Hydrogel Responsive Nanomaterials for Colorimetric Chemical Sensors

Abstract

The stimuli-responsive hydrogels are three-dimensional hydrophilic polymeric networks with a fascinating property that they will undergo an obvious and reversible volumetric variation in response to a small variation of external environmental stimuli. In particular, combining of the stimuli-responsive hydrogels with photonic crystals (PCs) or Au nanoparticles (NPs), the volumetric variation responded to external stimuli could be converted into a color change, thus creating a kind of colorimetric sensors. These colorimetric sensors attract more and more interest of researchers in different fields due to their simple operation and visualized readout. Herein, after presenting a brief review on the basis concept, synthesis methods and sensitive mechanisms of the stimuli-responsive hydrogels, this chapter mainly focuses on their applications as colorimetric chemical sensors by combining with PCs. And some typical applications are proposed in detail, such as detecting pH value, ionic species, solvents, humidity, and biomolecules. In order to meet the increasing requirements of practical applications, the selectivity, response rate, and resolution ratio of these colorimetric sensors need to be improved in the near further.