Shape Memory Polymer Dry Adhesive for Flexible Adherends
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing shape memory polymer (SMP) dry adhesives are unable to maintain strong adhesion to flexible adherends due to high stress concentration at the adhesive interface, causing them to peel when the adherend flexes.
Innovation Solution
A SMP dry adhesive with a glass transition temperature (Tg) above 25°C and a compliant backing layer is used, allowing the SMP to form a conformal and/or hermetic contact with flexible adherends at temperatures above Tg and maintain this contact during flexing at temperatures below Tg.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If SMP dry adhesive is used to attach to flexible adherends, then adhesion strength is improved, but the adhesive peels during flexing due to high stress concentration
Solution Approach 1:
The patent applies this principle by using a thin film structure for the SMP adhesive layer. The adhesive is formulated as a thin flexible layer that can conform to and flex with the adherend surface, reducing stress concentration at the adhesive interface that causes peeling during flexing operations
Solution Approach 2:
The patent applies this principle by changing the glass transition temperature (Tg) parameter of the SMP adhesive to above 25°C. This parameter change ensures the adhesive maintains appropriate mechanical properties at operating temperatures, providing both strong initial adhesion and flexibility to withstand subsequent flexing without peeling
2Strength
If SMP adhesive is in rigid glassy state during adhesion, then adhesion strength is improved, but flexing causes peeling due to stress concentration
Solution Approach 1:
The patent applies this principle by carefully selecting and controlling the glass transition temperature (Tg) parameter of the SMP adhesive. By setting Tg above 25°C, the adhesive maintains a rigid glassy state at operating temperatures for strong adhesion, while the thin film formulation allows sufficient flexibility to accommodate adherend flexing without peeling
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 SMP dry adhesive achieves strong and durable adhesion to flexible adherends, even during repeated flexing, without compromising adhesion strength, and can withstand exposure to water or other liquids.
Implementation Method 1
SMPs can be deformed and fixed into a temporary shape that can be maintained until the SMP is stimulated to return to its previous 'remembered' permanent shape. This transition may be generally referred to as a glass transition, corresponding to a glass transition temperature (Tg), below which the SMP may be said to be in its glassy state, and above which the SMP transforms to the rubbery state.
Implementation Method 2
SMPs can be deformed and fixed into a temporary shape that can be maintained until the SMP is stimulated to return to its previous 'remembered' permanent shape. This shape memory effect of many reported SMPs is thermally triggered but some of the athermal stimuli-triggered SMPs have also been reported such as electro, magnetic, water, or photo active SMP composites.
Data Source
AI summary
A dry adhesive for attachment to a flexible adherend comprises a shape memory polymer having a glass transition temperature (Tg) above 25° C. and a compliant backing layer attached to the shape memory polymer. The shape memory polymer is configured to form a conformal and/or hermetic contact with a flexible adherend at temperatures at or above the Tg and to retain the conformal and/or hermetic contact during flexing of the flexible adherend at temperatures below the Tg.