Water-Soluble Polyimide Synthesis via Stoichiometric Salts
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Solution Overview
Problem
Existing methods for preparing polyimides often require organic solvents and do not effectively utilize water-soluble monomer salts, limiting the production of high-quality polyimides with desirable properties.
Innovation Solution
Development of novel stoichiometric salts of tetracarboxylic acids and diamines, specifically those with specific structural formulas, which are water-soluble and can be used to form polyimides without organic solvents, utilizing a process that involves mixing tetracarboxylic acids or dianhydrides with diamines in a solvent and isolating the stoichiometric salt, followed by polycondensation in an aqueous solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional polyimide synthesis methods are used, then polyimides can be produced, but organic solvents are required which are harmful to the environment and increase process complexity
Solution Approach 1:
The invention changes the solvent parameter from organic solvents to water by designing monomer salts with specific molecular structures (combining hydrophobic aromatic rings with hydrophilic ammonium groups) that enable water solubility. This allows the polycondensation reaction to proceed in aqueous media, eliminating organic solvents while maintaining process feasibility.
Solution Approach 2:
The invention introduces monomer salts as intermediary compounds that bridge the gap between hydrophobic monomers and water. These salts contain both hydrophobic aromatic portions (from tetracarboxylic acids and diamines) and hydrophilic ammonium groups, acting as mediators that enable water solubility while preserving the ability to form polyimide structures.
2Object-affected harmful factors
If water-soluble monomer salts are used, then organic solvents can be eliminated, but finding suitable water-soluble salt combinations is difficult and limits material options
Solution Approach 1:
The invention creates a universal platform for water-soluble polyimide synthesis by establishing that monomer salts containing aromatic rings combined with ammonium groups can be made water-soluble through appropriate counterion selection. This universal approach enables multiple different aromatic diamine and tetracarboxylic acid combinations to form water-soluble salts, greatly expanding material options beyond single specific compounds.
Solution Approach 2:
The invention changes the solubility parameter of monomer salts by selecting appropriate counterions (such as sulfonate, carboxylate, or halide ions) that enhance water solubility while maintaining the aromatic character of the monomers. This allows a wide variety of aromatic diamine and tetracarboxylic acid combinations to form water-soluble salts.
3Adaptability or versatility
If non-water-soluble monomer salts are used, then a wider range of monomer combinations can be utilized, but organic solvents must be used which create environmental issues
Solution Approach 1:
The invention changes the solubility parameter of monomer salts by introducing hydrophilic counterions (such as sulfonate, carboxylate, or halide ions) that enable water solubility. This allows aromatic diamine and tetracarboxylic acid combinations to form water-soluble salts, eliminating the need for organic solvents while maintaining material versatility.
4Object-generated harmful factors
If aqueous solutions of monomer salts are used for polycondensation, then only water vapor is produced as by-product, but the solubility of salts must be enhanced which requires specific structural design
Solution Approach 1:
The invention changes the molecular structure parameter of monomer salts by combining hydrophobic aromatic portions with hydrophilic ammonium groups and appropriate counterions. This structural design enables water solubility while maintaining the ability to undergo polycondensation, allowing aqueous processing with water vapor as the only by-product.
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 allows for the production of high-quality, water-soluble polyimides with improved film-forming properties and environmental benefits, as it eliminates the need for organic solvents and enhances the solubility of salts, particularly when using aliphatic diamines with chain lengths of 4 to 9 carbon atoms or alicyclic diamines as mixtures of isomers.
Implementation Method 1
the anhydrides undergo hydrolysis to form the free tetracarboxylic acids
Implementation Method 2
the coating can be dried by heating and imidized at the same time, with only water vapor as a by-product
Data Source
AI summary
The invention relates to a stoichiometric salt of a tetracarboxylic acid and a diamine of the following general formula (I),wherein R1 is selected from tetravalent residues of butane, cyclobutane, cyclopentane, cyclohexane, tetrahydrofurane and benzophenone and R2 is selected from divalent residues of unbranched, branched or cyclic aliphatic hydrocarbons with 3 to 15 carbon atoms, with the proviso that the salt of the formula (I) is water-soluble and is selected from compounds (1) to (28); and to the polyimides prepared from these salts by polycondensation.