Researchers at TU Berlin Develop Breakthrough in Silicone Recycling
Scientists at the Institute of Chemistry at TU Berlin have developed a method to break down silicone polymers into their base molecule, dimethyldichlorosilane. The process, which has been submitted for a patent, enables the reuse of recycled silicone in new product manufacturing. The research, published in Nature, addresses a long-standing challenge in green chemistry due to silicone’s exceptional thermal and chemical stability, which previously made recycling difficult.
Why This Matters for Green Chemistry and the Circular Economy
The global silicone market, valued at over 21 billion euros in 2025, is projected to surpass 33 billion euros by 2033. Silicones are widely used in medical devices, consumer goods, and industrial applications due to their durability and water-repelling properties. However, their energy-intensive production—requiring silicon extraction from quartz at 2,000°C—has made recycling a critical goal. “Due to its robust properties, recycling used silicone is very difficult,” said Prof. Dr. Martin Oestreich, head of the “Organic Chemistry/Synthesis and Catalysis” department at TU Berlin.
How the Process Works: Silylium Ions and Phosgene
The breakthrough hinges on a chemical process using a silylium ion as a catalyst and phosgene, a toxic gas. The silylium ion facilitates the breakdown of silicon-oxygen bonds, while phosgene enables the release of oxygen as carbon dioxide. To mitigate safety concerns, researchers used triphosgene, a solid form that releases phosgene during the reaction.
Testing on Everyday Products Yields High Results
The team tested the process on common silicone items, including baking pans, baby bottle nipples, and silicone lids. Results showed a 99% recovery rate of dimethyldichlorosilane from individual products and 86% from mixed waste. The reaction operates at 80°C, allowing the process to be carried out without significant energy consumption. Oestreich has led research on silylium ions for 15 years.
Researchers Seek Ways to Purify Recovered Dimethyldichlorosilane
While the process eliminates the need for high-temperature extraction, phosgene’s toxicity remains a hurdle. Researchers are exploring alternatives and methods to purify recovered dimethyldichlorosilane from residual phosgene. “Our success is proof that basic research can eventually pay off in very concrete applications that no one had thought of before,” Oestreich noted.
What Is the Significance of Recovering Dimethyldichlorosilane?
What is the significance of recovering dimethyldichlorosilane?
Dimethyldichlorosilane is the fundamental building block for silicone production. Recovering it allows for the creation of new silicones without relying on raw materials like quartz sand, reducing energy use and environmental impact.
Why is phosgene used despite its toxicity?
Phosgene is a critical reagent in chemical synthesis, including the production of polyurethanes. While toxic, it is widely used in industry. Researchers replaced direct phosgene use with triphosgene, a safer solid derivative, to mitigate risks.
How does this process compare to existing recycling methods?
Traditional methods often produce lower-quality silicones by breaking polymers into ring-shaped siloxanes. The new method fully degrades polymer chains, enabling the creation of silicones with different properties.
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