2D MATERIALS AT INTERFACES
Particles of 2D materials can be confined to a fluid-fluid interface where they can be assembled to form larger structures and subsequently deposited onto solid substrates. We have found that 2D particles have unique interactions when at a fluid-fluid interface that determine the structures formed, and that these interactions are not well understood. To understand these interactions better we have developed methods for creating shape-controlled 2D particles and imaging them with microscopy. The microcopy image to the left shows square particles of graphene at an air-water interface that we have fabricated in-house. Funding for this project comes from the National Science Foundation.
Underground tunneling requires the management of drilling fluids pumped at high flow rates in order to remove rock and soil at sufficient rates. Increasing tunneling speed is a goal of the tunneling community that requires understanding the relationship between pressure drop, drilling mud viscosity, and the viscosity of the soil slurry as it returns to the surface. We are currently using a custom built flow loop to testing these highly shear-thinning materials. Funding for this project comes from Defense Advanced Research Projects Agency (DARPA).
During the feeding of pyrolysis reactors to generate bio-oil, lignocellulosic biomass can begin to react, or degrade, before entering the reactor, ultimately blocking the feed of material and stopping processing. This is an engineering challenge that requires a better understanding of the fundamental transport phenomena associated with feeding biomass into the reactor. In collaboration with Jonathan Stickel at the National Renewable Energy Laboratory (NREL) we are try to better understand the transport phenomena that govern this process. Funding for this project comes from the Alliance Partner University Program (APUP) in collaboration with NREL.
Cyclopentane hydrates can be formed and studied at atmospheric pressure, and temperatures that are accessible in the lab. This makes these hydrates a good candidate to study fundamental aspects of hydrate formation and dissociation, and also to seek connections between interfacial properties and the rheological properties of bulk hydrate rheology. Funding for this project comes from the American Chemical Society’s Petroleum Research Fund.
Microrheology is a technique where micron-size particles can be used to determine the rheology of the material in which they are immersed, or embedded. Passive microrheology relies on thermal energy to move the probe particles (shown in the GIF to the left), while active microrheology relies on external forces to move the probe. An example is the use of electromagnetic coils to drive the motion of magnetic particles. One set of our 1D tweezer apparatus is shown below.
ASPHALTENES AT INTERFACES
Asphaltenes are natural molecules in crude oil that stabilized oil-water emulsions. This is beneficial in some aspects of processing oil, but detrimental in others. The ability to alter the stability of asphaltene-stabilized emulsions is a great processing advantage, and we are equipped with the tools necessary to investigate the structure and rheology of asphaltene molecules confined to fluid-fluid interfaces. The image to the left was obtained on our inverted microscope using fluorescence microscopy to observe model asphaltene molecules at an air-water interface. These molecules form complex structures that give rise to unique interfacial rheological properties that have consequences for emulsion stability.