Mechanical Properties of Compliant Polymer Nanoscale Films and Structures from Wrinkling Instabilities and Pattern Collapse

The microelectronics industry depends on the stability of polymeric nanostructures that have been formed photolithographically to produce microprocessors with ever decreasing feature sizes. Molecular dynamics simulations have predicted a decrease in the modulus of polymeric nanostructures deep in the glass below a critical dimension. Experimental confirmation of these predictions, however, has been instrumentally limited since the presence of a hard substrate generally convolutes the measurement signal. This project exploits the wrinkling instability of a glassy film stressed on a compliant substrate to determine the mechanical properties of thin films while avoiding substrate limitations. Moreover, additional predictions from molecular dynamics simulations on nanoscale mechanics of glassy materials will be tested experimentally. The moduli of the thin films will be directly compared to the mechanical strength of polymeric nanostructures formed with nanoimprint lithography to unambiguously address the correspondence between thin films and nanostructure of identical dimensions. This study will greatly enhance the knowledge base for polymeric nanostructures and also provide insight into understanding glassy behavior of materials.

A fundamental understanding of polymer mechanics at the nanoscale impacts a range of industries and applications where polymer nanostructures are being utilized for microelectronics, organic electronics, protective coatings, and membranes for separations. Mechanical robustness of these materials is, therefore, necessary to provide sufficient service life for commercialization. Further, this project will integrate research and education through (1) undergraduate student participation, (2) immersion of a middle school teacher in the laboratory for exposure to nanotechnology and (3) K-12 outreach efforts, specifically at the middle school level, with hands-on activities using the wrinkling instability concept, thereby stimulating student interest in and awareness of nanotechnology. Furthermore, this curriculum material will be provided to multiple school districts in Arizona through Mathematics, Engineering, Science Achievement (MESA) program.