A unique feature of nanoscale carbon materials is the nature of their surfaces and how their surfaces interact with other species. The carbon materials specifically studied here include single-wall carbon nanotubes, nanoscale carbon nitrides, and a brief study of nanodiamonds from meteorite carbon, and related diamond surface chemistry. These nanometer sized carbon materials often possess curved surfaces. These curved surfaces can result in special structure-property relationships, such as a unique resistance to oxidation in the case of the nanotubes. Also the synthesis of nanoscale structures can be governed by surface interactions with the growth substrate, as shall be demonstrated with the carbon nitrides. The final materials obtained after such chemical treatments, should prove useful in applications such as catalysis, gas storage, chromatography, molecular electronics, high-strength composites, batteries and fuel cells, and abrasives.

Carboxylate alumoxanes were cast onto alpha-alumina supports by slip-coating to develop asymmetric ceramic membranes. Carboxylate ferroxanes were also analyzed as possible precursor for ceramic membranes. Different support materials were studied. Membrane layers as thin as 1 or 2 mum were achieved. The effect of sintering conditions was investigated. The molecular weight cut off was evaluated for these membranes and compared to pore size data obtained by nitrogen adsorption in an effort to correlate pore size and actual performance of the membrane. Membranes were sintered at temperatures between 600°C and 1100°C. The pore sizes increased with higher sintering temperature, from 7 nm at 600°C to 10 nm at 1000°C, followed by a sharp increase due to the transformation to alpha alumina at higher firing temperatures. The molecular weight cut off showed no considerable variation up to 1000°C. These results are in good agreement with equations reported by several authors that correlate molecular weight with size.

Metals have been used in the past to grow diamond in high temperature/high pressure reactors. In our research we used metals to grow diamond at low pressures and low temperatures. A vertical vibratory hot-walled reactor was used along with metal powders. We started our investigation by first examining the etching of polished diamond windows coated with metal films. Metal films made from Fe, Ni and Co were deposited on diamond windows then scratched for post-reaction analysis with an Atomic Force Microprobe (AFM). The etching gases used were hydrogen, oxygen and nitrous oxide. A stable diamond interface formed between the diamond and the metal film. This interface allows for the removal of carbon from the diamond lattice. The carbon diffuses through the film to the surface were it forms C-O, and C-H species with dissociated H2 and O2 on the film surface. We analyzed the impact of various parameters on the etching reaction such as film thickness, length of reaction, temperature, crystal face, % of N2O and % of O2 in H2. Problems with surface poisoning and film adherence created problems with reaction reproducibility. Metal films were replaced with metal powders. In a hot-walled vibratory reactor the metal particles continuously collide with the surfaces of the diamond suspended in the powder. During these collisions, carbon transfer occurs at the diamond-metal interface which results in either etching or growth depending on the carbon potential of the gas phase. Metal sintering limited the maximum temperature to 400°C or less. In a series of fourteen reactions the pit depth and volume of six etch pits were monitored using the AFM. A gas mixture of CO/CO2 was used and its carbon potential varied. We were able to document growth and etching by measuring the change in pit depth and pit volume. Under growth conditions a decrease in pit depth and pit volume occurred. Under etching conditions an increase in pit depth and pit volume occurred.

Reaction temperatures and time are probed to get the optimal fluorination conditions in order to produce C2F carbon nanotubes. Possible fluorotube structures are optimized with molecular mechanics calculation. Results show that fluorines would like to add along the circumference of the tubes instead of going down the tube axis. The (1,4) isomer has the lower total steric energy (TSE) between the two proposed fluorotube structures, but the energy difference is small. Scanning tunneling microscopy has been used for atomic scale imaging of the fluorotubes. Significant band features are seen on fluorotubes, not on pristine carbon nanotubes. Butylated tubes have also been investigated by STM imaging. Instead of bands, relatively large, distinct features with spacing of about 50 A are observed. Both theoretical and experimental results indicated the (1,4) isomer with bands around the tubes should be the preferred structure.

The goal of this work was to examine the chemistry that one can do with various fluorinated forms of elemental carbon. As a prelude to the experimental worked out for this thesis, a brief discussion of the various allotropic forms of carbon is given followed by a brief discussion of elemental fluorine and fluorination procedures. Graphite fluorides have been defluorinated with ammonia, trimethyl amine and hydrazine and functionalized with organolithium species to give soluble, submicron sized graphitic particles. C60 has been fluorinated to yield C60Fn species which n is predominately 42--46. These fluorinated fullerenes were then reacted with organolithium species to yield highly alkylated species having properties which differed greatly from C60 or their fluorinated counterparts. While the fluorination of graphite and fullerenes has been reported before, the fluorination of single wall carbon nanotubes (SWNTs) has not. The first report of the fluorination of SWNTs is described here as is our finding that hydrazine can defluorinate the "fluorotubes" to regenerate the original SWNTs. It was also determined that the fluorotubes were soluble in alcohol solvents and that reactions could be carried out on them while in solution. Using a technique which we developed here at Rice called "Ultrasonic assistance," we were able to react the fluorotubes with organolithium species in solution to yield alkylated SWNTs which could then be isolated by filtration and dissolved in chloroform.

Elastic-plastic behavior of porous materials is analyzed using a hollow sphere micromodel and the NIKE2D finite element program. Surface average responses are computed for several displacement controlled homogeneous loadings. The data provides simple equations for elastic constants in terms of porosity. Yield surfaces are plotted and approximated by a yield function. The function's shape, hydrostatic strength, and deviatoric strength closely match the data for a wide range of porosities. Most significantly, plotting plastic strain rates relative to this yield function validates the common normality assumption for porous materials.

The hydration of cement and its individual mineral phases in the presence of different inhibitors has been investigated. The behavior of an exemplary oligo-phosphate, nitriltris(methylene)phosphonic acid (H6ntmp), is compared to the behavior of more traditional retarders. The reaction between H6ntmp and calcium hydroxide, tricalcium silicate, tricalcium aluminate, and cement have revealed that the calcium phosphonate complex, [Ca(H 4ntmp)]infinity, plays a role in inhibition with phosphonates. NMR and XPS data suggest that the presence of uncoordinated P-O bonds in calcium phosphonates lends phosphonates the unique ability to simultaneously complex calcium ions while adhering to hydrating aluminate surfaces, promoting heterogeneous nucleation of calcium phosphonates at the surface of aluminate minerals and blocking normal hydration reactions. Reactions with tartaric acid also forms a calcium complex on top of the aluminate phases. In contrast, sucrose, appears to act directly on the silicate phases actually accelerates the reactions of the aluminate phases. The reactions of borate ions with diols and monosaccharides have been used to model cross-linking in the guar-borate system. Specifically, the reactions of borate with alcohols were characterized by 11B NMR to determine which reactions are most favorable. It was found that the acidity of the hydroxyl groups plays an important role in the efficiency of cross-linking, and has a greater effect on the energy of the resulting borate-diol complexes than the conformation (i.e., cis versus trans) in reactions of borate with cyclohexanediols and monosaccharides. The role of Group 1 metal salts in the borate-diol reactions was also investigated by 11B NMR and by the synthesis of model compounds. It was found that the metal cations play an important role in stabilizing the borate-diol complexes in the solid state. In solution, it was found that cross-linking is enhanced by the presence of strongly coordinating cations, as opposed to more purely ionic cations, and cross-linking is decreased in the presence of non-coordinating ammonium cations.

Characterization of raw nanotube materials produced by different methods is demonstrated. Depending on the production methods, tubes of different diameters can be produced. Purification of single wall carbon nanotubes produced by laser-oven and HiPco process is also discussed. Metal catalyzed oxidation at low temperature has been shown to selectively remove non-SWNT carbon and permit extraction of metals with concentrated HCl. These multi-stage purification methods have been investigated and the sample purity is documented by EDAX, ESEM, TGA, Raman and UV-vis-Nir spectroscopy. Covalent attachment of functional groups and molecules, including fluorine, methyl, n-butyl and n-hexyl groups, to the sidewalls of single wall carbon nanotubes has been achieved. Further fluorination study is done to investigate the effect of HF which is used as catalysts. Parallel fluorination experiments are performed on both laser-oven-grown and HiPco SWNTs. Larger diameter tubes, i.e. laser-oven-grown SWNTs, require higher fluorination temperatures. A limiting stoichiometry of C2F can be reach for Fluorotubes. Quantitative measurement of the alkylation was done by thermal gravimetric analysis. A mechanism involving electron transfer and effects of reaction temperature, solvents and steric effects of the alkyl groups are discussed. Prolonged exposure of small diameter SWNT ropes (diameters < 5 nm) to hot fuming sulfuric acid has been shown to grow super-ropes with approximately 10,000 tubes in cross-section from rope sizes of approximately 10 tubes. This represents the largest rope sizes ever seen. Examination of the spectral properties of the SWNTs indicates that the roping occurs without changing the chemical state of the nanotubes. Acid intercalation of single wall carbon nanotubes is examined. Several super acids and strong acids are used to study the charge transfer and protonation effects on SWNTs. The degree of charge transfer is clearly correlated with the ability of acid to intercalate into the nanotube packs. A molecular mechanics calculation is used to optimize the proposed Fluorotube structures. This is the first theoretical work on the modeling of Fluorotubes. Results show that fluorine would like to add along the circumference of the tubes instead of going down the tube axis. The (1,4) isomer has the lower total steric energy (TSE) between the two proposed Fluorotube structures, but the energy difference is small. Scanning tunneling microscopy has been used for atomic scale imaging of the fluorotubes. Significant band features are seen on fluorotubes, not on pristine carbon nanotubes. Butylated tubes have also been investigated by STM imaging. Instead of bands, relatively large, distinct features with spacings of about 50 A are observed. Both theoretical and experimental results indicated the (1,4) isomer with bands around the tubes should be the preferred structure.

Single wall carbon nanotubes (SWNTs) possess many properties that are both novel and desirable. Most notable of said properties include electrical conductivity (metallic and semiconducting), high thermal conductivity, directionality in both electrical and thermal conductivity, high geometric aspect ratio (about 1nm diameter and up to 1 micron or greater length), unprecedented tensile strength and a versatile chemistry. There is growing eagerness in academia, industry and government to see this exciting new material developed into viable technologies. Current production levels are too low to meet the needs of manufacturers looking to develop products based on SWNTs. This is especially true for those looking to make structural polymer composites. Thus there is a need for large-scale production of SWNTs. Of the numerous techniques for growing SWNTs the technique described here in, the HiPco process, is the most apt candidate for large-scale production. The two principal advantages that distinguish HiPco from other processes are (1) HiPco is a continuous process and (2) HiPco SWNTs are extremely clean as-grown. All of the other production techniques lack one or both of these qualities making them much less economical as a large-scale process. This thesis describes the results of the research on the HiPco process, the theory and mechanisms of the HiPco reaction, the HiPco reactor and directions for future development toward the goal of mass production.

The optical response of sulfuric acid anodized 5657 aluminum alloy coatings was determined to be greatly dependent upon trace and alloying element concentration. An improved method for WDS analysis of anodized coatings was developed to preclude processing errors and improve spatial resolution since it was shown that the possibility of contamination and/or coating modification must be considered in the development of sample preparation procedures and electron beam parameters. Measured element concentrations were compared with reflectance data to determine the affect of each on absorptance. Silicon and zinc concentrations were much higher than expected, the source of these elements being the substrate 5657 Al alloy. Both of these elements play a role in absorptance and the glass forming abilities of silicon may also affect the structural characteristics of SAA coatings produced on 5657 Al alloy.