Sometimes it seems as though the whole world is made of plastic: Whether it's the plastic bags we tote home from the supermarket, our plastic-encased computer monitors, or the acrylic nails we tap on our laminated card tables.
Experts at Carnegie Mellon University's Center for Macromolecular Engineering recently announced the discovery of an improved version of a process commonly used to make plastics, which they outline in the Oct. 17 issue of the Proceedings of the National Academy of Sciences.
The new method not only makes plastic manufacturing faster and less expensive, but could also help reduce the amount of industrial waste produced.
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"We have made this process at least 100 times more efficient and much more amenable to industrial processes," said Krzysztof Matyjaszewski, the lead author of the paper and director of the Center for Macromolecular Engineering, in a press statement.
About half of everyday plastics—including Styrofoam, Plexiglass, and the plastic used to make bags—is produced in a process known as radical polymerization, said James Spanswick, who is the associate director of the Carnegie Mellon center but was not involved in the research.
Radical polymerization is a process in which a polymer, a large molecule of repeating units, is created by adding one molecular subunit (or monomer) at a time to a growing chain. The researchers studied a slightly different version of this reaction—known as atom transfer radical polymerization—allows scientists precise control over the structure of the resulting polymer.
"Plastics can be designed to do a task in a more efficient way," Spanswick said, citing examples such as better flowing lubricants, easier-to-apply paints, and more stable chemical mixtures. "Because we can add a few monomers to a polymer chain at a time, we can add functionality to the polymer in a designed fashion."
In order to proceed, the polymerization requires the presence of a chemical catalyst, a substance that can speed up the rate of the reaction without being consumed by it.
Matyjaszewski and his research team found that by adding simple chemical additives, such as sugars and vitamin C, they could reduce the amount of a copper catalyst required by 500-fold. The reduction virtually eliminated the time-consuming and expensive task of removing excess catalyst in the product.
The benefits of reducing the amount of catalyst needed are varied: It minimizes the amount of toxic waste produced in the plastic-making process, lessening its impact on the environment. Additionally, it allows plastics to be used in medical implants without worries about copper levels adversely affecting body chemistry.
"This [new process] almost allows us," Spanswick said, "to design molecules for any application."