Surface rheology of heterogeneous interfaces

我们建议将均匀亚相上的准二维单层悬浮液作为复杂纳米/微观结构膜[1]-[4]的模型系统。我们将用微型磁针表面流变仪测量它们的有效流变行为。目标是通过实验揭示主要参数及其对有效表面流变行为的影响，从结构特征和亚相和单组分膜成分的流变特性来预测复杂膜结构的表面流变特性。特别研究了四个重要参数：a)单层中较粘或较粘组分的面积分数，b)各组分之间静态相互作用的强度，c)单层中各组分的内部自由度，如大分子的构象，d)单层中固体或较粘组分的大小。已知参数a-c与三维（3D）复杂流体的流变行为有关。交叉长度尺度，由表面与体粘度的比例定义，使胶体颗粒的尺寸与交叉长度相比，成为复杂单层有效流变行为的额外和关键数量。

We propose to view quasi two-dimensional monolayer suspensions on a homogeneous subphase as model sys-tems for complex nano/micro-structured membranes [1]-[4] We will measure their effective rheological behavior with a miniaturized magnetic needle surface rheometer. The goal is to enable predictions of surface rheological properties of a complex membraneous structure from the characteristics of the structure and the rheological properties of the subphase and the single component membrane constituents by experimentally unravelling the major parameters and their effect on the effective surface rheological behavior. Four important parameters are studied in particular: a) The area fraction of the more viscous or solid component of the monolayer, b) the strength of static interactions between the components, c) the internal degrees of freedom of the constituents of the monolayer, such as the conformations of macromolecules, and d) the size of the solid or more viscous constituents of the monolayer. The parameters a-c are known to be relevant for the rheological behavior of three-dimensional (3D) complex fluids. The cross-over length scale, defined by the ratio of the surface to bulk viscosity, renders the size of the colloidal particles as compared to the cross-over length into an additional and crucial quantity for the effective rheological behavior of the complex monolayer.