Materials Science and Engineering Videos
Below are all of the videos we've mentioned throughout this section of the web site. Please note that not all have sound.
Technical requirements for watching our videos:
The movies provided are in QuickTime (.mov) or Windows Media (.wmv) format, and will open in a new window. You will need a viewer such as the Apple QuickTime Player or the Windows Media Player (both free) to watch them. We recommend a DSL connection or higher for viewing. If you attend one of our undegraduate Visit Maryland Days, you can learn more about the department and major, tour our facilities, and see the demos in person! (Graduate students, please e-mail msegrad@umd.edu to schedule a visit.)
If a movie does not play in your browser when you click its link, right-click or control-click to download and save it.
Now You See Me, Now You Don't!
Polymer dispersed liquid crystals (PDLCs) can be applied as a coating to windows and simple displays. PDLCs are made from a mixture of a liquid crystal and a polymer. The polymer is isotropic, meaning its optical properties are always the same—in this particular case, transparent. But the liquid crystal in the coating is anisotropic, meaning its optical properties can change. Initially, the glass appears to be frosted. When an electrical field is applied to the coating, the liquid crystal reacts by realigning its molecular structure to match that of the transparent polymer's, and almost instantly the window becomes clear! (In this movie, the liquid crystals appear to darken as they realign and we see through them, the clear polymer and the glass to the dark background.) PDLCs have been used for privacy, in exhibits, for safety visors used by pilots, and in heads-up displays.
See a movie demonstrating a polymer dispersed liquid crystal (QuickTime .mov, 42.1 MB) »
Plasma: The 4th State of Matter
Plasma is widely considered to be the fourth state of matter due to its unique properties. Plasma is a gas in which the atoms are ionized, meaning there are free negatively charged electrons and positively charged ions. This collection of charged particles can be controlled by electromagnetic fields and this allows plasmas to be used as a controllable reactive gas. The electronics industry uses this concept to etch very small patterns into silicon to make our modern day devices smaller and more efficient.
This movie was produced by students Bobby Bruce and Michael Sweatt for the 2008 Vid/Terp competition.
See the movie (Windows Media Video .wmv, 50MB) »
Can also be played in Real, QuickTime with Flip4Mac component, and other players.
Nobody Likes A Noisy Refrigerator!
Thermoelectric devices can produce cooling by using the electrons in semiconductors to carry heat away from an area, not much differently than the way electrons carry a charge along copper wires and in electrochemical cells. Refrigerators using this technology could be made very small, light and portable, and have a fast response time and good temperature stability. They would have no moving parts that degrade with time. Our movie demonstrates the operation of a 1-inch device made with the semiconductor Bi2Te3 that cools a copper plate to more than 20° below room temperature.
See a movie demonstrating a thermoelectric device (QuickTime .mov, 65MB) »
Super absorbent polymers are a special class of polymers called polyelectrolytes that have a charge on the polymer chain that increases the solubility in water. They are generally used in the form of small particles that are crosslinked so they will form gel rather than completely dissolving. The polymer gel absorbs water and the charges along the chain repel each other, stretching out the chain and enhancing the swelling of the gel. Super absorbent polymers can readily absorb 100 times their volume in water!
Super absorbant polymers are used in products like disposable diapers, for cleaning up water based environmental spills, and for preventing rain water runoff in agricultural areas.
Shape memory materials display an unusual property of "remembering" the shape they were formed into at high temperature. They experience a solid state phase change, in which atoms are rearranged, but the material remains a solid. If a piece of shape memory metal alloy wire is deformed, for example, it will return to its original state when exposed to the heat of a hair dryer—the heat triggers the "memory" of where the atoms were at the time of its production under similar heat.
See a movie demonstrating shape memory metal (QuickTime .mov, 23.6MB) »
No, It's Not a New Kind of Piercing!
Nd2Fe14B magnets are incredibly strong, easily holding 100-300 times their weight. They allow for the production of smaller, stronger electric motors and higher capacity disk drives. The field of Materials Science and Engineering is constantly trying to improve the properties of advanced materials such as Nd2Fe14B magnets.
See a movie demonstrating these magnets (QuickTime .mov, 13MB) »
An amorphous metal is an alloy combining elements of differing atomic diameters. The dark grey disk (left) is an amorphous metal formed by combining 5 different atoms together: zirconium, titanium, copper, nickel, and beryllium (Zr41.2Be22.5Ti13.8Cu12.5Ni10.0). The differing atomic diameters and unusual composition prevents the atoms from arranging in a regular crystalline structure. The atoms have no easy way to slip by each other under deformation, resulting in a very hard material. When a steel ball bearing is dropped on the amorphous metal, it does not permanently deform and the ball bounces many times before coming to rest.
See a movie demonstrating amorphous metal (QuickTime .mov, 9MB) »
These two balls look, but do not behave, in the same way. When dropped, the "happy" ball will bounce while the "sad" one will not. This is because the "happy" ball is made of neoprene, an elastic polymer, and the "sad" ball is made of polynorborene, a polymer material designed to absorb energy. The polynorborene ball absorbs the impact when it hits a surface, causing it to "drop like a stone." Materials like polynorborene could be used in athletic shoes to absorb energy during running or jumping, preventing shock to the foot or leg.
See a movie demonstrating the "happy" and "sad" balls (QuickTime .mov, 10MB) »
Superconductors and Levitation
A superconductor is a material that has no electrical resistance to current flow. A "high" temperature superconductor exhibits this property at liquid nitrogen temperatures (-321°F /-196°C). An important property of superconducting materials is the ability to repel magnetic fields. Placing a magnet above a superconductor will cause the magnet to levitate. Maglev trains make use of this phenomenon, as they are lifted and propelled forward by a magnetic field, free of friction. We can see this effect by placing a magnet atop a superconductor resting in liquid nitrogen.
See a movie demonstrating levitation using a superconductor (QuickTime .mov, 21MB) »
