The ability to utilize cheaper starting materials in the synthesis of commercially
important materials has been a goal of scientists since the advent of the chemical
industry. The ideal situation would be one in which by combining the correct
proportions of hydrogen, nitrogen, carbon and oxygen that virtually anything from
simple sugars to complex polymers could be produced. Unfortunately, such processes
are flights of fancy often reserved for movies and television shows. On a more realistic
level, the utilization of simple molecules and a transition metal catalyst has been a
process that industry has exploited for many years. The most easily identifiable process
is that for polyolefin production, that employs homopolymerization of simple monomers
such as ethylene and catalysts ranging from Ziegler-Natta to metallocene type catalysts.
On a more difficult level copolymerization reactions require a delicate balance between
two competing reactions and as a result these reactions have been much less successful.
For over a decade now the Darensbourg Research Laboratories have focused on
utilizing another simple molecule: carbon dioxide. Carbon dioxide is a cheap, inert,
nontoxic starting material that appears to be an ideal monomer. Although simplistic,
CO2 is also very stable and its utilization in polymerization reactions have proven to be
quite complex. In order for us to facilitate these reactions we employ both a transition
metal catalyst and a comonomer. Epoxides act as an effective comonomer because the
thermodynamic energy gained from breaking the strained three membered epoxide ring
overcomes the stability of CO2 and allows the copolymerization reaction to occur. We
have demonstrated a great deal of success with this process, most of which will be
mentioned throughout this report. The majority of this dissertation will detail our use of
salen complexes to optimize this copolymerization process, in order to further the use of
CO2 as a viable source of C1 feedstock. Herein, I will illustrate how we have obtained
more than a 100 fold increase in the rate of polymer formation as well as detailed
mechanistic data that will provide a basis for future catalyst design studies.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/3849 |
| Date | 16 August 2006 |
| Creators | Mackiewicz, Ryan Michael |
| Contributors | Darensbourg, Donald |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | 2725696 bytes, electronic, application/pdf, born digital |
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