Liquid crystal-assisted manufacturing of flexible holographic polymer nanocomposites for high-security level anticounterfeiting
GN Chen and W Wei and S Li and XP Zhou and ZA Li and HY Peng and XL Xie, MATERIALS CHEMISTRY FRONTIERS, 6, 3531-3542 (2022).
Holographic polymer nanocomposites show considerable value for advanced anticounterfeiting due to their unique capabilities of reconstructing three-dimensional (3D) images to the naked-eye. However, their flexible manufacturing without using common volatile solvents remains a formidable challenge because they are basically produced via in situ photopolymerization induced phase separation. Low-viscosity reaction systems are normally required to boost the phase separation, which are unfortunately ready to flow randomly and thus hamper flexible processing. Herein, we demonstrate that this challenge can be effectively tackled by controlling the phase separation via the synergy of the thiol-ene click reaction with hydrogen bonding networks, supported by the combination of experiments and molecular dynamics (MD) simulations. Excitingly, holograms with well-regulated phase separation structures and high diffraction efficiency of 94 +/- 4% have been successfully produced at a high-system viscosity, leading to the first demonstration of volatile solvent-free flexible manufacturing of holographic polymer nanocomposites. In addition, polarization-sensitive colored 3D images are also reconstructed due to the incorporated liquid crystals, which are easily recognizable by the naked-eye while physically unclonable, and thus promising for high-security level anticounterfeiting.
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