Phase Kinetics and Surface Modification of Polymer Nanocomposite Thin Films

1. FIGURE 1: Room temperature crystallization of 30 wt% POSS-MA thin films 61 and 560 min after deposition. FIGURE 4: Effect of solvents on Au adhesion to PMMA as-deposited (light blue) and after 96 hrs. (green) in 10-7 Torr vacuum. FIGURE 3: SEM images of 3.5 mm x 50 m PMMA membrane in cross section (left). 30 wt% silica / PMMA composite filters before (top right) and after HF etching (bottom right). FIGURE 2: Avrami-type curves for several representative crystallization events. Phase Kinetics and Surface Modification of Polymer Nanocomposite Thin Films Brian H. Augustine, James Madison University DMR-1005641 Real-Time AFM Study of Crystallization In POSS-MA Thin Films Photopolymerized Membranes and Composite Filters Produced for Microfluidic Applications Solvent Effects of Au Adhesion to Polymer Surfaces We have discovered that simply exposing the surface of PMMA with spun-cast solvents can change the adhesion of magnetron sputtered Au thin films from nearly 0% to over 90% Au thin film adhesion. Manuscripts are being prepared for the Journal of Vacuum Science and Technology: B and Macromolecules. • Non-complexing solvents such as chloroform and dichloromethane improve adhesion on PMMA substrates nearly a factor of 10. • ATR-FTIR evidence that there is a residual monolayer of CHCl3 and CH2Cl2 which remains after several days. We believe that a Lewis acid-base adduct is formed with the ester groups in PMMA which does not happen in complexing solvents such as acetone, THF, hexanes, etc. • The monolayer of solvent allows a Cr adhesion layer to bond to the solvent molecules which results in significant Au adhesion when deposited onto the Cr adhesion layer. We have used photopolymerization techniques to produce two novel PMMA structures with potential application in microfluidic devices. 1. High Aspect Ratio Membranes and Porous Composite Filters • 3.5 mm × 20-100 m thick membranes have been fabricated by photopolymerizing methyl methacrylate over a long chain (C32H66) parafin plug that has filled a 3.5 mm ×200 m thick hole in a PMMA substrate. • The ability to fabricate and control the thickness of such a membrane can be integrated into a microfluidic oscillator as reported by Begley et al (Appl. Phys. Lett, 95, 203501, 2009). Since PMMA is a much stiffer material, the resonance frequency of such a resonator should be much higher and the bandpass sharper than the Begley device. • Filter structures have been produced by blending silica beads into photopolymerizable MMA and etching with HF to open the filter structure. • Polymer crystallization observed in POSS-MA thin films using real-time AFM over the course of up to 23 hrs. • Real-time analysis performed from room temperature to 40°C. • Kinetics modeled using Avrami model resulting in Avrami fitting parameters with n=1.95 and ln(k) = -10.77. These numbers are consistent with 2D crystallization and prior literature on POSS-based thin films. • Dendridic features observed at ~3.4 nm and needle-like features measured at ~8 nm.

2. Phase Kinetics and Surface Modification of Polymer Nanocomposite Thin Films Brian H. Augustine, James Madison University DMR-1005641 Undergraduate Mentoring • Four undergraduate students were directly funded through this project this past summer. Three of these students are undergraduate chemistry majors and one is an undergraduate physics major at JMU. For the summer 2010 term, two were rising seniors, Alan Mo (chemistry) and Alex Burant (physics), one was a May 2010 graduate, Matthew Bradley, and one a rising sophomore, Skylar White. Mo worked on the Au adhesion project, Burant worked on the novel microfluidic structures and Bradley and White worked on AFM studies of the phase kinetics of POSS-MA thin films. In addition, Vezekile Zungu (Chemistry: University of KwaZulu Natal, South Africa) worked of ATR-FTIR of POSS-MA thin films and Natalie Trihn (Chemistry: JMU) worked on self-assembly onto plasma treated POSS-MA materials. • Four students who worked on this and our prior related RUI project (DMR-0804213) are enrolled or enrolling in graduate school: • Mr. Matthew Bradley is enrolling in a PhD program in materials chemistry at Penn State U in the Fall 2010. • Mr. Jon Wyrick is enrolled in a PhD program in physics specializing in nanomaterials at the University of California at Riverside • Ms. Katy Zimmermann is enrolled in a PhD program in environmental science at the University of California-Riverside • Mr. Jacob Forstater is enrolled in a PhD program in physics and astronomy specializing in polymer physics at the University of North Carolina-Chapel Hill Vezekile Zungu (University of KwaZulu Natal, South Africa) and Brian Augustine discussing ATR-FTIR results used to monitor POSS percentage in POSS-MA thin films. Alex Burant working on preparing microfluidic devices for plasma exposure and coverplate bonding.