Evolution of Ordered Block Copolymer Serpentines into a Macroscopic, Hierarchically Ordered Web

摘要

In the process of drying, a sessile drop containing nonvolatile solutes such as polymers, nanocrystals, and carbon nanotubes readily self-assembles into a number of concentric "coffee rings" through the repetitive "stick-slip" motion of a three-phase contact line. However, owing possibly to convection and a lack of control over the evaporation process of the drop, the rings are often irregular and stochastically organized. The challenge therefore remains to use evaporative self-assembly rationally to prepare such rings and other dissipa-tive structures (e.g., fingering patterns and polygonal network structures) of high regularity and fidelity for use in microelectronics, data storage devices, and biotechnology applications. To date, only a few studies have focused on precise control of the evaporation process to produce such highly ordered structures.Surface patterning by controlled solvent evaporation offers a lithography- and external-field-free means to organize nonvolatile materials into ordered microscopic structures over large surface areas in a simple and cost-effective manner.