265360 Perfect Mixing of Immiscible Macromolecules At Fluid Interfaces

Wednesday, October 31, 2012: 3:15 PM
Butler West (Westin )
Jing Zhou1, Jamie Boyce1, Krzysztof Matyjaszewski2, Michael Rubinstein1 and Sergei Sheiko1, (1)Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, (2)Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA

Mixing of chemically different substances is an emblematic problem confronted by the health care, nutrition, and materials industries. This problem becomes particularly challenging when mixing large species, such as macromolecules and colloidal particles that exhibit particularly low increase of specific translational entropy upon mixing - the main driving force of mixing. One of the strategies for enhancement of mixing propensity is to modify the interaction energy by introducing a net attraction between chemically dissimilar molecules. The implications of this strategy can be observed in many natural systems, e.g., salts, stereoregular polymers, and lock-and-key assemblies. In all these systems, the mixing largely relies on a specific nature of chemical structures and/or physical shapes of objects being mixed. We propose a different strategy which requires neither chemical nor shape complementarity. The “perfect” mixing (intercalation) is achieved at fluid interfaces due to steric repulsion between brush-like macromolecules. The net repulsion is caused by the decrease of conformational entropy of polymeric branches in densely packed monolayers, which effectively creates evenly spaced potential wells attracting species of various chemistries and shapes. This strategy was successfully applied to mixing of polymer bottlebrushes, stars, and linear chains possessing hydrophilic, hydrophobic, and lypophobic chemical compositions. Interfacial mixing has vital implications in biological systems and also offers a new approach to surface patterning of thin films on sub-100 nm length scales.

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See more of this Session: Structure and Properties in Polymers II
See more of this Group/Topical: Materials Engineering and Sciences Division