This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
This CAREER award supports research and education involving the computational and theoretical study of the dynamics of molecular layering in thin films near vapor and solid interfaces. As an example, the order in a polymer liquid near a solid interface will exhibit a transition from solid-like, molecular layering in the fluid near the interface to more liquid-like order further from the interface. The extent over which this transition occurs is commonly denoted as the penetration depth, and is found to be directly related to the temperature, the solid-liquid molecular interactions, and the surface structure of the solid. Given that the magnitude and extent of the layering has pronounced effects on the electrical, mechanical, and optical properties of the film, understanding the stability or time-evolution of the molecular layering in the film is extremely important. A major motivation for the current approach comes from a recent computer simulation study by the PI that shows that the extent of layering in an alkane film next to a solid substrate oscillates in time with an amplitude and period that strongly depend on temperature.
Atomic-scale computer simulations will be used to study two major topics: is the observed oscillation in the extent of the layering with time a general property of other polymer melts near solid surfaces, and what are the nucleation kinetics involved in the formation and growth of the ordered monolayers near the polymer melt/vapor interface during the surface freezing phase transformation. This research will provide an atomistic-scale explanation to the structure and dynamics of polymer molecules near interfaces. Our detailed investigation on the adsorption of polymer films on different surfaces will provide us with the means of understanding how nucleation barriers can be altered by appropriate surface templates.
As part of the education component, undergraduate and graduate students involved in the project will be trained in this area of materials research that is interdisciplinary between chemistry, physics, and materials science, and the students will also develop computational skills applicable to these disciplines. Major efforts will be made to recruit minority and female students. Additional educational outreach efforts are planned that will develop a seminar program on "Physics in Africa" for inner city schools with a goal of increasing enrollment of African-American students in STEM degree programs, as well as a collaborative effort at SIUC to develop a computational science course that will integrate computer simulations into a science methods course for certified and in-training high-school teachers.
NONTECHNICAL SUMMARY This CAREER award supports research and education involving the computational and theoretical study of how polymeric liquids are structured near a solid interface, and how this ordered structure changes with time. One of the major differences between liquids and crystalline solids is that liquids show no ordering over long distances as solids do. At a liquid-solid interface (e.g., a solvent in a glass container), however, the molecules in a liquid usually align into thin films with the alignment decreasing with distance from the solid surface. This research will use computer simulations to examine how this ordering for polymeric liquids changes with time. Given that the magnitude and extent of the layering has pronounced effects on the electrical, mechanical, and optical properties of polymer films, it is extremely important to understand the stability or time-evolution of the molecular layering in the film. This research will not only contribute to the fundamental understanding of molecular ordering at interfaces, but it will also have huge potential in addressing problems encountered in industry, such as producing uniaxially oriented mesostructured films which are very desirable for electronics, optics, and sensors.
As part of the education component, undergraduate and graduate students involved in the project will be trained in this area of materials research that is interdisciplinary between chemistry, physics, and materials science, and the students will also develop the computational skills useful for these disciplines. Major efforts will be make to recruit minority and female students. Additional educational outreach efforts are planned that will develop a seminar program on "Physics in Africa" for inner city schools with a goal of increasing enrollment of African-American students in STEM degree programs, as well as a collaborative effort at SIUC to develop a computational science course that will integrate computer simulations into a science methods course for certified and in-training high-school teachers.
