One-pot synthesis of hyperbranched polymers via visible light regulated switchable catalysis

Area of Science:

• Polymer Chemistry
• Catalysis
• Materials Science

Background:

• Switchable catalysis offers advanced control in polymer synthesis.
• Current methods are limited to linear block copolymers.
• Developing methods for complex polymer architectures like hyperbranched polymers is crucial.

Purpose of the Study:

• To develop a visible light-regulated switchable catalytic system for synthesizing hyperbranched polymers.
• To utilize glycidyl acrylate (GA) as a heterofunctional monomer in a one-pot/two-stage procedure.
• To explore the potential of the synthesized polymers in material applications.

Main Methods:

• A visible light-switchable catalytic system using (salen)Co^IIICl (1) was employed.
• The first stage involved regioselective ring-opening of GA under CO atmosphere.
• The second stage utilized the intermediate for organometallic-mediated radical self-condensing vinyl polymerization (OMR-SCVP) upon light exposure.

Main Results:

• High regioselectivity (>99%) was achieved in the ring-opening of GA.
• Hyperbranched poly(glycidyl acrylate) (hb-PGA) was synthesized with organocobalt chain-end functionality.
• A core-shell copolymer with brush-on-hyperbranched arm architecture was successfully created.
• Post-modification with TEMPO yielded metal-free hb-PGA with enhanced toughness and glass transition temperature in epoxy thermosets.

Conclusions:

• The developed switchable catalytic system enables efficient synthesis of hyperbranched polymers.
• The resulting hb-PGA can be further modified for advanced material applications.
• The metal-free hb-PGA shows promise for improving epoxy thermoset properties without compromising storage modulus.