Tailoring Polymerization Controllability and Dispersity Through a Photoswitchable Catalyst Strategy.

Area of Science:

• Polymer Chemistry
• Macromolecular Science
• Organic Synthesis

Background:

• Controlling polymerization on demand remains a significant challenge in synthetic macromolecular chemistry.
• Living radical polymerization techniques offer enhanced control over polymer architecture but often lack external tunability.
• Single-electron transfer mediated living radical polymerization (SET-LRP) provides a platform for controlled polymer synthesis.

Purpose of the Study:

• To develop a photoswitchable catalyst for precise control over SET-LRP of methyl methacrylate (MMA).
• To achieve on-demand modulation of polymerization kinetics and polymer dispersity.
• To enable repeatable resetting of polymerization processes.

Main Methods:

• Utilized hexaarylbiimidazole (HABI) as a photoswitchable catalyst.
• Employed light irradiation to reversibly switch HABI between active and inactive states.
• Investigated the SET-LRP of MMA under varying light conditions.

Main Results:

• Demonstrated reversible control over SET-LRP of MMA using HABI.
• Achieved first-order polymerization kinetics and narrow molecular weight distribution when the catalyst was active (light on).
• Showcased the ability to reset polymerization by deactivating the catalyst (light off), allowing for repeatable control.

Conclusions:

• HABI acts as an efficient molecular switch to photomodulate polymerization dispersity in SET-LRP.
• The proposed mechanism elucidates the switchable catalytic activity of HABI in SET-LRP.
• This work offers a novel strategy for on-demand polymerization control and polymer synthesis.