Research Initiation: Restricted Diffusion and Partitioning of Macromolecules in Assemblages of Spheres

研究了大分子在球团中的限制扩散和分配现象。过去的研究使用了只含有圆柱形孔的多孔介质。然而，许多工程应用感兴趣的多孔介质更好地表示为均匀球体的组合。制备了直径为40 ~ 200nm的均匀硅球。此外，球体在四种压力下被压实，得到平均孔径在8到96纳米之间的球团。由于球体均匀性和已知的二氧化硅表面化学性质，这些颗粒是理想的多孔介质模型。在该项目中，使用不同孔隙度/球体大小的球团测量了几种溶剂中许多大分子的扩散系数。由于观察到的分配效应是由于粒径排除和吸附作用，因此对未压实球进行了吸附测量。这允许“退出”分子/孔径比和分配系数之间的关系。这是比较的分配理论，是发展和过去的实验和理论表达式产生的工作与圆柱形孔隙。

The phenomena of restricted diffusion and partitioning of large molecules in assemblages of spheres is studied. Past investigations have used porous media which contain only cylindrical pores. However, porous media of interest to many engineering applications is better represented as assemblages of uniform spheres. Uniform silica spheres with diameters of 40 to 200 nm have been fabricated. Further, spheres have been compacted at four pressures, resulting in pellets with a mean pore size ranging from 8 to 96 nm. Due to the sphere uniformity and the known surface chemistry of silica, these pellets are ideal porous media models. Diffusion coefficients for a number of macromolecules in several solvents are measured in the project using pellets of varying porosity/sphere size. Since the observed partitioning effect is due to both size exclusion and adsorption, adsorption measurements on uncompacted spheres are made. This allows the 'backing out' of the relationship between the molecule/pore size ratio and the partition coefficient. This is compared to a partitioning theory that is developed and past experimental and theoretical expressions arising from work with cylindrical pores.