Coenzyme-Catalyzed Electro-RAFT Polymerization

Abstract

Here we report an electrochemically switchable reversible addition− fragmentation chain transfer polymerization (eRAFT). A new family of biochemical coenzymes are discovered that can be used as highly efficient electroredox catalysts to mediate this polymerization. The oxidation of coenzyme, nicotinamide adenine dinucleotide (NADH), can promote the reduction of a chain transfer agent, triggering generation and propagation of polymer radicals. External potential can activate the reduction of the NAD + oxidized state and pause the propagation. Tuning the applied potential to reversibly switch the catalyst between its reduced and oxidized states can toggle the polymerization between ON and OFF states. This new strategy is universal to a broad scope of monomers, and ppm-level coenzymes result in the desirable polymer structures with targeted molecular weight, dispersity, and excellent chain-end fidelity. We envisage that the bioorganic-based catalysts would open new directions of organocatalyzed electro-controlled polymerization and be of value in electrocatalysis for well-structured polymers.

Electrochemically-initiated polymerization of reactive monomers via 4-fluorobenzenediazonium salts

“…The latter is important for the polymerization of reactive monomers since functional groups could potentially interfere with the redox behaviour of the initiator and undergo side reactions during the reaction. Additionally, the fluorine-label in the initiator as well as in the two reactive monomers DFPA and PFPA permits the straightforward analysis of the resulting polymers by 19 F NMR spectroscopy, which also allows for determination of the numberaverage molar mass of the as-prepared macromolecules.…”

“…1 H NMR, 13 C NMR, and 19 F NMR spectra were recorded on a Bruker Ascend III 400 MHz spectrometer at a frequency of ν = 400 MHz, ν = 101 MHz, and ν = 377 MHz, respectively. All samples were dissolved in deuterated solvents, chemical shifts are reported relative to the residual solvent signals.…”

“…1 H NMR (CDCl 3 ): δ/ppm = 6.72 (dd, J = 17.3, 0.9 Hz, 1H), 6.37 (dd, J = 17.3, 10.5 Hz, 1H), 6.18 (dd, J = 10.5, 1.0 Hz, 1H). 19…”

“…Unlike ATRP and NMP, the RAFT process relies on degenerate chain transfer, resulting in enhanced polymerization rates compared to its contenders, which are based on equilibria between active and dormant species. RDRP methods have been excessively explored, electrochemical approaches were utilized among others in RAFT polymerization [17][18][19][20] and ATRP (e.g. eATRP).…”

Organoselenium chemistry-based polymer synthesis

“…Dithiocarbonate compounds as chain transfer agents (CTAs) are added in reversible addition-fragmentation chain transfer (RAFT) polymerization, which is a kind of reversible deactivation radical polymerization (RDRP) that is widely used in the controllable polymerization of vinyl monomers. 109,110,[112][113][114][115][116][117][118][119][120][121] Diselenocarbonate compounds, because of their similar structure to that of dithiocarbonate, were also employed in RAFT polymerization to obtain selenium-containing polymers. In 2008, Lee and his coworkers reported the synthesis of diselenophosphates, named P1 and P2.…”