Functionalization, coordination, and coating of carb on nanomaterials
Hamilton, Christopher Eric
Barron, Andrew R.
Doctor of Philosophy
Single-walled carbon nanotubes were covalently end-functionalized with various donor ligands in order to facilitate the coordination of metal catalyst nanoparticles. The purpose of this study was to optimize catalyst complexation to SWNT ends, allowing growth from preformed seeds (SWNT-cats). The "SWNT amplification" method is envisioned as a route to bulk single-chirality nanotube samples. Study by 31 P MAS NMR was undertaken in order to characterize SWNT phosphine derivatives. The synthesis of new N -aryl dipyridylamines (dpas) and related compounds is reported. The products, chelating N-donor ligands, will be used to prepare copper complexes. Copper dpa complexes are able to discriminate between olefin isomers in simple mixtures. Similar triarylamines have been similarly prepared and characterized; these have been tested for their ability to separate SWNTs of particular diameters (or chiral angles) by selective π-π stacking interactions. This method is a possible route to single or few-chirality samples, which could then be subjected to SWNT amplification. A novel method for production of high-yield dispersions of single and few layer graphene is presented. o -Dichlorobenzene suspensions of graphene provide twice the yield of previous methods. Moreover, ODCB graphene dispersions form a convenient platform from which to pursue covalent derivatization of graphene in a nonpolar medium. ODCB dispersions have been used to covalently functionalize graphene with perfluoroalkyl groups by a free radical method. Initiation of radical reactions was achieved by both UV photolysis and thermal decomposition of peroxides. Perfluoroalkylated graphene is highly exfoliated and shows great promise for use in polymer composites, lubricants and coatings. Chemical bath deposition (CBD) of II-VI semiconductor materials on SWNT substrates is demonstrated. Bulk heterojunction photovoltaic devices have been prepared from these SWNT-semiconductor composites. The CBD process of depositing CdSe/CuSe layers onto SWNT buckypapers will allow production of low-cost solar cells on flexible substrates. The manufacture of solar cells will be possible using roll-to-roll processing, in ambient conditions, without need for high-vacuum or specialized equipment.