The Ultimate Guide to Super Absorbent Polymer

What are Absorbent Polymers?

Absorbent Polymers are a special substance that excels at holding liquids. When contacting water, the polymers uncurl from a dry state into a moist, water-filled state.

Absorbent polymers are used for a variety of consumer and industrial needs where controlling liquids is important.

What are Absorbent Polymers made out of?

Absorbent Polymers are made out of sodium polyacrylate or poly-acrylic acid sodium salt. It’s the last part of that, the ‘sodium salt’ part, that gives a clue as to why it’s such an important material. It loves water.

Absorbent polymers can absorb up to 1000% of their weight in water under ideal conditions. Even when they absorb a measly 100% of their weight in water, it makes them one of the best absorbers around.

How do Absorbent Polymers work?

Absorbent polymers often come to consumers as a dry powder. As the polymer interacts with water, the water becomes absorbed into its structure and turns the powder into a gel-like material. The polymers would normally dissolve in water but part of the creation of the absorbent polymers comes by cross-linking them. This structure of cross-linking the polymers gives them their stretchy properties without breaking. The polymers can stretch and shrink over and over again, making them ideal to absorb and reabsorb liquids.

Once expanded, the polymer resembles a mush. This mush results when the polymer has maxed out its water absorbing capacity. Even if it’s absorbed 100 times its weight, the polymer still has limits. The material can feel a little strange to touch or hold since it’s not quite like any other material.

Are Absorbent Polymers Safe?

Yes. Absorbent Polymers are used in a variety of applications including being used as an absorbing material in diapers. Since diapers spend hours and hours on the bodies of sensitive babies, absorbent polymers in diapers have been studied for decades. No one wants to harm their babies with unsafe diapers. The good news is that no study has found absorbent polymers to be harmful to the skin.

However, most absorbent polymers come sold as a fine powder. It’s not a good idea to inhale the powder despite it being non-toxic. Consumer-grade absorbent polymers have been tested to see if ingesting them is toxic and while it’s not a good idea to ingest them, there are no known negative consequences for eating them.

Most absorbent polymers do not biodegrade easily. A diaper with absorbent polymer can take 500 years to decompose. While much shorter than many plastic products, the chemical makeup of absorbent polymers degrades only slowly. If reducing your environmental impact is important to you, you may want to avoid them. Particularly, the form found in diapers is used and discarded after a single use, adding to the environmental impact. 

However, absorbent polymers can be reused for long periods of time in other products. These products have limited environmental impact since a small amount of the polymers are used for years to absorb and release liquids.

Are Absorbent Polymers Expensive?

Not at all. The great thing about absorbent polymers is that a small amount of them can absorb huge amounts of liquid relative to its size. A 20 ounce bag of garden-grade absorbent polymers can be purchased for around $10. Absorbent polymers have been mass produced for decades and the chemical processes to create them are relatively simple (for chemists anyways). The end result is an inexpensive product.

What else are Absorbent Polymers used for?

Absorbent polymers can be found in garden applications. Since the polymers can’t harm plants but will hold large volumes of water, they’re used to deliver nutrients to roots in soil and hydroponic settings.

Once the polymer begins reacting to water and expanding, the polymer gives the plant more surface area to draw nutrient solution from. The plants will take water from the absorbent polymers the same way they would from soil. The polymer expands and contracts over and over again as the plant draws water again and again. This means the polymer doesn’t need replacing once it’s on the plant’s roots.

Superabsorbent polymers are also found in food packing. The ability to absorb large amounts of liquid make them great when used with foods that dribble and thaw. The polymers absorb the liquid rather than increasing the risk of mildew or bacteria hanging out in liquids sloshing in the packaging.

As mentioned above, the most common use of absorbent polymers in consumer products is diapers. Though not great for the environment, the need for quick and thorough liquid absorption make absorbent polymers ideal for diapers. While a full diaper may look like it takes a lot of absorbent polymers, the diaper only holds a small amount of fine powder of the polymer hidden underneath a secondary absorbing layer.

The consumer uses and demand for absorbent polymers has grown year after year. New products and technologies stretch the capabilities of the polymers even further. As they’re a primary material in diapers, finding a biodegradable form of the material or other ways of improving the polymers can potentially make a company a lot of money. Don’t be surprised if new uses or improved absorbent polymers appear in a product near you in the future.