Diffusion in Polymer Melts

前向反冲光谱(FRES)将被用来确定扩散到非氚聚合物中或相反扩散到非氚聚合物中的氚聚合物的浓度与深度的关系。通过研究具有不同臂数的聚苯乙烯(PS)星在由以下组成的基质中的扩散来探索分子拓扑的重要性：不同分子质量的线性PS、PS微凝胶和伽马辐射交联PS以及PS星。结果将与目前关于恒星的矩阵无关和矩阵相关的扩散理论进行比较。将开始跟踪聚苯乙烯和聚乙烯吡啶的嵌段共聚物在嵌段共聚物基质中的扩散，以确定基质的形态对扩散的作用。这些实验将被解释为次要块被该块的磁区结构俘获。在可混溶聚合物共混物中，重点是确定两组分在二元聚合物共混物中的示踪扩散行为，以及确定由于自由能平方梯度项而增加的互扩散系数。相互扩散系数的测量也将允许灵敏地确定共混物的负Flory参数。最后，将启动实验来测量大分子沿表面的扩散，即在两个维度上的扩散。所有这些实验的结果都将用当前的理论来解释。

Forward recoil spectrometry (FRES) will be used to determine the concentration versus depth profiles of deuterated polymers diffusing into undeuterated ones or vice versa. The importance of molecular topology will be explored by investigating the diffusion of polystyrene (PS) stars with various arm numbers into matrices consisting of the following: linear PS of various molecular weights, PS microgels and gamma-irradiation crosslinked PS, and PS stars. Results will be compared with current theories of the matrix-independent and matrix-dependent diffusion of stars. Experiments will be initiated to follow the diffusion of block copolymers of polystyrene and poly(vinylpyridine) into block copolymer matrices to determine the role of the morphology of the matrix on the diffusion. These experiments will be interpreted in terms of the trapping of the minor block by the domain structure of this block. In miscible polymer blends, emphasis will be placed on determining the tracer diffusion behavior of the two components in binary polymer blends and on determining the enhancement of the mutual diffusion coefficient due to the square gradient term in the free energy. Measurements of the mutual diffusion coefficient will also permit a sensitive determination of the negative Flory parameter for the blend. Finally experiments will be initiated to measure the diffusion of macromolecules along surfaces, i.e., in two dimensions. The results of all these experiments will be interpreted in terms of current theory.