Polyimide Copolymer Alicyclic Ether Structure
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Solution Overview
Problem
Polyimide copolymers exhibit low transmittance in the visible light region due to their high-density aromatic ring structure, limiting their application in fields requiring transparency and high transmittance, such as flexible displays and solar panels.
Innovation Solution
A polyimide copolymer is developed with structural units derived from dianhydride and aromatic diamine, incorporating an alicyclic structure and ether groups to suppress charge transfer complexes, enhancing optical characteristics and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a high-density aromatic ring structure is used in polyimide copolymer, then heat resistance and mechanical properties are improved, but transmittance in the visible light region is reduced
Solution Approach 1:
The patent changes the chemical structure parameters by introducing alicyclic structures (aliphatic rings) instead of traditional aromatic rings, and incorporates ether groups and fluorine atoms. This structural parameter change reduces electron cloud conjugation and light absorption in the visible region, thereby improving transmittance while maintaining mechanical strength and heat resistance through the rigid alicyclic framework
Solution Approach 2:
The patent creates a composite molecular structure combining alicyclic rings, aromatic rings, ether groups, and fluorine atoms within the polyimide backbone. This composite structure leverages the rigidity of alicyclic rings for mechanical strength, the thermal stability of aromatic rings for heat resistance, and the light-transmitting properties of ether groups and fluorine atoms for high transmittance
2Temperature
If aromatic ring structure is increased to improve heat resistance, then thermal stability is enhanced, but the polyimide copolymer becomes colored and transmittance is reduced
Solution Approach 1:
The patent fundamentally changes the chromophore structure by replacing traditional aromatic ring systems with alicyclic structures containing ether groups. This parameter change eliminates the extended π-conjugation system that causes light absorption and coloration, while the alicyclic framework with fluorine substitution maintains high thermal stability and resistance to degradation at elevated temperatures
3Reliability
If traditional polyimide structure is used to ensure mechanical strength, then durability is improved, but optical characteristics such as transmittance and yellow index are deteriorated
Solution Approach 1:
The patent modifies the polyimide backbone structure by incorporating alicyclic rings with specific substitution patterns and fluorine atoms at strategic positions. These structural parameter changes reduce chain packing density and eliminate chromophoric groups, achieving yellow index ≤4.5 and high transmittance while the rigid alicyclic structure maintains mechanical durability and resistance to environmental degradation
Data Source
Figure 1~2
Figure 3
AI summary
Embodiments of the present invention provide a polyimide copolymer including a plurality of structural units and a polyimide film including the same. The plurality of structural units include a structural unit derived from dianhydride having an alicyclic structure and a structural unit derived from aromatic diamine including an ether group, thereby mechanical properties, thermal stability and optical characteristics of the polyimide film may be improved.