Advanced Methods, Materials, and Devices for Microfluidics Celesta E. White 217 Pages Directed by Dr. Clifford L. Henderson Microfluidics is a rapidly growing research area that has the potential to influence a variety of industries from clinical diagnostics to drug discovery. Unlike the microelectronics industry, where the current emphasis is on reducing the size of transistors, the field of microfluidics is focusing on making more complex systems of channels with more sophisticated fluid-handling capabilities, rather than reducing the size of the channels. While lab-on-a-chip devices have shown commercial success in a variety of biological applications such as electrophoretic separations and DNA sequencing, there has not been a significant amount of progress made in other potential impact areas for microfluidics such as clinical diagnostics, portable sensors, and microchemical reactors. These applications can benefit greatly from miniaturization, but advancement in these and many other areas has been limited by the inability or extreme difficulty in fabricating devices with complex fluidic networks interfaced with a variety of active and passive electrical and mechanical components. Several techniques exist for the fabrication of microfluidic devices, but these methods have significant limitations, and alternative fabrication approaches are currently desperately needed. One such method that shows promise for its ability to integrate the desired high levels of functionality utilizes thermally sacrificial materials as place holders. An encapsulating overcoat material provides structural stability and becomes the microchannel walls when the sacrificial material is removed from the channel through thermal decomposition. Disadvantages of this method, however, include numerous processing steps required for sacrificial layer patterning and elevated temperatures needed for the decomposition of initial sacrificial materials. These limitations keep this method from becoming an economical alternative for microfluidic device fabrication. The materials needed for this method to reach its full potential as a valid fabrication technology for m-TAS are not currently available, and it was a major focus of this work to develop and characterize new sacrificial materials, particularly photosensitive polycarbonate systems. In addition to the development of new sacrificial polymers, the framework for a working microfluidic device was developed to show that this concept will indeed provide significant advancements in the development of future generations of microfluidic systems. Finally, novel fabrication methods for microfluidics through combined imprinting and photopatterning of photosensitive sacrificial materials was demonstrated.

It is the goal of this body of work to research an assortment of different photoacid generators (PAGs) and quantify their ability to perform the decomposition of poly(propylene carbonate) (PPC). Adding PAGs to PPC allows for a decreased polymer decomposition temperature, which can in turn be used as a sacrificial polymer for the fabrication of various microelectromechanical and microfluidic devices. A focus will be placed on relating the properties of the PAG such as acid strength, acid volatility, and PAG activation to processing issues like percentage of total film decomposition, amount and composition of film residue, decomposition rate, decomposition temperature, and environmental dependencies. This research discovered that the use of superacid triflic and nonaflic based PAGs were not adequate for the decomposition of PPC due to the high vapor pressure of the acid. Furthermore, the non-fluorinated sulfonic acid based PAGs do not posses the super-acid level acidity needed to sufficiently decompose PPC. Conversely, a perfluorinated methide and a tetrakis(pentafluoropheyl)borate based PAG both demonstrated the capability for high level PPC decomposition. Building on the knowledge gained through experimentation with these individual PAGs, the creation of a novel Combination PAG was accomplished. The Combination PAG uses acid groups with different physical properties collectively working to achieve what neither could complete individually.

Thèse de doctorat : SCIENCES ET TECHNIQUES : Metz : 1999. / 1999METZ032S. 103 ref.

Polycarbonates are a type of engineering thermoplastic that have countless uses in modern society. Currently, the major industrial production of polycarbonates involves the polycondensation of a diol and phosgene or phosgene derivative. Though there are many advantages to this process, it creates large amounts of waste and requires dangerous chemicals in order to proceed. Over the past four decades, the coupling of CO_(2) and epoxides has grown into a viable, greener alternative for the production of select polycarbonates. The byproduct of this reaction, cyclic carbonates, also have use as polar, high boiling solvents. This dissertation will be divided into three parts. First, the coupling of indene oxide and CO_(2) to form poly(indene carbonate) and cis-indene carbonate will be discussed. Poly(indene carbonate) has the highest Tg yet reported for polymers derived CO_(2) /epoxides coupling, up to 138degreeC. Polycarbonate production requires the use of (salen)Co(III) catalysts and low temperatures, though some cyclic carbonate production is still observed. Selective production of poly(indene carbonate) has been achieved through the use of bifunctional cobalt(III) complexes. The effects of temperature and cosolvent choices on polymer production will be thoroughly discussed. Though polycarbonate is the kinetic product from the coupling of CO_(2) and epoxides, the thermodynamic product is cyclic carbonate. There are six potential mechanisms that yield this undesired byproduct, though there is limited research into which pathways are the most active during polymerization reactions. Temperature-dependent kinetic studies were performed to obtain the activation parameters for the direct, polymer-free coupling of cyclopentene oxide, indene oxide, 1,2-butylene oxide, and styrene oxide with CO_(2) utilizing (salen)CrCl/nBu_(4)NCl to yield their corresponding cyclic carbonates. Additionally, the metal-free backbiting of the singly-coupled styrene oxide/CO_(2) intermediate was simulated utilizing the halohydrin 2-chloro-1-phenylethanol. Finally, the coupling of cyclopentene oxide with carbon disulfide to yield poly[thio]carbonates and cyclic [thio]carbonates utilizing (salen)CrCl/PPNX will be discussed. In each reaction, scrambling of the oxygen and sulfur atoms in both the polymeric and cyclic product is observed. Long reaction times lead to increased amounts of [thio]ether linkages and therefore polymers with lower glass transition temperatures. Insights into both the coupling and scrambling mechanisms will be presented.

Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2004. / Includes bibliographical references (p. 61-66).

Thesis (Ph. D.)--University of Missouri-Columbia, 2002. / Typescript. Vita. Includes bibliographical references (leaves 105-120). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2002. / Typescript. Vita. Includes bibliographical references (leaves 105-120). Also available on the Internet.

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