Quantifying CO₂ Insertion Equilibria for Low-Pressure Propene Oxide and Carbon Dioxide Ring Opening Copolymerization...

Area of Science:

• Catalysis
• Polymer Chemistry
• Green Chemistry

Background:

• Ring-opening copolymerization (ROCOP) of carbon dioxide (CO2) and epoxides is crucial for sustainable polymer production.
• Existing catalysts often require high CO2 pressures, limiting their practical application.
• Development of efficient catalysts for low CO2 pressure conditions is highly desirable.

Purpose of the Study:

• To develop and evaluate novel Co(III)M(I) heterodinuclear catalysts for CO2 and propene oxide (PO) ROCOP.
• To investigate catalyst performance under low CO2 pressure conditions.
• To establish a unified rate law and quantify the CO2 equilibrium constant for the reaction.

Main Methods:

• Synthesis and characterization of a series of Co(III)M(I) heterodinuclear catalysts.
• Activity and selectivity testing for ROCOP of CO2 and PO under varying CO2 pressures.
• Kinetic studies to determine rate laws and equilibrium constants.

Main Results:

• The Co(III)K(I) complex demonstrated superior activity (TOF = 1728 h-1) and selectivity (>90% polymer, >99% CO2 incorporation).
• High efficiency was observed at low CO2 pressures (<10 bar).
• The CO2 equilibrium constant (Keq = 1.27 M-1) was quantified for the first time, and a unified rate law was derived and validated with literature data.

Conclusions:

• Co(III)K(I) heterodinuclear catalysts are highly effective for CO2/PO ROCOP, particularly under low CO2 pressure.
• The study provides fundamental insights into the reaction mechanism and establishes a predictive rate law.
• This work advances the development of efficient catalytic systems for CO2 utilization in polymer synthesis.