Electrochemically Switchable Ring-Opening Polymerization of Lactide and Cyclohexene Oxide

Abstract

An electrochemical method was developed for the redox switchable polymerization of lactide and cyclohexene oxide. Using a lithium reversible sacrificial electrode and a high surface area carbon working electrode, efficient transformation between formally iron(II) and iron(III) oxidation states of a bis(imino)pyridine iron alkoxide complex was possible, which led to the ability to activate the complex for ring opening polymerization reactions. In addition to serving as a redox trigger, an electrochemical toggle switch was developed in which the chemoselectivity for lactide and epoxide polymerization was altered in situ. These findings led to the synthesis of poly(lactic acid- b-cyclohexene oxide) block copolymers in which the sequence of monomers incorporated is controlled by the electrical potential applied.

Oxygen‐Triggered Switchable Polymerization for the One‐Pot Synthesis of CO2‐Based Block Copolymers from Monomer Mixtures

“…[5] Byers and co-workers demonstrated that controlling the oxidation state of Fe catalysts by redox or electrochemical triggers enabled the facile discrimination of lactide and epoxide in the ring-opening polymerization (ROP). [6] Long and co-workers have successfully tailored polyethylene branching with ar edox switch. [7] Recently,t he groups of Williams and Rieger achieved switchable ring-opening copolymerization (ROCOP)o fC O 2 /anhydrides/epoxides and ROPofcyclic esters by controlling the chemistry of the metal chain end group,thus demonstrating the possibility of switching the reactivity of as ingle-site catalyst between different polymerization mechanisms.…”

Controlling the Ring‐Opening Polymerization Process Using External Stimuli

“…In this sense, electrochemical control can serve as an attractive and alternative external stimulus. In 2018, Byers and coworkers demonstrated the efficient transformation between 6 and 6 ox using electrochemical control in a bis(imino)pyridine iron(II) bis(alkoxide) system . As reported before, the two complexes showed orthogonal discrimination between the ROP of LA and cyclohexene oxide.…”

Controlled Synthesis of Block Copolymers by Mechanistic Transformation from Atom Transfer Radical Polymerization to Iniferter Process

“…In recent years, there has been tremendous interest in developing new controlled/living polymerization (CLP) methods, involving almost all modes of polymerization processes …”

“…In recent years, there has been tremendous interest in developing new controlled/living polymerization (CLP) methods, involving almost all modes of polymerization processes. [25][26][27][28][29][30][31][32][33] Following the invention of living anionic polymerization by Szwarc in 1956, [34] there has been an increasing attention to develop new CLP techniques because of their usefulness to access various macro molecular architectures with designable molecular weights, low polydispersity, and beneficially preserved end-functionalities. A recent example of controlled/ living polymerization process is related to the polymerization of vinyl ethers by photoinduced radical oxidation addition deactivation (PROAD) processes.…”