Stabilization of nanostructures and their applications

The dispersion of nanostructured materials into liquid and solid matrices is an old challenge in the field of material sciences. In order to exploit the properties of nanoparticles or nanotubular structures they must be homogeneously distributed into the final material. The present thesis is part of a significant work devoted to the preparation of new surfactants and functional polymers for the dispersion in different media of carbon-based and metal-based functional and nanostructured materials. More specifically, chemical modification of species able to stabilize nanostructures is carried out for the realization of nanocomposites with smart features. To this aim, different organic low and high molecular weight surfactants are investigated. The first part of this work aims to investigate the use of a functionalized ethylene-propylene rubber (EPR) as a polymeric dispersant for pristine or chemically-modified multi-walled carbon nanotubes (MWCNTs). The soft covalent approach allows higher compatibility with the polymer matrix and superior properties in terms of electric conductance. Spectroscopic, thermo-mechanical and morphological studies are carried out to evaluate the nanocomposite properties and their final applications as innovative stress-strain sensors. The second part of this work investigates the synthesis of low molecular weight surfactants for MWCNTs dispersion. In particular, two different perylene bisimides derivatives are synthetized and their dispersions with MWCNTs in different solvents investigated by Raman spectroscopy and thermogravimetric analysis in order to explore the ability of π-π stacking interactions and effective electrostatic repulsion to promote nanotubes exfoliation and stabilization in different media. Solid mixtures are eventually studied as nanostructured and cost-effective temperature sensors. The final part is devoted to the synthesis and the characterization of polyisobutene succinic anhydrides (PIBSAs) and their succinimide (PIBSI) derivatives as capping of silver nanoparticles prepared by bottom-up approaches. PIBSAs and PIBSI supramolecular assemblies are characterized by new spectroscopic procedures and their utilization is eventually extended as dispersants of MWCNTs.