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Experimental Photo

Experimental Photo

Have you ever wondered why marshmallows, while solid, seem to behave a little like a liquid when you chew them?

Marshmallows are made up mostly of polymers:  a collagen gel network to be exact.  Unlike traditional materials, polymers have a interesting trait known as a second order phase behavior.  You probably know about the three states (or four) of matter:  solid, liquid, gas (and plasma) but there are materials that have an additional distinction.  These polymer materials have a transition we call the glass transition.  When a solid at cold temperatures, they act like a glass and are easily broken.  This is the “glassy state.”  At high temperatures, they are in their “rubbery state” and are easily deformed.  In the photo above, I am cooling marshmallows down with liquid nitrogen (-321 degrees F!) to show how they transform into their “glassy state.”  You can eat them too!  They are very similar to the marshmallows you’ll find in Lucky Charms Cereals as those are “freeze dried,” a process where the marshmallows are first frozen but the water is then sublimated off.