Science Buddies: "Ask an Expert"

O.K. I did the Bouncy Polymer Chemistry experiment this weekend. It was fun, and I thought my class would find it fun. I'm just wondering what the monomer is for Solutions #1 and #2 mixed together And just when did these three molecules become a polymer? I mean don't polymers have certain characteristic properties? Were they just a polymer when they began to "form a sticky glob?" Thank you for any help Dustin Vuori

Referring to the Science Fair Project about polymers and putty, when is Solution #1 50% H20 and 50% Elmer's glue and Solution #2 1Cup H20 and 2 tsp Borax a polymer? At 3 Tbsp of Solution #1 and 1 Tbsp of #2, it begins to form a sticky glob. How about the monomer formula?

Dustin,

Welcome to the Ask an Expert Forums. Our experts come from many different places, and we all check the forums on different days, so it usually takes 24-48 hours to get a response. Posting two topics for the same question gets people confused, and it won't get your question answered any faster. Your two topics have been merged together to make it easier for the experts to respond.

This is a quite common experiment. I would suggest looking around online for the answers to your question. A quick Google search yielded this:http://www.stevespanglerscience.com/experiment/00000039. See what else you can find; if you have any questions about what you read or don't understand something, please post back and well help you figure it out!

Good Luck!

I'm just wondering what the monomer is for Solutions #1 and #2 mixed together And just when did these three molecules become a polymer? I mean don't polymers have certain characteristic properties? Were they just a polymer when they began to "form a sticky glob?"

I'm not a chemist or plastics expert and it has been many years since I've worked side-by-side with them, so take my comments as a generalization. I'm sure there are plenty of sublte meanings to monomer, polymer, and polymerization and variations on their precise definitions in specific contexts.

http://en.wikipedia.org/wiki/Monomer
http://en.wikipedia.org/wiki/Polymer
http://en.wikipedia.org/wiki/Polymerization

Most polymers are formed by mixing two chemicals (monomers) together in such a way that polymerization occurs. Solution #1 is a dilute Elmer's glue solution (in water). Solution #2 is a borax solution (again in water). Solution #1 is definitely a monomer because it is a hydrocarbon chain and #2 may or may not be considered a monomer depending on your precise definition of a monomer. In any case, when mixed, they undergo polymerization to form a polymer. Polymerization reactions always involve long chains that somehow cross bond. The borax reacts with the Elmer's glue hydrocarbons to cross bond chains into flexible structures which you describe as a sticky glob. I haven't done this experiment so I don't know what happens to all the water. I suspect some water is left over. Some maybe trapped in the polymer mechanically. Some may have been ionized ( H+ and OH-) and chemically bonded to the chain.

How about the monomer formula?

I don't know the formula for Elmer's glue. Try searching and see if it is public knowledge. It is definitely a monomer.

The chemical formula for borax is easily found with a simple search http://en.wikipedia.org/wiki/Borax.

As to when is something in your mixture considered a polymer, theoretically speaking, that happens as soon as the first cross bond is formed creating the first altered molecule even if the transformation is incompleted (additional cross bonds will form later on that atomic chain). Obviously, one can't detect precisely when that occurs so questions like this are of pure theoretical interest only. A more interesting practical question is "When has the polymerization gone to completion?". This occurs when all of the borax is utilized or when the concentration of any excess borax remains constant in the solution.

Hey I'm doing this experiment and I need an answer quick. I need to know why this happens. I need to know the science behind this experiment. I have searched for a while and my project is due 3/6/13. Can you please help me because i need this very quick thx.

Dustin, I don't want to confuse you. You've asked a good question, but I believe one of the responses you got is in error.

A monomer means mono = one, mer means unit. Polymers are molecules of many "mer"s stuck together. Normally, polymers as we encounter them as consumers are composed of a very very large number of "mers" thousands and up. Elmer's glue was, and I believe still is, an emulsion of polyvinylacetate. Vinyl acetate is a monomer. It contains a double bond which can open and connect to another monomer to grow into a very large chain. In Elmer's, these chains are bound up in very tiny spheres which are surrounded by water. Sort of like milk.

So the monomer is vinyl acetate. You will not encounter it in your experiment.

Borax disrupts the layer that keeps these tiny spheres stable in water, and sticks the polyvinylactate spheres together. Sort of like adding vinegar to milk, only since milk isn't a polymer, only the instability is similar. Borax does this step in a special way that makes the resulting product bouncy. It is a very neat trick.

If anything was polymerizing in this experiment, it would get hot, as polymerization gives off lots of heat.