Isosorbide-Based Optically Clear Adhesives With Ultrahigh Transparency and Rapid Strain Recovery for Flexible Displays.

Flexible and foldable displays require optically clear adhesives (OCAs) that combine ultrahigh optical transparency with mechanical resilience under repeated deformation. However, conventional acrylic-based OCAs often fail to achieve both properties simultaneously. Herein, we synthesized a polyurethane diacrylate (PUDA) crosslinker incorporating biomass-derived isosorbide and photostable 1,3-bis(isocyanatomethyl)cyclohexane (H6XDI) for flexible display adhesives. The segmented polyurethane architecture forms a mechanically flexible yet robust network, enabling rapid strain recovery while maintaining ultrahigh optical transparency. Furthermore, the incorporation of an isosorbide-based PUDA crosslinker introduces a biomass-derived component and preserves excellent optical properties due to its intrinsically low birefringence. As a result, the PUDA crosslinked OCA exhibits exceptional optical transmittance (99.8%) and maintains high transparency (98.6%) even at 50% tensile strain, alongside low modulus, stable adhesion, and clean debonding behavior. These results highlight the potential of PUDA OCAs for high-performance and energy-efficient foldable display applications.