Synergistic fluorescent hydrogel actuators with selective spatial shape/color-changing behaviors via interfacial supramolecular assembly

Biomimetic intelligent polymeric hydrogel actuators with cooperative fluorescence-color switchable behaviors are expected to find great potential applications in soft robotics,visual detection/display,and camouflage applications.However,it remains challenging to realize the spatial manipulation of synergistic shape/color-changing behaviors.Herein,we report an interfacial supramolecular assembly(ISA)approach that enables the construction of robust fluorescent polymeric hydrogel actuators with spatially anisotropic structures.On the basis of this ISA approach,diverse 2D/3D soft fluorescent hydrogel actuators,including chameleon-and octopi-shaped ones with spatially anisotropic structures,were facilely assembled from two different fluorescent hydrogel building blocks sharing the same physically cross-linked agar network.Spatially control over synergistic shape/color-changing behaviors was then realized in one single anisotropic hydrogel actuator.The proposed ISA approach is universal and expected to open promising avenues for developing powerful bioinspired intelligent soft actuators/robotics with selective spatial shape/color-changing behaviors.

Mechanochemical transformation of fluorescent hydrogel based on dynamic lanthanide-terpyridine coordination

As a burgeoning research field, ultrasound-responsive materials have attracted intense interest in healthcare research. However, the basic mechanism of sonochemical effect in the quasi-solid state is far from being well understood than those in the solution. Herein, we showcase mechanochemical transformations of europium(Ⅲ) complexes in a supramolecular hydrogel matrix. With the combination of labile terpyridine-europium complexes(TPY-Eu^(3+)) as mechanochromic moieties and an ultrasound-responsive fluorogen(URF) as a molecular tweezer, the hydrogel produces a notable fluorescence change in response to ultrasound. The mechanochemical transformation was elucidated by molecular dynamics(MD) simulations, and fully probed and evidenced by electrochemical experiments, X-ray photoelectron spectroscopy(XPS), and attenuated total reflectance-Fourier transform infrared(ATR-FTIR) spectroscopy.