Acid-Enhanced Photoiniferter Polymerization under Visible Light

Area of Science:

• Polymer Chemistry
• Materials Science

Background:

• Photoiniferter (PI) polymerization offers an alternative to thermal reversible addition-fragmentation chain-transfer (RAFT) polymerization.
• Conventional PI typically requires high-energy UV light, limiting its application.
• Existing visible light PI methods often result in low molecular weight polymers, long reaction times, and broad dispersities.

Purpose of the Study:

• To develop a visible light PI method that overcomes the limitations of current approaches.
• To achieve rapid synthesis of high molecular weight polymers with controlled dispersity.
• To demonstrate the versatility of the new method for various polymer classes and copolymer synthesis.

Main Methods:

• Utilized an acid-enhanced photoiniferter polymerization strategy under visible light irradiation.
• Incorporated small amounts of citric acid to accelerate photolysis and polymerization rate.
• Synthesized polymers, including diblock copolymers, from acrylamides, acrylates, and methacrylates.

Main Results:

• Eliminated lengthy induction periods, reducing reaction times to two hours.
• Achieved near-quantitative conversions (>97%) and narrow molar mass distributions (Đ ~1.1).
• Successfully synthesized polymers with high degrees of polymerization (DP=3,000) within five hours without compromising control.

Conclusions:

• Acid-enhanced visible light PI is a robust and efficient method for polymer synthesis.
• The technique enables rapid production of high molecular weight polymers with excellent control.
• Demonstrated broad applicability across different monomer classes and for copolymer synthesis.