Bulk Metathesis Polymerization Using Ruthenium Catalysts
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Solution Overview
Problem
Current methods for olefin metathesis and metathesis polymerization are limited by degradation and olefin migration at elevated temperatures, restricting the attainment of high molecular weight polymers due to thermodynamic constraints and the high melting temperatures of resultant polymers, which hinder efficient step growth polymerization and industrial scalability.
Innovation Solution
The use of Ruthenium-based catalysts, such as Hoveyda-Grubbs type catalysts with asymmetric N-heterocyclic carbene ligands or cyclic (alkyl)(amino)carbene ligands, allows for metathesis reactions to be performed at temperatures greater than 100°C in bulk conditions, enabling the formation of high molecular weight polymers by maintaining the polymer chains in a molten state and facilitating intensive mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the polymerization temperature is raised above the melting temperature of the polymer to prevent crystallization and increase chain diffusion, then the molecular weight and productivity are improved, but the Ruthenium-based catalyst degrades
Solution Approach 1:
The patent changes the temperature parameter to exceed the polymer's melting temperature, transforming the polymer from a crystalline solid to a molten state. This parameter change prevents crystallization constraints and enhances chain diffusion, enabling high molecular weight polymerization despite the risk of catalyst degradation.
Solution Approach 2:
The patent applies preliminary vacuum treatment to remove gaseous ethylene before and during polymerization. This preliminary action shifts the metathesis equilibrium toward polymerization by removing the gaseous byproduct, enabling the reaction to proceed to high molecular weights without requiring the polymer to be in a crystalline state that would constrain chain diffusion.
2Ease of manufacture
If bulk polymerization is performed to avoid solvent purification and simplify the process, then the ease of manufacture is improved, but the high melting temperature of the polymer limits molecular weight attainment
Solution Approach 1:
The patent exploits the phase transition of the polymer from solid (crystalline) to liquid (molten) state by conducting polymerization above the polymer's melting temperature. In this molten phase, the polymer chains are unconstrained and can diffuse efficiently, enabling high molecular weight attainment in bulk polymerization without solvent.
Solution Approach 2:
The patent changes the temperature parameter to exceed the polymer's melting point, transforming the physical state of the polymer during polymerization. This parameter change resolves the contradiction by enabling both bulk polymerization simplicity and high molecular weight production through enhanced chain mobility in the molten state.
3Productivity
If solution polymerization is performed to achieve high molecular weight, then the molecular weight is improved, but vacuum application is required and solvent removal is cumbersome
Solution Approach 1:
The patent extracts and removes the gaseous ethylene byproduct through vacuum treatment, shifting the metathesis equilibrium toward polymerization. By removing the gaseous component, the reaction proceeds to high molecular weights in bulk conditions without requiring continuous vacuum application during polymerization, simplifying the overall process.
Solution Approach 2:
The patent applies vacuum treatment preliminarily to remove gaseous ethylene before and during polymerization. This preliminary removal of the gaseous byproduct drives the equilibrium toward polymerization, enabling high molecular weight attainment in bulk polymerization without the need for complex continuous vacuum systems.
4Ease of operation
If traditional Grubb's 1st generation catalyst is used for bulk polymerization, then the ease of operation is improved, but the high melting temperature of the polymer limits the achievable molecular weight
Solution Approach 1:
The patent changes the temperature parameter to exceed the polymer's melting temperature during polymerization. This parameter change enables bulk polymerization with enhanced chain diffusion and prevents crystallization constraints, achieving high molecular weights while maintaining the simplicity of bulk operation.
Solution Approach 2:
The patent applies preliminary vacuum treatment to remove gaseous ethylene, driving the metathesis equilibrium toward polymerization. This preliminary action enables high molecular weight attainment in bulk polymerization without requiring complex equipment, maintaining ease of operation while improving productivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the production of polymers with weight average molecular weights of at least 10,000 Da and a degree of polymerization of 10 to 100 within 3 to 24 hours, overcoming the limitations of traditional methods by allowing polymer chains to remain unconstrained and promoting chain diffusion and molecular weight increase.
Implementation Method 1
The use of Ruthenium-based catalysts, such as Hoveyda-Grubbs type catalysts with asymmetric N-heterocyclic carbene ligands or cyclic (alkyl)(amino)carbene ligands, allows for metathesis reactions to be performed at temperatures greater than 100°C
Implementation Method 2
heating the reaction mixture to a temperature greater than 100° C. enabling the formation of high molecular weight polymers by maintaining the polymer chains in a molten state
Implementation Method 3
allowing polymer chains to remain unconstrained and promoting chain diffusion and molecular weight increase
Data Source
AI summary
A method of carrying out a metathesis reaction includes the combination of at least one alkene or non conjugated diene with a Ruthenium-based catalyst with an cyclic(alkyl)(amino)carbene ligand to form a reaction mixture, heating the reaction mixture to a temperature of 100° C. or greater in the absence of a solvent in bulk conditions, and mechanically stirring the reaction mixture. The reaction can be an ADMET, ROMP, a metathesis ring-closure or an olefin exchange reaction.