High-strength scalable graphene sheets by freezing stretch-induced alignment.

Efforts to obtain high-strength graphene sheets by near-room-temperature assembly have been frustrated by the misalignment of graphene layers, which degrades mechanical properties. While in-plane stretching can decrease this misalignment, it reappears when releasing the stretch. Here we use covalent and π–π inter-platelet bridging to permanently freeze stretch-induced alignment of graphene sheets, and thereby increase isotropic in-plane sheet strength to 1.55 GPa, in combination with a high Young’s modulus, electrical conductivity and weight-normalized shielding efficiency. Moreover, the stretch-bridged graphene sheets are scalable and can be easily bonded together using a commercial resin without appreciably decreasing the performance, which establishes the potential for practical applications. Stretch-induced alignment of graphene sheets is frozen by sequential covalent and π–π bridging, leading to high in-plane isotropic strength of 1.55 GPa. The graphene sheets are fabricated at near room temperature and are scalable.