Diffusion Studies of Multicomponent Penetrants in Polymers using Fast FTIR Imaging

使用新的焦平面阵列探测器和步进扫描干涉仪的快速FTIR成像允许获取扩散过程的多组分图像，从该图像中可以测量扩散过程的性质和扩散常数的大小。 图像允许检测聚合物样品中由空隙或裂纹引起的异常扩散。 这些研究将首先针对聚（甲基丙烯酸甲酯）（PMMA）中的残留和扩散水的作用的表征。 初步研究将水扩散到不同分子量的超纯和超干聚甲基丙烯酸甲酯样品，并在不同的温度以上和以下的玻璃化转变。PI将研究PMMA中残留水对其他物质扩散行为的增塑作用。 固态NMR将用于测量由于PMMA中存在水而导致的聚合物动力学变化，以确定聚合物链流动性的影响。 PI将研究PMMA物理老化的作用，并建立多组分扩散与玻璃态聚合物中微腔或空隙平均尺寸变化的相关性（通过正电子湮没寿命测量）。 随后，将用水和环境剂进行多组分扩散研究，以确定物质分子大小、形状和化学相互作用对多组分扩散过程的作用。 此外，PMMA将被系统地氧化，并评价从表面到本体的聚合物降解梯度的作用。 实验结果将与目前的分子扩散理论进行比较。 实验图像将被用作教育模块（PCL.cwru.edu）中的可视化辅助工具，该模块将用于以交互方式向学生讲授聚合物中扩散过程的机制和参数。%该奖项由材料研究和化学与运输系统部门共同资助，旨在利用强大的分析工具-傅立叶变换红外（FTIR）成像研究多组分反渗透剂扩散到聚合物中。 小分子如单体、催化剂、稀释剂和溶剂在材料中的扩散在许多应用中至关重要。 在许多工业过程中，如脱挥发分、聚合、膜分离、干燥、涂布和涂漆，有关扩散系数的信息是必需的。 涂料的塑化、着色、固化和干燥都受到溶剂、染料和低分子量添加剂的流动性的影响。

Fast FTIR imaging using newly available Focal Plane Array detectors and step-scan interferometers allows the acquisition of multicomponent images of the diffusion process from which the nature of the diffusion process and the magnitude of the diffusion constants can be measured. The images allow the detection of anomalous diffusion in the polymer samples arising from voids or cracks. These studies will be initially directed at characterization of the role of residual and diffusing water in poly(methylmethacrylate) (PMMA). The initial studies will be made on diffusion of water into ultrapure and ultradry PMMA samples of varying molecular weights and at different temperatures above and below the glass transition. The PI will study the plasticizing effect of residual water in PMMA on the diffusion behavior of other substances. Solid state NMR will be used to measure the changes in the polymer dynamics due to the presence of water in the PMMA in order to determine the impact of polymer chain mobility. The PI will study the role of physical aging of the PMMA and establish the correlations of multicomponent diffusion with the changes in the average size of microcavities or voids in the glassy polymer (measured by Positron Annihilation Lifetimes). Subsequently, multicomponent diffusion studies will be made with water and environmental agents to determine the role of substance molecular size, shape and chemical interactions on the multicomponent diffusion process. Additionally, the PMMA will be systematically oxidized and the role of gradient in polymer degradation from the surface to the bulk evaluated. The experimental results will be compared with current theories of molecular diffusion. The experimental images will be utilized as visualization aids in an educational module (PCL.cwru.edu) which will be used to interactively teach students the mechanisms and parameters of the diffusion process in polymers.%%%This award, co-funded by the Division of Materials Research and Chemical and Transport Systems, is directed toward the utilization of a powerful analytical tool-Fourier Transform Infrared (FTIR) Imaging for the study of diffusion of multicomponent penetrants into polymers. Diffusion of small molecules such as monomers, catalysts, diluents, and solvents in materials is of vital importance in many applications. Information concerning diffusion coefficients is necessary in many industrial processes such as devolatization, polymerization, membrane separation, crying, coating, and painting. The plasticization, coloration, curing and drying of coatings are all influenced by the mobility of solvents, dyes, and low molecular weight additives.