Zwitterionic Alternating Polymerization to Generate Semicrystalline and Recyclable Cyclic Polythiourethanes

Area of Science:

• Polymer Chemistry
• Materials Science
• Sustainable Chemistry

Background:

• Development of novel polymers with enhanced properties and recyclability is crucial for sustainable materials.
• Polythiourethanes offer unique characteristics but their synthesis and recycling often face challenges.

Purpose of the Study:

• To synthesize cyclic, semicrystalline, and recyclable polythiourethanes.
• To investigate a novel catalyst-free zwitterionic alternating copolymerization method.
• To evaluate the thermal properties and recyclability of the synthesized polythiourethanes.

Main Methods:

• Catalyst-free zwitterionic alternating copolymerization of N-alkyl aziridines with carbonyl sulfide (COS).
• Mild reaction conditions: room temperature, solvent-free.
• Characterization using 1H NMR and MALDI-TOF mass spectroscopy.

Main Results:

• Efficient copolymerization (>99% selectivity) achieved in 5 minutes at room temperature.
• Synthesized polythiourethanes exhibit semicrystalline thermoplastic properties with high melting temperatures (up to 170 °C).
• Predominantly cyclic structures confirmed by spectroscopic analysis.
• Quantitative recycling into N-substituted cyclic thiourethanes achieved by heating at 250 °C.

Conclusions:

• Successful synthesis of cyclic, semicrystalline, and recyclable polythiourethanes via a novel, efficient, and mild copolymerization route.
• Demonstrated high thermal stability and quantitative recyclability, highlighting the potential for sustainable polymer applications.
• The catalyst-free zwitterionic alternating copolymerization offers a green and effective pathway for advanced polythiourethane materials.