University of Pittsburgh
May 16, 2000

ETHER-CARBONATES HOLD PROMISE AS "GREEN" SOLVENTS Pitt researchers believe entire class of inexpensive compounds possible

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PITTSBURGH, May 16 -- In a paper published in the May 11 issue of Nature, University of Pittsburgh researchers reveal that they have successfully developed a highly CO2-soluble (carbon dioxide-soluble) material that is much less expensive than previous versions. This new material could be used as building blocks for products such as CO2-soluble soaps, chelating (metal-binding) agents, and additives for enhanced oil recovery.

Further, they believe that the method they used to create the new poly(ether-carbonate) copolymers holds promise for creating similar compounds that will open the door for CO2 to be used in a variety of manufacturing processes.

"Carbon dioxide is considered an environmentally benign solvent, but it is also rather feeble," says Eric Beckman, professor of chemical engineering at Pitt. "In order to dissolve even small amounts of many compounds, such as metals and proteins, very high CO2 pressures are often needed, which makes CO2-based processing prohibitively expensive."

To capitalize on the potential of carbon dioxide as a solvent, many researchers turned to fluorocarbons, which, though highly CO2-soluble, are prohibitively expensive to use in industry if they cannot be recycled efficiently.

Using inexpensive propylene and CO2 as raw materials, Beckman and his colleagues synthesized a series of poly(ether-carbonate) copolymers, and showed that these materials will dissolve in CO2 at lower pressures than a poly(perfluoroether).

"Our design strategy is relatively straightforward," said Beckman. "To create a CO2-philic compound, we use two monomers, one that contributes high flexibility, the other with attributes that provide favorable points where interactions with CO2 might occur.

"Generation of CO2-philes from low cost raw materials opens the door to a variety of economically favorable CO2-based processes, particularly where recycle of the CO2-phile is difficult," said Beckman. "We suspect that the

ether-carbonate copolymers described here are but one example of a larger class of non-fluorous CO2-philes."