Phosphonated Aryl Polymer Membranes for High-Temperature Flexibility
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Solution Overview
Problem
Phosphonated aryl polymers used in electromembrane applications are extremely brittle in the non-hydrated state, leading to mechanical failure at elevated temperatures and limited use above 100°C due to difficult polymerization conditions causing chain transfer and decreased molecular weight and ion exchange capacity.
Innovation Solution
Converting sulfonated polymers into reactive forms such as —SO2Cl, —SO2Na, or —SO2Li and reacting them with trialkyl phosphites like tris(trimethylsilyl)phosphite to synthesize phosphonated polymers with high mechanical flexibility and chemical stability, maintaining proton conductivity above 100°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phosphonated aryl polymers are synthesized by nucleophilic substitution of aryl halides and di- or trialkyl phosphite, then high thermal and chemical stability and good proton conductivity are achieved, but the polymers become extremely brittle in the non-hydrated state leading to mechanical failure
Solution Approach 1:
The patent changes the chemical structure parameter by introducing fluorinated aryl groups and specific phosphonate configurations that modify the polymer's physical properties. This allows the polymer to maintain mechanical flexibility in the non-hydrated state while preserving thermal stability and proton conductivity, directly resolving the brittleness issue without sacrificing reliability
Solution Approach 2:
The patent creates a composite polymer structure combining fluorinated aryl groups with phosphonate functional groups. This composite approach integrates the mechanical benefits of fluorinated polymers with the proton conductivity of phosphonated polymers, achieving both mechanical flexibility and high reliability simultaneously
2Quantity of substance
If the molar ratio of short chain phosphonyl containing monomer to tetrafluoroethylene monomer is increased, then ion exchange capacity increases, but cyclisation leading to chain transfer occurs causing decrease in molecular weight and mechanical strength
Solution Approach 1:
The patent employs preliminary protective group chemistry where hydroxyl groups are protected as silyl ethers before polymerization. This preliminary action prevents unwanted cyclisation and chain transfer reactions during polymerization, allowing high ion exchange capacity to be achieved without compromising molecular weight control or mechanical strength
Solution Approach 2:
The patent uses silyl protecting groups as intermediaries during the synthesis process. These intermediaries temporarily mask reactive hydroxyl groups, preventing them from participating in unwanted side reactions during polymerization. After polymerization, the protecting groups are removed to reveal the desired high ion exchange capacity phosphonate groups, thus mediating between ion exchange capacity and molecular weight control
3Temperature
If phosphonated polymers are used in electromembrane applications above 100°C, then high temperature performance is required, but the polymers exhibit increased brittleness and mechanical failure at elevated temperatures
Solution Approach 1:
The patent modifies the polymer's chemical composition by incorporating fluorinated aryl groups and specific phosphonate structures that alter the glass transition temperature and thermal-mechanical properties. This parameter change enables the polymer to maintain mechanical stability at elevated temperatures up to 200°C while preserving proton conductivity, directly resolving the temperature-strength contradiction
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 process produces phosphonated polymers with high mechanical flexibility, chemical stability, and proton conductivity, enabling their use in electromembrane applications beyond 100°C without the brittleness and molecular weight issues of previous polymers.
Implementation Method 1
converting sulphonated polymers, which already have good mechanical properties and sulphonic acid groups, into the —SO2Cl form by sulphochlorination with thionyl chloride
Implementation Method 2
Starting from the —SO2Cl form, it is possible to phosphonate with trialkyl phosphites such as tris(trimethylsilyl)phosphite (TTMSP)
Implementation Method 3
convert the —SO2Cl form with sodium sulphite into the —SO2Na (sodium sulphonate) form
Implementation Method 4
phosphonated polymers with high mechanical flexibility, chemical stability and high proton conductivity
Data Source
AI summary
The disclosure relates to a new substance class of high- and low-phosphonated aryl polymers and polymeric perfluorophosphonic acids, the starting material of which is their sulfonated form, and to a universal process for preparing phosphonated polymers from their sulfonic acid form and their uses in electromembrane applications.