POLYMERIZATION OF CYCLIC MONOMERS .2. SYNTHESIS AND RADICAL POLYMERIZATION OF VINYLCYCLOPROPANES

New 1,1-disubstituted 2-vinylcyclopropanes were synthesized by reactio n of the corresponding malonyl diesters with trans-1,4-dibromo-2-buten e and of sodium hydride. The structure of the 2-vinylcyclopropanes cou ld be confirmed by elemental analysis, IR, H-1 NMR and C-13 NMR spectr oscopy. Radical polymerization of the 2-vinylcyclopropanes in bulk wit h 2,2'-azoisobutyronitrile (AIBN) and di-tert-butyl peroxide (DtBPO), respectively, gives transparent polymers. In case of the liquid monome rs, the polymerization is accompanied by negative volume changes. Spec troscopic investigations show that 2-vinylcyclopropanes primarily unde rgo opening of the cyclopropane ring forming an 1,5-addition polymer.