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Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes
Published on: November 21, 2017
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Urea Anions: Simple, Fast, and Selective Catalysts for Ring-Opening Polymerizations
Binhong Lin1, Robert M Waymouth1
1Department of Chemistry, Stanford University , Stanford, California 94305, United States.
Journal of the American Chemical Society
|January 21, 2017
Summary
New urea-based catalysts enable fast and selective ring-opening polymerization (ROP) of various cyclic monomers. These efficient catalysts produce high-quality biodegradable polymers rapidly at room temperature.
Area of Science:
- Polymer Chemistry
- Materials Science
Background:
- Aliphatic polyesters and polycarbonates are valuable biorenewable, biocompatible, and biodegradable materials.
- Ring-opening polymerization (ROP) is a key method for synthesizing these polymers from cyclic monomers.
Purpose of the Study:
- To develop novel, efficient catalysts for the ring-opening polymerization (ROP) of cyclic monomers.
- To investigate the catalytic activity and selectivity of deprotonated ureas in ROP.
Main Methods:
- Deprotonation of diaryl ureas to generate anionic catalysts.
- Ring-opening polymerization (ROP) of lactide, valerolactone, caprolactone, cyclic carbonate, and cyclic phosphoester using the urea catalysts.
- Analysis of polymer molecular weight distributions (Đ) and reaction kinetics.
Main Results:
- Deprotonated ureas function as fast and selective catalysts for ROP.
- Catalyst reactivity correlates with electron-withdrawing substituents on aryl rings.
- High conversions (∼90%) achieved within seconds (1-12 s) at room temperature.
- Polymers with narrow molecular weight distributions (Đ = 1.06 to 1.14) were produced.
Conclusions:
- Diaryl urea anions are versatile catalysts for living ROP.
- Catalyst activity can be tuned by modifying aryl substituents.
- These catalysts offer a rapid, efficient, and tunable method for synthesizing biodegradable polymers.
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