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Solubility-Equilibrium-Assisted Kinetic Resolution Polymerization toward Isotactic Polyesters Containing Axial
Qing Cao1, Hua-Zhong Fan1, Min Xie1
1National Engineering Laboratory of Eco-Friendly Polymeric Materials (Sichuan), College of Chemistry, Sichuan University, 29 Wangjiang Rd, Chengdu 610064, P. R. China.
Journal of the American Chemical Society
|December 16, 2024
Summary
Researchers developed novel yttrium catalysts for stereocontrolled polymerization of rac-Me-DBO. Exploiting solubility equilibrium significantly improved polymer tacticity, achieving highly isotactic P(Me-DBO) with a Pm up to 0.93.
Area of Science:
- Polymer Chemistry
- Catalysis
- Stereochemistry
Background:
- Achieving high-level control over polymer stereochemistry is crucial for tailoring material properties but remains a significant challenge in synthetic polymer chemistry.
- Axially chiral catalysts offer a promising route for stereocontrolled polymerization.
Purpose of the Study:
- To prepare novel yttrium catalysts with axially chiral binaphthyl moieties for stereocontrolled polymerization of rac-Me-DBO.
- To investigate the effect of catalyst structure and reaction conditions on polymerization stereoselectivity.
- To develop a versatile strategy for enhancing stereocontrol in polymerization.
Main Methods:
- Synthesis of new salphen yttrium catalysts featuring axially chiral binaphthyl units.
- Kinetic resolution polymerization of rac-Me-DBO using the developed catalysts.
- Exploitation of solubility equilibrium to maintain monomer concentration.
- Mechanistic investigations to elucidate the polymerization pathway.
Main Results:
- The (S)-Y3 catalyst with bulkier binaphthyl groups achieved moderate isoselectivity (Pm up to 0.80) via kinetic resolution.
- Utilizing solubility equilibrium to control monomer concentration significantly boosted polymerization isoselectivity.
- Highly isotactic P(Me-DBO) products were obtained with a tacticity (Pm) up to 0.93.
- Mechanistic studies validated the solubility-equilibrium shifting hypothesis.
Conclusions:
- A novel strategy employing solubility-equilibrium-assisted kinetic resolution polymerization was successfully developed.
- This approach enhances stereocontrol in polymerization without requiring new catalyst designs.
- The developed strategy is expected to be a versatile platform for improving polymer stereochemistry.
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