Electrochemical Atom Transfer Radical Polymerization in Miniemulsion with a Dual Catalytic System

Abstract

An electrochemical approach was used to control atom transfer radical polymerization (ATRP) of n-butyl acrylate (BA) in miniemulsion. Electropolymerization required a dual catalytic system, composed of an aqueous phase catalyst and an organic phase catalyst. This allowed shuttling the electrochemical stimulus from the working electrode (WE) to the continuous aqueous phase and to the dispersed monomer droplets. As aqueous phase catalysts, the hydrophilic Cu complexes with the ligands N,N-bis( 2-pyridylmethyl)-2-hydroxyethylamine (BPMEA), 2,2′-bipyridine (bpy), and tris(2-pyridylmethyl)amine (TPMA) were tested. As organic phase catalysts, the hydrophobic complexes with the ligands bis(2-pyridylmethyl)-octadecylamine (BPMODA) and bis[2-(4-methoxy-3,5-dimethyl)-pyridylmethyl]octadecylamine (BPMODA*) were evaluated. Highest rates and best control of BA electropolymerization were obtained with the water-soluble Cu/BPMEA used in combination with the oil-soluble Cu/BPMODA*. The polymerization rate could be further enhanced by changing the potential applied at the WE. Differently from traditional ATRP systems, reactivity of the dual catalytic system did not depend on the redox potential of the catalysts but instead depended on the hydrophobicity and partition coefficient of the aqueous phase catalyst.

Electrochemically Mediated Reversible Addition–Fragmentation Chain-Transfer Polymerization

“…14,16 e ATRP has been applied to various monomers, 9,15,17 preparing copolymers with different architectures 18,19 in a range of reaction media. 20,21 Computational simulations were also conducted for e ATRP, elucidating the key parameters. 22 The application of Fe-based catalyst broadened the application of e ATRP.…”

Precise Synthesis of Ultra‐High‐Molecular‐Weight Fluoropolymers Enabled by Chain‐Transfer‐Agent Differentiation under Visible‐Light Irradiation

“…On the contrary, without the aid of SG agent, a broad polydispersity ( Đ =1.67, M n =1.71×10 6 Da) was obtained, which is attributed to unbalanced monomer‐incorporation caused by the loss of degenerative chain‐transfer between the propagating chains implemented by SG agents. These results manifest that the interaction between SG and PG agents is critical to maintaining the livingness during polymerization …”

Harnessing the Interaction between Surfactant and Hydrophilic Catalyst To Control eATRP in Miniemulsion

“…Ratios of [Cu II Br 2 /L] water /[Cu II Br 2 /L] tot were determined by calibration curve in water (Figures S4–S5); b Initiation efficiency ( I eff = M n,th / M n ), from Table 2 (at E app = E pc − 0.03 V or E app = E pc ). c 13.5 wt% of BA; d 27.8 wt% of BA. e No Cu complex was detected in the Vis-NIR spectrum of the organic phase. f From reference 6 . …”

“…2–5 Thus, in a recently reported e ATRP miniemulsion procedure, a dual catalytic system was utilized, composed of one hydrophobic and one hydrophilic catalyst. 6 The presence of a second water-soluble catalyst was required to close the electrochemical circuit between the WE and the hydrophobic catalyst complex residing within monomer droplets. The WE was in contact with the aqueous phase, from which the water-soluble catalyst shuttled the electrochemical stimulus to the hydrophobic catalyst confined in the dispersed droplets.…”