Graphene‐Based Films with Integrated Strength and Toughness via a Novel Two‐Step Method Combining Gel Casting and Surface Crosslinking

We reported herein a novel two‐step method combining gel casting and surface crosslinking to fabricate mechanically robust films. Polymer‐mediated graphene oxide (GO) films (GOFs) were initially prepared by cast‐drying gels containing GO and small amounts of rationally designed polymer, followed by surface crosslinking in EuCl 3 solution. Multiple interactions including hydrogen bonds, π–π interactions, and coordinative bonds were purposefully engineered among GOFs. The resulting GOFs exhibited high strength (112.1 MPa) and toughness (1.7 MJ m −3 ). Moreover, chemical reduction endows these films with high electrical conductivity (21.2 S cm −1 ), and they could be used as flexible electromagnetic interference shielding materials with a shield effectiveness of 15.9 dB. This method for the fabrication of functional graphene‐based films with strength‐toughness balance is simple, environmentally friendly, and scalable to industrial levels.