Cross-linked Polymer Composition with Exchangeable Imine Bonds
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Solution Overview
Problem
Existing polymer compositions fail to combine the mechanical properties of thermosets with the processability of thermoplastics, as they either lack the ability to be transformed after hardening or suffer degradation when heated, and often require primary amines that induce unwanted reactions.
Innovation Solution
Development of cross-linked polymer compositions with exchangeable aldehyde-imine or imine-imine links, formed through aldehyde-imine or imine-imine exchange reactions, which do not require primary amines and can be modified to exhibit thermoplastic behavior, allowing for transformation at elevated temperatures without structural degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If cross-linked polymer compositions are used to achieve mechanical properties of thermosets, then strength and stability are improved, but the ability to be transformed after hardening is lost
Solution Approach 1:
The patent applies dynamics by introducing dynamic covalent bonds (imine and aldehyde functions) into the cross-linked network. These bonds can reversibly break and reform under external stimuli such as heat, allowing the rigid thermoset structure to become temporarily flexible for reshaping, then re-harden upon cooling. This enables the material to switch between rigid and flexible states, resolving the contradiction between strength and transformability.
Solution Approach 2:
The patent utilizes parameter changes by controlling the equilibrium between bonded and unbonded states through temperature variations. At elevated temperatures, the equilibrium shifts toward bond dissociation, enabling flow and reshaping. At service temperatures, the bonds remain intact, providing structural strength. This temperature-dependent parameter change allows the material to exhibit both thermoset strength and thermoplastic processability.
2Productivity
If primary amines are used to form cross-links, then cross-linking efficiency is improved, but unwanted reactions and degradation occur
Solution Approach 1:
The patent extracts the problematic primary amine component from the system and replaces it with alternative cross-linking mechanisms using imine and aldehyde functions. This removal eliminates the source of unwanted reactions such as degradation and side reactions, while maintaining cross-linking efficiency through the dynamic covalent chemistry of the imine-aldehyde exchange reactions.
Solution Approach 2:
The patent employs transient imine bonds that can form and break reversibly during processing. These short-lived dynamic bonds allow for efficient cross-linking during formation, then can be temporarily disrupted for reshaping, and finally reformed to restore structural integrity. This disposable-like behavior of the dynamic bonds enables multiple processing cycles without permanent degradation.
3Ease of operation
If polymers are heated for transformation, then processability is improved, but structural degradation occurs
Solution Approach 1:
The patent applies dynamics by utilizing the temperature-dependent reversibility of the imine-aldehyde bonds. During heating for transformation, the dynamic bonds reversibly break, allowing the polymer to flow and be reshaped without permanent degradation. Upon cooling, the bonds reform, restoring the structural integrity. This dynamic behavior enables processing at elevated temperatures while maintaining composition stability.
Solution Approach 2:
The patent provides beforehand cushioning by designing a cross-linked network with built-in reversible bond exchange capability. This pre-configured dynamic architecture cushions the material against thermal degradation by allowing controlled bond breaking and reforming, preventing irreversible damage while enabling thermal processing. The dynamic bonds act as a buffer that protects the overall structure during thermal cycles.
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 polymer compositions achieve mechanical properties similar to thermosets while being recyclable and transformable at high temperatures, maintaining structural integrity and mechanical properties, thus combining the benefits of both thermosets and thermoplastics.
Implementation Method 1
the imine metathesis reaction enables an exchange reaction between the substituents carried by the imines
Implementation Method 2
the imine-aldehyde exchange reaction enables an exchange reaction between the substituents carried by the imines and the aldehydes
Data Source
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AI summary
The object of the invention is a composition comprising (a) cross-linked polymers containing pending links and cross-links that are exchangeable by aldehyde–imine exchange reactions and/or by imine–imine exchange reactions, obtained by cross-linking of linear or branched polymers; and (b) free monofunctional aldehydes and/or free monofunctional imines. Another object of the invention is preparation processes of such a composition and the uses of the composition. Another object of the invention is compositions for cross-linking linear or branched polymers and their use to form a composition comprising cross-linked polymers containing pending links and cross-links that are exchangeable by aldehyde–imine exchange reactions and/or by imine–imine exchange reactions. Finally, an object of the invention is the use of aldehyde to catalyse imine–imine metathesis reactions and imine–aldehyde exchange reactions.