R. Araya-Hermosilla, L.M. Polgar, A.A. Broekhuis, F. Picchioni
University of Groningen,
Keywords: thermally reversible networks, carbon nanotubes, self-healing
Summary:This work focuses on the synthesis and characterization of different kinds of reversible thermosets and thermoset nanocomposite materials by using alternating aliphatic polyketones (PK) as raw material. Fundamental knowledge was generated regarding the molecular design of new polymers via chemical modification of PK with aliphatic and aromatic amine compounds. The resulting thermally reversible thermoset systems were investigated to outline the benefits for the synergistic cooperation between reversible covalent and supramolecular interactions (i.e. hydrogen bonding). Moreover, improvements regarding the mechanical performance, reversibility, recyclability, self-healing and electrical conductivity of the thermosets were investigated by incorporating rubber particles and nanofillers into the thermoset matrices in a thermally reversible manner. The materials display the desired mechanical properties and in order to confer also electrical properties to these materials, conductive nanocomposites containing well-distributed, exfoliated and undamaged MWCNTs were prepared. These new materials, designed by mixing furan-functionalized polyketone cross-linked with aromatic bis-maleimide and MWCNTs via Diels-Alder (DA) reversible cycloaddition, display electrically-induced self-healing properties. Form an applicative point of view, the prepared nanocomposites are electrically conductive, can be recycled at least one time without significant deterioration of mechanical properties and display self-healing capabilities by application of heat or electricity. The reason for such outstanding ensemble of characteristics lies in the underlying concept of thermally reversible networks. The crosslinked nature of these materials ensures the desired mechanical behaviour, while the thermally reversible character underpins the ability to be recycled (cradle-to-cradle) and the self-healing behaviour.