Organomodification of sepiolite clay using bio-sourced surfactants: Compatibilization and dispersion into epoxy thermosets for properties enhancement

A new ammonium-based surfactant (PkH+), synthesized from a 3-alkyl phenol glycidyl ether issued from renewable cashew nutshell liquid (CNSL), has been used to modify the surface of sepiolite clay. This surfactant is especially designed to enhance the compatibility of the needle-like clays with epoxy networks (e.g. DGEBA): ionic PkH+–sepiolite interactions are provided by the ammonium groups, and covalent grafting of DGEBA onto the surfactant is enabled by NH and OH reactive groups. MALDI-ToF-MS was used with success to evidence the grafting of DGEBA units onto the modified clay. Morphological analyses by SEM highlighted the promoted compatibilization and dispersion of sepiolite in DGEBA networks. The properties of the filled networks were characterized by DSC, DMA and evidenced a strong shift of 20 °C of the Tg of the network to higher temperatures and an enhancement of the storage modulus below the Tg. Interestingly, the thermal stability of the network was not affected by the modification of sepiolite by the ammonium. In conclusion, the intercalation of PkH+ onto sepiolite subserves its compatibilization into epoxy networks with a remarkable thermal and thermomechanical properties improvement.