Fluorinated Polymer Composition for Molecular Weight Control
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Solution Overview
Problem
The production of fluorinated polymers with dioxolane ring structures faces challenges in maintaining molecular weight due to the presence of impurities like PDD-H monomers, which are difficult to remove without significant loss of the PDD monomer, and the molecular weight is susceptible to decrease when contacted with bases during ion exchange group conversion.
Innovation Solution
A method is developed to efficiently utilize PDD monomers by controlling molecular weight through the inclusion of fluorinated monomers m11H and m12H, which act as chain transfer agents, reducing the need for separate purification and minimizing molecular weight loss during base contact, while maintaining high molecular weight polymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If PDD-H monomer is removed by purification methods such as distillation to increase purity, then the purity of PDD monomer is improved, but the yield of PDD monomer is largely lowered due to loss during purification
Solution Approach 1:
The invention converts the harmful impurity PDD-H monomer into a beneficial chain transfer agent. By controlling its content to be greater than 0 and less than or equal to 500 ppm, the PDD-H monomer that would otherwise need to be removed through lossy purification processes now serves to control molecular weight during polymerization, eliminating the need for extensive purification while maintaining product quality.
2Manufacturing precision
If highly pure PDD monomer is used for polymerization, then the molecular weight of fluorinated polymer tends to be high, but a chain transfer agent will be required to make the molecular weight within proper range
Solution Approach 1:
The PDD-H monomer serves multiple functions simultaneously: it acts as both a chain transfer agent to control molecular weight and as part of the polymer structure. This multi-functionality eliminates the need for separate chain transfer agents and extensive purification processes, simplifying the overall polymerization system.
3Loss of substance
If precursor fluorinated polymer contains units based on PDD-H monomer, then the molecular weight of fluorinated polymer tends to be lowered due to base action during hydrolysis, but complete removal of PDD-H monomer requires lossy purification
Solution Approach 1:
The invention changes the parameter of PDD-H monomer content from being minimized (near zero) to being controlled within a specific range (greater than 0 and less than or equal to 500 ppm). This parameter change allows the system to benefit from the molecular weight controlling effect of PDD-H during polymerization while limiting its negative impact during subsequent base treatment.
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
The method allows for the production of fluorinated polymers with controlled molecular weight and stability against molecular weight reduction, even when exposed to bases, enhancing the yield and quality of fluorinated ion exchange polymers.
Implementation Method 1
the PDD monomer can be efficiently utilized, the molecular weight can be easily controlled to a proper level
Implementation Method 2
a base is used at the time when the precursor groups are hydrolyzed to be converted to ion exchange groups
Data Source
AI summary
To provide a method for producing a fluorinated polymer, in which it is possible to efficiently and easily control the molecular weight to be proper when polymerizing a perfluoromonomer having a dioxolane ring containing a polymerizable double bond in the ring skeleton, and in which the obtainable fluorinated polymer is less susceptible to a decrease in molecular weight even when contacted with a base. A method for producing a fluorinated polymer, comprising polymerizing a raw-material mixture which contains at least one of a monomer composition M11 which comprises a perfluoromonomer represented by the formula m11 and a fluorinated monomer m11H having at least some of fluorine atoms of said perfluoromonomer substituted by hydrogen atoms, and a monomer composition M12 which comprises a perfluoromonomer represented by formula m12 and a fluorinated monomer m12H having at least some of fluorine atoms of said perfluoromonomer substituted by hydrogen atoms, wherein the total amount of the fluorinated monomer m11H and the fluorinated monomer m12H is from 10 to 1,100 ppm to the total amount of the monomer composition M11 and the monomer composition M12.