Thermoplastic Polyimide Synthesis via Solid-State Polymerization
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Solution Overview
Problem
Existing methods for synthesizing semi-aromatic polyimides face challenges such as the use of carcinogenic and environmentally harmful solvents, thermal degradation, and difficulty in controlling molar mass and viscosity, which affect the quality and processing costs of polyimide products.
Innovation Solution
A process involving solid-state polymerization of a solid salt of ammonium carboxylate formed from an aliphatic diamine and an aromatic tetracarboxylic acid is used to produce semi-crystalline thermoplastic polyimides with controlled particle sizes, avoiding the use of toxic solvents and reducing thermal degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solution synthesis using aromatic diamines and aromatic dianhydrides is used, then polyimides with remarkable thermal and mechanical properties are obtained, but carcinogenic solvents and toxic monomers must be used
Solution Approach 1:
The invention changes the chemical parameters by replacing aromatic diamines with aliphatic diamines and aromatic dianhydrides with aromatic tetracarboxylic acids, fundamentally altering the monomer structure to eliminate carcinogenicity while maintaining polyimide performance
Solution Approach 2:
The invention uses water as a solvent instead of toxic organic solvents, replacing harmful substances with a safe, inexpensive, and environmentally friendly alternative that can be easily removed
2Ease of operation
If melt polymerization between 275 and 290°C is used to make polyimides fusible, then processing by extrusion or injection molding is enabled, but rapid degradation reactions occur and aromatic diamines must be used
Solution Approach 1:
The invention changes the polymerization temperature parameter from 275-290°C to a lower range of 80-200°C, which prevents degradation reactions while still achieving fusible polyimide properties through solid-state polymerization
Solution Approach 2:
The invention utilizes solid-state polymerization, where the polymerization occurs in the solid phase rather than molten state, allowing chain growth without requiring high temperatures that cause degradation
3Ease of operation
If amorphous polyimides with Tg close to 200°C are used, then fusibility is achieved, but mechanical strength is lost when operating temperature exceeds Tg
Solution Approach 1:
The invention changes the structural parameters by using aliphatic diamines with controlled chain length and flexibility, which enable crystalline or semi-crystalline polyimide structures that maintain strength at elevated temperatures while remaining processable
Solution Approach 2:
The invention creates polyimides with composite molecular structures combining rigid aromatic tetracarboxylic acid units with flexible aliphatic diamine chains, achieving a balance between processability and high-temperature mechanical strength
4Manufacturing precision
If solid-state polymerization of salt from aliphatic diamine and aromatic tetracarboxylic acid is used, then polyimides with controlled particle sizes and stable viscosity are obtained without toxic solvents, but the process requires precise temperature control
Solution Approach 1:
The invention utilizes the self-regulating nature of solid-state polymerization where the reaction proceeds at controlled rates within the 80-200°C range without requiring complex external control systems, as the solid phase naturally limits reaction speed and heat generation
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 process enables the production of polyimides with stable relative viscosity and molar mass, suitable for various applications including composite manufacturing and cosmetics, while avoiding the use of harmful solvents and minimizing thermal degradation.
Implementation Method 1
solid-state polymerization of a solid ammonium carboxylate salt formed from an aliphatic diamine and an aromatic tetracarboxylic acid
Implementation Method 2
produce semi-crystalline thermoplastic polyimides
Implementation Method 3
at a temperature T obeying the following relationship: Tf of the salt from step (a) > T > Tg of the (co)polyimide (I) to be obtained
Data Source
AI summary
The present invention relates to thermoplastic polyimides and to the synthesis thereof. The invention relates in particular to a method for manufacturing semi-aromatic thermoplastic polyimides by means of the solid-state polymerization of a solid ammonium carboxylate salt formed from an aliphatic diamine and an aromatic tetracarboxylic acid, thereby enabling powders having controlled particle sizes to be produced.