Protected Organometallic Catalyst for Aqueous Polymerization
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Solution Overview
Problem
The challenge in polymerizing ethylenically unsaturated monomers in aqueous media lies in achieving a uniform distribution of water-sensitive organometallic catalysts, as existing methods like miniemulsions and microencapsulation in wax are difficult to control and offer limited protection against hydrolysis.
Innovation Solution
Incorporating an organometallic catalyst component into a protective substance, such as a low molecular weight amorphous saturated polymer or macromonomer, which provides protection against decomposition and destabilization of catalyst droplets, using a protective substance with specific molecular weight and solubility characteristics, and optionally a fugitive substance to enhance protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If organometallic catalysts are used in aqueous media for polymerization, then polymerization of ethylenically unsaturated monomers can be achieved, but the catalysts decompose due to hydrolysis and cannot be uniformly distributed
Solution Approach 1:
The patent embeds water-sensitive organometallic catalyst complexes inside hydrophobic droplets formed by protective substances (polymers or macromonomers). The catalyst is nested within the protective substance matrix, creating a core-shell structure where the hydrophobic core protects the catalyst from aqueous environment while enabling uniform distribution in water-based media.
Solution Approach 2:
The protective substance acts as an intermediary between the water-sensitive catalyst and the aqueous polymerization medium. This intermediary layer prevents direct contact between water and the catalyst, allowing the catalyst to function in aqueous environments without decomposition.
2Reliability
If miniemulsions or microencapsulation techniques are used to protect catalysts, then some protection is achieved, but the methods are difficult to control and offer limited protection against hydrolysis
Solution Approach 1:
The patent changes the molecular weight parameters of the protective substance to optimize protection. Specifically, it uses polymers with number average molecular weights between 1,000-100,000 g/mole or macromonomers with 50-500 repeating units. This parameter optimization provides sufficient protection while maintaining process simplicity.
Solution Approach 2:
The patent creates a composite system combining the organometallic catalyst with protective substances (polymers or macromonomers) having specific molecular characteristics. This composite approach provides superior hydrolysis resistance compared to simple encapsulation methods while avoiding the complexity of multi-step microencapsulation processes.
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 method ensures stable and uniform protection of organometallic catalysts, preventing decomposition and destabilization, thereby facilitating effective polymerization of ethylenically unsaturated monomers in an aqueous medium.
Implementation Method 1
the incorporation of an organometallic catalyst component into a protective substance, which can be a low molecular weight amorphous saturated polymer or macromonomer, protects the organometallic catalyst component from decomposition during and after formation of an aqueous dispersion
Implementation Method 2
protects droplets containing the organometallic catalyst component from becoming destabilized
Data Source
AI summary
A method for polymerizing ethylenically unsaturated monomers, including non-polar olefinic monomers, polar olefinic monomers, and combinations thereof, using a protected catalytic composition in an aqueous medium, is disclosed. An aqueous dispersion containing the protected catalytic composition is also disclosed, along with an aqueous dispersion of the addition polymer produced by the polymerization.