The broad spectrum of applications for silicones ranges from medical implants and cosmetics to hydraulic oils and sealants to corrosion protection - an important topic in view of global corrosion damage to the tune of about US$ 3.3 trillion per year.

To optimize silicon-based synthetic materials for specific applications, made-to-measure chlorosilane building blocks are required in order to produce and crosslink the long-chain polymers. This influences, for example, the material's viscosity and flow properties. Completely new challenges are emerging in the area of 3D printing, with the aid of which products such as individualized running shoes can be manufactured.

Since 1940, the Muller-Rochow Direct Process has formed the backbone of the silicone industry. In this process, elementary silicon is converted with methyl chloride into methylchlorosilanes at high temperatures and pressures in the presence of a copper catalyst.

The working group led by Professor Matthias Wagner at the Institute of Inorganic and Analytical Chemistry of Goethe University Frankfurt has now developed a complementary process that has several advantages over the Direct Process: It uses hexachlorodisilane and chlorinated hydrocarbons as starting materials.

"Hexachlorodisilane is already mass-produced for the semiconductor industry and the perchlorethylene (PER) we use particularly frequently is a non-flammable liquid which is so inexpensive that it's used worldwide as a solvent for dry cleaning," says Matthias Wagner.

In addition, the process runs at room temperature and under normal pressure. To activate it, just a small concentration of chloride ions is needed in place of a catalyst.

"Our process produces highly functionalized organochlorosilanes that are ideal crosslinkers. In addition, their special structure offers excellent possibilities to adjust the mechanical flexibility of the silicon chains as desired," explains co-inventor Isabelle Georg, whose doctoral dissertation is being sponsored by the Evonik Foundation. Julian Teichmann was also involved in the project.

He confirms that above all the close collaboration between Goethe University and Evonik had a tremendous influence on his training: "Regular discussion of our results with Evonik's industrial chemists opened my eyes from the beginning to economic constraints and ecological requirements. It was fascinating to follow the path from our discoveries in the lab via the patenting procedures to realization on a technical scale in practice."

The chemists in Frankfurt believe that their monomers' special potential lies in the fact that they contain not only silicon-chlorine bonds but also carbon-carbon multiple bonds. The purpose of the former is to construct the inorganic silicon-oxygen chains; the latter can be linked to form organic polymers. This unique combination permits new routes to inorganic-organic hybrid materials.

I. Georg et al: Exhaustively Trichlorosilylated C1 and C2 Building Blocks: Beyond the Muller-Rochow Direct Process, in: J. Am. Chem. Soc. 2018, DOI: 10.1021/jacs.8b05950

Related Links
Goethe University Frankfurt
Space Technology News - Applications and Research

Tweet

Thanks for being here; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor $5 Billed Once credit card or paypal		SpaceDaily Monthly Supporter $5 Billed Monthly paypal only

Root vegetables to help make new buildings stronger, greener
Washington (UPI) Jul 27, 2018
In effort to make new construction greener and stronger, engineers and material scientists are turning to beets and carrots. Researchers have combined Portland cement with nanoplatelets extracted from root vegetable fibers to produce a stronger, more eco-friendly building material. "The composites are not only superior to current cement products in terms of mechanical and microstructure properties but also use smaller amounts of cement," lead researcher Mohamed Saafi from Lancaster University s ... read more