The role of specific interactions on the dispersion and properties of carbon nanotube-polymer nanocomposites

This dissertation presents work that examines the role of specific chemical interactions in enhancing the dispersion of carbon nanotubes m a polymer matrix. Utilization of specific chemical interactions to induce/improve miscibility in polymer blends is well known. In this thesis, this approach is applied to carbon nanotubes polymer composites to enhance the dispersion of nanotubes in a copolymer of styrene and vinyl phenol with the idea that oxygenated functional groups on the nanotubes surface may potentially interact with the vinyl phenol groups on the polymer chain via hydrogen bonding.;The dispersion of single walled carbon nanotubes (SWNT) in the matrix of a copolymer of styrene and vinyl phenol containing 0, 10, 20, 40 and 100% vinyl phenol, is examined. The dispersion of the nanotubes was observed by optical microscopy. The dispersion of the SWNT in the polymer matrix is also quantified by optical microscopy and Raman spectroscopy. Raman spectroscopy is also used to investigate preferred interactions between the SWNTs and the copolymers via the shift in the characteristic Raman peak of the SWNTs in the composites. Optimal dispersion of the SWNT is observed in PSVPh with 20% vinyl phenol and oxidized nanotubes, which correlates with spectroscopic evidence that indicates that this system also incorporates the most interactions between SWNT and polymer matrix.;Polymer nanocomposite films containing 5 wt% single-walled carbon nanotubes (SWNT) or 5 wt% multi-walled carbon nanotubes (MWNT) with PSVPh copolymers were processed from dimethyl formamide solutions. The vinyl phenol mole ratio in the copolymers was 0, 10, 20, 30, and 40%. FTIR analysis indicates that the composites containing the copolymer with 20% vinyl phenol exhibit the maximum intermolecular interactions (hydrogen bonding) between the hydroxyl group of the vinyl phenol and the carbon nanotube functional groups. Tensile properties and electrical conductivity also are the highest in the samples containing the copolymer with 20% vinyl phenol. Thus, these results show that the optimization of the extent of intermolecular interactions between a polymer chain and a carbon nanotube results in an optimal increase in macroscopic properties.