Mechanically and chemically recyclable polyurethane-based optically clear adhesive with on-demand adhesion/deadhesion

Reuse/recycling of expensive components in next-generation optoelectronic systems (e.g., flexible electronics and foldable displays) for sustainability purposes impose stringent requirements on optically clear adhesive (OCA) with on-demand adhesion/deadhesion capability. Although some hot-melt OCAs have been developed, there still remain great challenges in balancing the mechanical property, adhesion/detachment and recyclability/reusability of the OCAs. Herein, we developed a debondable and robust polyurethane (PU)-based optically clear adhesive with both mechanical and chemical recyclability, overcoming the critical bottlenecks in sustainable advanced manufacturing. The ductile yet strong PU-based OCAs not only can adhere to various optically transparent glass and polymeric substrates (with a bonding strength high up to 5.0 MPa), but also exhibit deadhesion capability at high temperature owing to the thermally sensitive H-bonding interaction within the polymer network. The on-demand adhesion/deadhesion facilitates non-destructive detachment of functional assemblies and materials recycling/repair. The mechanical and chemical recyclability of PU-based OCAs can also effectively reduce the cost and address the end-of-life issues. Moreover, the PU-based OCAs outperformed some commercial optical adhesives. In view of the straightforward synthesis, easy industrial scale-up and exceptional comprehensive properties, the PU-based OCAs will provide promising transformative solutions for advancing the circular economy and sustainability in next-generation optoelectronic devices.