Design of Aromatic Thermosetting Copolyester Compositions and Blends for Thin Film Applications
This thesis is devoted to the development, synthesis, properties, and applications of aromatic thermosetting copolyester (ATSP) and multicomponent systems of ATSP and polyimide thin films. Originally, ATSP was developed as a high performance structural polymer. One drawback to this system is the inability to prepare uniform thin films from NMP solutions of ATSP oligomers. To be used in thin film applications, the synthesis and curing of ATSP oligomers are optimized, permitting formation of uniform thin films. The optimized ATSP thin films display sharp improvements in their dielectric properties. Two thin film applications have been investigated. One, because foaming can reduce the dielectric constant, the possibility of foaming ATSP using the reaction byproduct during curing is an attractive concept in developing ATSP as a low k dielectric. To this end, the nature of pore formation was investigated and avenues of research for producing foamed ATSP with controlled pore morphology are suggested. Second, the application of ATSP as a sub-micrometer adhesive in solid-state integration of microelectronic devices is explored. In this study we characterize the adhesion mechanism between ATSP and polyimide using DSIMS and demonstrate the effectiveness of this solid state integration technique in a mesoscopic device. In addition, two approaches have been taken to design multi-component systems of ATSP and polyimide thin films with the aim of obtaining optimized properties from the combination of both polymers. In the first approach, thin film blends of ATSP and polyimide have been prepared. Emphasis is placed on the study of the phase separation and surface segregation behavior using a combination of techniques including DSIMS, 3He NRA and AFM. A remarkable yet stable five-layered lamellar structure has been observed in a thin film blend of ATSP and polyimide, representing the first observation of surface directed spinodal decomposition in a thin film blend of high performance polymers. To our knowledge, all other studies on this phenomenon have been limited to model polymers. In the second approach, a hyperbranched copoly(imide-ester) (HBPIE) has been synthesized and characterized. Most interestingly, the HBPIE has a surface area of 83 m2/g, due to their intrinsic and stable microporosity (pore size 12.7 A). Further, HBPIE thin films displays an intermediate dielectric constant (3.6) and high dielectric breakdown strength (330 V/mum). HBPIE thin films could find potential application as reverse osmosis membranes or dielectric thin films in capacitors.
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign