Tri-functional Crosslinked Polyimides for High-Temperature Shape Memory

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Solution Overview

Problem

Current shape memory polymers (SMPs) lack the desired high temperature mechanical properties necessary for advanced applications, as they are not self-thermosetting, limiting their suitability for applications such as advanced sensors and heat-responsive packaging.

Innovation Solution

Incorporating tri-functional crosslinking and non-terminal phenylethynyl moieties into SMPs enhances their modulus of elasticity and mechanical properties, enabling them to be programmed for sustainable applications in high temperature actuators, responder matrix materials, and heat-responsive packaging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If current SMPs are used without tri-functional crosslinking, then shape memory effect is achieved, but mechanical properties and high temperature stability are insufficient

Engineering Contradiction:

Improvemechanical propertiesVSAvoidcrosslinking structure

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent combines tri-functional crosslinking agents with phenylethynyl-containing monomers to create a composite polymer network structure. This composite approach integrates the shape memory capability from the phenylethynyl groups with the enhanced mechanical strength from the tri-functional crosslinks, resolving the contradiction between achieving shape memory effect and obtaining sufficient high-temperature mechanical properties.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent introduces localized tri-functional crosslinking nodes within the polymer chain structure. These crosslinking points are strategically positioned to provide mechanical reinforcement and thermal stability at specific locations without requiring complete crosslinking of the entire polymer structure, thus maintaining shape memory flexibility while improving overall mechanical properties.

Inventive Principle:

Principle #3Local quality

2Temperature

If tri-functional crosslinking with phenylethynyl moieties is added, then modulus and high temperature stability are enhanced, but manufacturing complexity increases

Engineering Contradiction:

Improvehigh temperature stabilityVSAvoidfabrication process

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent incorporates phenylethynyl-containing monomers into the polymer structure during the initial polymerization stage, before the crosslinking step. This preliminary incorporation ensures uniform distribution of the functional groups throughout the polymer matrix, simplifying the subsequent crosslinking process and avoiding the need for complex post-processing steps to achieve high-temperature stability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The tri-functional crosslinking agents with phenylethynyl moieties are designed to self-assemble and crosslink autonomously under controlled conditions without requiring complex external intervention. The chemical structure enables spontaneous crosslinking reactions that form the desired network structure, reducing manufacturing complexity while achieving the target high-temperature stability.

Inventive Principle:

Principle #25Self-service

3Reliability

If non-terminal phenylethynyl moieties are incorporated, then shape memory performance and modulus are improved, but polymer synthesis complexity increases

Engineering Contradiction:

Improveshape memory performanceVSAvoidpolymer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent selects phenylethynyl-containing monomers that serve multiple functions simultaneously: they provide the shape memory effect through their molecular structure, contribute to the polymer chain flexibility, and enable crosslinking reactions. This multi-functionality reduces the need for additional specialized components, simplifying the overall polymer structure while enhancing shape memory performance and reliability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 improved SMPs exhibit enhanced shape memory performance, with increased modulus and stability at elevated temperatures, making them suitable for advanced applications beyond the limitations of existing SMPs.

Implementation Method 1

heating said substrate to a temperature of from greater than 250° C. to about 400° C. The crosslinking of the non-terminal, phenylethynyl groups is evidenced by an increase in Tg and an increase in the modulus of the SMP.

Methodology Applied

Scientific EffectThermal crosslinking:

Implementation Method 2

The crosslinking of the non-terminal, phenylethynyl groups is evidenced by an increase in Tg

Methodology Applied

Scientific EffectGlass transition:

Data Source

PatentUS11992995B2Lightly crosslinked polyimides with phenylethynyl pendants for shape-memory effect and programmed enhancement in Tg and modulus

Publication Date: 2024.05.28 THE GOVERNMENT OF THE UNITED STATES AS REPRESENTED BY THE SECRETARY OF THE AIR FORCE

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 mechanical property enhancements that make the SMP suitable, among other things, for advanced sensors, high temperature actuators, responder matrix materials and heat responsive packaging.