Multistimuli-responsive hydrogels with both anisotropic mechanical performance and anisotropic luminescent behavior

Anisotropic luminescence emission is the basis to achieve some key parameters in optoelectronic fields. As compared with mechanical anisotropy, however, achieving anisotropic emitting behavior is still challenging. Thus, integrating multiple stimuli into one luminescent hydrogel orthogonally while retaining its anisotropic structure remains an open challenge. Herein, we report the construction of a multistimuli-responsive mechanical/luminescent dual anisotropic hydrogel through the copolymerization of superparamagnetic nanoparticle-coated alumina (Fe/Al2O3) platelets, lanthanide complex, photochromic diarylethene molecule, and N-isopropylacrylamide (NIPA) in an oriented magnetic field. The aligned Fe/Al2O3 platelets impart the hydrogel an anisotropic mechanical property, and the orientation-dependent “shading effect” of the aligned Fe/Al2O3 platelets on the lanthanide complex also endow the hydrogel with anisotropic emission behavior. Significantly, photoreversible luminescence on/off switch and thermoreversible anisotropic deformation are realized in the hydrogel based on the conformation-dependent fluorescence resonance energy transfer between the lanthanide donor and photochromic diarylethene acceptor, and phase transition of polymerized NIPA, respectively. As a proof-of-concept, multidimensional intelligent anticounterfeiting is demonstrated by using this hydrogel. Thus, this work demonstrates a general preparation strategy of multistimuli-responsive dual anisotropic hydrogels for purposely designed applications, offering insights in the field fundamentally and practically.