Enrichment of SWNT species with chemical approaches and mechanism investigation.
Date of Issue2011
School of Chemical and Biomedical Engineering
This thesis was devoted to both development of new chemical approach for SWNT species enrichment as well as deciphering of the mechanism underlying the selective processes. To these ends, a variety of chirality selective surfactants were employed and their effects on SWNTs separation were explored. A series of pyrene derivatives were synthesized and their separation effects on SWNTs based on the electronic properties and diameters have been demonstrated. To overcome the problem enforced by the poor dispersion with the amide-functionalized pyrene derivatives, a series of Polymethacrylates with pendant aromatic functional groups were investigated for their selectivity in SWNTs separation. The involvement of photon in the separation processes was first time identified and the metallicity selectivity was tentatively ascribed to Resonance Energy Transfer induced intermolecular pairing force. To clarify the role of photon/Resonance Energy Transfer induced intermolecular pairing force in the separation processes, two conjugated polymers with distinct optical properties were employed in SWNT species enrichment. The involvement of RET induced intermolecular pairing force was brought out by their different illumination responsive behaviors. The magnitude of this kind of weak interaction scales with an external stimuli parameter, i.e., illumination irradiance (I) and thus tunable. The relationship between the chirality selectivity and the chemical structures of the polymer may provide some instructive criteria for the search and design of molecules/polymers with novel structures for the purpose of SWNTs separation. This suggests a facile technique to modify molecules/polymers’ selectivity towards some specific SWNT species by altering the corresponding intermolecular interaction.