NIRT: Dynamic Heterogeneity and the Behavior of Glass-Forming Materials at the Nanoscale

该NIRT奖项由材料研究部的聚合物计划和化学和运输系统部的界面，运输和热力学计划资助。 这项工作的目的是了解如何在聚合物和小分子玻璃形成的空间动态异质性的影响，在纳米级的限制，这反过来又如何影响分子和热力学性质的松弛。 动态异质性将系统地探讨使用荧光探针的研究和溶剂化动力学在nanocolinated材料作为限制大小的函数。 此外，体积和焓松弛将被研究作为一个功能的限制与特定的目的，检查是否动态的异质性影响这些属性的松弛，以及它是否是达到平衡所需的时间发散的原因。 纳米限制将包括交联橡胶中低分子量玻璃形成剂的“软”限制，纳米多孔基质中低分子量玻璃形成剂和聚苯乙烯的“刚性”限制，以及聚苯乙烯对纳米薄膜的限制。 此外，冷冻干燥的聚苯乙烯玻璃的宏观和分子松弛行为将被检查。 这项工作将包括许多以前没有进行过的新的测量，预计将导致对动态不均匀性如何受到限制的影响的理解，以及更一般地说，动态不均匀性对Tg附近宏观性质松弛的重要性。这项工作将提供一个更好的了解材料的行为接近其玻璃化温度在介观或纳米尺度，是重要的最终有用性和功能的材料，例如，纳米复合材料和纳米电子应用。 该计划还将为研究生和博士后研究人员以及高中生提供良好的培训。 将努力将本科研究人员和高中学生包括在内。 将通过在得克萨斯州和西南地区的女子和少数民族学院进行特别招聘，努力将妇女和代表性不足的少数民族包括在内。 此外，将努力包括本科生谁参加TTU麦克奈尔学者计划的第一代大学生（往往是少数民族）。 这项工作将通过在国家论坛上介绍和在会议记录、会议和档案期刊上发表的方式在科学界广泛传播。 该项目的成果还将尽可能纳入各专业研究所教授的本科和研究生课程。

This NIRT award is being funded by the Polymers Program of the Division of Materials Research and the Interfacial, Transport and Thermodynamics Program of the Division of Chemical and Transport Systems. The work is aimed at understanding how spatially dynamic heterogeneity in polymeric and small molecule glass formers is influenced by confinement at the nanoscale, and how this in turn, influences the relaxation of molecular and thermodynamic properties. Dynamic heterogeneity will be systematically probed using fluorescent probe studies and solvation dynamics in nanoconfined materials as a function of confinement size. In addition, volume and enthalpy relaxation will be studied as a function of confinement with the specific aim of examining whether or not dynamic heterogeneity influences the relaxation of these properties and whether or not it is the cause of the divergence of times required to reach equilibrium. Nanoconfinement will include "soft" confinement of low molecular weight glass-formers in crosslinked rubber, "rigid" confinement of both low molecular weight glass-formers and polystyrene in nanoporous matrices, and confinement of polystyrene to ultrathin films. In addition, the macroscopic and molecular relaxation behavior of freeze-dried polystyrene glasses will be examined. The work will include many novel measurements that have not been performed previously and is anticipated to lead to an understanding of how dynamic heterogeneity is influenced by confinement, and more generally, the importance of dynamic heterogeneity on the relaxation of macroscopic properties near Tg.%%%The work will provide a better understanding of the behavior of materials near their glass temperatures at the meso- or nanometer scale and is important for the ultimate usefulness and function of materials in, for example, nanocomposites and nanoelectronics applications. The program will also provide excellent training for the graduate students and post-doctoral researchers and high school students. Efforts will be made to include undergraduate researchers and high school students. Efforts will be made to include women and underrepresented minorities through special recruiting efforts at women's and minority colleges in the Texas and southwest region. In addition, an effort will be made to include undergraduate students who participate in the TTU McNair Scholars Program for first generation college students (often minorities). The work will be broadly disseminated within the scientific community by presentation at national forums and publication in both proceedings conferences and archival journals. The results of the project will also be incorporated to the extent feasible in both undergraduate and graduate courses taught by the respective PIs.***