Biodegradable plastics have been around for a long time, but have so far only been of limited use for food. Researchers at the Fraunhofer Institute for Silicate Research in Würzburg want to change this with a new class of materials. Four questions to Sabine Amberg-Schwab, chemist and head of the Barrier and Multifunctional Coatings Department.

What is missing from biodegradable plastics so far to be used for food packaging?

Amberg-Schwab: Biopolymers do not provide adequate protection of the packaged foods against water vapour and oxygen, carbon dioxide and flavourings. Therefore, the required minimum durability cannot be guaranteed. We have therefore upgraded these bioplastics with special bio-based and biodegradable coatings and improved their properties. Sufficient protection against water vapour, gas ingress and undesirable transfer of the foreign matter to the contents of the packaging can now be achieved. After use, the coated film decomposes completely under the conditions of compost.

How did you get the biological coating?

Amberg-Schwab: The Fraunhofer Institute for Silicate Research in Würzburg has long been developing barrier coatings based on inorganic-organic hybrid polymers (ORMOCER). This class of materials offers good barrier properties against gases, moisture and aromas. The further development to bio-ORMOCERs takes place through the exchange of non-biodegradable organic components of fossil origin with biologically degradable components of biological origin.

How long will it take for cheese or chips to be sold in compostable packaging with the coatings you developed?

Amberg-Schwab: Conventional Plastic packaging based on fossil fuels is extremely inexpensive and optimized for the respective applications. Our new materials cannot yet compete in price. Nevertheless, I am optimistic: We have developed the basic material system, now we are looking for companies that will push the idea forward with us.

As part of the “Circular Materials Challenge”, where we won the “New Plastic Innovation Prize”, we are participating in a twelve-month accelerator program. This brings us into contact with companies that are also interested in the development of sustainable packaging materials. Our first new compostable coating materials are available for testing and further optimization.

Please be honest, would it not be most sensible not to use any packaging materials at all?

Amberg-Schwab: Right, we should try to avoid packaging in as many places as possible. But that won’t work across the board. For a real packaging revolution, we therefore need different models. This includes compostable packaging as well as recycling.