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Published on: November 29, 2018
Covalent Borane-Thiourea Organocatalyst for Stereoselective Ring-Opening Polymerization
Xue Wang1,2, Yanchao Wang1, Qunliang Zhang1
1State Key Laboratory of Polymer Science and Technology, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, People's Republic of China.
Angewandte Chemie (International Ed. in English)
|June 30, 2026
Summary
A new metal-free organocatalyst enables stereoselective polymerization of dithiolactones into high-performance, recyclable polythioesters. This breakthrough addresses monomer racemization, yielding tough, semicrystalline plastics with properties rivaling polyolefins.
Area of Science:
- Polymer Chemistry
- Organocatalysis
- Sustainable Materials
Background:
- Ring-opening polymerization is crucial for addressing plastic waste, but synthesizing high-performance, recyclable polythioesters faces challenges.
- Existing catalysts often cause monomer racemization, hindering the creation of tactic crystalline polymers and reducing material performance.
- There is a need for selective catalysts that can overcome stereochemical hurdles in polythioester synthesis.
Purpose of the Study:
- To design and synthesize a novel organocatalyst for stereoselective ring-opening polymerization.
- To overcome monomer racemization issues inherent in typical ring-opening polymerization catalysts.
- To produce chemically recyclable, high-performance polythioesters from dithiolactones.
Main Methods:
- Development of a covalent borane-thiourea organocatalyst featuring a 9-borafluorene moiety.
- Utilizing the catalyst for stereoselective ring-opening polymerization of enantiopure dithiolactones.
- Characterization of polymer tacticity, molecular weight, and material properties.
Main Results:
- The organocatalyst enabled rapid polymerization with minimal monomer racemization.
- Achieved polythioesters with near-perfect isotacticity (Pm = 0.97) and high molecular weights (Mn up to 58.1 kDa).
- The resulting stereoregular polymers exhibited toughness and semicrystalline properties comparable to commercial polyolefins and demonstrated complete chemical recyclability.
Conclusions:
- The covalent borane-thiourea organocatalyst effectively solves stereochemical challenges in ring-opening polymerization.
- This metal-free system provides a powerful strategy for producing sustainable, high-performance thermoplastics from dithiolactones.
- The developed polythioesters offer a promising route towards a circular economy for plastics.
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