This is a simplified, elevator-pitch version of PVA slime science if you’re in a hurry.
Most liquids, such as water (H2O), are made up of separate, unconnected molecules moving around and tumbling over and bouncing into and off of one another. These single, unconnected molecules are called monomers (mono = one). Monomer liquids – like water – flow easily and are seldom gooey or sticky.
In other substances, identical monomers are chemically bonded into very long, separate chains of many molecules called polymers (poly = many). These long chains don’t often flow like water; they’re gooier and may even ooze a little. Imagine a bowl of tiny steel chains. The chains can roll over and around one another but they are still long and separate. One chain is not hooked to another chain. If you grab one chain and pull it out, that’s what you get: one chain. Liquid polymers tend to flow more slowly than liquid monomers. Polyvinyl alcohol (PVA) and is a liquid polymer. It looks a little thicker than water because, well… it is!
To make slime, the molecules in the Activator solution “cross-link” (or bond with) the long strands of PVA molecules. Think of the bowl of chains again. What happens if you toss a million tiny magnets into the bowl and stir? This time when you reach in and grab just one chain, they all come out at once. The Activator solution is the “magnet” and it links to water molecules throughout the PVA chains. (NOTE: Activator solution links chemically, not magnetically.) When you try to pull out one PVA chain, all the cross-linked chains come with it. You’ve got slime on your hands!
Part 2 – Deeper into the Science…
WEEK FOUR: GLUE SLIME VS PVA SLIME
There are naturally occurring polymers that can produce a true, non-Newtonian slime, e.g. guar gum (taken from guar beans), methylcellulose (taken from plants), milk (taken from cows) and cornstarch (taken from – well, you get the idea). Another favorite is an ordinary glue like Elmer’s® School Glue (either white or clear – both washable). You need to keep in mind that there will be huge differences in consistency and flow between glue slime and PVA slime. But heck, both are true slimes so you might as well explore them!
PVA is used by the plastics industry to form surface coatings and, among other things, to make surface films resistant to gasoline. It’s also used to make artificial sponges, hoses, and printing inks. If you check out the ingredients of contact lens wetting solutions, you may find PVA used as a lubricant and a cleanser. Most PVA solutions contain a special disinfectant to help resist those pesky germs found on those not-so-clean hands of yours, too. PVA is also used as a thickener, stabilizer, and binder in cosmetics, paper cloth, films, cements, and mortars. PVA solution dries to a thin plastic-like film that is finding use in packaging materials. If left in the environment, the PVA film will naturally break down rather than require a major clean-up effort. It’s good stuff!
Do you know something about Borax?
Borax: Sodium Tetraborate Decahydrate Is the Borate ION, the borate compound that’s the perfect linking agent for slime. Where was it originally discovered? – In Tibet, in evaporate lake beds, these dry lake beds, these salts that they mine, that’s how they originally found Borax.
Now it’s used as a detergent, in cosmetics, it’s actually even used in some food. There are so many uses. Just a quick glance of wikipedia and you’ll find all the natural sources of it, where it comes from and all the things that can be used for.
Now everything is “Borax is bad”. Where did that come from? How did Borax get to be bad?
Well, Borax had to be bad because of an irresponsible article that came out on TV, (I’ll let you figure out who said this) of a mom who allowed a kid to make as much slime as she wanted to for a long period of time. This kid was soaking in borax and water making slime, having fun and what happened? Her hands got irritated… Her skin got irritated… you’d think that would make some sense but no… We’re gonna let her kid continue to play, continue to play until you take her to the hospital, claim that there’s burns on her and now of a sudden, you can’t use Borax.
I wonder what the people from Elmer’s think about us not being able to use Borax. They must have a solution, we gotta find Elmer’s glue!
You know what’s making me lose my mind now?
The people who hate Borax. What do you know about Borax? NOTHING!
I’ve been using Borax for almost 30 years to teach kids how to make slime. Borax is the perfect linking agent; Sodium Tetraborate.
Our news stories were totally irresponsible telling people that this is dangerous. It has vilified something that we need to get kids excited about science and I’ll venture to guess, you know nothing about Borax.
Is it a solid? Is it a liquid? Just what is this slick, stringy, rubbery stuff?
This variation on PVA slime will probably remind you of a similar material found in many toy stores. Glue slime is the most popular version of “slime” among teachers because it’s so easy to make (with very little messiness) and serves as a great visual tool for introducing students to the properties of polymers. Normally, the glue hardens as water evaporates from it. The result is that two objects are held together tightly. If you can prevent or slow the water from evaporating out of the glue, you get a slime. The Activator solution locks up the water and evaporation drops to a minimum. Eventually, the slime will dry out and the drying process will actually speed up over time.