Flexible Anti‐Counterfeiting Circularly Polarized Luminescent Elastomer from Supramolecular Polyurethanes

Abstract

AbstractSupramolecular polymers with circularly polarized luminescence (CPL) have promoted future intelligence development of polymer‐based materials for flexible display. However, preparing polymer‐based CPL materials with simultaneous enhanced luminescence dissymmetry factor (|glum|) and mechanical performance for industrial applications remains challenging. This work develops an eco‐friendly preparation method for preparing CPL elastomers from supramolecular polyurethanes bearing chiral fluorescent S (or R)‐1,1′‐Bi(2‐naphthol) (BINOL) groups in a solvent‐free system. Surprisingly, a polymer system containing 0.0028 mol% of chiral BINOL unit is sufficient to emit the significant CPL‐activity with a |glum| value of 2.30 × 10−2, appear a good mechanical toughness of 56.28 ± 3.9 MJ·m−3, thereby exhibit multiple flexible anti‐counterfeiting behaviors. The long‐range ordered microphase arrangement in polyurethanes is the key to improving both mechanical properties and |glum|. This is attributed to in‐situ additive polymerization of BINOL‐based isocyanate prepolymer and macromolecular polyols induced helical supramolecular structure, afforded solid‐state films with flexibility and chiral amplification. Furthermore, these results from Circular dichroism, CPL, Fourier transform infrared, X‐ray diffraction analyses, and atomic force microscope confirm the formation of long‐range ordered microphase arrangement through the synergistic effect of hydrogen bonding and π–π interactions. This work offers significant insights into the construction of CPL elastomers for developing novel flexible display materials.