Flexible Graphene Oxide Hydrogel with Enhanced Mechanical Properties for Electromagnetic Wave Absorption and Thermal Insulation

In light of rapid advancements in electronic information technology, flexible electromagnetic wave (EMW)-absorbing materials with high mechanical reliability have been at the forefront of research. Although traditional absorbing coatings possess good electromagnetic loss capabilities, their rigid structure, limited deformation tolerance, and susceptibility to mechanical fatigue under dynamic stress severely restrict their application in emerging flexible electronics and wearable devices. To address this challenge, this study innovatively employs graphene oxide (GO) as a functional reinforcement phase to construct a GO hydrogel that improves flexibility and EMW absorption performance. Specifically, benefiting from the dynamic hydrogen bonding interactions between GO's oxygen-containing groups and polymer chains alongside interlayer sliding of GO's lamellar structure, the GO hydrogel achieves a 1.4-fold increase in fracture strain, rising from 410.6% for pure hydrogel to 578.7%. Meanwhile, compared with pure hydrogel, the maximum tensile strength of GO hydrogel has increased from 0.10 to 0.25 MPa. Regarding EMW absorption property optimization, GO's surface hydroxyl and carboxyl groups effectively reduce the dielectric constant of the hydrogel via hydrogen bonding with water molecules, thereby improving impedance matching. As a result, the GO hydrogel achieves a minimum reflection loss of -43.5 dB at 11.2 GHz and a broad effective absorption bandwidth spanning 6.2 GHz. Moreover, the GO hydrogel demonstrated excellent thermal insulation performance. This study provides a feasible pathway for developing flexible electromagnetic protective materials that hold significant application prospects in flexible electronics and wearable devices.