Chemoselective Polymerizations from Mixtures of Epoxide, Lactone, Anhydride, and Carbon Dioxide

Abstract

Controlling polymer composition starting from mixtures of monomers is an important, but rarely achieved, target. Here a single switchable catalyst for both ring-opening polymerization (ROP) of lactones and ring-opening copolymerization (ROCOP) of epoxides, anhydrides, and CO2 is investigated, using both experimental and theoretical methods. Different combinations of four model monomers-ε-caprolactone, cyclohexene oxide, phthalic anhydride, and carbon dioxide-are investigated using a single dizinc catalyst. The catalyst switches between the distinct polymerization cycles and shows high monomer selectivity, resulting in block sequence control and predictable compositions (esters and carbonates) in the polymer chain. The understanding gained of the orthogonal reactivity of monomers, specifically controlled by the nature of the metal-chain end group, opens the way to engineer polymer block sequences.

Switching from Controlled Ring-Opening Polymerization (cROP) to Controlled Ring-Closing Depolymerization (cRCDP) by Adjusting the Reaction Parameters That Determine the Ceiling Temperature

“…5−7 These polymers, which are most often obtained by ring-opening polymerization of the respective cyclic monomers, allow, through different addition schemes or inherent reactivity behavior, the construction of refined macromolecular architectural features. 8−10 This enables control of many polymer properties, such as degradation, 11−13 mechanical performance, 11,14 and the placement of functional groups along the polymer chain. 15,16 …”

‘Switch’ catalysis: from monomer mixtures to sequence-controlled block copolymers

“…The fundamental basis for 'Switch' catalysis was further investigated using DFT [32]. The entire cycle of monomer additions was explored using catalyst 1 and the differences between the relative barriers and stabilities of intermediates compared.…”

Functional Polycarbonates from Carbon Dioxide and Tailored Epoxide Monomers: Degradable Materials and Their Application Potential

“…The synthesis relies on switching of the polymerization process: when the autoclave contained CO 2 , only the epoxide reacted, and with nitrogen only the lactone was polymerized using a dizinc catalyst . They expanded this approach using additionally phthalic anhydride in a further work and investigated it with experimental and theoretical methods . Rieger and co‐workers also recently developed a one‐pot approach for, AB, ABA, and statistical terpolymers from β‐butyrolactone, CHO and CO 2 by varying the amount of CO 2 during the reaction (without CO 2 , 3 bar CO 2 , and 40 bar CO 2 ) .…”