Busan National University Develops Smart Adhesive with Temperature-Dependent Attachment... 'Strong at Room Temperature, Detachable at High Temperature'

Ahn Seokgyun's Team Develops Enhanced Reversible Adhesive Technology by Introducing Polyrotaxane Crosslinking to Liquid Crystal Elastomers
Achieves 13 Times Stronger Adhesion and Reusability Compared to Existing Products... Expected Applications in Semiconductors and Displays

Pusan National University (President Choi Jae-won) announced on the 22nd that Professor Ahn Seok-gyun’s research team from the Department of Chemical Engineering successfully developed a smart pressure-sensitive adhesive that can switch its adhesion on and off depending on temperature.

From the left, Professor Ahn Seok-gyun, Researcher Choi Su-bi, Professor Seo Ji-hoon. Provided by Pusan National University

‘Pressure-sensitive adhesives’ are non-reactive adhesives that form bonds solely through pressure, widely used not only in everyday adhesive products such as labels and Post-it notes but also in advanced technology fields like protective films for semiconductors and displays.

In particular, ‘high-performance adhesives’ must have the ability to repeatedly adhere and detach or change adhesion strength under specific conditions, considering substrate recyclability and user convenience.

However, existing high-performance adhesives controlled adhesion by chemically functionalizing or altering surface topography, which involved complex processes and treatments. They also had limitations such as weakened or irregular adhesion changes after repeated use.

To address these issues, recent academic attention has focused on pressure-sensitive adhesives based on liquid crystal elastomers. Liquid crystal elastomers exhibit excellent damping effects due to the ability of liquid crystal molecules to rotate upon external impact, and these damping properties are known to be closely related to adhesive performance. However, previous studies focused only on liquid crystal elastomers composed of covalently bonded crosslinking points, which fundamentally limited adhesion improvement.

In response, the Pusan National University research team introduced a substance called ‘polyrotaxane’ as a crosslinker into liquid crystal elastomers, developing a novel concept of liquid crystal elastomer for the first time. Polyrotaxane is a supramolecular material composed of ring-shaped molecules that, when external force is applied, allow the ring molecules to move along the chain, dispersing the force. This movement effectively alleviates stress concentration at crosslinking points and efficiently dissipates energy within the adhesive.

As a result, the polyrotaxane liquid crystal elastomer with these dynamic crosslinking points exhibits superior damping effects compared to conventional liquid crystal elastomers due to its structural characteristic that allows crosslinking points to move freely under external force. The adhesive developed by the research team demonstrated adhesion strength 3.5 times higher than conventional liquid crystal elastomers and 13 times higher than existing commercial adhesives at room temperature.

Additionally, the team proposed an innovative method to reversibly control adhesion strength by utilizing the phase transition changes of the liquid crystal elastomer according to temperature. The adhesive provided adhesion capable of supporting approximately 2 kg dumbbells at room temperature, while at high temperature (100℃), adhesion dropped to zero, allowing perfect detachment from the substrate. Thanks to these properties, the adhesive maintained stable adhesion performance even after repeated use.

Professor Ahn Seok-gyun of Pusan National University, who led the research, explained, “The damping-based liquid crystal elastomer adhesive developed in this study not only offers adhesion performance surpassing existing commercial adhesives but is also innovative in that adhesion strength can be reversibly changed by external stimuli.”

He added, “Thanks to these characteristics, liquid crystal elastomers can establish themselves as promising candidates for next-generation adhesive technologies, especially opening up significant application possibilities in advanced industrial fields such as semiconductor manufacturing and display processes where repeated adhesion and detachment are required.”

The research results were published in the January 15 issue of the world-renowned materials science journal Advanced Functional Materials.

This research was supported by the Mid-career Researcher Support Program and Nanomaterials Technology Development Project of the National Research Foundation under the Ministry of Science and ICT. It was conducted under the leadership of Choi Subi, a graduate student in the integrated master’s and doctoral program at the Department of Chemical Engineering, Pusan National University (first author), and Professor Ahn Seok-gyun (corresponding author). The study was carried out in collaboration with Professor Seo Ji-hoon’s research team from the Department of Materials Science and Engineering at Korea University, and Dr. Mohand Saed and Professor Eugene Terentjev’s research teams at the University of Cambridge in the UK.

This content was produced with the assistance of AI translation services.