Glassiness and Miscibility in Polymers: Simple Models Applied to Complex Systems

In modeling the complex behaviour of polymers and their mixtures the
challenge is to include the minimum amount of local detail required for
increased understanding and credible predictions. We have developed a
number of simple approaches involving both analytic theory, as well as
simulation. In this talk I will focus on two major areas of research: The first
involves application of our Locally Correlated Lattice (LCL) theory to study
polymer solutions and blends1,2, with our most recent efforts leading to
connections between free volume, glassy behavior, local energetics, and
miscibility3. One strong feature of this approach is that pure component
analysis leads to transportable characteristic parameters. This means that a
bright line can be drawn between microscopic structure, theoretical
characterization, and macroscopic properties, thus providing a route for
blend and nanocomposite design. The second part of the talk will focus on a
simulation method that has allowed us to model the approach to glassiness in
bulk4 and thin film systems5, with the goal of understanding how interfaces
and additives affect physical behaviour. Our initial work has provided new
insight into how local changes in mobility lead to averaged behavior
observed experimentally. In addition, having established connections
between model and real systems for the cases of freestanding and supported
films, we are now in a position to consider extending the treatment to model
membranes, which will allow us to tackle issues of optimizing both barrier
and separation properties. In all parts of the talk there will be a strong
emphasis on connection with experiment.
1. Lipson, J.E.G.; White, R.P. J. Chem. Eng. Data 59, 3289 (2014).
2. White, R.P.; Lipson, J.E.G.; Higgins, J.S. Macromolecules 45 8861 (2012).
3. White, R.P.; Lipson, J.E.G. ACS Macro Letters 4, 588 (2015).
4. Tito, N.B.; Lipson, J.E.G.; Milner, S.T. Soft Matter 11, 3173 (2013).
5. DeFelice, J.; Milner, S.T.; Lipson, J.E.G. Macromolecules 49, 1822 (2016).