Nuvoli, Daniele (2011) Produzione di dispersioni di grafene ad elevata concentrazione e loro utilizzo per la sintesi di nanocompositi polimerici. Doctoral Thesis.
The main purpose of this thesis was the graphene production and the synthesis and characterization of its polymer nanocomposites. Graphene was produced at high concentration through the improvement of colloidal dispersion-based techniques, using either inert solvent media and reactive compounds that give rise to polymerization. In particular, this method is based on graphite exfoliation achieved in a common ultrasound bath: it is effective, inexpensive, and it allows the obtainment of materials without impurities or defects. Moreover, the graphene concentrations are the highest ever obtained with any method and any solvent. Some of these dispersions were used for the synthesis of nanocomposites (hydrogel, polyacrylates) by applying classical methods or through the use of frontal polymerization and new radical initiators. In addition, for the first time graphene based polymer nanocomposites were prepared by in situ polymerization, using the monomer itself as the dispersing medium, thus avoiding any further manipulation. Graphene affects the polymer properties: with respect to mechanical properties, a reinforcement effect was observed for relatively low concentrations of nanofillers, while at higher concentrations graphene acts as a lubricant (due to the sliding of the sheets); finally, graphene improves the hydrogel swelling capacity.
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