Borax Slime

Elmers (white school) Glue is a polyvinyl acetate (C₄H₆O₂)_n. The glue is sensitive to base hydrolysis (the cleavage of chemical bonds by the addition of water) and will slowly convert PVAc into polyvinyl alcohol (the gluey part) and acetic acid (vinegar).  The glue reacts with water to some extent to replace some of the acetate groups with OH (alcohol) groups.Under alkaline conditions, boron compounds such as boric acid or borax cause the polymer to cross-link, forming tackifying precipitates or toys such as Slime and Flubber.  The B-OH groups on the borax molecules react with the acetate groups on the glue molecules (relatively long polymer chains) to eliminate acetic acid and form new bonds between the borax and two glue molecules. The linking of two glue molecules via one borax molecule is called polymer cross-linking and it makes a bigger polymer molecule, which is now less liquid-like and more solid.  If you don’t add enough borax  there may not be enough borax present to fully polymerize the glue molecules. This will lead to a very gooey, slime-like product. The thickening observed is a result of hydrogen bonding between the molecules



Borax                                    +            Glue                              =            Polymer Slime