Copper‐mediated controlled radical polymerization in continuous flow processes: Synergy between polymer reaction engineering and innovative chemistry

Abstract

Copper(0)-mediated controlled radical polymerization (CRP), or single-electron transfer-living radical polymerization (SET-LRP) is a robust and dynamic technique that has attracted considerable academic and industrial interest as a synthetic tool for novel value-added materials. Although SET-LRP possesses many advantages over other forms of CRP, this novel chemistry still requires concurrent engineering solutions for successful commercial application. In this highlight, the evolution of atom-transfer radical polymerization chemistry and development in continuous processes is presented, leading to recent research on the use of SET-LRP in continuous flow tubular reactors. The proofs of concept are reviewed, and remaining challenges and unexplored potential on the use of continuous flow processes with SET-LRP as a powerful platform for the synthesis of novel polymeric materials are discussed.

An old kinetic method for a new polymerization mechanism: Toward photochemically mediated ATRP

“…9 In ATRP, the use of low oxidation state transition-metal catalyst (commonly Cu I salt) inevitably leads to contamination of products and time-consuming deoxygenation process. [9][10][11] Scientists have been focusing on diminishing the catalyst dosage and applying high oxidation state catalytic complex or metallic copper through experimental and kinetic modeling investigations. [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] For example, initiators for continuous activator regeneration (ICAR) ATRP, [13][14][15][16] activators regenerated by electron transfer (ARGET) ATRP, [17][18][19] single electron transferliving radical polymerization (SET-LRP), [20][21][22] supplemental activator and reducing agent (SARA) ATRP, [23][24][25] and electrochemically mediated ATRP (eATRP) 26 have been investigated.…”

Aqueous SET-LRP catalyzed with “in situ” generated Cu(0) demonstrates surface mediated activation and bimolecular termination

“…6,7,[48][49][50][51]57,[71][72][73][74][75][76][77] Narrow molecular weight distribution is an important feature of the polymers prepared by LRP but the most significant structural parameter of these polymers is the quantitative or near quantitative chain-end functionality combined with narrow molecular weight distribution. Chain-end functionality is the major parameter of a polymer that allows the construction of complex architectures such as multiple block copolymers, 64,73,[76][77][78][79] and dendrimers by iterative synthesis. [77][78][79][80][81] In a previous publication from our laboratory it was reported that the Cu(0) mediated SET-LRP of 2-hydroxyethyl acrylate (HEA) in H 2 O and in mixtures of protic solvents with H 2 O produces a gel of poly(HEA) (PHEA) exclusively on the surface of the catalysts.…”

“…10,46,57 The catalyst most frequently employed in SET-LRP is Cu(0) in the form of powder 2,4,12,58 including powder generated by the disproportionation of Cu(I)X in a large diversity of solvents, 12 wire, 12,64,69 activated wire [59][60][61][62] and tubes. 63,64 Almost all initiators employed in other metal catalyzed LRP such as alkyl halides, 65,66 sulfonyl halides, 33,48,65,[67][68][69] N-halides 2,70 can be used as such or modified to become soluble for SET-LRP in various media including H 2 O. Only very few systematic investigations on SET-LRP with Cu(0) generated by disproportionation of Cu(I)X "in situ" in water 26,37,38,42 and in mixtures of water with other solvents are available.…”

Simultaneous Monitoring of the Effects of Multiple Ionic Strengths on Properties of Copolymeric Polyelectrolytes during Their Synthesis

“…Much work in SRP research makes use of controlled radical and other living type reactions [9][10][11][12][13][14] nucleobase polymers [15,16], and information containing polymers [17,18].…”