Three-Dimensional Chemical Analysis and Molecular Dynamics Simulations: Application to Flame Retardants in Polymers

路易斯安那州立大学和农业与机械学院的Leslie G.Butler和Randall W.Hall教授在化学系的分析和表面化学计划的支持下，进行三维化学分析和分子模拟，并将其应用于聚合物中的阻燃剂。三维成像方法在化学中的应用是一种新的方法，因此，图像分析方法将得到发展。图像将通过同步加速器X射线断层扫描获得，其模式是以3微米的分辨率在2毫米的立方体内产生元素浓度。随着样品老化，良好的阻燃剂会溶解到聚合物中，而不良的阻燃剂会形成内部区域和表面气泡。实验将测量扩散速率、活化能和扩散机制，并与理论模拟进行比较。三维成像为固体中的化学提供了新的视角，如分子在玻璃聚合物中的扩散。玻璃的计算机模拟可以描述玻璃的结构和动力学，从而描述分子在玻璃中的扩散。一个实际的例子是阻燃剂在聚合物中的缓慢(数年)扩散。有时，老旧的CRT和打印机外壳上的灰尘感觉是由于阻燃剂的沉淀造成的，非正式地被称为“开花”。开花的一个常见例子是可可脂在旧巧克力表面的扩散和表面沉淀。将创建一个基于网络的教程，向学生介绍这项研究的基础科学和三维图像分析方面。

Professors Leslie G. Butler and Randall W. Hall of the Louisiana State University and Agricultural and Mechanical College are supported by the Analytical and Surface Chemistry Program in the Division of Chemistry for conducting three- dimensional chemical analysis and molecular simulations with applications to flame retardants in polymers. The application of three-dimensional imaging methods to chemistry is new, thus, methods for image analysis will be developed. Images will be acquired with synchrotron X-ray tomography in a mode that yields elemental concentrations throughout a 2 millimeters cube at a resolution of 3 micrometers. As sample ages, it is expected that good flame retardants dissolve into the polymer and bad flame retardants form internal domains and surface blooms. The diffusion rates, activation energies, and diffusion mechanisms will be measured experimentally and compared with theoretical simulations.Three-dimensional imaging offers new views of chemistry in solids, like the diffusion of molecules through glassy polymers. Computer simulations of glasses can describe the structure and dynamics of glasses and thus diffusion of molecules through a glass. A practical example is the slow (years) diffusion of flame retardants through polymers. Sometimes, the dusty feel on old CRTs and printer cases is caused by the precipitation of flame retardants and is informally called "blooming". A common example of blooming is the diffusion and surface precipitation of cocoa butter on the surface of old chocolate. A web-based tutorial will be created to introduce the students to basic sciences and the three dimensional image analysis aspects of this research.