Tri-Functional Crosslinked Polyimides for Shape Memory
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Solution Overview
Problem
Current shape memory polymers (SMPs) lack the desired high temperature mechanical properties for advanced applications due to their non-self-thermosetting nature, which limits their suitability for applications requiring sustainable mechanical performance.
Innovation Solution
Incorporating tri-functional crosslinking and multiple non-terminal phenylethynyl moieties into SMPs to enhance their mechanical properties, allowing for improved shape memory and elasticity, making them suitable for advanced sensors, high temperature actuators, and heat responsive packaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If current SMPs are used without tri-functional crosslinking and multiple phenylethynyl moieties, then the polymer synthesis is simpler, but the mechanical properties at high temperature are insufficient
Solution Approach 1:
The patent creates a composite crosslinked network by combining tri-functional crosslinking agents with multiple phenylethynyl moieties within the polymer structure. This composite approach integrates two crosslinking mechanisms (tri-functional crosslinking and phenylethynyl self-crosslinking) to achieve superior mechanical properties and thermal stability while maintaining shape memory functionality.
Solution Approach 2:
The patent modifies the polymer structure by incorporating multiple phenylethynyl moieties (changing the chemical composition parameter) and using tri-functional crosslinking agents (changing the crosslinking density parameter). These parameter changes result in enhanced mechanical strength and high-temperature stability while preserving the shape memory effect.
2Reliability
If tri-functional crosslinking and multiple phenylethynyl moieties are added to SMPs, then the modulus of elasticity and mechanical properties are enhanced, but the polymer synthesis and fabrication process becomes more complex
Solution Approach 1:
The patent incorporates the phenylethynyl moieties and tri-functional crosslinking agents during the initial polymer synthesis stage rather than adding them later. This preliminary action allows the crosslinking to occur in-situ during fabrication, simplifying the overall manufacturing process while ensuring reliable mechanical performance.
Solution Approach 2:
The phenylethynyl moieties are designed to self-crosslink through proximity reactions on the same polymer chain, forming radicals that create crosslinking pathways without requiring external crosslinking agents. This self-service mechanism reduces process complexity while maintaining sustainable mechanical properties.
3Speed
If multiple non-terminal phenylethynyl moieties are used, then the reactivity barrier is reduced and crosslinking occurs more readily, but the control over crosslinking density becomes more difficult
Solution Approach 1:
The patent places multiple phenylethynyl moieties at specific locations within the polymer chain (non-terminal positions) to create localized crosslinking zones. This local quality approach ensures rapid crosslinking where needed while maintaining control over overall crosslinking density through strategic placement of the moieties.
Solution Approach 2:
The patent uses multiple phenylethynyl moieties (excessive crosslinking potential) but controls the actual crosslinking density by regulating the concentration of these moieties and the tri-functional crosslinking agent. This partial action approach allows rapid crosslinking to occur while maintaining precise control over the final crosslinking density for optimal mechanical properties.
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 modified SMPs exhibit increased modulus of elasticity and sustainable mechanical properties, enabling them to perform effectively in high-temperature applications and maintain shape memory functionality, addressing the limitations of existing SMPs.
Implementation Method 1
heating the substrate to a temperature of from greater than 250° C. to about 400° C., preferably 290° C. to about 325° C., more preferably from about 295° C. to about 305° C.
Implementation Method 2
Shape memory polymers (SMPs) are a class of active materials that can be programmed to 'fix' a temporary shape or a series of temporary shapes, and then later to recover to a 'memorized' permanent shape established by a covalent or physical network by applying an environmental stimulus, for example, heat to the SMP.
Implementation Method 3
the initial glass transition temperatures (Tg,ini) of from about 200° C. to about 250° C.
Data Source
AI summary
The invention generally relates to shape memory films that are tri-functionally crosslinked and that comprise multiple, non-terminal, phenylethynyl moieties. In addition, the present invention relates methods of fabricating such films. Due to the improved properties of such SMPs, the SMP designer can program in to the SMP thermomechanical property enhancements that make the SMP suitable, among other things, for advanced sensors, high temperature actuators, responder matrix materials and heat responsive packaging.