Bending of nanoscale filament assemblies by elastocapillary densification

Zhouzhou Zhao, Sameh H. Tawfick, Sei Jin Park, Michael De Volder, A. John Hart, and Wei Lu

Phys. Rev. E 82, 041605 – Published 27 October 2010

Abstract

We report a mechanism by which nanoscale filaments self-assemble into asymmetric aggregates by elastocapillary action. Specifically, capillary rise of liquid into an asymmetric pattern of vertically aligned filaments causes the filaments to deflect laterally during elastocapillary densification. We quantitatively show that the lateral deflection can be controlled precisely by the pattern shape and the coupling strength among the filaments. We exploit this mechanism to fabricate asymmetric micropillars and multidirectional bridges of densely packed carbon nanotubes. Analogous behavior occurs as biological filaments interact with liquids, and these findings enable scalable fabrication of anisotropic filament assemblies for manipulating surface interactions between solids and liquids.