In spite of the stablility (lack of reactivity) of diamond powder, I have developed a method for tethering alkyl chains and polymers to deuterium/hydrogen-terminated diamond. One method is through ether linkages via thermolysis of di-tert-amyl peroxide (DTAP). This reaction with DTAP has also been applied to grow polymers on the diamond surface. The other method is atom transfer radical polymerization (ATRP), which was applied to grow polystyrene at the surface of diamond. Both polystyrene-modified diamond and sulfonated polystyrene-modified diamond can be prepared by either method, and can be used for solid phase extraction. Diamond stationary phases are stable under basic conditions, which is not the case for silica-based stationary phases. Surface characterization was performed by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and diffuse reflectance Fourier transform infrared spectroscopy (DRIFT). While the main focus of my graduate research has been the surface modification of diamond, I also describe other projects on which I have worked. The use of radical-based processes for modifying diamond is related to a different radical-based synthesis of monolayers or polymers I performed by scribing silicon (Siscr). After preparation of homogeneous olefin-terminated monolayers on scribed silicon made from 1,9-decadiene and chemisorption of Grubbs' catalyst, ring-opening metathesis polymerization (ROMP) of norbornene was demonstrated. These surfaces were characterized by XPS and ToF-SIMS. I also investigated the extent of PDMS oligomers transfer onto different surfaces with a wide range of hydrophobicities, using an uninked, unpatterned PDMS stamp. The effect of surface free energy on PDMS transfer in microcontact printing was investigated and the relationship between the amount of PDMS in ToF-SIMS spectra and the surface tensions of initial surfaces was revealed. Therefore, PDMS transfer can be applied as a probe of surface free energies using ToF-SIMS, where PDMS preferentially transfers onto more hydrophilic surface features during stamping, with little transfer onto very hydrophobic surface features. In much of my thesis work, I performed multivariate analysis of my data, especially of my ToF-SIMS data. Such chemometrics methods include principle components analysis (PCA), partial least squares (PLS) cluster analysis, and multivariate curve resolution (MCR). I also applied these tools to analyze electrospray ionization (ESI) mass spectrometry data from a lipidomics study.
| Identifer | oai:union.ndltd.org:BGMYU2/oai:scholarsarchive.byu.edu:etd-2715 |
| Date | 20 March 2009 |
| Creators | Yang, Li |
| Publisher | BYU ScholarsArchive |
| Source Sets | Brigham Young University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations |
| Rights | http://lib.byu.edu/about/copyright/ |
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