• reduced graphene oxide
• Polyketone
• self healing

Smart polymers are largely studied and they represent the future of the research into the material’s field.
In particular, self healing materials are studied because of their ability to restore the occurred cracks.
Polymers are normally insulators but, adding a conductive nanofiller into the polymer matrix, they can become conductive. This is due to the creation of percolation paths into the matrix which permits the flowing of electrons through the material. To this purpose, a homogeneous dispersion on the nanofiller into the matrix and a good superficial interaction between the nanofiller and the matrix are needed. Also the concentration of the nanofiller must reach a precise value called percolation threshold, where the formation of percolative paths into the matrix is possible and permits the flowing of electrons through the material.
In the present work, a thermoset high performance material is used as a matrix for the preparation of a nanocomposite which shows electrical conductivity and self-healing ability. The polymer used is a polyketone, where a repetitive 1,4-dicarbonyl unit presents in the backbone of the polymer, is used to modify the macromolecule in order to insert a furan pendant group able to interact with reduced graphene oxide, used as a conductive nanofiller. The preparation of the nanocomposite occurs via solution mixing. The modification of the backbone of the polyketone proceeds successfully as well as the preparation of the nanocomposite. The obtained nanocomposite is characterized and the electrical conductivity is measured. The electrical behaviour of the polymer shows a conductivity activadet by temperature: the nanocomposite is an insulator at low temperatures, but it is conductive for temperatures higher than 100°C. This behaviour is probably due to the semiconductor behaviour of the reduced graphene oxide itself.
Another nanocomposite is obtained using the same modified polyketone, the same nanofiller and bismaleimide as a cross-linker. The cross-linking of the macromolecule proceeds via the formation of a Diels-Alder adduct between the furan moiety present as a pendant group of the polyketone and the maleimidic unit of the bismaleimide added to the reaction mixture. The formation of the Diels-Alder adduct is reversible with temperature. The formation occurs at 50°C, and the retroDIels-Alder reaction, able to break the 3D network, occurs around 120°C. The reversibility of the cross-linking confers the self-healing ability to the material, wich is able, thanks to an external stimulus like temperature, to repair the occurred cracks or scratch. The obtained nanocomposite is characterized and the mechanical properties result implemented if compared with the same properties of the non-cross-linked nanocomposite. The electrical behaviour is found to be the same as the non-cross-linked nanocmposite. An ON-OFF behaviour activated by temperature is registered, due to the semi conductor nature of the nanofiller, and the conductivity values registered result to be the same as the non-cross-linked nanocomposite. A percolation threshold is found between 0 and 3%, in accordance with the previous literature.
The self-healing abilities of the material are tested by measuring mechanical and electrical properties before and after the remoulding of the sample. The self- healing results to be effective only for the first cycle of breaking and remoulding of the sample.
We can conclude that the formation of a new and cheap nanocomposite material with a semiconductor properties is effective. The material is also able to restore the occurred cracks for the first cycle.