Isoselective Ring-Opening Polymerization to Access High-Performance Poly(α-Substituted-β-Propiolactone)s

Area of Science:

• Polymer Chemistry
• Materials Science
• Sustainable Chemistry

Background:

• Poly(α-substituted-β-propiolactone) (P(αRPL)) shows promise as a biodegradable plastic, similar to natural polyhydroxyalkanoates (PHAs).
• The synthesis of isotactic P(αRPL) via ring-opening polymerization has been a significant challenge.

Purpose of the Study:

• To explore the chemical synthesis of highly isotactic P(αRPL) using a novel catalytic system.
• To investigate the properties and recycling potential of the synthesized isotactic P(αRPL).

Main Methods:

• Utilized a robust salalen yttrium complex (Y2) as a catalyst for ring-opening polymerization.
• Characterized the synthesized P(αRPL) for tacticity, thermal properties (e.g., melting transition temperature), and mechanical properties.
• Evaluated the depolymerization behavior of P(αRPL) to assess recyclability.

Main Results:

• Successfully synthesized highly isotactic P(αRPL) with a probability of monomeric dyad placement (P_m) greater than 0.95.
• Demonstrated tacticity-dependent thermal and mechanical properties, with highly isotactic P(BPL) reaching a melting transition temperature of 165 °C.
• Showcased P(αRPL) as strong, ductile materials comparable to high-density polyolefins and capable of clean depolymerization for closed-loop recycling.

Conclusions:

• Established a powerful synthetic platform for accessing isotactic P(αRPL) using a salalen yttrium catalyst.
• Highlighted the potential of P(αRPL) as a sustainable plastic alternative with tunable properties and efficient recyclability.
• Paved the way for the discovery of novel sustainable plastics based on P(αRPL) structures.