Disorder in Crystals and Mesophases

这个项目的目的是探索在 线性大分子和小分子的结晶和中间相状态 分子模型化合物的构象，大幅度运动。 更好地理解这个主题将使我们能够更好地管理 这些重要的技术过程，如改进 材料性能通过退火，大规模变形 拉伸和轧制，以及设计新的聚合物材料， 具体属性。 该项目使用的核心技术是 热分析用于评价无序度 （熵）。 一种特殊的高级热分析系统（ATHS）， 经过多年的发展，允许建立热 作为仅振动参考的完全有序固体的性质 状态，以及完全无序的固体（玻璃态）和液体 参考状态。 与这些参考状态的偏差为 解释为移动的无序（中间相）或刚性 无序（中间相玻璃或刚性无定形部分）。 上 然后在微观水平上分析无序和运动， 通过固态NMR，X射线衍射，中子散射， 光学和原子力显微镜。 了实验结果 与进行的分子动力学模拟相比， 超级计算机 待分析的典型材料为：尼龙和 蛋白质、硬链聚合物、部分和完全氟化 短链和长链分子，四烷基铵盐，和 中间相聚合物。

The objective of this project is to explore disorder introduced in crystalline and mesophase states of linear macromolecules and small molecule model compounds by conformational, large-amplitude motion. Better understanding of this topic will enable us to better manage such important technological processes as the improvement of materials performance by annealing, large-scale deformation on drawing and rolling, and the design of new polymeric materials with specific properties. The central technique used in this project is the thermal analysis for evaluation of the degree of disorder (entropy). A special Advanced THermal Analysis System (ATHAS), developed over the years, permits the establishment of the thermal properties of fully ordered solids as a vibration-only reference state, as well as fully disordered solid (glassy) and liquid reference states. The deviations from these references states are interpreted in terms of mobile disorder (mesophases) or rigid disorder (mesophase glasses or rigid amorphous fraction). On a microscopic level the disorder and motion are then analyzed in detail by solid state NMR, X-ray diffraction, neutron scattering, optical and atomic force microscopy. The experimental results are compared to molecular dynamics simulations carried out on supercomputers. Typical materials to be analyzed are: nylons and proteins, stiff-chain polymers, partially and fully fluorinated short-chain and long-chain molecules, tetraalkylammonium salts, and mesophase polymers.