Explanation of the Slime Demonstration

Two liquid solutions, one of polyvinyl alcohol and the other of borax, are mixed.  These clearly liquid solutions result in a clear substance that can best be described as "slime."  The slime can be made to act as a solid by snapping it, causing it to break like a solid, or a liquid by giving it time to ooze, demonstrating the ability to flow as if it were a highly viscous liquid.  Formed as a ball, the elastic nature of the material can be demonstrated by bouncing it on a surface.

The borax causes cross polymerization to occur in the polyvinyl alcohol.  The smaller molecules link together to generate VERY long molecules, which have a difficult time moving around each other, kind of like a tangled mass of string.  This causes a material that is randomly ordered like a liquid, but takes a long time to rearrange itself, much like a solid.    

This demonstration is based on that by Bassam Z. Shakhashiri, Chemical Demonstrations: A Handbook for Teachers of Chemistry, Volume 3 (The University of Wisconsin Press, Madison, Wisconsin, 1989), pp. 362-363.  The explanation is much more in-depth in this textbook, and the demonstration is far more impressive in person; I would highly recommend the purchase of this extraordinary set of books for anybody interested in this or other chemical demonstrations.  As with any demonstration, be sure to follow the directions very carefully and observe all applicable safety precautions.  This web site does not purport to be a site designed to convey directions for chemical demonstrations, and is not liable for any injuries or damages sustained by those who would attempt to re-create this demonstration without proper training, supervision or instructions.  

Concepts:   Polymerization

Time Required:   15 minutes

Chemicals Needed:  Polyvinyl alcohol, borax detergent