Fluorinated Polymerization Using PDD-H for Molecular Weight Control
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Solution Overview
Problem
The synthesis of fluorinated polymers with dioxolane ring structures faces challenges in achieving high molecular weight due to the generation of impurities during the polymerization process, leading to reduced yields and susceptibility to molecular weight decrease when contacted with bases, particularly in the production of fluorinated ion exchange polymers.
Innovation Solution
A method involving the polymerization of a raw material mixture containing perfluoromoners and their hydrogen-substituted counterparts within specific concentration ranges, without the need for chain transfer agents, to efficiently control molecular weight and maintain polymer integrity when exposed to bases.
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 process, resulting in largely lowered yield of the PDD monomer
Solution Approach 1:
The invention converts the harmful impurity (PDD-H monomer) into a beneficial component by intentionally introducing it in controlled amounts during polymerization. This eliminates the need for extensive purification that causes monomer loss, while still achieving desired polymer properties through controlled impurity utilization.
Solution Approach 2:
The invention changes the parameter of PDD-H monomer content from being minimized (as an impurity to be removed) to being controlled within specific ranges (10-1000 ppm). This parameter change allows optimization of both polymerization efficiency and final polymer molecular weight without requiring high-purity monomer separation.
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 uses the PDD-H monomer impurity as a natural chain transfer agent. By controlling its amount to 10-1000 ppm, the polymerization process achieves proper molecular weight control without requiring additional chain transfer agents, simplifying the overall process.
Solution Approach 2:
The polymerization system uses its own impurity (PDD-H monomer) to perform the function of molecular weight control. The PDD-H monomer acts as a self-regulating chain transfer agent, eliminating the need for external additives and reducing process complexity.
3Ease of manufacture
If the precursor fluorinated polymer has units based on a PDD-H monomer, then 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 during hydrolysis
Solution Approach 1:
The invention optimizes the PDD-H monomer content parameter to a specific range (10-1000 ppm) that prevents excessive base-catalyzed degradation during hydrolysis. This controlled parameter ensures that the polymer maintains proper molecular weight while still allowing complete conversion of precursor groups to ion exchange groups.
Solution Approach 2:
The invention prepares the polymer with an optimal amount of PDD-H units before the hydrolysis step. These units act as a cushion against base-catalyzed degradation, preventing excessive molecular weight loss during the subsequent ion exchange group formation process.
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 efficient utilization of PDD monomers, maintaining high molecular weight fluorinated polymers and their ion exchange counterparts, even when contacted with bases, thereby enhancing the production yield and stability of the polymers.
Implementation Method 1
polymerizing a monomer component containing a ring-structured monomer
Implementation Method 2
converting the precursor groups to ion exchange groups. For example, —SO2F can be converted to a sulfonic acid group via a hydrolysis step using a base
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.