Sodium polyacrylate

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Sodium polyacrylate
Sodium polyacrylate skeletal.svg
IUPAC name
Poly(sodium prop-2-enoate)
ECHA InfoCard 100.118.171
Molar mass Variable
Density 1.22 g/cm3
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Sodium polyacrylate, also known as waterlock, is a sodium salt of polyacrylic acid with the chemical formula [−CH2−CH(CO2Na)−]n and broad application in consumer products.[citation needed] This superabsorbent polymer has the ability to absorb 100 to 1000 times its mass in water. Sodium polyacrylate is an anionic polyelectrolyte with negatively charged carboxylic groups in the main chain. While sodium neutralized polyacrylic acids are the most common form used in industry, there are also other salts available including potassium, lithium and ammonium.

The origins of superabsorbent polymer chemistry trace back to the early 1960s when the U.S. Department of Agriculture developed the first super absorbent polymer materials.[citation needed]


Dyed sodium polyacrylate hydrogel beads

Sodium polyacrylate is used in paper diapers and Maximum Absorbency Garments as the absorbent material.[1]

Safety for humans[edit]

Acrylic acid

As a leftover of producing sodium polyacrylate, acrylic acid would cause a rash when contacts with skin. It should be less than 300 PPM as the absorbent material in paper diaper.


  1. ^ "Diapers Ingredients". Retrieved 2019-10-08.