Organocatalyzed Controlled Copolymerization of Perfluorinated Vinyl Ethers and Unconjugated Monomers Driven by Light

Abstract

Perfluorinated vinyl ethers (PFVEs) are an important category of monomers for producing fluoropolymers that have found broad applications. In this work, by developing a dibenzo­[a,c]­phenothiazine-based organic photoredox catalyst, we realize photo-controlled radical copolymerization of various PFVEs and unconjugated comonomers (e.g., vinyl esters, vinyl amides, and vinyl ethers) with a high reaction efficiency when exposed to visible-light irradiation, affording a large series of main- and side-chain fluorinated copolymers of low dispersities (D̵ = 1.06–1.24) and good chain-end fidelity at excellent conversions of unconjugated comonomers. Furthermore, this method not only facilitates the “ON/OFF” temporal switch of the chain growth with tunable kinetics for the “ON” states upon altering the wavelengths of light sources but also allows photo-controlled chain extensions with copolymers and homopolymers as additional blocks, presenting a facile and versatile platform to customize complex fluoropolymers for material engineering.

Facile Control of Molecular Weight Distribution via Droplet‐Flow Light‐Driven Reversible‐Deactivation Radical Polymerization†

“…High‐throughput RDRPs have attracted considerable interests in recent years, because it dramatically promotes material screening by providing necessary substances in massive numbers and in short times. [ 26,44‐45 ] Based on our continuous interests in fluoropolymers, [ 46‐51 ] we carried out high‐throughput flow copolymerization using DMA and TFEA as modal comonomers under visible‐light irradiation with a computer‐aided four‐pumps setup (pump 1 for DMA, CTA 2 and PC, pump 2 for TFEA, CTA 2 and PC, pump 3 for hexane, pump 4 for N 2 , Figure S23). The initial [DMA]/ [TFEA] ratio and V hex / V DMSO ratio were precisely manipulated through a program by altering flow parameters ( i.e ., flow rates).…”

Photocontrolled RAFT polymerization: past, present, and future

“…212 PTH-5 with the extended conjugation exhibited lower E Ã red and higher E 0 ox than PTH-3, which led to favored initial electron transfer from the excited-state PC to xanthate and subsequent electron transfer from the xanthate anion to the one-electronoxidized PC. 213 A series of phenazine-based PCs developed by structural modification of 5,10-diphenyl-5,10-dihydrophenazine exhibited disparate photocatalytic activities in PET-RAFT polymerization under blue light irradiation (460 nm). 125 Likewise, covalent structural modification of the known PC scaffolds, including extension of the conjugated structure or change of substituents, has been widely applied to modulate the performance of PCs in polymerization under desired reaction conditions (e.g., irradiation wavelengths and chemical properties of reagents).…”

Controlled Radical Copolymerization toward Well‐Defined Fluoropolymers

“…For their photoredox CRCPs with vinyl ethers, the adoption of CTA4 (−1.23 V vs SCE) with a pyrryl and a fluorinated benzyl affords optimal dispersity control ( Ð <1.3) at excellent conversions (Figure 10). [31b,34] Although CTA4 and CTA2 exhibit similar oxidative potentials, the dithiocarbamate fragment generated from CTA2 precipitated from the reaction mixture, leading to low conversions. When vinyl esters and N ‐vinylpyrrolidinone are used to copolymerize with PFVEs, CTA3 furnishes low Ð , agreeing to the CTA selection in the photoredox CRCPs of CTFE.…”