Water beads: fun experiments, unexpected results

Days like today is the reason I don’t plan more than 1 week ahead in our homeschool. 

I prepared a really fun inertia unit. Water beads (“They’re called hydrophilic polymers, Mom,” my 4 year old scientist corrected me) were meant to keep the kids busy while  I set up the experiments and gathered my thoughts.  Guess what we did all day? Hint: not inertia experiments. 

1. We hydrated/dehydrated the polymers

2. “What will happen if we freeze the beads?” We wondered.

Hypothesis 1: as beads freeze, water will expand and shred the polymers.

Hypothesis 2: nothing. Nothing will happen, polymer beads will keep their shape.

The results surprised us! While both hypotheses were right, some beads reacted in unexpected way. They…jumped out of their ice suits and returned to their original size, leaving a bead of ice behind! 

3. A handful of beads + 1 balloon = great stress ball! It helped us with the school work for the rest of the day. 

4. Shaving cream and hydrophilic polymer mix created a fun sensory bin. The entire family enjoyed it!

5. I tried to show my kids a magic trick. Apparently there is no such things as magic, only illusion and science, so I was forced to reveal my secrets: 


No, I did not make the beads disappear, clear polymer beads have the same index of refraction (1.333) as water, so the light treats water and the clear polymer as the same substance. Not magic. Bummer.

7. Well, when we froze water beads, they did something weird…any guesses what we did next? 

I vividly remember my mom asking me if I knew how to tell whether the frying pan is hot enough too cook. “You touch it?” I guessed. Dude, no. Don’t.  You add a drop of water to a hot frying pan. The droplet will seemingly dance over the surface (the side that comes to a contract with hot pan vaporizes so quickly that they float around on a cushion of vapor.) Without knowing it, she introduced me to Leidenfrost effect.

How does it relate to the superabsorbent polymers and the video below?

This week we pan fried hydrophilic polymer beads. Turn up the sound!!!!

Mommy, WHY ARE THEY SCREAMING?  

Because the released vapor interacts with the squishy sphere to create the bouncing and the high pitch sound.

The spheres act like engines, harvesting surface energy. All of the engine’s part are included in 1 squishy sphere! 

Whoa!

 Soft engine concept can be used in robotics. 

More information: Scott R. Waitukaitus, Antal Zuiderwijk, Anton Souslov, Corentin Coulais, Martin van Hecke, Coupling the Leidenfrost Effect and Elastic Deformations to Power Sustained Bouncing, Nature Physics <——I need dis book. Now!

Inertia can wait  another day. Or two. Today we will play with superabsorbent polymers and make messes!