2. Radical ring-opening polymerization

2.1 Concept and different monomer families

Although traditional vinyl monomers are polymerized by chain addition with the creation of carbon-carbon bonds, some cyclic monomers bearing vinyl/exomethylene groups or equivalents can be polymerized free-radically by a ring-opening mechanism. Polymerization of cyclic monomers bearing a vinyl group leads to polymers with a double bond in the polymer backbone, while polymerization of cyclic compounds with an exomethylene group produces polymers with a pendant double bond. The functionality (e.g. ketone, ester, amide, thioester, etc.) derives from the nature of the W and Z atoms in the α position of the initial C=Y double bond (figure