Scientists turn plastic waste Into water sponges

October 19, 2026

Researchers at the University of Vienna have developed an innovative method to transform discarded plastics into water-absorbing materials capable of extracting moisture directly from the atmosphere. The technology could provide a new approach to plastic waste recycling while supporting sustainable water harvesting in regions facing water scarcity.

The research demonstrates how everyday plastic products, including food packaging, old CDs, and LEGO bricks, can be converted into reusable polymer sponges. These materials absorb atmospheric moisture even in relatively dry environments and release the collected water when exposed to moderate heat, potentially supplied by sunlight.

Published in the scientific journal Chem Circularity, the study highlights the potential of converting plastic waste into valuable materials without breaking the original polymers down into their basic molecular components.

Turning discarded plastics into water-harvesting materials

Plastic pollution remains a major environmental challenge, with large quantities of packaging and consumer products discarded every year. Researchers are exploring ways to give these materials new functions rather than relying exclusively on conventional recycling or disposal.

The University of Vienna team focused on aromatic polymers, a category of plastics containing molecular structures built around carbon rings.

These structures provide suitable sites for chemically connecting polymer chains into highly crosslinked networks. The resulting materials contain numerous microscopic spaces that can accommodate water molecules.

Scientists then treat the polymer networks with sulfuric acid, introducing sulfonic acid groups that strongly attract moisture.

This chemical modification produces a porous, water-loving material that functions like a molecular sponge, capturing water vapor from the surrounding air.

 Old CDs, LEGO bricks and packaging gain a second life

One of the most promising aspects of the technology is its compatibility with several commonly discarded plastic products.

The researchers successfully produced water-absorbing polymer networks using different waste materials, including:

• Polystyrene packaging: Commonly found in disposable food containers, cutlery and CD cases.

• Polycarbonate CDs: Discarded compact discs containing aromatic polymer structures.

• LEGO bricks: Products manufactured from acrylonitrile butadiene styrene (ABS).

• Mixed plastic waste: Selected combinations of compatible plastic materials processed together.

The successful treatment of mixed plastics is particularly important because separating different polymer types can make recycling processes more complicated and expensive.

Although further research is necessary, the findings suggest that certain mixed plastic waste streams could be converted into useful products with less extensive sorting.

Recycled plastic sponges capture water even in dry air

Laboratory experiments demonstrated that the newly developed materials can absorb substantial amounts of atmospheric moisture.

The strongest results came from sponges produced using general-purpose polystyrene, a widely used plastic found in disposable products and packaging.

 ~60% Water absorption in humid air

Relative to the sponge's dry weight

~20%  Water absorption in dry air

Under desert-like conditions

These findings indicate that recycled plastic materials could potentially contribute to atmospheric water harvesting in locations where humidity levels are relatively low.

Unlike conventional water collection systems that depend on rivers, reservoirs or groundwater, atmospheric water harvesting uses moisture already present in the surrounding air.

However, the amount of water collected in practical applications will depend on environmental conditions, system design and the efficiency of the complete harvesting process.

Sunlight could help release captured water

Another advantage of the polymer sponges is their ability to release absorbed moisture through relatively mild heating.

Once the material has collected water vapor, heat can drive the moisture out of the polymer network, allowing it to be condensed and collected as liquid water.

According to the researchers, much of the absorption and release process can take place within approximately one hour under the tested conditions.

The materials also demonstrated good resistance to repeated absorption and desorption cycles, suggesting they could be reused multiple times without immediately losing their functionality.

Using solar energy as a heat source could eventually reduce the external energy requirements of water-harvesting systems, particularly in sunny regions.

Nevertheless, practical devices would still need effective condensation and water collection components, and their overall performance requires further evaluation.

A potential breakthrough for circular plastic recycling

The research introduces a different approach to plastic recycling by transforming existing polymer structures into functional materials rather than chemically breaking them down into monomers.

Through a combination of hypercrosslinking and sulfonation, discarded aromatic plastics acquire new properties that allow them to capture atmospheric moisture.

This strategy could support the circular economy by extending the useful life of plastic materials while creating products with potential environmental applications.

The ability to process several plastic types also opens possibilities for developing more flexible recycling technologies.

However, researchers emphasize that additional work is necessary before the process can be considered suitable for industrial-scale implementation.

Key challenges include evaluating the environmental impacts of chemical processing, recovering solvents and reagents, controlling manufacturing costs, and ensuring that the materials remain effective during long-term use.

Could plastic waste help address global water scarcity?

Atmospheric water harvesting is attracting scientific interest as communities around the world face increasing pressure on freshwater resources.

Materials that absorb moisture from air and release it using low-temperature heat could complement existing water supply technologies, especially in remote or water-stressed regions.

The University of Vienna's research suggests that discarded plastic products could become a feedstock for these emerging systems.

Before commercial deployment, scientists will need to establish how efficiently the materials perform outside laboratory conditions, how much usable water complete devices can produce, and whether the process delivers environmental benefits over its full life cycle.

Water quality and suitability for drinking would also require testing and, where necessary, treatment.

If these challenges can be addressed, the technology could create a valuable connection between plastic waste management, sustainable materials development and alternative freshwater production.

By converting everyday plastic waste into reusable moisture-absorbing sponges, the research offers a promising example of how materials chemistry could help tackle two environmental challenges: plastic pollution and water scarcity.