Jane E. G. Lipson
Albert W. Smith Professor of Chemistry
Professor Lipson received her B.Sc. (1978), M.Sc. (1980), and Ph.D. (1984) from the University of Toronto. Her graduate work focused on the physical chemistry of polymers, and she continued working in this area as a NATO Science Fellow with Professor W.H. Stockmayer at Dartmouth College. In 1986 she accepted an appointment as an Assistant Professor at the University of Guelph, but returned to Dartmouth the following year as a Visiting Assistant Professor. In 1990 she joined the faculty as an Assistant Professor and became an Associate Professor in 1994 and a Professor in 1999.
Research Interests
Much of the chemical industry is focused on the formulation and application of polymers, and yet the connection between microscopic structure and bulk properties is still not well understood. This presents an opportunity, and in my research group we use theory and simulation to study the effect on thermodynamic properties of changing the chemical nature of a component, as well as such variables as molecular weight, temperature and pressure. We are primarily interested in polymer fluids, solutions, and mixtures, however, studies on small molecule systems can provide useful insights to the behaviour of more complex fluids.
We use the strategies of statistical mechanics in deriving thermodynamic descriptions of liquids and liquid mixtures. Theoretical and simulation studies on polymers often employ a so-called 'lattice' model. In such a description one imagines placing the molecules of interest on the sites of a lattice. A two-dimensional analogy might be to imagine placing the beads of a bead necklace on a series of contiguous checker-board spaces, as opposed to just tossing the necklace down on a tabletop and allowing any resulting arrangement. The latter picture would correspond to a 'continuum' type of description. Clearly there are local differences between lattice and continuum models, however, the effect of imposing an underlying lattice structure cannot easily be understood, since the two kinds of models usually differ in many of the approximations used for their respective derivations. We have derived lattice and continuum versions using the same theoretical methods. The lattice theory yields simple analytic expressions for thermodynamic quantities, and we have applied it to investigate a variety of polymer solutions and blends. The continuum theory yields results which must be obtained through numerical analysis, and has been applied to rather simpler systems. In addition to extending the applications of both lattice and continuum theories, an area of great interest is the comparison of results using the two analogous descriptions, as this provides a unique opportunity to assess the effects of imposing a lattice structure on our thermodynamic understanding of complex mixtures.
A snapshot of work currently going on includes: examining the effects of deuteration on miscibility; investigating the effects of short branches on the entropy and enthalpy of mixing for hydrocarbon mixtures (from alkanes to polyolefins); proposing alternatives to the Flory-Huggins chi parameter for characterization of blend behaviour; mapping from lattice to continuum in square-well mixtures; effects of local concentration and density fluctuations on miscible blend dynamics; modeling the glass transition of polymer-diluent mixtures.