Fluorinated Polymer Composition for Molecular Weight Stability
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Solution Overview
Problem
The synthesis of fluorinated polymers with dioxolane ring structures faces challenges due to the generation of impurities, which hinder the achievement of high molecular weight and lead to reduced yields and susceptibility to molecular weight decrease during polymerization and base contact.
Innovation Solution
A method involving the polymerization of a raw material mixture containing perfluoromoners and fluorinated monomers with hydrogen-substituted fluorine atoms, within specific ppm ranges, to efficiently utilize the monomers and control molecular weight, without the need for chain transfer agents, and to minimize molecular weight loss when contacted with a base.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the PDD-H monomer is sufficiently removed by purification methods such as distillation to increase the purity of the PDD monomer, then the molecular weight of the polymer can be made high, but the PDD monomer will be lost much during the purification and the yield of the PDD monomer will be largely lowered
Solution Approach 1:
The invention changes the parameter of PDD-H monomer content from being removed to being controlled at a specific level (5-500 ppm). Instead of pursuing complete removal through multiple purification steps that cause monomer loss, the invention establishes that a controlled presence of PDD-H monomer within this range is sufficient to prevent main chain decomposition while maintaining high polymer molecular weight and product yield.
2Manufacturing precision
If a highly pure PDD monomer is used for the polymerization, then the molecular weight of the fluorinated polymer tends to be high, but a chain transfer agent or the like will be required at the time of the polymerization in order to make the molecular weight of the fluorinated polymer within a proper range
Solution Approach 1:
The invention employs the PDD-H monomer itself as a chain transfer agent. The PDD-H monomer present in the reaction mixture (at 5-500 ppm) performs chain transfer during polymerization, automatically controlling the molecular weight of the fluorinated polymer to an appropriate range without requiring external chain transfer agents or additional process steps.
3Manufacturing precision
In a case where the precursor fluorinated polymer has units based on a PDD-H monomer, there have been such cases that the molecular weight of the fluorinated polymer has tended to be lowered due to the action of the base
Solution Approach 1:
The invention applies preliminary anti-action by having the PDD-H monomer units incorporated into the polymer chain during synthesis. These PDD-H units preemptively protect the polymer main chain from base-induced decomposition by providing hydrogen atoms that prevent the formation of decomposition sites, thereby maintaining molecular weight stability even when the polymer is contacted with bases during subsequent processing.
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 allows for the production of fluorinated polymers with controlled molecular weight and stability, even when exposed to bases, enhancing their properties and application in fuel cells and other membrane systems.
Implementation Method 1
comprising polymerizing a raw material mixture containing at least one of a monomer composition M11 which comprises a perfluoromonomer represented by the following formula m11 and a fluorinated monomer m11H having at least some of fluorine atoms in the perfluoromonomer substituted by hydrogen atoms
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 mil H 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.