Hybrid polymer-inorganic materials represent an important development in the polymer materials field due to the ability to potentially tailor the physical properties of these materials with varying chemical composition and percentage of the inorganic component. This Research at Undergraduate Institutions (RUI) proposal addresses several areas of intellectual merit. The primary technical objective of this study is to understand the fundamental physicochemical surface properties of polyhedral oligomeric silsesquioxane (POSS)-based nanocomposite polymer materials when modified by oxidizing or reducing plasma environments, and their longterm stability at elevated temperatures or with ultraviolet light exposure. A second objective is to determine whether plasma-modified POSS-based polymers can be used as a coating material for improved polymer microfluidic devices. Plasma control of the spatial and chemical composition of the POSS-based polymer surface will be achieved using a remote plasma treatment tool and the properties will be studied using a combination of surface analysis techniques including x-ray photoelectron spectroscopy (XPS), atomic and lateral force microscopy (AFM/LFM), scanning electron microscopy (SEM), and contact angle measurements. Test designs for PMMA-based microfluidic devices have been fabricated, and POSS-based thin films will be deposited onto these to determine the change in electroosmotic flow (EOF) characteristics using plasma surface modification. Spatial control of the surface will be accomplished through a microfabricated shadow mask allowing for a hydrophilic / hydrophobic gradient to be patterned into the microfluidic channel. EOF and fluid flow measurements will be made in collaboration with the University of Virginia to determine whether fluid flow can be controlled through a spatially modulated surface within a microfluidic structure. A further objective is to design and develop an integrated detection methodology for microfluidic devices using ultraviolet-visible absorption spectroscopy taking advantage of the lower absorption edge of PMMA compared to the glass substrates typically used in microfluidic devices. A final objective related to the broader impacts of this proposal is the scientific training of undergraduate research students and high school science teachers in a highly interdisciplinary research environment. This project will involve the training of six to ten undergraduate researchers and three high school chemistry, physics or biology teachers over the duration of the program. In both cases, this project will introduce undergraduate chemistry and physics students and secondary school teachers to the materials science issues of structure-property relationships. Both students and teachers will be exposed to surface analytical techniques, vacuum science, polymer materials characterization and processing, and microfluidic technology and science. The participants in this program will also interact with graduate students and post-doctoral researchers at the University of Virginia through direct laboratory exposure in order to experience research at a research institution. These activities help serve to broadly impact the pipeline of future scientists from the high school through the graduate level.
