title: Switching from Controlled Ring-Opening Polymerization (cROP) to Controlled Ring-Closing Depolymerization (cRCDP) by Adjusting the Reaction Parameters That Determine the Ceiling Temperature.
abstract: Full control over the ceiling temperature (Tc) enables a selective transition between the monomeric and polymeric state. This is exemplified by the conversion of the monomer 2-allyloxymethyl-2-ethyl-trimethylene carbonate (AOMEC) to poly(AOMEC) and back to AOMEC within 10 h by controlling the reaction from conditions that favor ring-opening polymerization (Tc> T0) (where T0is the reaction temperature) to conditions that favor ring-closing depolymerization (Tc< T0). The ring-closing depolymerization (RCDP) mirrors the polymerization behavior with a clear relation between the monomer concentration and the molecular weight of the polymer, indicating that RCDP occurs at the chain end. The Tcof the polymerization system is highly dependent on the nature of the solvent, for example, in toluene, the Tcof AOMEC is 234 °C and in acetonitrile Tc= 142 °C at the same initial monomer concentration of 2 M. The control over the monomer to polymer equilibrium sets new standards for the selective degradation of polymers, the controlled release of active components, monomer synthesis and material recycling. In particular, the knowledge of the monomer to polymer equilibrium of polymers in solution under selected environmental conditions is of paramount importance for in vivo applications, where the polymer chain is subjected to both high dilution and a high polarity medium in the presence of catalysts, that is, very different conditions from which the polymer was formed.
authors: Department of Fibre and Polymer Technology, KTH Royal Institute of Technology , SE-100 44, Stockholm, Sweden.
authors: Peter
authors: P
authors: Olsén
authors: Department of Fibre and Polymer Technology, KTH Royal Institute of Technology , SE-100 44, Stockholm, Sweden.
authors: Jenny
authors: J
authors: Undin
authors: Department of Fibre and Polymer Technology, KTH Royal Institute of Technology , SE-100 44, Stockholm, Sweden.
authors: Karin
authors: K
authors: Odelius
authors: Institute of Technical and Macromolecular Chemistry, RWTH Aachen University and DWI-Leibniz Institute for Interactive Materials , Forckenbeckstrasse 50, 52056 Aachen, Germany.
authors: Helmut
authors: H
authors: Keul
authors: Department of Fibre and Polymer Technology, KTH Royal Institute of Technology , SE-100 44, Stockholm, Sweden.
authors: Ann-Christine
authors: AC
authors: Albertsson
mesh_terms: D002384:Catalysis; D004146:Dioxanes / Q000737:chemistry*; D008970:Molecular Weight; D058105:Polymerization; D011108:Polymers / Q000737:chemistry*; D013696:Temperature
chemical_list: D004146:Dioxanes; D011108:Polymers; C443643:trimethylene carbonate