Memory Wire
Materials
1 piece of memory wire, hot water or hair dryer, tongs
(can be purchased at http://www.teachersource.com/)
Procedure
1. Write down observations about the color, shape, and length of the metal wire.
2. Coil the metal wire around a pencil. Holding the coiled metal with tongs, observe what
happens when you place the coiled wire in hot water or heat it with a hair dryer.
3. Name three ways that you think that a metal with this unusual property could be of benefit in
manufacturing a new product.
How does it work?
Ninitol memory wire was named from the site of its
discovery, the Nickel Titanium Naval Ordnance
Laboratory in 1965. Ninitol has a chemical structure
similar to most metals, it is crystalline, meaning the
atoms are ordered in a particular pattern. The
arrangement of atoms in the Ninitol is different at
different temperatures which enables this material to
“remember” its original shape. At room temperature,
a phase called Marstenite is present, and at higher
temperatures Austenite is present. Another key
difference is what happens to the atoms when the
metal is bent. When a normal metal is bent, planes of
atoms slide long distances past one another so atoms
are in a completely different place relative to their
original neighboring atoms. They have no “memory”
of the original atomic arrangement. In contrast, when
Ninitol is bent all of the shape deformation is
accommodated by a shift in local arrangement, but
each atom still has the same original neighbors.
When the material is heated the atoms shift back to
their original positions relative to their neighbors and
the wire reforms to its original shape.
Is Ninitol currently being used in consumer products?
Materials scientists call Ninitol a Shape Memory Alloy (SMA). Eye glasses, dental wires, and
cell phones all utilize the ability of this material to be kinked or bent and still return to its
original shape without permanent damage. There are potential applications in medicine as
well. A stent is a tube shaped device that is inserted into arteries to keep them open. With
memory wire it could be possible to fold the stent into a tiny volume so that it could be
inserted in a non-invasive way. Localized heating could then be applied and the stent would
unfold to its full volume.
(Adapted from: Jones, G. M, Falvo, M.R., Taylor, A. R., Broadwell, B. P, Nanoscale Science:
Activities for Grades 6-12, NSTA press, 2007, pg. 109-114.
Stain Resistant Fabric -Nanotex
Materials
Piece of nanotechnology stain resistant fabric (Nano-tex)
Clothing made from nano-tex fabric can be found in most stores (look for stain resistant fabric
with “Nano” in the name)
Piece of regular fabric (100% cotton, synthetic such as polyester ,or cotton/poly blend)
Hydrophobic (water-hating) plant leaf such as lotus, leafy kale, brocilli, or Chinese cabbage
Eye dropper
Water
Various stain agents such as grape juice, oil, ketchup, mustard, jelly, peanut butter, dirt
Paper towels
Procedure
Part I: The Lotus Effect
Use the eye dropper to squeeze a drop of water on the nano-tex fabric, the regular fabric, and the
leaf. Describe the difference in the behavior of the water droplet.
Part II: Testing Stain Resistance
Add drops or small globules of stain agents on the two types of fabric. Observe. Using a wet
paper towel gently blot the stain agents off the fabric. Record observations. Did the stain
resistant fabric live up to its name? Was the stain resistant fabric more susceptible to certain
agents? Repeat the process and now try rinsing off the stain agents with a gentle stream of
water. Observe.
Other properties to investigate:
Compare the feel and texture of regular fabric and nano-tex fabric.
Is there a difference in the wrinkle resistant properties of the two fabrics?
Do the stain resistant properties of nano-tex disappear after washing it? How about after ven
many washes?
Does the nano-tex fabric still have stain resistant properties if the stain has set for a long time or
dried?
How does it work?
Stain resistant fabrics are examples of nanotechnology- along
with self cleaning paint and windows- that mimic the waterrepelling “lotus effect” of some plant leaves. The surface of
these leaves have nanometer sized waxy bumps that keep water
and dirt from sticking to them. The fabric is made by dipping the
fabric into a solution that coats it with tiny, nano-sized
“whiskers.” The whiskers point outward, like peach fuzz,
creating a layer of air next to the fabric. This cushioning layer
keeps water and other liquids from soaking into the fabric.
Water just beads up and rolls off the fabric.
For variations and extensions of this activity see
The University of Wisconsin’s Materials Research Center Outreach page.
http://www.mrsec.wisc.edu/Edetc/IPSE/educators/activities/nanoTex.html