Thermal response of grain boundaries in graphene sheets under shear strain from atomistic simulations

Thermal transport properties of pristine and defective graphene sheets under shear strains are investigated by molecular dynamics simulations. It is found that the graphene symmetric tilt grain boundary with a higher (lower)-dislocation density has a higher (lower) shear failure strength. This counter-intuitive result is attributed to the mutual cancelation of strain field of grain boundary dislocations when they are close to each other. In particular, we compute the thermal conductivity across the graphene grain boundaries with different grain boundary dislocation densities. The applied shear strain ε is between 0 and 0.2 to avoid rupture of the defective graphene. In this range of strains, the thermal conductivity of polycrystalline graphene with lower-dislocation density can be modulated up to 23% (0 < ε < 0.12), which is significantly greater than that of the pristine graphene (below 10% in the same range), thereby opening the possibility for thermomutability by using the defective graphene under shear strain.