THERMODYNAMIC RECYCLING - ON RING-OPENING POLYMERIZATION AND RING-CLOSING DEPOLYMERIZATION

The ring-opening polymerization of various cyclic monomers has been ex tensively investigated in the past, e.g., the cationic polymerization of tetrahydrofuran, the anionic polymerization of epsilon-caprolactone , the metathesis polymerization of cycloalkenes, and the anionic or ca tionic polymerization of cyclohexamethyltrisiloxane and cyclooctamethy ltetrasiloxane. In conjunction with ring-opening polymerization, monom er-polymer equilibrium (ceiling temperature) and/or the formation of a ring-chain equilibrium have also been studied. In the last few years we have studied extensively the anionic ring-opening polymerization an d copolymerization of cyclic carbonates, the monomers mostly being pro vided by depolymerization of the polymers which were obtained by poly- condensation polymerization. This fact has led to the development of a new polymer recycling concept by depolymerization and repolymerizatio n, which we call thermodynamic recycling.