Confined dynamics, forms and transitions in colloidal systems: from clay to DNA.

摘要: Colloidal suspensions are a classic example of confining systems developing large specific surfaces, presenting rich variety shapes and exhibiting complex organization on length scale ranging from 1 nm to several micrometers. Two distinct confined dynamics generally considered in such systems: (1) the embedded fluid entrapped pore network with two main contributions, surface interaction long-range connectivity, (2) host matrix, associated time evolution interfacial geometry. This last contribution is particularly important during dynamic structural transitions colloidal as jamming, glass transition, phase separations flocculation. It believed that characteristic needed describe movement geometrical reorganization much slower than (except trivial situation where molecule irreversibly adsorbed surface). Thus, few connections made between these dynamics. In this presentation, we show how slow water at proximity provides an original way probe shape orientation topics presented. First all, field-cycling NMR relaxometry used transition strong rotational slowing down system plate-like particles, synthetic clay (laponite). Second, analyze case long thin rods (either mineral or biologic DNA cylinders) dispersed very diluted suspensions. At distance and/or time, particles appear portion line. We discuss can be sensitive morphological crossover may provide information about particle shape. Some comparisons recent experiments