Rational synthesis of nanoparticle-MWCNT hybrid nanostructures through non-covalent interactions with organic polymers

The synthesis of hybrid nanostructures comprised by CNTs and nanoparticles is a promising field of research due to their potential applications in catalysis, energy storage, energy generation and biomedical technologies. However, the field lacks of synthetic guidelines for the rational design of hybrid nanostructures. This Thesis aims to stablish synthetic guidelines that consider the forces involved during the synthesis of iron oxide nanoparticle-CNT hybrids where polymers are used to mediate the interactions between the nanomaterials. The functionalisation of MWCNTs with polystyrene is studied as the first level of hierarchy representing the polymer-MWCNT interactions. Non-covalent methods were found the most effective way to create polystyrene functionalised MWCNTs. It was found that the solvent used during the functionalisation was the parameter that had a higher effect in the amount of polystyrene found in the MWCNTs. The surface energy solubility parameter theories were proposed as a predictive synthetic model for the design of polymer functionalised MWCNTs. The predictions of the model were compared with the amount of polystyrene found in the functionalised MWCNTs synthesised in different solvents, finding good agreement between the predictions and the experimental evidence. The next level of nanostructural hierarchy was addressed by studying the synthesis of polystyrene coated iron oxide nanoparticle-CNT hybrids. The solvent was found to play a key factor in the amount of polystyrene coated iron oxide nanoparticles found in the hybrid structures. The surface energy based solubility parameter theory was used to understand the amount of iron oxide nanoparticles found in the hybrids synthesised in different solvents, showing a better agreement with the experimental results than other parameters previously highlighted in the literature. The results and ideas proposed in this Thesis will contribute to the future development of the rational synthesis of nanoparticle-CNT hybrid structures.