DuPont Co.'s powerful, new polymer catalyst system appears likely to drive formidable advances in polymers in the near future. Developed by Maurice S. Brookhart, professor of chemistry, and his associates, Lynda K. Johnson and Christopher M. Killian at the University of North Carolina in Chapel Hill, the catalyst system is based on the metals nickel and palladium. The system opens doors that may lead to new families of polymers.
The research was done in cooperation with DuPont, which has applied for a comprehensive patent on the technology, materials and applications.
On a practical basis, the technology may broaden applica-tions while also lowering prices for polymers that are fully recyclable. Also, the technology may produce new materials that would make some mechanical constructions, such as multilayer extrusions, obsolete because the performance of the new polymers would reproduce that of multilayer constructions.
As previously reported, Joseph A. Miller, DuPont's senior vice president for research and development, disclosed Jan. 26 that DuPont had applied for a patent for the technology.
Brookhart and Steven Ittel, research manager for polymer catalysis at DuPont, talked about the technology in telephone interviews Feb. 14.
The catalyst system can produce - at low temperatures and low pressures - polyolefin polymers with a definite polarity, Brookhart said. Temperatures for the reactions can be as low as room temperatures. Pressures can be from one atmosphere to 400 pounds per square inch, he said.
A defined polarity can make polyolefins compatible with other monomers, such as styrenics and acrylics, and can lead to combinations of monomers that were impossible to produce using previous technology.
Ittel said the technology seems to be applicable to the production of such products as DuPont's Surlyn and Nucrel copolymer products that combine ethylene with methylacrylate monomers, excepting that the new technology would make those products at lower temperatures and lower pressures.
Industry analysts and consultants said the scant information DuPont has released indicates the technology could be used to make new resin products from wild combinations of monomers - such as olefins with nylons -in a reactor. It also may be possible to make resins from monomer combinations that were studied and dismissed years ago, and at costs lower than currently available polymers, consultants said.
Ittel said DuPont initially may use the technology to produce within five to six years polymers for automotive surface coatings and very low density polyethylenes. The latter products, with densities as low as 0.85, could be used to modify automotive lubricants.
Ittel said DuPont hopes to license the technology to DuPont Dow Elastomers, a joint venture created in 1995 by DuPont and Dow Chemical Co. to make and market elastomers using Dow's metallocene catalyst technology. The new technology is not related to metallocene catalysts.
Brookhart said the technology could be used to make a variety of PEs, from the very low density PE mentioned by Ittel, to linear LDPE and high density PE products.
A synthetic-organo-metallic chemist, Brookhart said he could not discuss blends of polymers or their likely performance characteristics. However, he said the new catalysts are promising as tools for making new polymers because they perform well at low temperatures and low pressures.
The catalysts' performance is expected to improve at higher temperatures and pressures. The catalysts can produce types of PE that have more elaborate branches than LDPE, he said.
As a result of the complex branching and the polarity of the polymers, other monomers can be incorporated into resins made with the catalyst system.