The Technical University of Berlin has developed a new catalytic process for the complete decomposition of silicone waste.
Everyday things like the silicone spatula in your mixing bowl, the leak-proof cap in your travel mug, and the soft pacifier that keeps a toddler calm all have a hidden downside. All are immortal.
Silicones resist heat, water and chemical degradation. Therefore, throwing away the waste usually means sending it to a landfill or an incinerator. Until now, closed-loop recycling has been a difficult task from a chemical perspective. TU Berlin says it has found a way forward after years of research.
Under the direction of Professor Dr. Martin Oestreich’s team developed a catalytic process that breaks down silicon-oxygen polymers back into their original, high-quality building block: dimethyldichlorosilane.
The study describes a strategy that enables up to 99% recovery rates for common items such as muffin tins and baby bottles.
“Our success is proof that basic research can ultimately pay off in very specific applications that no one had thought of before,” said Oestreich. “We have been researching silylium ions for 15 years, and only in the last five years have we suddenly identified the recycling of silicones as a key application for this research.”
Break the bad silicone
The discovery simply solves a difficult chemical problem.
To make fresh silicone from scratch, manufacturers first extract raw silicon from quartz sand in electric arc furnaces fired at extreme temperatures. It is a massive, energy-intensive undertaking. Once formed, the resulting silicon-oxygen bonds behave like molecular superglue. Breaking them requires immense energy or unprecedented catalytic precision.
Oestreich’s team studied silylium ions (positively charged silicon ions) for 15 years before realizing the hidden potential for waste management.
According to the study paper, a new silylium ion-initiated depolymerization strategy was developed to enable the sustainable closed-loop recycling of chemically inert silicone materials (siloxane).
When combined with triphosgene—a handy solid-state reagent—the silylium ion removes a chloride ion and creates a hyperreactive species known as chlorocarbonyl cation (COCl+). These molecular scissors cut the silicon-oxygen chain.
When the bonds break, the oxygen escapes cleanly into the air as carbon dioxide gas (CO2), preventing the reaction from reversing. The entire sequence runs at a gentle 80°C and requires negligible energy compared to primary production.
Growing silicone waste crisis
Tests on items such as cupcake pans and lids proved promising. Under moderate conditions at 80 °C (176 °F), the low-energy process was able to recover up to 99 percent dimethyldichlorosilane from individual items within 24 hours. Even when the method was applied to a mixed batch of different silicone waste, a recovery rate of 86 percent could be achieved.
The market for silicone products is continuously growing. In 2025, it was around $19.55 billion and is expected to reach $37.70 billion or more by 2035.
Common recycling methods use mechanical processing or chemical breakdown into small, ring-shaped siloxanes. Although these recycled compounds can create new silicone products, the resulting materials are typically of lower quality than virgin silicone.
The newly detailed process enables the recycling of silicone waste, turning non-recyclable plastic-like materials back into useful industrial ingredients.
After a patent has already been filed, researchers turn their attention to commercial scaling. And currently looking for non-toxic phosgene alternatives and developing purification steps to remove trace contaminants.
The study results were published in the specialist journal Nature on October 28th.
