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

微电子工业依赖于聚合物纳米结构的稳定性，这些纳米结构是通过光刻形成的，以生产特征尺寸不断减小的微处理器。分子动力学模拟预测，玻璃深处的聚合物纳米结构的模数将降低到临界尺寸以下。然而，由于硬衬底的存在通常使测量信号卷曲，这些预测的实验证实一直受到仪器的限制。该项目利用玻璃薄膜在柔性衬底上所受压力的不稳定性来确定薄膜的机械性能，同时避免衬底限制。此外，来自分子动力学模拟的关于玻璃材料纳米尺度力学的额外预测将得到实验验证。薄膜的模数将直接与用纳米压印光刻形成的聚合物纳米结构的机械强度进行比较，以明确地解决薄膜和相同尺寸的纳米结构之间的对应关系。这项研究将极大地增强聚合物纳米结构的知识基础，并为理解材料的玻璃化行为提供洞察力。在纳米尺度上对聚合物力学的基本理解影响到一系列工业和应用，其中聚合物纳米结构被用于微电子、有机电子、保护涂层和用于分离的膜。因此，这些材料的机械坚固性是为商业化提供足够的使用寿命所必需的。此外，该项目将通过(1)本科生参与，(2)让中学教师沉浸在实验室中接触纳米技术，以及(3)K-12外展努力，特别是在中学层面，与使用皱纹不稳定概念的动手活动相结合，从而激发学生对纳米技术的兴趣和认识。此外，该课程材料将通过数学、工程、科学成就(MESA)计划提供给亚利桑那州的多个学区。

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.