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Tarrytown Scientists Take Changes In Stride

by Michael McCoy
May 7, 2007 | A version of this story appeared in Volume 85, Issue 19

Silanes That Roll
The mercapto and blocked mercapto groups bind to the rubber in tires through different reaction mechanisms.

Leaving the safety of General Electric for the no-nonsense arms of a private equity owner is a significant change, but change is one thing that the chemists and chemical engineers at Momentive Performance Materials' Tarrytown, N.Y., technical center are used to.

After all, many of these men and women started their careers in the 1990s at Union Carbide. They stayed with the business when it was spun off as the independent company OSi Specialties, when it was acquired by what was then called Crompton, when it was sold to GE and folded into an existing silicones business, and now as it has been spun off again as a company called Momentive.

"We've been through seven names since 1993," say Kenrick M. Lewis, a research fellow at the Tarrytown labs. "But we have continued to be productive and innovative."

Lewis was part of a team of scientists who won the 1999 Kirkpatrick Chemical Engineering Achievement Award for a new methyl chloride-free route to the building block molecule trimethoxysilane that doesn't generate the by-product hydrochloric acid. Something of an elder statesman at the laboratories, Lewis says he and his colleagues are taking the latest ownership change in stride. He points out that customers knew them not as GE employees but as fellow scientists who help solve technical problems. That, he says, isn't going to change.

The Tarrytown lab mostly supports the former Union Carbide businesses, which make silicone fluids and surfactants rather than the better known silicone rubber, caulks, and sealants. The company's customers are in markets such as personal care, agriculture, urethane additives, and tires.

One breakthrough to come out of the Tarrytown laboratories is the NXT family of silanes, which are used in silica-containing tires.

Eric Pohl, a senior research scientist at Momentive, explains that tires have long contained carbon black as a reinforcing agent. About 10 years ago, companies such as Michelin began replacing the carbon black with silica to improve traction and raise fuel economy. The catch was that a coupling agent was needed to help the polar silica molecules disperse evenly and chemically bond to the rubber.

Initially, Pohl says, tire makers opted for a polysulfide silane that accomplished the coupling, but only after multiple mixing steps. His group developed a new generation of silanes that couples silica and rubber with only one mixing step and without releasing ethanol, an unwanted by-product. Wayne M. Hewett, Momentive's chief executive officer, told financial analysts recently that sales of NXT silanes have enjoyed 50% annual growth since their introduction in 2004.

A more recent breakthrough for which Hewett has high hopes is Silwet superspreaders, a family of silylated surfactants that reduce the surface tension of aqueous products such as spray-on crop protection formulas.

George Policello, a program leader who works in the Tarrytown facility's agrochemical applications lab, notes that farmers typically add a surfactant to their pesticide sprays to aid wetting and spreading on plant surfaces.

Trisiloxane alkoxylates perform this task much more effectively than standard nonionic surfactants, Policello says, but they are limited by a lack of stability in acidic or basic environments and thus have had to be added to pesticide spray tanks within 24 hours of application. The new superspreaders are stable from pH 2 to 12, he says, and can reduce water and pesticide use by up to 50%.

According to Policello, the Environmental Protection Agency was impressed enough by the new product to suggest that Momentive submit it for a Presidential Green Chemistry Challenge Award. The company also has been working with China's Ministry of Agriculture to make the product available in water-starved parts of that country.

Other potential applications for siloxane-based superspreaders are glass cleaners that prevent fogging and automatic dishwasher detergents that don't cause spotting.

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