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  • jeffrey4209

Superabsorbent Polymer - Diaper and Water Beads

Updated: Dec 14, 2021

Most people had the experience of wearing a diaper …… at least when they were a baby. Additionally, lot of kids have played with water beads before. These two seemingly completely unrelated objects, diapers and water beads, have a surprising connection. They are made out of the same material! This common material allows both products to absorb lots of liquids, many times their own weight.

At HandsOnSTEM, we taught students a lesson on polymers using diapers and water beads. However, first we had to introduce the concept of polymers to students. Most students were already familiar with plastic as a polymer; we came up with many examples that used plastic like chairs, bottles, and many toys. However, we also highlighted some common polymers that students were unaware of, these included clothes and paper which are can be made from cellulose, water proof jackets and other clothes which can have nylon, spandex, and a variety of other polymers.

The experiment we performed introduced super absorbent polymers, a special type of polymer that is used in diapers and water beads. First, we compared the ability of both diapers and paper towels to absorb water. The students were able to see two remarkable properties of the diaper polymer, it absorbed noticeable more water with respect to its own weight, and the absorbed water could not be squeezed out.

At the end of the class, we gave a small bag of water beads to students and ask them to grow them at home, and measure the diameter of one of the water beads periodically. Below is a table with the data gathered by one of our students.

If we plot out the data, it will look like the chart shown below. We can see that the water beads grow in a nonlinear speed. If you are really curious, you can also try to grow the water beads in distilled water, salt water, and sugar water. See if you notice any difference and, if so, try to understand why. Feel free to send me a note if you'd like to have more discussion on this interesting topic.


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