Degradable Polyimide Substrates for Recyclable Flexible Electronics
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Solution Overview
Problem
Current flexible electronic substrates, such as Dupont Kapton®, are difficult to recycle due to high heat requirements and non-degradability, leading to significant electronic waste accumulation, as they do not easily break down to recover precious metals and polymers, hindering the recycling of electronic devices.
Innovation Solution
Development of degradable polyimide substrates using thiol-ene click chemistry, which can be processed with UV or visible light and thermally degraded at mild conditions to yield reusable monomer units, allowing for the formation of similar polymers, thus enabling recycling of electronic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polyimide substrates (e.g., Dupont Kapton®) are used for flexible electronics, then the substrates possess good physical, thermal, and electrical properties, but they require high heat to polymerize and do not easily degrade, making extraction of precious metals difficult and leading to e-waste accumulation
Solution Approach 1:
The patent changes the chemical parameters of polyimide by incorporating degradable ester linkages into the polymer backbone through thiol-ene click chemistry. This modification allows the material to degrade under mild conditions (room temperature with methanol solution) while maintaining the necessary physical and electrical properties for flexible electronics during its service life.
Solution Approach 2:
The patent creates a composite polymer structure combining robust imide linkages (for thermal and mechanical stability) with degradable ester linkages (for recyclability). This composite approach at the molecular level allows the material to exhibit both durability during use and ease of degradation for recycling, resolving the contradiction between reliability and recyclability.
2Stability of the object's composition
If high heat is applied to degrade conventional polyimide substrates, then the polymer breaks down, but the high temperature damages embedded electronic components and precious metals
Solution Approach 1:
The patent changes the degradation temperature parameter by designing ester linkages that break down at room temperature in the presence of methanol. This allows complete polymer degradation without applying heat, thereby protecting embedded electronic components and precious metals from thermal damage while achieving the goal of material breakdown for recycling.
3Ease of manufacture
If degradable linkages are incorporated into polyimide to enable recycling, then the polymer can be degraded at room temperature, but the polymerization process becomes more complex requiring UV light and thiol-ene click chemistry
Solution Approach 1:
The patent replaces traditional thermal polymerization methods with UV light-initiated thiol-ene click chemistry. This substitution allows the incorporation of degradable ester linkages into the polymer structure while maintaining a controlled and efficient polymerization process. The UV initiation provides precise spatial and temporal control over polymerization, offsetting the added chemical complexity.
4Productivity
If conventional polyimide substrates are used, then electronic devices can be manufactured, but the substrates accumulate as e-waste because they are rarely recycled
Solution Approach 1:
The patent enables the discarding of polyimide substrates in their intact form (without high-heat incineration) and subsequent recovery of precious metals and polymers through room-temperature degradation in methanol. The degradable ester linkages allow the polymer to break down into soluble components, facilitating the recovery and reuse of valuable materials, thereby eliminating e-waste accumulation while maintaining manufacturing productivity.
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 degradable polyimide substrates possess suitable physical, thermal, and electrical properties for flexible electronics, allowing for recycling of electronic components without damaging them, reducing waste and enabling cost-effective reuse of valuable materials.
Implementation Method 1
the diallyl imide or other difunctional alkene monomers and the thiol monomers polymerize to form the polyimide substrate
Implementation Method 2
the degradable linkages can be degraded at room temperature to yield base monomer units that can be used to form similar polymers again
Data Source
AI summary
Disclosed herein is a degradable polyimide substrate that may be reliably used as an electronic substrate in flexible electronics. The degradable polyimide substrate is formed via thiol-ene click chemistry reactions between diallyl imide or other alkene monomers and thiol monomers, that can be activated by photoirradiation at relatively low temperatures (e.g., about 80° C.). As a result, the degradable polyimide substrates disclosed herein may be cured using a simple, energy efficient curing process that allows for streamlined manufacturing of circuits including multilayered circuits. In some instances, epoxy monomers may be added to the monomer resin used to form the polyimide substrate, wherein selective curing may yield polymer substrates with varying degrees of flexibility and rigidity.