(184e) Directed Assembly of Carbon Nanotubes By Capillary Focusing | AIChE

(184e) Directed Assembly of Carbon Nanotubes By Capillary Focusing

Authors 

Wirth, C. L. - Presenter, Katholieke Universiteit Leuven
De Volder, M., Katholieke Universiteit Leuven
Vermant, J., ETH Zürich



Carbon nanotubes (CNTs) are promising candidates for components of advanced materials, microelectronics and electrochemical systems. Directed assembly of CNTs over multiple length scales is key to the performance of these technologies. Unfortunately, state of the art methods for the growth of assembled CNT structures typically require harsh conditions. In an effort to achieve controlled deposition and assembly of CNTs at mild conditions, we developed a technique called “capillary focusing” that uses the differences in capillarity experienced by fluid evaporating from a substrate with a chemically heterogeneous surface. A silicon wafer substrate modified to have hydrophilic and hydrophobic regions of specified geometry was coated with an aqueous suspension of electrostatically stabilized CNTs. The combined effect of convective and Marangoni flows and capillarity focuses particles suspended in solution to preferentially deposit onto hydrophilic regions during evaporation. The deposition process was studied by systematically changing the size, shape, and spacing of hydrophilic regions as well as the substrate coating method. These experiments demonstrated that capillary focusing is a robust method for the preferential deposition of CNTs at ambient conditions and could be used for CNT device fabrication.