Cationic-Catalyst Strategy Enabling Ultrafast and Controlled Polymerization and Efficient Depolymerization Toward a...

Area of Science:

• Polymer Chemistry
• Sustainable Materials

Background:

• Growing polymer waste necessitates chemically recyclable solutions.
• Amino acid (AA) polymers are crucial for a circular polymer economy.
• Existing N-carboxyanhydride (NCA) polymerization methods for AA polymers lack molecular weight control and suffer from side reactions.

Purpose of the Study:

• To develop a highly efficient cationic-catalyst strategy for ultrafast, controlled AA polymer synthesis.
• To enable closed-loop recycling of AA polymers using the developed catalyst.
• To demonstrate the scalability and practical applications of the catalyst in polymerization and depolymerization.

Main Methods:

• Development of a novel cationic-catalyst strategy for N-carboxyanhydride (NCA) polymerization.
• Compatibility testing with various organic strong base initiators.
• Hectogram-scale (∼120 g) synthesis of AA polymers.
• Evaluation of the catalyst's efficiency in depolymerizing AA polymers back to amino acids.
• Assessment of catalyst recyclability.

Main Results:

• Achieved ultrafast, molecular weight-controlled AA polymer synthesis within minutes on a hectogram scale.
• Demonstrated efficient depolymerization of AA polymers into amino acids with an 85.9% recovery rate.
• Confirmed quantitative recyclability of the cationic catalyst.

Conclusions:

• The developed cationic-catalyst strategy offers a robust, scalable, and efficient method for both AA polymer synthesis and recycling.
• This approach holds significant potential for advancing the circular polymer economy and managing polymer waste sustainably.
• The catalyst facilitates practical applications in polymerization and depolymerization chemistry.