April 2024 Visit on Friday, April 19, 2024
Experiment Leads: Clare Froehlich & Eric Rachita
Find instructions for a similar experiment on our Do It Yourself page!
For our final SFA visit of the 2023-24 school year, Clare and Eric led an experiment covering polymer science! We started with a discussion of the basics of polymers: what a polymer chain looks like (a long string of paper clips), where we find polymers in our daily lives, and the properties scientists look for when making new polymers. For our experiment, we introduced the concept of superabsorbent polymers, which can absorb 100 times their weight in water!
Before the visit, the SFA team extracted the superabsorbent polymer from several dozen diapers, it was messy work! We provided each student team with 1 gram of polymer from each of three diaper brands: Pampers, Huggies, and Tippy Toes. Before diving into the experiment, the students were asked to hypothesize which of the brands would absorb the most water. For their experiment, the students weighed a plastic bottle containing the dry polymer from one of the diaper brands, added tap water until the polymer couldn’t absorb any more, and weighed the swollen polymer to determine how much it absorbed. They were surprised to find such a small amount of polymer powder could absorb enough water to fill the container! The students chose their own scientific criteria for “completely absorbed,” and loved shaking their gelatin-like swollen polymer to encourage one last drop of water to absorb. In the end, we found the three brands of diapers performed very similarly, since the polymer itself was the same from brand to brand. As a final experiment, the students found that saltwater solution is hardly absorbed by the polymer at all! They learned that sodium ions found in the saltwater stop water molecules from interacting and sticking to the polymer, so none is absorbed.
The SFA team had a blast planning experiments and visiting Murray Middle School this semester. We can’t wait to host Ms. Crowley’s students at the University of Minnesota for our annual field trip in May!
