Hydrogel against microplastics

A research team at Leibniz University Hannover has developed a new environmentally friendly technology that can be used to break down plastic particles with intelligent material.

© Stephan Siroky

Oceans, lakes and rivers are full of them: microplastics can now be found in almost all bodies of water. Researchers at Leibniz University Hannover (LUH) have now developed a new type of material that can potentially absorb and break down microplastic particles in bodies of water on its own - without any external control. The results were recently published in the renowned journal Nature Communications.

Exposure to microplastics

The pollution of the environment and organisms by microplastics is considered one of the most pressing environmental problems of our time. The tiny plastic particles can cause inflammation and oxidative stress in living organisms. Previous methods for removing these particles are often based on stationary filter systems, the use of which is associated with high costs and energy expenditure. 

Intelligent material developed

A research team led by Prof. Dr. Sebastian Polarz at the Institute of Inorganic Chemistry (ACI) at LUH has now developed an intelligent material that opens up new avenues in environmental remediation: a hydrogel that absorbs microplastic particles like a self-regulating shuttle, transports them to the water surface and degrades them there under the influence of light - in a repeatable, autonomous cycle. 

A float with brains

The basic principle is simple. The hydrogel is added to the contaminated water, sinks to the bottom, collects the microplastic particles there and rises back to the surface like a shuttle. There, the plastic particles are broken down - partly by the effects of the sun. "Ideally, only water and CO₂ would be left," says Dr. Dennis Kollofrath from ACI, lead author of the study. So far, the gel is a prototype, but the initial tests on a laboratory scale are promising.

The newly developed shuttle gel combines a thermoresponsive polymer, porous organosilicate particles and a photocatalyst. At low temperatures at the bottom of the water, the polymer swells and absorbs microplastics and glucose, which is present in low concentrations in bodies of water. An embedded enzyme converts the glucose into oxygen, which is stored in the pores and gives the gel buoyancy. If enough gas is formed, it rises to the surface. "It works a bit like a hot air balloon under water," explains Kollofrath. On the surface, the hydrogel heats up, shrinks and releases the gas bubbles again - the buoyancy disappears and the gel sinks. At the same time, the photocatalyst produces reactive oxygen species (ROS) under the influence of light, which decompose the microplastic. Through this automatic alternation between ascent and descent, the gel continuously purifies the water.

A flexible tool for environmental technology

"Our system combines several functions in a single material: an autonomous drive system as well as the absorption and targeted decomposition of pollutants - all without external control," explains Kollofrath. In the current study, the decomposition of polystyrene was examined as a representative example. The high adaptability of the concept is particularly noteworthy: the nanoparticles used can, in principle, be modified in such a way that other pollutants - such as polyethylene or PET - can also be specifically removed.

(Published: 19 August 2025)