Electrochemically Mediated Atom Transfer Radical Polymerization Employing Rapid Alternating Polarity.

Area of Science:

• Electrochemistry
• Polymer Chemistry
• Materials Science

Background:

• Mass transfer limitations hinder electrochemical synthesis, especially in viscous media, leading to electrode fouling and polymerization termination.
• Existing methods struggle with efficient transport of redox-active species, impacting control and yield.

Purpose of the Study:

• To investigate electrochemically mediated atom transfer radical polymerization (eATRP) using rapid alternating polarity (rAP) to overcome mass transfer limitations.
• To develop a straightforward, efficient strategy for eATRP in undivided cells using graphite electrodes.

Main Methods:

• Implementation of a constant alternating current on a millisecond timescale throughout the polymerization process.
• Utilizing readily available graphite electrodes in an undivided cell setup.
• Systematic investigation of eATRP under varying applied current and pulse durations.

Main Results:

• Near-quantitative monomer conversions and exceptionally narrow dispersities (Đ < 1.1) achieved for methyl acrylate polymerization.
• Effective prevention of copper catalyst over-reduction and electrode fouling.
• Demonstrated ability to produce ultrahigh molecular weight polymers (Mn = 1,598,000, Đ = 1.26) with significantly reduced copper catalyst loading (2.5 ppm).
• Successful extension of the monomer scope to methyl methacrylate and styrene.
• One-pot synthesis of block and star-shaped polymers (PMMA-b-PMA, 4-star-PMA) due to high 'livingness' and chain-end fidelity.

Conclusions:

• Rapid alternating polarity (rAP) is a highly effective strategy for addressing mass transfer limitations in electrochemical polymerizations.
• This approach enables precise control over polymerization kinetics, molecular weight, and dispersity.
• The developed method offers a versatile platform for synthesizing advanced polymer architectures with reduced catalyst loading, paving the way for future research in controlled electrochemical polymerizations.