Membranes for tomorrow’s world

Matthias Wessling is among the leaders in membrane and polymer research which can be applied in areas such as water treatment, energy production or medicine. In an effort to accelerate new developments, the internationally acclaimed researcher at RWTH Aachen University wants to forge closer links between engineering and the natural sciences.

Text: Trio MedienService Bonn

Matthias Wessling is an engineer and an architect at the same time: he constructs membranes, high-tech filters made from extremely fine plastic components. In order to produce them he liquefies solid plastics with solvents and creates new configurations. “It’s a bit like milk: if you add vinegar to it, it curdles,” explains the engineering scientist. “But unlike milk, we can determine the shapes of the plastics when they congeal.” The configurations either look like thin paper or little straws, and their pores measure less than one nanometre, so they are incredibly minute. After all, the relationship between one nanometre and a metre is the equivalent of a grain of sand to the size of the Earth. “By liquefying and solidifying the plastic we give it a new functional property, and it becomes a molecular filter,” says the scientist. The structural design and the size of the membranes produced in this process are determined by the substances that are to be filtered out later. So the engineering scientist can precisely customise the membranes for their future applications. He creates the membranes to satisfy their specific function by systematically manipulating the pores at the nanometre level.

One product, many solutions

“Membrane-based nanotechnology is extremely relevant to society and has wide-ranging fields of application,” says Wessling. For example, it saves the lives of millions of dialysis patients. In Germany alone some 70,000 people are dependent on artificial kidneys. Membranes in dialysis machines partially take over the tasks of the kidneys by filtering water and toxins out of the blood. “In the brief period since starting here in Aachen I’ve already had inspiring contacts with kidney specialists at University Hospital Aachen. I’m hoping we will be able to work closely together, so that we can build even better dialysis machines in the next 20 years based on new interactions between cell research and basic research in materials science,” says the Humboldt Professor.

Membranes not only filter out toxins from the blood but also from the air, which means they play a major role in climate protection. “Many new coal-fired power stations are still being built today. So we have to act now by making them more environmentally friendly,” says Wessling. That is why he develops membranes to filter out carbon dioxide from the emissions that are produced when coal is burnt. And that is also why the scientist has been involved for some time now in large research consortiums in Twente, the Netherlands, where he worked before becoming a Humboldt Professor, as well as in Aachen.

High-tech filters can also help in energy production, for instance in delta regions where rivers enter the sea. In this case a natural phenomenon is used: osmosis. The fresh water flows through a membrane into the salt water which, however, is unable to penetrate the filter. “In this way pressure builds up on one side. This can be captured by turbines which then generate electricity,” explains Matthias Wessling. The engineering scientist has already developed suitable membranes for a similar project in the Netherlands.

Looking to future applications

At RWTH Aachen University Wessling wants to forge closer links between his discipline and the natural sciences. “The road from scientific discovery to applications in the technological landscape is long. I want to cross borders and accelerate this process,” says the pragmatist. “RWTH has the research capacity to make new discoveries and understand fundamentals, and it has the know-how to convert them into products as well.” These are two worlds which, in the eyes of the engineering scientist, belong together, and which RWTH wants to integrate much more in the coming years.

This is the concept the university and its Aachen Chemical Engineering are pursuing with the new research focus “New Generation Processes and Products”, which translates into biorefining. Engineering scientists, chemists and physicists will develop new building blocks for tomorrow’s industry from renewable raw materials.

It’s a huge challenge, because in the next 30 years the supply of raw materials will change dramatically as oil resources decline. “Our present-day chemistry is based on oil. This means that we urgently need alternatives which we can derive from nature, for instance from wood, grass or straw,” explains Matthias Wessling. Membranes play a key role here, because only they enable scientists to separate and cleanse the building blocks and molecules of the biomass in preparation for their new purpose. “In this way we gain a variety of Lego bricks with which we can build new chemicals.” The advantage is that these are renewable resources. They are not dependent on oil, and their production requires less energy. So the research focus area, in which Wessling will play a decisive role, is a key to the industrial processes of the future.