Aqueous Polyamic Acid Gel Synthesis Using Carbonate Salts
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Solution Overview
Problem
Current methods for preparing polyamic acid and polyimide gel materials rely on organic solvents and reagents, which are environmentally harmful and costly, and do not allow for the formation of mechanically robust and transparent polyimides.
Innovation Solution
The use of water-soluble carbonate or bicarbonate salts to form polyamic acid salts in aqueous solutions, allowing for the conversion to polyimide gels and carbon aerogels without the need for organic solvents, using a reaction between a water-soluble diamine and a tetracarboxylic acid dianhydride, resulting in mechanically robust and optically transparent polyimides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If organic solvents and reagents are used to prepare polyamic acid and polyimide gel materials, then the formation of polyimides is achieved, but environmental harm and cost increase
Solution Approach 1:
The patent changes the fundamental parameter of the reaction medium from organic solvent to water. By using water-soluble carbonate or bicarbonate salts as reagents instead of organic bases, the process transforms from harmful to environmentally benign while maintaining polyimide formation capability
Solution Approach 2:
The patent replaces expensive organic solvents and reagents with water and inexpensive carbonate/bicarbonate salts. This substitution reduces both material cost and environmental impact, making the process economically and ecologically advantageous
2Ease of manufacture
If organic solvents are used to prepare polyimide gel materials, then polyimide formation is achieved, but mechanical robustness and optical transparency are not obtained
Solution Approach 1:
The patent changes the reaction medium parameter from organic to aqueous, which fundamentally alters the polyimide formation process. This parameter change leads to superior mechanical robustness and optical transparency in the resulting polyimide materials
Solution Approach 2:
The patent uses water-soluble carbonate or bicarbonate salts as intermediary reagents that facilitate polyimide formation in aqueous media. These intermediaries enable the reaction to proceed in water while producing high-quality polyimides with enhanced mechanical and optical properties
3Productivity
If conventional organic solvent-based methods are used, then polyimide production is achieved, but environmental impact increases and costs increase
Solution Approach 1:
The patent fundamentally changes the reaction medium parameter from organic solvent to water, transforming the entire production process. This parameter change eliminates environmental harm while maintaining productive polyimide synthesis through water-soluble reagents
Solution Approach 2:
The patent replaces costly organic solvents with water and inexpensive carbonate/bicarbonate salts, reducing both material costs and environmental impact while sustaining efficient polyimide production
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 method enables the production of polyimides with properties similar to those produced by conventional organic solvent-based methods, while minimizing environmental impact and reducing costs by eliminating the use of harmful solvents and reagents, and allows for the formation of carbon aerogels with preserved physical properties.
Implementation Method 1
combining in water a water-soluble diamine, a water-soluble carbonate or bicarbonate salt, and a tetracarboxylic acid dianhydride; and allowing the components to react, providing the solution of the polyamic acid salt
Implementation Method 2
formation of the wet gel (may involve additional heating or cooling steps)
Implementation Method 3
solvent removal by a supercritical drying technique or any other method that removes solvent from the gel without causing contraction or pore collapse
Implementation Method 4
supercritical drying (or drying using supercritical fluids, such that a low surface tension supercritical fluid replaces the high surface tension gelation solvent within the gel)
Implementation Method 5
solvent removal by a supercritical drying technique
Implementation Method 6
sublimating a frozen solvent in a freeze-drying process
Implementation Method 7
sublimating a frozen solvent in a freeze-drying process
Implementation Method 8
converting the polyamic acid or polyimide aerogel to an isomorphic carbon aerogel
Data Source
AI summary
The present disclosure is directed to methods of forming polyamic acid, polyamic acid metal salt, and polyimide gels under aqueous conditions, the methods utilizing water-soluble carbonate or bicarbonate salts. These gels may be converted to aerogels or xerogels, which may further be converted to carbon aerogels or xerogels. Such carbon aerogels or xerogels have the same physical properties as carbon aerogels or xerogels prepared from polyimide aerogels obtained according to conventional methods, i.e., organic solvent-based methods.