Atomic force microscopy (AFM) is an important technology that allows researchers to probe local surface properties at nanometer length scales. In addition to surface topography, the AFM can probe many types of tip-surface interactions (including adhesion and friction) to gain a better understanding of the chemical properties of surfaces. This thesis contains two experiments which utilize AFM to in addition to several other techniques to study (1) Self Assembled Monolayer (SAM) formation and corrosion and (2) intermolecular and surface/molecular effects on gramicidin film formation and molecular orientation.
In the first experiment, N-octadecyltrichlorosilane (OTS) molecules were self-assembled onto silicon samples. We observed that OTS required a very short time (about 15 seconds) to complete the formation of the monolayer on surface. However, this SAM film was highly susceptible to corrosion by the strong oxidant (KMnO4), resulting in a chemical change to the film from hydrophobic functional groups (CH3) to hydrophilic functional groups (OH). In subsequent experiments, we observed that if the SAMs were formed using longer exposure times (about 24 hours), they were highly resistant to corrosion. Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray Photoelectron Spectroscopy (XPS) also showed that the 24 hour growth SAM films were densely packed. These results indicate that SAM films based on organosilane molecules can protect the surface from corrosion, and further that more densely packed SAMs exhibit better anti-corrosion performance than less dense films.
In the second experiment, the antibacterial peptide Gramicidin was used to study how intermolecular and surface energy properties can influence the aggregation and film formation of molecules on several surfaces. Gramicidin has a unique physical and chemical structure with hydrophobic side chain and hydrophilic ends. Here, we have used three different substrates (Silicon, Mica, and Graphite) to study intermolecular interactions, aggregation, and orientation of Gramicidin peptide. Langmuir-Blodgett methods were also used to study aggregation and molecular orientation at the solid-liquid interface.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0727109-164229 |
| Date | 27 July 2009 |
| Creators | Chao, Wei-chieh |
| Contributors | Michael Yen-Nan Chiang, Shuchen Hsieh, Chao-Ming Chiang |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0727109-164229 |
| Rights | not_available, Copyright information available at source archive |
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