Polymers: Playing is Learning!
This week the Saltonstall 5th graders had a really fun chemistry lesson on polymers. The students learned how common and important polymers are in their lives, since polymers include starches (pasta, potatoes), cellulose (wood, plants), plastics, fabrics both natural (cotton, wool) and manufactured (rayon, nylon), and proteins. But exactly what is a polymer, you might ask? Polymers are a type of molecule made of linked chains of individual units, or monomers. Students saw how monomers form chains to create polymers, and that chains of polymers can be cross-linked together to get even different properties. Cross linking tends to make polymers thicker, stickier, or harder depending on the amount of cross linking.
We did a fun experiment to demonstrate the effects of cross linking. Each student started out with a small cup of white glue and colored water. After mixing the glue and water together and making observations about its appearance and texture, we started adding in a cross-linking agent (Borax dissolved in water). The results were instant and very dramatic! The thin, slimy glue suddenly changed into a rubbery, squishy substance much like silly putty! It could be molded, stretched, rolled into a ball, and pulled apart. We call this material “Glubber,” and it is easy and safe to make at home under adult supervision.