Ortho-Hydroxy Diamine Polyimides for Gas Separation Membranes
Solution Overview
Problem
The synthesis of microporous polyimides is challenging due to limitations in suitable reagents, and existing polyimides exhibit poor processability due to high melting points and limited solubility in organic solvents, hindering their industrial applications.
Innovation Solution
The development of aromatic ortho-hydroxy-functionalized diamines and their use in synthesizing polyimides through specific reaction sequences, including acetylation, Baeyer-Villiger oxidation, hydrolysis, nitration, and reduction, to produce high-performance polyimides suitable for gas separation membranes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polyimides are used to achieve high thermal and mechanical stability, then excellent thermal and mechanical properties are obtained, but poor processability occurs due to high melting points and limited solubility
Solution Approach 1:
The patent introduces microporous structures into polyimide membranes through controlled phase separation during synthesis. The porous architecture provides free volume that facilitates gas permeation while maintaining the thermal and mechanical stability of the polyimide matrix, thus resolving the contradiction between reliability and processability for membrane applications
Solution Approach 2:
The patent modifies the chemical structure of polyimides by incorporating specific diamine monomers with flexible spacers and aromatic rings. This changes the physical parameters such as glass transition temperature, free volume, and chain flexibility, enabling the material to maintain high thermal stability while improving processability through better solvent compatibility and reduced melting temperature
2Productivity
If microporous polyimides are synthesized to improve gas permeability, then separation performance is enhanced, but synthesis difficulty increases due to limitations of suitable reagents
Solution Approach 1:
The patent divides the synthesis process into modular stages: first synthesizing the core diamine structure, then introducing hydroxy functional groups, and finally polymerizing with dianhydrides. This segmentation allows each step to be optimized independently, making the overall synthesis of microporous polyimides more manageable and less difficult
Solution Approach 2:
The patent uses ortho-hydroxy-functionalized diamines as intermediary compounds that bridge the gap between conventional diamines and the desired microporous polyimide structure. These intermediaries contain both the aromatic core for structural stability and hydroxy groups that facilitate micropore formation, simplifying the synthesis pathway
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 resulting polyimides demonstrate enhanced permeability and selectivity, making them economically attractive for industrial applications such as gas separation, reducing capital costs and energy consumption, and improving separation efficiency in processes like nitrogen enrichment and hydrogen recovery.
Implementation Method 1
A includes acetylation of the bulky starting structures by Friedel-Crafts reaction
Implementation Method 2
B includes transferring the diacetyl intermediate to diester via Baeyer-Villiger oxidation reaction
Implementation Method 3
C includes the hydrolysis of the diester
Implementation Method 4
D includes the nitration of the diphenol intermediate
Implementation Method 5
E includes the reduction of the ortho-diphenol-dinitrol intermediate to the corresponding ortho-hydroxy-functionalized diamine
Data Source
AI summary
Embodiments of the present disclosure provide for an ortho (o)-hydroxy-functionalized diamine, a method of making an o-hydroxy-functionalized diamine, an o-hydroxy-functionalized diamine-based polyimide, a method of making an o-hydroxy-functionalized diamine imide, methods of gas separation, and the like.