Science Buddies: "Ask an Expert"

Posting on behalf of individual
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Project: https://www.sciencebuddies.org/science- ... -hydrogels

I prepared agar hydrogels, left for 28 hours and then conducted the water absorption test. The agar hydrogel absorbed no water (I even left for 24 hours). Another site suggests to dry the hydrogels (which I am currently doing)... Has anyone investigated this please?

Hi - I talked with our staff scientist about your question. She notes that it is important not to "assume" that hydrogels will expand, then desiccate."

Hydrogels made with different gelling agents may behave differently. The hydrogel may not expand in water if it's already supersaturated.

She advises following the "Testing Hydrogel Water Absorption and Desiccation" directions in the project and keeping in mind that "no change is still a result" if that's what you are observing. Not all hydrogels will expand in water, but many of them do desiccate in the presence of air since the water in the hydrogel can evaporate.

Amy
Science Buddies