1. What inspires your research and what opportunities do you want to tap into?
Polyurethane is a versatile plastic used in mattresses, packaging, sports equipment, seals, paints, adhesives, construction foam, and even medical technology. It is manufactured using a modular system with isocyanates, chain extenders, and polyols, whereby the high reactivity of the isocyanates enables rapid processing. However, isocyanates are toxic and can cause allergies or asthma. The European Chemicals Agency (ECHA) has therefore imposed a restriction: since 2023, only specially trained personnel may work with formulations containing more than 0.1 percent isocyanate. This has prompted us to develop a synthesis that does not use toxic isocyanates.
Another driving factor was the fact that conventional polyurethanes use fossil fuels such as petroleum or natural gas as a carbon source. We, instead, are focusing on a sustainable alternative by incorporating carbon dioxide and polyurethane recyclates into polyurethanes. To do this, carbon dioxide is concentrated as much as possible and obtained at a high level of purity right where it is produced, for example in power plants, before it enters the atmosphere. By specifically incorporating carbon dioxide into material structures, we not only reduce climate-damaging emissions, we also actively contribute to the carbon cycle economy. NIPUs can therefore also offer long-term ecological benefits – an approach that we believe has considerable potential.
2. What successes or insights from your work to date make you particularly optimistic? What exciting challenges are on the horizon?
One significant milestone was when we realized that our isocyanate-free polyurethane materials are just as versatile as conventional polyurethanes and therefore represent a genuine alternative. We have also shown that NIPUs can be produced in a similar way to classic polycondensation processes, e.g., PET processes – even on a pilot plant scale. This suggests that NIPUs can also be produced on an industrial scale. The processing properties are also very similar to classic thermoplastic polyurethanes, which allows for easy integration into existing manufacturing processes. In addition, life cycle analyses and toxicity studies show that NIPUs have advantages in terms of sustainability and can be certified as biocompatible.
We are also proud of our success in using carbon dioxide as a raw material for NIPUs and in developing chemical recycling processes. This ensures the recyclability of these materials, thereby contributing to a reduction in fossil raw materials and a more sustainable use of resources.
A key challenge with NIPUs is developing reactive formulations for applications such as foams, coatings, and adhesives. These require specific reactivity profiles in order to achieve processing properties and performance characteristics that are comparable to conventional polyurethanes. We have also developed innovative solutions for this and now have a solid knowledge base for developing customized NIPU types. This is very valuable because it will enable us to replace conventional thermoplastic polyurethanes in many areas of application in the future, as well as to open up completely new applications, such as resorbable NIPU fibers for medical applications.
3. Where could your research have a concrete impact in the future?
In principle, NIPUs can be used as a sustainable alternative wherever conventional thermoplastic polyurethanes are used. Not only do they offer the advantage of isocyanate-free production, they can also be processed more energy efficiently through extrusion at lower temperatures, for example. This not only reduces energy consumption but also opens up new processing options, especially in temperature-critical applications.
NIPUs are particularly useful in sensitive areas such as medical technology. Their uniform processability and high batch consistency ensure reliable material properties – a decisive advantage as they exhibit less cross-linking, and no gel particles compared to classic thermoplastic polyurethanes. This can significantly improve the manufacture of high-precision medical products such as flexible implants and biocompatible tubing materials, or even the aforementioned resorbable fibers.
In addition, NIPUs have great potential for use in other applications, for example in the automotive industry, where they can contribute to the development of lighter, more durable, and environmentally friendly materials. They could also play a role in the field of sustainable packaging and functional materials by enabling new material solutions that are both high-performance and recyclable.
4. In closing, do you have any insights, thoughts, or perspectives that you would like to share with the professional community or the public?
Our research on NIPUs is ongoing and we are developing them specifically for new applications. At the same time, we are always on the lookout for new innovative applications and new cooperation partners to further exploit the potential of these sustainable materials.
We are convinced that isocyanate-free polyurethanes are a promising alternative to traditional polyurethane materials and can contribute to a more environmentally friendly and safer future in many areas. We therefore cordially invite experts to exchange ideas with us and to jointly develop sustainable material solutions. Only through interdisciplinary cooperation and open dialogue can innovative technologies be successfully put into practice.
Fraunhofer Institute for 