Reprocessable Polymeric Networks via Dynamic Covalent Bonds
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Solution Overview
Problem
Current polymer materials, such as thermosets, lack the ability to be reshaped or recycled after full curing due to their rigid molecular architecture, while thermoplastics cannot match the mechanical properties of thermosets, presenting a challenge in developing materials that combine the benefits of both.
Innovation Solution
The development of polymeric networks with vinylogous-urethane, vinylogous-amide, or vinylogous-urea units that exhibit chemical reversibility, allowing for flow at elevated temperatures without losing insolubility, enabling the creation of materials with high mechanical properties and the ability to be reshaped or recycled.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermosetting polymers are used to achieve high mechanical properties and dimensional stability, then strength and stiffness are improved, but the ability to be reshaped or recycled is lost
Solution Approach 1:
The patent applies dynamic covalent chemistry by incorporating bonds that can reversibly break and reform under specific conditions (heat, catalyst). This allows the polymer network to transition from a static, rigid structure to a dynamic, reconfigurable one, enabling reshaping while maintaining mechanical integrity. The dynamic bonds provide temporary flexibility for processing while preserving the permanent crosslinked network structure for final performance.
Solution Approach 2:
The patent utilizes changes in physical parameters (temperature, catalyst presence) to control the state of the polymer network. At elevated temperatures or in the presence of catalysts, the dynamic bonds become labile allowing flow and reshaping. Upon cooling or catalyst removal, the bonds stabilize and the material regains its rigid, high-strength properties. This parameter-dependent behavior resolves the contradiction between processability and mechanical performance.
2Ease of manufacture
If thermoplastics are used to enable multiple processing and recycling, then ease of manufacture is improved, but mechanical properties and dimensional stability deteriorate
Solution Approach 1:
The patent creates a composite molecular architecture that combines features of both thermosets and thermoplastics. The permanent crosslinked network provides the structural framework for high mechanical properties, while the dynamic bonds introduce thermoplastic-like reconfigurability. This molecular-level composite structure allows the material to exhibit both the strength of thermosets and the processability of thermoplastics under appropriate conditions.
3Reliability
If permanent crosslinks are introduced to achieve high strength and creep resistance, then reliability is improved, but the ability to flow upon heating is lost
Solution Approach 1:
The patent introduces dynamic character to the permanent crosslinks by using bonds that can reversibly break and reform. These dynamic crosslinks maintain the permanent network structure for creep resistance and dimensional stability, but can temporarily open under heat or catalysis to allow flow and processing. This dynamic permanence resolves the contradiction between structural integrity and thermal processability.
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
These materials maintain high mechanical properties and can be reworked into new shapes while remaining permanently cross-linked, bridging the processing limitations of thermosets and recyclability of thermoplastics.
Implementation Method 1
These bonds should be able to rearrange themselves in a reversible manner, providing on a molecular level a mechanism for macroscopic flow
Implementation Method 2
Polymer networks containing such exchangeable bonds, also known as covalent adaptable networks or CAN's
Implementation Method 3
Interestingly, as with all chemical reactions, the rate of this associative exchange increases with the temperature, leading to an Arrhenius-like viscosity dependence rather than a sudden and marked viscosity drop at the sol/gel transition
Data Source
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AI summary
The present invention relates to a composition comprising a polymeric network having at least one unit of formula (I), (II), and/or (III); (I) (II) (III) wherein said composition is obtained by contacting at least one compound A comprising at least two functions selected from the group of function of formula X-C(=O)-CHR1-C(=O)-R2, -C(=O)-C -R2; or -C(=O)-CR1=CR2-NR4R5; wherein at least 25 % by weight of compounds A have a functionality ≤5, with % by weight relative to the total weight of compounds A; with at least one compound B comprising at least one NH2, or NH3 + groups; wherein X, R1, R2, R3, R4, R5, L1 and L2 have the same meaning as that defined in the claims. The present invention also relates to a compound comprising at least two units and at most 5 units of formula (I), (II), and/or (III); wherein R1, R2, R3, X, L1 and L2 have the same meaning as that defined in the claims. The present invention also relates to processes for preparing said composition and said compounds, to material, articles, and polymers comprising or using said compositions and compounds, and the use thereof.