Physico-Chemical Characterization and Processing of Nanocomposite Polymers for Microfluidic Applications

1. Physico-Chemical Characterization and Processing of Nanocomposite Polymers for Microfluidic Applications Surface hydrophobicity can be controlled via remote plasma of spun-cast thin films of polylymethylmethacrylate-45% polyhedral oligomeric silsesquioxane (PMMA-POSS) from highly hydrophobic to highly hydrophilic depending on exposure conditions. Work is ongoing to understand the surface chemistry change affected by plasma exposure. Prior results with contact angles and ToF-SIMS data suggested that the surface becomes enriched with SiOx and that the plasma degrades the isobutyl groups surrounding the POSS cages. Current work involves XPS and spectroscopic ellipsometry (SE) data. Film thickness as-deposited is ~ 130Å SE shows that the film etches up to ~22Å after plasma exposure and then appears to stop etching suggesting that the SiOx layer passivates the surface (Figure 1). A calculation of the thickness of 45 wt% PMMA-POSS film required to be removed to fully cover the surface is ~25Å. Ongoing work is to repeat this experiment with 10 wt% PMMA-POSS film to determine if this saturates at a greater thickness change. XPS data shows a decrease in C percentage with a corresponding increase in O and Si percentage (Figure 2). Ongoing high resolution XPS is being performed to understand changes in surface chemistry of the plasma treated films.

2. Physico-Chemical Characterization and Processing of Nanocomposite Polymers for Microfluidic Applications Eight undergraduate students were directly funded through this project from the Departments of Physics and Chemistry at James Madison University this past year. For the summer 2006 term, rising senior, Jacob Forstater (Physics), is working on development of ?-PIC PCR devices and rising sophomore, John Wyrick (Physics), is working on a rapid prototype scheme for polymer microfluidic fabrication. Summer 2005, six students were funded through this grant. These were Forstater and rising seniors, Katy Zimmermann and Patrick Turner (Chemistry) who worked on plasma surface modification of POSS based polymers and characterization and soft lithographic patterning of polymers, respectively. May 2006 graduate Melissa Lane and May 2005 graduate Rozine Lindamood (both Chemistry) worked on microfabrication of polymeric structures. A middle school science teacher, Karen Bland (May 2003 graduate in physics) worked for eight weeks on a project of microfabrication of demonstration devices for middle and high school science teachers. Three women funded through this project this past year are enrolled or will be enrolling in graduate school: Ms. Toni Bonhivert is enrolled in a PhD in chemistry at Georgia Tech studying biomaterials / materials chemistry Ms. Rebekah Esmaili is enrolling in a PhD program in Materials Science and Engineering at North Carolina State University Ms. Karen Bland is enrolling in a MS program in astrophysics at Baylor University. Forstater, Zimmerman, Turner and Wyrick plan on attending graduate school in SMET disciplines after graduation Jacob Forstater has worked half of the summer 2006 in the Augustine / Hughes lab at JMU and is currently spending six weeks working in the lab of Dr. James Landers at the University of Virginia. He is working on comparison of device performance of polymeric ?-PIC PCR chips with glass PCR devices fabricated by the Lander’s group.