Carbon nanotubes (CNT) provide an outstanding property spectrum which can be used to improve a wide range of materials. However, the transfer of properties from the nanoscale to a macroscopic material is a limiting factor. Different approaches of functionalizing the surface of a CNT can improve the interaction with the surrounding matrix but is connected to difficult and expensive treatments, which are usually inconvenient for industrial applications. Here, a simple and eco-friendly method is presented for the oxidation of CNT, where hydrogen peroxide (H₂O₂) is the only chemical needed and no toxic emissions are released. Also, the extensive step of the incorporation of CNT to an epoxy matrix is simplified to an ultrasonic dispersion in the liquid hardener component. The effectiveness is proven by mechanical tests of produced CNT/CFRP and compared to a conventional processing route. The combination of those simple and cost efficient strategies can be utilized to produce multiscale composites with improved mechanical performance in an ecological and economical way.

Carbon nanotubes (CNTs) have already been considered for medical applications due to their small diameter and ability to penetrate cells and tissues. However, since CNTs are chemically inert and non-dispersible in water, they have to be chemically functionalized or coated with biomolecules to carry payloads or interact with the environment. Proteins, although often only randomly bound to the CNT surface, are preferred because they provide a better biocompatibility and present functional groups for binding additional molecules. A new approach to functionalize CNTs with a closed and precisely ordered protein layer is offered by bacterial surface layer (S-layer) proteins, which have already attracted much attention in the functionalization of surfaces. We could demonstrate that bacterial S-layer proteins (SbpA of Lysinibacillus sphaericus CCM 2177 and the recombinant fusion protein rSbpA_31-1068GG comprising the S-layer protein and two copies of the IgG binding region of Protein G) can be used to disperse and functionalize oxidized multi walled CNTs. Following a simple protocol, a complete surface coverage with a long-range crystalline S-layer lattice can be obtained. When rSbpA_31-1068GG was used for coating, the introduced functionality could be confirmed by binding gold labeled antibodies via the IgG binding domain of the fusion protein. Since a great variety of functional S-layer fusion proteins has already been described, our new technology has the potential for a broad spectrum of functionalized CNTs.

Sample preparation is an important step when testing the mechanical properties of materials. Especially, when carbon nanotubes (CNT) are added to epoxy resin, the increase in viscosity complicates the casting of testing specimens. We present a vacuum casting approach for different geometries in order to produce specimens from functional nanocomposites that consist of epoxy matrix and oxidized multi-walled carbon nanotubes (MWCNTs). The nanocomposites were characterized with various mechanical tests that showed improved fracture toughness, bending and tensile properties performance by addition of oxidized MWCNTs. Strengthening mechanisms were analyzed by SEM images of fracture surfaces and in-situ imaging by digital image correlation (DIC).