Hydrogels with both mechanical strength and luminescence anisotropy

Abstract

How to produce luminescent materials with anisotropic emission properties in a universal manner remains an open issue. We here report a range of hydrogels with both anisotropic mechanical strength and anisotropic luminescent behaviors, which are prepared by the copolymerization of ultra-high magnetic response two-dimensional (2D) nanofillers, polymer monomers and lanthanide complexes in an aqueous dispersion under an orientated magnetic field. As the reinforcement of aligned Fe/Al₂O₃ platelets to the hydrogel network is orientation dependent, the resultant hydrogels show anisotropic mechanical behaviors. Specifically, the orientation-dependent shading effect of the aligned non-emissive 2D nanofillers on the lanthanide emitting centers impart anisotropic emission properties to the hydrogel, which has been proved to be feasible for different lanthanide complexes. This work is expected to provide a general strategy to prepare hydrogels with anisotropic optical signals.