Self-assembly of quaternized chitosan nanoparticles within nanoclay layers for enhancement of interfacial properties in toughened polymer nanocomposites

Role of montmorillonite nanoclay in self-assembly of quaternized chitosan nanoparticles (QCn) within the clay layers was investigated. Inorganic-organic nanohybrid of clay-chitosan was used as a reactive reinforcing agent in preparation of toughened epoxy nanocomposites. Intercalation of QCn within the clay layers increases d-spacing of clay layers from 1.2 nm to 3.6 nm, leading to an enhanced exfoliation degree in epoxy nanocomposites. The nanohybrid of clay modified with QCn was then incorporated into an epoxy matrix. It was found that the strong interfacial interactions benefit not only the dispersion of the clay within epoxy but also the effective interfacial stress transfer, leading to significantly improved mechanical properties. Rheological investigations showed that the interfacial interactions between the QCn modified clay and epoxy are dominated by the covalent/hydrogen bondings between the amine/hydroxyl enriched QCn and the epoxy matrix.