Programming Copolymer Microstructure and Selective Degradability via Red-Light Photoinduced Electron/Energy Transfer...

Area of Science:

• Polymer Chemistry
• Materials Science
• Organic Synthesis

Background:

• Radical ring-opening polymerization (rROP) enables degradable vinyl polymers but thionolactone incompatibility with light limits applications.
• Existing light-mediated polymerization methods are hindered by the thiocarbonyl group's photoreactivity.

Purpose of the Study:

• To develop a light-controlled method for synthesizing degradable vinyl polymers using thionolactone monomers.
• To overcome the limitations of blue/green light sensitivity in thionolactone-based polymerization.
• To enable controlled copolymerization of thionolactone with other monomers for tunable degradability.

Main Methods:

• Utilized red-light-mediated photoinduced electron/energy transfer reversible addition-fragmentation chain transfer (PET-RAFT) polymerization.
• Employed dibenzo[c,e]oxepine-5(7H)-thione (DOT) and acrylamide as comonomers.
• Exploited minimal spectral overlap between DOT and 635 nm light to prevent side reactions.

Main Results:

• Achieved the first controlled copolymerization of DOT with acrylamide using red-light PET-RAFT.
• Demonstrated predictable molar mass, narrow dispersities (<1.3), and high incorporation of degradable thioester units.
• Showcased spatiotemporal control over monomer incorporation for enhanced degradation efficiency and tunable microstructures.

Conclusions:

• Established red-light PET-RAFT as a viable strategy for light-controlled synthesis of degradable polymers.
• Enabled precise control over copolymer microstructure to program polymer degradability.
• Extended the platform to lipoate-based monomers for advanced degradable architectures and selective degradation pathways.