Preparation and Properties of a Self-Healing, Multiresponsive Color-Change Hydrogel

Multiresponsive Color-Changing and Tough Hydrogels Enabled by Self-Assembled Epoxy Oligomer Microspheres

The fabrication process of hydrogels often incorporates various strategies to achieve multiple responses and enhance strength, which always make the procedure complex and even hinder the incorporation. Here, we develop a facile and flexible method to simultaneously achieve multiresponsive color-changing and tough properties in hydrogels by introducing epoxy oligomer microspheres (DEPMS) to hydrophobic association (HA) hydrogels. DEPMS is responsive to both pH and solvents, showing color changes due to conversion to a conjugated structure. The obtained DEPMS composite hydrogels could demonstrate diverse color-changing patterns by simply adjusting the components and pH of the solvents. Meanwhile, amphiphilic DEPMS helps to disperse hydrophobic regions of the HA hydrogel, resulting in more uniform cross-linking and thereby contributing to the enhanced mechanical properties. The tensile strength and toughness of the composite hydrogels could be easily adjusted and reach 1.00 MPa and 11.18 MJ m-3, respectively. This work provides an approach to the design of multiple responsive and tough hydrogels while offering insights into the recycling of waste epoxy resins.

Reversible Photo-, Thermal-, and pH-Responsive Functionalized Wood with Fluorescence Emission

A reversible photo-, thermal-, and pH-responsive high-performance functional wood with fluorescence has been prepared. The properties, structure, multi-response, fluorescence, water resistance, and corrosion resistance of original wood (ORW) and functional wood (FUW) were investigated with an X-ray photoelectron spectroscopy (XPS) spectrometer, a Fourier-transform infrared (FTIR) spectrometer, a N₂ adsorption–desorption analyzer, an atomic force microscope (AFM), tensile tests, a scanning electron microscope (SEM), an ultraviolet–visible (UV–Vis) spectrophotometer, a fluorescence spectrometer, the equilibrium swelling ratio (ESR), and corrosion tests. The results of XPS, FTIR, N₂ adsorption–desorption, and AFM exhibited that FUW was successfully prepared. Additionally, the results of the tensile test and SEM revealed that FUW had better mechanical properties than ORW, due to the filling of epoxy resin in the pores of the wood. Moreover, the UV–Vis and fluorescence spectra demonstrated that the introduction of epoxy resin induced multi-response and fluorescence functions to FUW. Furthermore, the data of ESR and corrosion test showed that the introduction of epoxy resin greatly improved the water and corrosion resistance of wood. This study provides ideas and methods for preparing novel high-performance multi-response FUW.

Multi-stimuli-responsive hydrogels and their medical applications

This review highlights the medical applications of multi-stimuli-responsive hydrogels as self-healing hydrogels, antibacterial materials and drug-delivery systems.