Green Solvent Enhancement
Liquid and superficial carbon
dioxide have attracted a great deal of interest as environmentally
benign solvents, but their practical use has been limited by the
need for high CO2 pressures to dissolve even small
amounts of polar, amphiphilic, organometallic, or high-molecular-mass
compounds. So called "CO2-philes" efficiently transport
insoluble or poorly soluble materials into CO2 solvent,
resulting in the development of a broad range of CO2-based
processes. But as the most effective CO2-philes are
expensive fluorocarbons, such as poly (perfluoroether), the commercialization
of otherwise promising CO2-based processes has been
met with only limited success.
Dr. Beckman at work in his lab
Dr. Beckman
and his research personnel have shown that copolymers can
act as efficient, non-fluorous CO2- philes if their
constituent monomers are chosen to optimize the balance between
the enthalpy and entropy of solute-copolymer and copolymer-
copolymer interactions. Guided by heuristic rules regarding
these interactions, researchers have used inexpensive propylene
and CO2 to synthesize a series of poly(ether-carbonate)
copolymers that readily dissolve in CO2 at low
pressures. To summarize the importance of his research, Dr.
Beckman explained, "we expect that our design principles can
be used to create a wide range if non-fluorous CO2-philes
from low-cost raw materials, thus rendering a variety of CO2-based
processes economically favorable, particularly in cases where
recycling of CO2-philes is difficult."
