Polymerization of hetero‐and vinyl‐cyclic monomers initiated by donor‐acceptor interaction

Abstract

An ever growing interest of research workers in donor-acceptor (DA) interactions of all kinds is characteristic of the present development of chemistry and physical chemistry of polymers. Our attention has been attracted to the reactions of heterocycle opening under the action of DA complexes with the formation of linear polymers in whose chains charge transfer complexes (CTC) are left and also to the possibility of using DA complexes for involving monomers which would not polymerize according to the free-radical mechanism in radical polymerization.We were the first to find that the interaction of the S-, 0-, and N-containing heterocyclic monomers, typical n-donors, with organic electron acceptors leads to the n n-type CTC formation initiating the polymerization process.1-5The formation of DA complexes is evidenced by the appearance of new absorption bands which are absent in the spectra of the individual components in the UV or visible part of the spectrum. The new absorption bands are due to the electron transfer being shifted to the longwave region as the electron affinity of acceptor increases. This can be seen from Table I through an example of various cyclic sulphides : 3-membered propylenesulphide (PS), Cmembered trimethylenesulphide (TMS), and 5-membered tetrahydrothiophene and thiophene. The data given show that the optical density maximum of CTC of tetranitromethane and tetracyanoethylene with TMS is shifted to the longwave region as compared to the analogous complexes of PS, tetrahydrothiophene, and thiophene. This fact shows that the donor ability of the 4membered S-containing cycle is higher than that of 3-and 5-membered ones.The CTC formation by the interaction of cyclic sulphides with organic electron acceptors such as maleic anhydride (MA), trinitrobenzene (TNB), tetranitromethane (TNM), tetracyanoquinonedimethane (TCQDM), and tetracyanoethylene (TCE) causes the shift of the electron density on the sulphur atom and additional polarization of the C = S bond. This facilitates the 95 96 STOTSKAYA ET AL.