An important nanomanufacturing challenge is to develop rapid and continuous manufacturing schemes to control material structures from the dimensions of individual nanoparticles (nanometers), to assembled microstructures (micrometers), to device features on the order of the electromagnetic wavelengths of interest (micrometer to meters). Such multi-scale materials are routinely observed in nature in photonic architectures within butterfly and beetle wings, or in common mechanical elements within wood, silk, and sea shells. Unfortunately, synthetic approaches to create large scale materials that encompass both the complexity and hierarchical features found in natural materials are still lacking. The objective of this award is to develop the fundamental understanding necessary for the creation of a method to fabricate multiscale colloidal nanomaterials. The project will result in advancements in critical scientific and technological areas such as transport, assembly and polymerization. The development of assembly processes to produce colloidal nanomaterials is useful for any application that aims to manipulate electromagnetic radiation, for example, sensors and solar cells, and more exotic emerging applications like optical computing and optical cloaking. Outreach efforts include engagement and participation of high school and undergraduate students in the laboratory. Students participating in the project will be encouraged to present at conferences and be involved with additional outreach efforts at local elementary schools.
The hierarchical colloidal materials nanomanufacturing project is based on combining strong and weak interactions towards a processing method that continuously assembles nanoparticle structures over a large area. This approach relies on coupling hydrodynamics and capillary interactions for rapid transport and organization of nanoparticle-loaded droplets on predefined patterned surfaces, balancing bulk convection and local diffusion-mediated assembly of nanoparticle microstructures via field-mediated interactions, and rapidly arresting or immobilizing structures through polymerizable media to quench nanoparticle configurations. Individually, these steps can be met with existing technologies, but combining them brings significant engineering and scientific challenges. For example, it is necessary to orchestrate the disparate time- and length-scales associated with diffusive, capillary, and hydrodynamic transport to enable multiscale structure formation in a single step. Given the imperfect separation between the scales at which these processes operate, understanding of how to control interactions in regimes where they compete and/or are coupled will be accomplished via optical microscopy, and simulations.
