Engineering Hierarchical Nanostructures by Elastocapillary Self‐Assembly

Abstract

Surfaces coated with nanoscale filaments such as silicon nanowires and carbon nanotubes are potentially compelling for high-performance battery and capacitor electrodes, photovoltaics, electrical interconnects, substrates for engineered cell growth, dry adhesives, and other smart materials. However, many of these applications require a wet environment or involve wet processing during their synthesis. The capillary forces introduced by these wet environments can lead to undesirable aggregation of nanoscale filaments, but control of capillary forces can enable manipulation of the filaments into discrete aggregates and novel hierarchical structures. Recent studies suggest that the elastocapillary self-assembly of nanofilaments can be a versatile and scalable means to build complex and robust surface architectures. To enable a wider understanding and use of elastocapillary self-assembly as a fabrication technology, we give an overview of the underlying fundamentals and classify typical implementations and surface designs for nanowires, nanotubes, and nanopillars made from a wide variety of materials. Finally, we discuss exemplary applications and future opportunities to realize new engineered surfaces by the elastocapillary self-assembly of nanofilaments.

Three-dimensional SERS hot spots for chemical sensing: Towards developing a practical analyzer

“…The solvent evaporation controlled self-approach of the nanorods is an extremely simple and efficient strategy for the spontaneous formation of highly reversible Raman hotspots. [78] These kind of 3D reversible hotspots promises a generic platform for molecule trapping and SERS sensing with high sensitivity and reproducibility. In these cases, the reversible hotspots would depend on the precise control of surface chemistry or environmental stimulus, yet further developments are required to fully elucidate the intricacies of flexibility.…”

One-dimensional silicone nanofilaments

“…One-dimensional particles are used to modify the properties of a matrix material, as highly sensitive gas and biosensors and for hydrogen storage or catalysis. They can selfassemble to form new hierarchical structures on surfaces and they have found numerous applications in the fields of nano-optics and nanoelectronics [44][45][46][47][48][49][50][51]. One-dimensional particles are the lowest dimensional particles for studying transport phenomena at the nanoscale, such as conduction of heat or electrical current, and they are the simplest mechanical, electrical or thermal interconnectors.…”

Strain-engineered manufacturing of freeform carbon nanotube microstructures

“…On the other hand, use of locally directed actions, such as mechanical stresses, capillary forces and electromagnetic fields, along with their interactions with templates, offers opportunity to create novel self-organized geometries and to design fabrication processes that achieve attractive combinations of dimensional control and throughput 2,8,[11][12][13][14][15] . Examples abound in soft materials and chemical systems including microscale reactiondiffusion patterns 16,17 , self-assembly of block copolymers 18 and helical aggregation of polymer nanopillars 19,20 .…”