Computational Quantum Chemistry, Polymer Chemistry Dr Michelle Coote

 

We use computer calculations to determine the structure of molecules and to help understand how molecules react with one another. Using the laws of quantum mechanics, we can calculate from first principles the structures of molecules, their vibrational frequencies and their energies. This provides detailed information on the mechanisms of reactions, as well as calculations of their kinetics and thermodynamics.

Much of this information is very difficult to obtain experimentally, particularly for very reactive or hazardous compounds. Quantum chemistry provides a viable alternative approach for studying these compounds.

We use this technique to solve a range of problems in chemistry, especially for improving the synthesis of polymers.

 

Current research activities

Computational Polymer Chemistry

Free-radical polymerization is an important industrial process, used to prepare a wide range of polymers. The properties of the resulting polymer depend on the rates of the competing reactions within this complex multi-step process, and information on their mechanism and kinetics can assist in the design of better polymers. Unfortunately such information is difficult to obtain via experiment without recourse to model-based assumptions. To address this problem, our group has been attempting to adapt quantum chemistry for the study of radical polymerization processes. We've recently demonstrated that "chemical accuracy" is possible, and have used our methodology to solve practical problems in the polymer field. We have provided evidence for long-lived radicals in the RAFT polymerization process, helped an experimental group to identify the mechanisms for structural defect formation in PVC and designed (entirely by computer) an improved agent for controlling free-radical polymerization and a new method for incorporating phosphorus into the backbones of ordinary polyolefins. We are also working toward the design of stereoregular polyphosphines via the ring-opening polymerization of small phosphorus heterocycles.

Radical Chemistry

Free radicals are not only important in polymer chemistry, but also in such diverse applications as organic synthesis, atmospheric chemistry, and biochemistry. We have been investigating fundamental aspects of radical reactivity, such as what causes the differences in behaviour when radicals add to different types of double and triple bonds, what governs reactivity in hydrogen abstraction reactions, and how substituents influence the stability of different types of radicals. We then use this information to solve practical problems in chemical and biochemical systems.

Annual Research Report   (PDF format)

 

Group members

Academic Staff:
Dr Michelle Coote (Leader)   |   Dr Ching Yeh (Leaf) Lin   |   Dr Mansoor Namazian

PhD Students:
David Brittain   |   Junming Ho   |   Jennifer Hodgson

 

Key publications

1. Izgorodina EI, Lin CY, Coote ML "Energy-directed tree search: an efficient systematic algorithm for finding the lowest energy conformation of molecules." Phys. Chem. Chem. Phys. (2007), 9(20), 2507-2516. http://dx.doi.org/10.1039/b700938k
2. Coote M L, Krenske E H, Izgorodina E I "Computational Studies of RAFT Polymerization-Mechanistic Insights and Practical Applications." Macromol. Rapid. Comm. (2006), 27(7),473-497. http://dx.doi.org/10.1002/marc.200500832
3. Ah Toy A, Chaffey-Millar H, Davis T P, Stenzel M H, Izgorodina E I, Coote M L, Barner-Kowollik C "Thioketone spin traps as mediating agents for free radical polymerization processes." Chem. Commun. (2006), (8), 835-837.http://dx.doi.org/10.1039/b515561d
4. Izgorodina E I, Coote M L "Accurate ab initio prediction of propagation rate coefficients in free-radical polymerisation: acrylonitrile and vinyl chloride." Chem. Phys. (2006), 324(1), 96-110. http://dx.doi.org/10.1016/j.chemphys.2005.09.042
5. Hodgson, J.L., Coote, M.L. "Propagation mechanisms in ring-opening polymerization of small phosphorus heterocycles: toward free-radical polymerization of phosphines?" Macromolecules (2005), 38(21), 8902-8910. http://dx.doi.org/10.1021/ma051691s

>>more publications

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Michelle Coote has been at the Research School of Chemistry since 2001, and is a member of the ARC Centre of Excellence in Free Radical Chemistry and Biotechnology. She is a graduate of the University of New South Wales, where she completed a B.Sc. (Hons) in industrial chemistry (1991-1995), followed by a Ph.D. in polymer chemistry (1996-2000) under the supervision of Prof. Tom Davis. She has published extensively in the fields of free-radical polymerization kinetics, radical chemistry and computational quantum chemistry. She was awarded the IUPAC prize for young scientists in 2001, the RACI Cornforth medal in 2000 and the RACI Rennie Medal in 2006.

group photos

Dr M L Coote Research School of Chemistry, Building 35 Australian National University Canberra ACT 0200 AUSTRALIA Ph: +61 2 6125 3771 Fx: +61 2 6125 0750 E-mail: mcoote@rsc.anu.edu.au