Smart, responsive polyelectrolyte materials

Weak Polyelectrolyte Phases
An illustration of the inherent tug of war between solvophobic (self-association) interactions, charge coupling strength, and pH in determining the swelling behavior of an isolated weak polyelectrolyte.

Polyelectrolyte materials, both natural and man-made, have a wide variety of applications. Within the Whitmer Group, we are interested in elucidating important phase transitions, instabilities and responses of polyelectrolytes and their complexes.

A topic of particular interest is the use of oligomers and polymers within charge-sensitive separation membranes. Our work has demonstrated through a minimal thermodynamic model that a host of effects, including molecular size, pH responsiveness, and competetive ion rejection may be engineered into these materials through predictive simulations.

Additionally, our group is interested in the fascinating interplay of charge, topology, and adhesive interactions which arise in complex coacervate materials. These materials occur in systems of oppositely charged macromolecules, and are intimately related to the phenomenon of layer-by-layer deposition. We are currently developing minimal models to test the limits of available theories of polyelectrolyte, and to understand the microstructure, including salt and small-molecule partitioning effects, within these phases.

Related Publications:

[1] Jian Qin, Dimitrios Priftis, Robert Farina, Sarah L. Perry, Lorraine Leon, Jonathan Whitmer, Kyle Hoffmann, Matthew Tirrell, and Juan J. de Pablo. "Interfacial tension of polyelectrolyte complex coacervate phases." ACS Macro Letters 3, 6 (2014): 565-568. Link
[2] Sarah L. Perry, Lorraine Leon, Kyle Q. Hoffmann, Matthew J. Kade, Dimitrios Priftis, Katie A. Black, Derek Wong, Ryan A. Klein, Charles F. Pierce III, Khatcher O. Margossian, Jonathan K. Whitmer, Jian Qin, Juan J. de Pablo and Matthew Tirrell. "Chirality-selected phase behaviour in ionic polypeptide complexes." Nature Communications 6 (2015): 6052. Link
[3] Vikramjit Singh Rathee, Siyi Qu, William A. Phillip, and Jonathan K. Whitmer. "A coarse-grained thermodynamic model for the predictive engineering of valence-selective membranes." Molecular Systems Design & Engineering 1, 3 (2016): 301-312. Link
[4] Vikramjit Singh Rathee, Aristotle J. Zervoudakis, Hythem Sidky, Benjamin J. Sikora and Jonathan K. Whitmer. "Weak Polyelectrolyte Complexation Driven by Associative Charging." Submitted, (2017).
[5] Vikramjit Singh Rathee, Benjamin J. Sikora, Hythem Sidky and Jonathan K. Whitmer. "Simulating the Thermodynamics of Charging in Weak Polyelectrolytes. The Debye-Hückel limit." In Preparation, (2017)