G3 Program 13: Magic Diapers and Slimy Goo!

There’s no better way to kick off the Fall season than a G3 program full of squishy, gooey polymers 🙂  Polymers can be found just about everywhere – in places you might not even have realized. They are in natural products like wool and silk (among many others), and then also in many man-made synthetic materials like nylon and rubber. Even the double-helix strand of DNA is a form of a polymer known as a “biopolymer.”  But what exactly is a polymer?

The word polymer means “many parts.” The individual parts that actually combine to form a polymer chain are called monomers.  Sometimes a substance can actually help polymer chains link together and form a more solid substance. The youtube video below, uploaded by TTScienceClub, does a great job of graphically showing the basic formation of polymers and linked polymer chains:

Our G3 scientists had the opportunity to test out polymers with two fun experiments:

  1. “Diaper Magic”
  2. “Goo!”

We’ve all seen diaper commercials on TV, where one brand after another claims to be the “most absorbent.”  But what makes a diaper so absorbent in the first place? Is it the cotton stuffing? Not really. It’s one of many uses of modern polymers. Tiny polymers no larger than a grain of sand are mixed into the cotton lining the inside of a diaper. Modern diapers actually contain a super absorbent polymer called polyacrylic acid that is designed to attract water molecules. Each polymer can absorb about 30 times it’s weight in water. All said, most modern diapers can absorb about a half cup of water. Well, our G3 scientists got a chance to test this out!  Steve Spangler’s web site provides a great description of this experiment, along with the following how-to video:

Each scientist received their own diaper. We cut into the lining, pulled apart the cotton, and shook the polymer grains onto a piece of colored construction paper (to make it easier to see the white polymers). We poured the polymers into a clear plastic cup, and then added water. Some scientists poured a full 1/2 cup of water in at once, others did it in spurts. In both cases, the polymers absorbed the water, and congealed to form a squishy, gel-like substance. Most scientists added even more than 1/2 cup of water. At a certain point, the polymers reached their limit and could no longer absorb more water.  In theory, if you leave the cup full of squishy polymers on a counter top for a few days and allow the water to evaporate, the polymers should return to their original state…

Our second experiment involves every scientist’s favorite concoction:  GOO!  There are many different goo (or slime) experiments available online. We based our goo on a formula provided by Science Bob that is equal parts water, liquid starch, and glue. We specifically used 1/4 cup of each item in our mix. Though we didn’t do this the day of our program, food coloring can be added during the early stages to make goo of a specific color. First we stirred together the water and glue in a small bowl. Then we slowly added the liquid starch. The starch is our key goo ingredient; it is the substance that binds together (links) the polymer chains present in the glue and gives us our slimy goo. Our G3 scientists loved the goo, describing it as “slimy,” “snotty,” and “gross” 🙂 Many of our scientists even chose to combine both the diaper goo and the glue goo…just to see what would happen. One scientists described this combination as a “grainier goo.”

Each scientist happily went home with baggies full of goo and instructions for how they can recreate the experiments at home…

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