New Flexible Adhesive

New Flexible Adhesive with Superior Recovery and Bonding Properties Advances in flexible electronics technology have enabled the emergence of innovative devices such as foldable displays, wearable devices, e-skin and medical devices. These breakthroughs have created growing demand for flexible adhesives that can rapidly regain their shape while effectively bonding various components in these devices. However, conventional pressure-sensitive adhesives (PSAs) typically face challenges in balancing recovery capability and bonding strength. In an exceptional study conducted at UNIST, researchers successfully synthesized new urethane-based cross-linker types that address this critical challenge. A research team led by Professor Dong Woog Lee from the UNIST Energy and Chemical Engineering Faculty developed new cross-linkers using m-xylene diisocyanate (XDI) or 1,3-bis(isocyanatomethyl)cyclohexane (H6XDI) as hard segments and poly(ethylene glycol) (PEG) groups as soft segments. By incorporating these newly synthesized materials into pressure-sensitive adhesives, the research team achieved significantly improved recoverability compared to conventional methods. PSA formulated with H6XDI-PEG diacrylate (HPD) exhibited exceptional recovery properties while maintaining high adhesive strength (~25.5 N 25 mm-1). The PSA cross-linked with HPD demonstrated remarkable stability under repeated deformation through versatile tensile tests encompassing a total of 100,000 folds and 10,000 cycles, demonstrating its potential for applications requiring both flexibility and recoverability. Furthermore, the adhesive exhibited high optical transparency (>90%) even after being subjected to strains of up to 20%, making it suitable for applications such as foldable displays that require not only flexibility but also optical clarity. Professor Lee stated, "This breakthrough in adhesive technology offers promising opportunities for electronic products that require both high flexibility and rapid recovery properties. Our research addresses the long-standing challenge of balancing adhesive strength and flexibility, opening new avenues for the development of flexible electronic devices." Hyunok Park, one of the researchers involved in the study, emphasized the significance of the research: "The implementation of this new cross-linking structure enabled us to obtain an adhesive with exceptional adhesive and recovery properties. We believe this will contribute to advances in the flexible electronics field while directing future progress in adhesive research." The findings from the study were published in the journal Advanced Functional Materials. Academic Reference: Hyunok Park et al, Tailoring Pressure Sensitive Adhesives with H6XDI-PEG Diacrylate for Strong Adhesive Strength and Rapid Strain Recovery, Advanced Functional Materials (2023). DOI: 10.1002/adfm.202305750 Source