Ulsan, South Korea – The recent growth in the market for flexible electronics, from wearable sensors to foldable phones, has created a need for flexible adhesives with rapid recovery properties. Conventional pressure-sensitive adhesives can struggle to achieve a balance between adhesive strength and recovery properties.
Scientists at the Ulsan National Institute of Science & Technology have developed novel urethane-based crosslinkers that have improved recoverability. These are based on m-xylylene diisocyanate (XDI) or 1,3-bis(isocyanatomethyl)cyclohexane (H6SDI) as the hard segment, in combination with polyethylene glycol as the soft segment. When these were incorporated into pressure-sensitive adhesives, the team said, significantly improved recoverability was achieved, in conjunction with high adhesion strength.
Extensive folding tests and multi-directional stretching tests showed that the PSA crosslinked with H6XDI-PEG diacrylate was extremely stable under repeated deformation. After strains of up to 20%, the adhesive had optical transmittance in excess of 90%, highlighting its potential in foldable displays.
“The introduction of this new crosslinking structure has led to an adhesive with exceptional adhesion and recovery properties,” said Hyunok Park, one of the researchers. “We believe it will drive future advancements in adhesive research while contributing to further developments in flexible electronics.”
The work has been published in the journal Advanced Functional Materials.