Temperature-responsive hydrogels with adaptive coloration and superior mechanical performance

Abstract

Temperature-adaptive coloration hydrogels, which mimic the thermally responsive color-changing abilities of animals such as chameleons and certain fish species, can reversibly adjust their optical appearance in response to temperature changes. This dynamic responsiveness is vital for applications in smart sensing, dynamic camouflage, and anti-counterfeiting technologies. In this study, we developed a multifunctional hydrogel (AP-β-Py) that exhibits temperature-responsive color modulation alongside outstanding mechanical performance. The hydrogel was synthesized via the copolymerization of acrylamide (AAM) and a fluorescent monomer, pyrene-functionalized 2-hydroxyethyl methacrylate (Py-HEMA), and structurally reinforced through supramolecular host–guest interactions, where β-cyclodextrin (β-CD) served as the host and dialdehyde-functionalized polyethylene glycol (DF-PEG) acted as the guest. This design enables the hydrogel to form a dynamic yet robust polymer network with tunable fluorescence, mechanical strength, self-recovery properties, and superior adhesion to various surfaces. Additionally, the AP-β-Py hydrogel exhibits extraordinary mechanical properties, including high elongation (>1000%), excellent puncture resistance, and the ability to recover its original properties after stretching, twisting, and being subjected to high-load conditions. These attributes ensure its structural integrity and functionality, even under extreme deformation. The AP-β-Py hydrogel represents a novel material platform with immense potential for use in smart sensors, biological imaging, anti-counterfeiting applications, and next-generation robotic skin.