termination hardly occurs due to the 1,1-disubstituted structure similar to that of DRFs. From the results of radical copolymerizations of DRIs with styrene, the monomer reactivity ratios (r1, r2) and Q, e values for DRIs were determined. The relative reactivities of DRIs were found to be correlated with both polar and steric effects of the ester alkyl groups from the results of Taft's plot. The characterization of poly(DRIs) obtained was also investigated and discussed.