Purdue Chemistry Show uses slime, flames to promote polymers

10-06-2013

Pouring the slime

Chemistry's Paul Smith dumps out the slime at the 2013 Purdue Chemistry Show.


Slime has been a toy, a gross-out tool and part of a famous scene in “Ghostbusters.”

But to Paul Smith, director of lecture and demonstration for the Department of Chemistry, he sees slime as a simple polymer.

With three large tables chock full of chemicals, beakers and everyday objects like balloons, bags, Styrofoam and soda bottles, Smith thrilled more than 100 science fans of all ages Oct. 5 at the annual Purdue Chemistry Show. The theme for the 2013 edition was “Chemistry of Polymers.”

A polymer is a large molecule composed of many repeated subunits or monomers, which occur naturally or synthetically. The repeating units are low in mass and are essential in substances like rubber, plastic and processed cotton.

In between experiments, Smith showed magnified images of polymers. At microscopic levels, the molecules resemble long chains and are all mixed together like a plate of spaghetti. There is also space among the chains, which allow for pliable movement. Smith illustrated this by putting a bamboo skewer through a special polymer-coated balloon and, with the help of a young assistant from the audience; he pierced a polymer-coated bag full of water with a regular ink pen without spilling a drop.

With safety goggles in place, several tiny future chemists enthusiastically helped Smith make quick-rising plastic from some chemicals, dissolve packing peanuts in a boiling solution and form Gack!, a cousin to silly putty that stiffens when manipulated but is a formless puddle when the user stops using it. The audience was impressed to see a toy made in front of their eyes with the simple ingredients of water, glue, food coloring and Borax.

Other crowd-pleasing experiments included the forming of ghost crystals and the burning of pingpong balls and cotton. Throughout the show, Smith gave a linear history of the development of polymers that helped give the world necessities like tires and diapers, common materials like nylon and Teflon, and classic toys like super balls and silly string.

The flames drew gasps and awe from the crowd, especially the small wad of cotton that had to be lit from a candle on a pole. The cotton’s flames shot up several feet.

Smith saved his slimiest demo for last as he made up a large vat of yellow slime. Children were then invited to put their safety gloved hands through the stuff and were able to take latex gloves filled with slime home with them: a polymer carrying another polymer.

Science, slime, flames and fun wrapped up another Purdue Chemistry Show well.

Chem show girls

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