A multifunctional diffusion barrier comprising at least one organic polymer and a 2D graphene or 2D graphene derivative material and a method for preparing the multifunctional barrier. The multifunctional diffusion barrier can be used as a liquid and/or gas barrier, or as structural material, or as sealing material, or as a self-cleaning material or as protective material against UV radiation in aeronautical, automotive, marine or building field. The multifunctional diffusion barrier is suitable in producing parts of aircraft such as a fuel tank, a fuel tank conduit and a gasket.