Using environmentally safe compounds such as sugars and vitamin C, Carnegie Mellon University chemists have improved a process for producing specialty plastics to make the technology more attractive to industrial manufacturers.
"I think this might be the critical hurdle that we had to get over to take this process from something actively examined with curiosity to something that really might make a difference," said James Spanswick, associate director of CMU's Center for Macromolecular Engineering.
A decade ago, the center's director and founder, Krzysztof Matyjaszewski, invented a polymer-making technique called atom transfer radical polymerization, or ATRP.
Polymers are long chemical chains made by linking smaller, repeating units. Until the discovery of ATRP, synthetic chemists had little say over the shape, size and composition of the polymers they created.
ATRP transformed polymer-making from a chaotic business into a controlled operation, giving scientists a way to engineer materials of desired length and pattern that otherwise would have been impossible to manufacture.
Industry experts anticipate a multibillion-dollar-a-year market for products created using this method, which has been licensed to several plastics and medical device companies.
But large-scale production of paint coatings, oil additives and other materials with ATRP has been limited because the process required using high concentrations of copper as a catalyst to speed up the reactions, Spanswick said.
The copper had to be removed from the finished products, a costly step requiring special equipment. It tinted the materials an undesirable dark green.
In a special issue of the Proceedings of the National Academy of Sciences that will be published next Tuesday, Matyjaszewski -- a CMU chemistry professor -- and his colleagues report that by adding chemical substances called reducing agents, they can cut the amount of copper catalyst needed for ATRP by a thousand-fold.
The reducing agents -- such as vitamin C or sugars -- keep the copper chemically active and forestall the need to add more catalyst.
Less copper needed to run the reaction means less leftover copper in the plastics made, which are clear instead of green and pure enough for most applications without removing the minuscule amounts of residual metal, Spanswick said.
Companies that were reluctant to use ATRP for large-scale plastics production are considering the technology, Spanswick said.
Alan Russell, director of the McGowan Institute of Regenerative Medicine, said the improvements to ATRP should make it more efficient for synthesizing materials in smaller quantities for biomedical applications.
"Anything that reduces the burden of purifying a material you produce and removing toxic by-products is a really significant advance," said Russell, who has collaborated with Matyjaszewski's research team for years. "It's a big stride forward."
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