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Boronic Ester Based Vitrimers with Enhanced Stability via Internal Boron-Nitrogen Coordination
Xiaoting Zhang1, Shujuan Wang1, Zikang Jiang1
1School of Chemistry, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, P. R. China.
Journal of the American Chemical Society
|December 17, 2020
Summary
New nitrogen-coordinating cyclic boronic diester (NCB) linkages offer improved water and heat resistance in polymers. These novel linkages enable the creation of sustainable, self-healing, and reprocessable vitrimers with enhanced stability.
Area of Science:
- Polymer Chemistry
- Materials Science
- Organic Chemistry
Background:
- Boron-containing polymers offer unique properties for advanced applications.
- Organoboron species with reversible B-O bonds are used in self-healing and reprocessable polymers.
- Conventional boronic esters and boroxines suffer from hydrolytic instability, limiting their use.
Purpose of the Study:
- To investigate the hydrolytic stability and dynamic covalent chemistry of nitrogen-coordinating cyclic boronic diester (NCB) linkages.
- To develop a new class of vitrimers based on NCB linkages with enhanced stability and reprocessability.
- To explore the potential of NCB linkages for designing next-generation sustainable materials.
Main Methods:
- Synthesis of novel vitrimers incorporating NCB linkages via reactions of reactive hydrogen with isocyanate.
- Thermodynamic and kinetic studies to evaluate the stability and exchange reactions of NCB linkages.
- Characterization of model compounds (NCBC-X1, NCBC-X2) and resulting polyurethane/poly(urea-urethane) vitrimers.
Main Results:
- NCB linkages demonstrate enhanced resistance to water and heat compared to conventional boronic esters.
- Vitrimers based on NCB linkages exhibit excellent solvent resistance and mechanical properties.
- Transesterification of NCB linkages upon heating allows for repair, reprocessing, and recycling of the materials.
- Internal N → B coordination in NCB linkages contributes to improved hydrolytic and thermal stability.
Conclusions:
- NCB linkages represent a promising alternative to conventional boronic esters for creating stable and dynamic covalent polymers.
- The developed NCB-based vitrimers offer a sustainable pathway for designing materials with tunable properties and extended lifecycles.
- This work provides a new strategy for advancing the field of sustainable polymers through enhanced hydrolytic and thermal stability.
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