Date of Completion

Spring 5-2014

Thesis Advisor(s)

Dr. Mu-Ping Nieh

Honors Major

Materials Science and Engineering

Disciplines

Chemical Engineering | Materials Science and Engineering | Polymer and Organic Materials | Polymer Science | Transport Phenomena

Abstract

Pyrene is commonly used for explosives detection, as when mixed with polystyrene, the fluorescence intensity of the resulting film can be used as an indicator of the presence of nitro-aromatic, nitro-ether, or nitro-amine explosives. Previous studieshave tested a three-component system including pyrene, polystyrene, and a salt, tetrabutylammonium hexafluorophosphate (TBAHP). From these previous studies, it has been seen that vapor pressure of the preparation area is a governing factor in the formation of excimers, which are instrumental in achieving and maintaining fluorescence intensity. In this study, three parameters – solution concentration, film thickness, and molecular weight of polystyrene are examined to determine the effect of film processing on fluorescence results. The results from this study show that excimer formation (and thereby excimer fluorescence) is directly proportional to both concentration and thickness, but will plateau at higher concentrations. This plateau may indicate of a quenching behavior of the films at higher concentrations, but instead may represent an inflection point for fluorescent behavior. Results also confirmed that molecular weight of polystyrene does not appear to directly affect excimer formation. Film polarity was proven to be inversely proportional to excimer fluorescence. That is, a less polar film will result in higher fluorescence. It is suggested in future quenching studies that 192K molecular weight at 4.77wt% or 6.34wt% would provide the greatest initial fluorescence, and is therefore the best choice.

Download

Share

COinS