Ethylene Polymerizations Using Parallel Pressure Reactors and a Kinetic Analysis of Chain Transfer Polymerization

Area of Science:

• Catalysis
• Polymer Chemistry
• Materials Science

Background:

• Developing efficient catalysts for ethylene polymerization is crucial for producing advanced polyolefins.
• High-throughput screening methods accelerate catalyst discovery and optimization.
• Understanding chain transfer mechanisms is key to controlling polymer molecular weight and properties.

Purpose of the Study:

• To develop and validate a high-throughput method for screening nickel α-diimine catalysts for ethylene polymerization.
• To establish procedures for optimizing reaction conditions and calculating kinetic parameters.
• To investigate the chain transfer behavior of the catalyst using diethylzinc.

Main Methods:

• Synthesis of nickel α-diimine polymerization catalysts.
• High-throughput screening using a parallel pressure reactor.
• Optimization of catalyst concentration, ethylene pressure, and reaction time.
• Calculation of initial propagation rates (kp) from gas-uptake data.
• Assessment of chain transfer using molecular weight and 13C NMR data.
• Calculation of chain transfer degree and rates (ke).

Main Results:

• Optimized reaction conditions for nickel α-diimine catalyzed ethylene polymerization.
• A validated procedure for calculating the initial rate of propagation (kp).
• Quantification of chain transfer to diethylzinc (ZnEt2).
• Established methods for calculating the degree of chain transfer and chain transfer rates (ke).

Conclusions:

• The developed method enables efficient high-throughput screening of polymerization catalysts.
• The study provides a robust framework for optimizing polymerization conditions and understanding catalyst kinetics.
• The nickel α-diimine catalyst exhibits significant chain transfer activity with diethylzinc, allowing for control over polymer molecular weight.