After many years of research, BASF has developed a new chemistry of insulation: SLENTITE® is a high-performance insulating material based on an organic aerogel that consists of 90 percent air. CORPUS has accompanied chemist and inventor Marc Fricke from the very beginning.
Air provides excellent protection from the cold – which anyone can confirm when putting on his or her down jacket in the first days of winter. The tiny air pockets between the thousands of down
fibers help the body to retain its heat.
Many classical materials for thermal insulation on buildings exploit the same effect. However, like many a down jacket, it has to be thicker to insulate better. But is it possible for insulation to be made slimmer without compromising on performance? After seven years of research, BASF chemist Marc Fricke and his team have found a pretty good answer to this: SLENTITE®, a high-performance insulating material based on an organic aerogel that consists of 90 percent air. It is also extremely sturdy and insulates twice as well as conventional materials. When Marc Fricke started investigating highly porous, fine-pored materials over seven years ago, the finished product was a long way off. “This was when BASF brought postdocs from all over the world together in a laboratory in Strasbourg. Equipped with all the necessary means, our job was to work on highly complex subjects. It was a question of developing new out-of-the-box chemical strategies or applying familiar strategies to new areas,” says Fricke explaining the launch of the project culminating in SLENTITE®, the aerogel-based high-performance insulating material. “At the beginning, we had no idea which direction we would ultimately take,” he adds. This is the risk inherent in research in new fields that a company like BASF is willing to take.
What was already widely known at the time was that aerogels display extremely low thermal conductivity. What had yet to be developed was a process for bringing this extremely brittle material into a stable form. Aerogels in insulation were not new. But so far they had only been used as powders applied to a carrier material. The idea of Fricke and his team was to develop a pure polyurethane aerogel that can be produced as a sturdy panel. And that has more to offer than just insulation performance. “That was a pretty tall order,” Fricke recalls – and it still is, long after its achievement on the laboratory scale. To understand the challenge facing the team, let’s take a brief excursion into the world of chemistry. “Imagine you’re at home in your kitchen and you’ve made a jelly. The jelly has about the same consistency as our gel at the beginning of the process,” explains Nicholas Leventis, Professor of Chemistry at the Missouri University of Science and Technology and BASF cooperation partner. “The task now involves replacing all the liquid in the jelly with air – and without the whole thing collapsing.” This is achieved with a process known as super-critical drying – something that gave Fricke and his colleagues plenty of headaches. “It’s essential that the material doesn’t shrink and retains its shape and porosity,” stresses Fricke, the only member of the team to have worked continuously on the project. “Throughout the process that was just about the biggest obstacle we had to negotiate.” Together with process experts of Hamburg University of Technology, they slowly inched toward the solution. The outcome is a PU panel consisting of an incredible 90 percent of air. It is trapped in myriad pores in the hundred-nanometer range and is very restricted in its movement – thus making the new aerogel panel one of the best insulating materials of the future.
SLENTITE® is therefore a real lightweight – heavier than polystyrene, but lighter than drywall. In addition it is extremely compression-resistant and easy to process: the insulating panels can be sawn, milled, drilled and bonded. Thanks to its open-porous structure, the material is also capable of absorbing and releasing atmospheric moisture – which is essential for a good indoor climate. “Because we can additionally reduce insulation thickness by 25 to 50 percent, we’re opening up new opportunities particularly in architecture,” says Fricke, who is enthusiastic about his material. “We can therefore address such urgent issues as the modernization of old buildings. And elaborate design solutions can be realized more flexibly with slimmer insulation.” All the same, it will still be a while until this becomes reality. At present, the pilot plant for the manufacturing of SLENTITE® on the BASF site in Lemförde, Lower Saxony, produces sufficient quantities of the insulation material – and SLENTITE® is already being used in different cooperation projects, e.g. with the cooperation partner’s applications of Beck+Heun, Okalux and Raico. Additionally the first SLENTITE® showcase is underway: In Hamburg, Germany, the mechanically strong panel is used for the interior insulation of an historic building. The slim material makes it possible to maintain the historic character and simultaneously ensure best insulation values for the building.
With SLENTITE® we can address urgent issues
as well as going new ways esthetically.
In the medium term, the aim is for innovative insulating materials like SLENTITE® to meet the architectural challenges of the future. First, buildings will be required to be increasingly energy-efficient. And, second, the advance of urbanization worldwide will call for the creation of comfortable housing in confined space. Just two of many tasks that need new solutions. Fricke and his team are already working on the next one.
The story of SLENTITE® began in Strasbourg, where BASF gathered postdocs to work on highly complex projects. Marc Fricke talks about now and then and explains what is so special about the new insulation material.