Thermodynamic Recycling—On Ring-Opening Polymerization and Ring-Closing Depolymerization

Abstract

Abstract The ring-opening polymerization of various cyclic monomers has been extensively investigated in the past, e.g., the cationic polymerization of tetrahydrofuran, the anionic polymerization of ∊-caprolactone, the metathesis polymerization of cycloalkenes, and the anionic or cationic polymerization of cyclohexamethyltrisiloxane and cyclooctamethyltetrasiloxane. In conjunction with ring–opening polymerization, monomer–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 and copolymerization of cyclic carbonates, the monomers mostly being provided by depolymerization of the polymers which were obtained by polycondensation polymerization. This fact has led to the development of a new polymer recycling concept by depolymerization and repolymerization, which we call thermodynamic recycling.