Lanthanide-Containing Hybrid Hydrogels with High Mechanical/Luminescent Anisotropic Parameters

Herein, we report the construction of hybrid hydrogels possessing mechanical anisotropy as well as luminescent anisotropy via the copolymerization of superparamagnetic nanoparticle-coated halloysite nanotubes (Fe/HNTs), a lanthanide complex, and acrylamide in a directed magnetic field. The aligned one-dimensional (1D) Fe/HNTs reinforce the polymer network in an anisotropic manner, thus leading to mechanical anisotropy. Meanwhile, the orientation-dependent shading effect of the aligned Fe/HNTs on the lanthanide emitting centers endows the hydrogels luminescent anisotropy. Notably, both the mechanical anisotropic parameter and luminescent anisotropic parameter (tensile, compressional, rheological, and emission anisotropic parameters are 4.8, 5.3, 4.9, and 5.5, respectively) of the hybrid hydrogels are significantly higher than those prepared using ferromagnetic 2D nanofillers. This work proposes a promising strategy to design mechanical/luminescent dual anisotropic soft materials with a high anisotropic parameter.