PDMA

1. Chain Dynamics and Layering within Polyelectrolyte Multilayer FilmsSvetlana A. Sukhishvili, Stevens Institute of Technology, DMR 0906474 PDMA Understanding and controlling the internal structure of layer-by-layer (LbL) polymer films is critically important for many emerging applications of such films in optics or for sequential drug delivery from surfaces. We aimto explore how molecular characteristics of polymers affect kinetics of chain interdiffusion within polyelectrolyte multilayer films (PEMs). We are specifically interested in comparing the rates of chain diffusion in directions parallel and normal to the substrate. Using controlled radical polymerization techniques, we have successfully synthesized well-defined PDMA and PDEA homopolymers,1 as well as converted them to cationic QPDMA and QPDEA copolymers of various charge densities.2 Attaching fluorescent labels to these polymers allows tracking their interactions with a polyacid in solution using fluorescence correlation spectroscopy. At surfaces, films of PDMA (or PDEA) assembled with a polyacid PMAA3 at different pH values (pH 5.0 or 6.0) showed switching between linear and exponential growth, and neutron reflectivity (NR) indicated that linearly growing films were internally structured (Fig. 1, top). We established a correlation between the rate of polymer interdiffusion and the type of ionic pairing in the film. Bottom panel in Fig. 1 shows that multilayers with larger inter-ionic distance within ionic pairs (i.e. PDEA/polyacid) demonstrated higher rate of polymer interdiffusion. PDEA Fig. 1. NR curves of PDMA/PMAA (top), and comparison of polymer layer interdiffusion rates in QPDMA/PSS and QPDEA/PSS systems (bottom). Every 5th bilayer contained deuterated polyacid.

2. Chain Dynamics and Layering within Polyelectrolyte Multilayer FilmsSvetlana A. Sukhishvili, Stevens Institute of Technology, DMR 0906474 Results of the project are now being incorporated into one course1 and presented inthree conference presentations2, as well as at the Research and Entrepreneurship Day at Stevens in April 2010, which gathers a broad audience of NY/NJ entrepreneurs, National Lab representatives, and high school teachers. Graduate students involved in the project are significantly enriching their knowledge through systematic interactions with researchers at NIST and ORNL. Specifically, two graduate students have travelled twice to ORNL to perform neutron reflectivity experiments. Experience obtained at ORNL is disseminated to undergraduate and high school students. In summer of 2010, one undergraduate student, Chris Stoddart, has been working on the NSF project (Fig. 1). We are now shaping the Polymers in Our Lives module for implementation in high school classrooms. To that end, graduate students met with Debra Brockway (Fig. 2), a science educator from Stevens’ Center for Innovation in Engineering and Science Education (CIESE) to discuss implementation of the module. CIESE is a nationally recognized center whose goal is to improve K-12 science and mathematics education through internet-based curriculum materials and bringing cutting-edge research into K-12 classrooms. 2010 Fig. 1. Graduate, undergraduate and high-school students during summer of 2010: graduate students Li Xu (in grey, left) Zhichen Zhu (in grey, right), and an undergraduate student Chris Stoddart (in white) participate in the project. Fig. 2. A science educator Debra Brockway collaborating with graduate students Li Xu (Fig.1, in grey, left) and Alex Zhuk (Fig. 1, in blue) to promote the development and implementation of Polymers in Our Lives moduleinto the high school setting.