Imagine a rubber band that stays stretched
out until you warm it up. Wait. You don’t
have to imagine it. Someone has made one.
A research team at the University of Rochester
has created an interesting new polymer. Oh,
and just in case you’ve forgotten, a polymer
is a long-chain molecule consisting of repeated
smaller molecules. The one you’re probably
the most familiar with is plastic.
The team built a polymer that is elastic,
which means it can change shape. But unlike
a rubber band, which snaps back to its original
shape once you let go of it, this polymer
holds the new shape. That is, until you heat
it up. When the polymer warms to around human
body heat temperatures, it returns to its
original shape.
It can also lift 1,000 times its own mass,
meaning this polymer can do work. Imagine
stretching out a large amount of polymer over
a pulley and down to a weight. Then you apply
heat to the polymer. The material will contract
back to its original shape, lifting the weight
for you. No engine required!
So what’s going on here? Well, when the
polymer gets stretched, the smaller molecules
in the chain begin to form crystallites. That’s
another way of saying they become stable in
a new arrangement. That’s why the polymer
stays stretched out even when you let it go.
Applying heat essentially breaks up the party,
melting the crystallites in the polymer. The
whole thing contracts back to its original
form.
The concept of a shape-changing polymer isn’t
new -- it’s also the basis of a technology
called 4D Printing, which relies on water
absorption instead of heat to trigger the
change. But the Rochester team’s polymer
opens up new possibilities.
The team’s primary focus is on the biomedical
field. A wound dressing that can apply pressure
once it warms up to body temperature is a
typical example.
But perhaps we’ll see non medical uses of
this material further down the road. Imagine
a pair of jeans that are loose when you put
them on, but then get snug as they heat up.
My butt would look great in those. But let
us know what you would like to see this polymer
do. And don’t forget to visit now.howstuffworks.com
every day to learn about all the coolest stuff
going on right now!
