PECASE: Nanoscale Confinement in Polymers: Integrated Research and Education in Nanoscale Experimental Mechanics

这个教师早期职业发展（CAREER）计划旨在量化聚合物的机械行为，这些聚合物受到纳米级限制，并在硬表面附近限制/增强大分子流动性。后者将被设计用于模拟聚合物纳米复合材料中原始和官能化纳米管和纳米纤维附近的聚合物分子的行为。在这些材料系统中的大的表面积与体积比使得硬相限制分子的移动性和构象。因此，整个复合材料实际上可能是一个界面，局部和有效的宏观性能与原始的本体聚合物非常不同。实验纳米探针的方法将被开发，以确定在纳米尺度上的分子耗散的变化，并量化的集体在超薄聚合物膜的表面分子的时间依赖性的响应。粘弹性蠕变函数和玻璃化转变温度作为聚合物层厚度的函数的测量将提供数据来评估硬界面附近的分子构象，由于缺乏关于硬表面附近的聚合物基体改性的局部信息，制造坚韧多功能和轻质聚合物纳米复合材料远未达到其预期的潜力。如果成功，该计划将为高性能纳米结构聚合物的控制和有效设计奠定基础，并为多相聚合物建立性能限制。该计划的实验结果将成为分子动力学和微观力学模型的基本材料参数，并应用于纳米复合材料，生物系统，纳米压印，纳米流体阵列，此职业奖的推广计划将（a）通过一个工程教学工具包，激发高中学生学习航空航天工程，这将提高高中学生对航空航天分层材料的技术意识应用程序，（B）提供纳米力学的本科生和研究生动手教育，和（c）支持纳米力学实验室培训的专业人员。

This Faculty Early Career Development (CAREER) program seeks to quantify the mechanical behavior of polymers subjected to nanoscale confinement and restricted/enhanced macromolecular mobility near hard surfaces. The latter will be designed to simulate the behavior of polymer molecules near pristine and functionalized nanotubes and nanofibers in polymer nanocomposites. The large surface-to-volume ratio in these material systems is such that the hard phase restricts molecular mobility and conformations. As a result, the entire composite may be practically an interphase, with local and effective macroscopic properties being very different from pristine bulk polymers. Experimental nanoscale probe methods will be developed to determine variations in molecular dissipation at the nanoscale and to quantify the collective time-dependent response of surface molecules in ultra-thin polymer films. Measurements of the viscoelastic creep functions and glass transition temperatures as a function of polymer layer thickness will provide the data to assess molecular conformations near hard interfaces.Due to the lack of local information on polymer matrix modification near hard surfaces, the fabrication of strong and tough multifunctional and lightweight polymeric nanocomposites is far from reaching its projected potential. If successful, this program will set the foundations for controlled and efficient design of high performance nanostructured polymers and establish property limits for multiphase polymers. The experimental results from this program will be essential material parameters for molecular dynamics and micromechanics models with applications to nanocomposites, biological systems, nanoimprinting, nanofluidic arrays, etc. The outreach plan of this CAREER award will (a) inspire high school students to study aerospace engineering via an engineering teaching kit that will increase high school student technology awareness in hierarchical materials for aerospace applications, (b) provide hands-on education on nanoscale mechanics to undergraduate and graduate students, and (c) support professionals with nanoscale mechanics laboratory training.