Self-Assembly of Rodlike Bio-nanoparticles in Capillary Tubes

摘要

The alignment of nanoparticle building blocks into ordered hierarchical structures is very important in colloidal and materials chemistry. Drying of nanoparticle suspensions is a relatively easy method that is used to fabricate large-scale patterns with well-defined superstructures. The formation of a ringlike structure at the contact line when a suspension dries on a solid surface is an everyday phenomenon that has been widely used to create hierarchical patterned structures. The contact line can stay pinned to form a single ring (i.e., "coffee ring") or can shrink in a discontinuous manner to generate multiple rings. This phenomenon can be used to tune the formation of different patterns in a confined geometry. Basic theoretical studies have been performed to understand how different patterns are formed during the drying process. In general, the pinning and depinning (stick-slip motion) at the contact line governs such pattern formation. Spherical colloidal particle suspensions and polymer solutions are two widely used systems for theoretical and experimental studies. A systematic study of the orientation of anisotropic particles, such as nanorods, at the contact line during the drying process can further improve the theoretical understanding of pattern formation induced by solvent evaporation. From a practical point of view, such knowledge may lead to a facile method of patterning and alignment of rodlike particles, which is critical for applications such as thin-film transistors, molecular electronics, and biosensors.