Visualization of Smart Gels

Summary:

A smart gel is a material that gels in response to a specific physical property. For example, it may gel at a specific temperature or pressure. The mechanisms that create a gel in response to a given environment are not well understood. So developing this understanding is key to being able to create materials that gel at designated points.   

The NIST team is studying a subclass of these materials called shake gels. Through some complex and as yet unknown process, these watery mixtures of clays and polymers firm up into gels when shaken, and then relax again to the liquid phase after some time has passed. A shake gel might be used, for example, in shock absorbers for cars. The material would generally be a liquid but would form a gel when the car drove over a pothole; the gel thickness would adjust automatically to the weight of the car and the size of the pothole. A more esoteric application might be the formation of gelled areas within a liquid where holograms could be created using a laser.   

Additional Technical Details:

Immersive visualization helps scientists understand how the molecules in the smart gel interact. Scientists immerse themselves in the 3D environment constructed using data from theoretical studies. This enables researchers to answer questions that might otherwise defy attempts at solution.  The 3-D visualization helped the scientists see that for the shake gel it is the water's oxygen atoms, instead of the hydrogen atoms as previously thought, that attach to the clay.  The team has also made theoretical calculations that may help to explain why and how the components of the liquid mixture bind together into a semisolid form. Electrical charges affect the binding process, resulting in water binding to clay surfaces in a perpendicular arrangement, which is believed to help create the firmness of the gel.  For more information, please refer to NIST Tech Beat: Recipe for a Shake Gel.

The immersive visualization used by the scientists is based on open source software, DIVERSE and additional software created in-house. The output of the numerical simulation is a series of time steps. At each time step, the x,y,z position and atom type for each atom is produced. In collaboration with Carlos Gonzales, Steven Satterfield developed software to connect the appropriate bonds between the atoms and output a series of graphics files. These graphics files are then loaded into Diversifly, the DIVERSE display and explore utility.  Diversifly has the ability to animate the time series of graphics files in an immersive visualization environment.   

Applications:

The potential for applications of smart gels is enormous.    Since smart gels expand or contract in response to external stimuli,    they could be useful in applications such as an artificial pancreas    that releases insulin inside the body in response to high sugar level.    Smart gels might someday be used to make exotic foods, cosmetics,    medicines, and sensors.