Mixed Macromolecular Interfaces: Structure and Stability

Summary

Many everyday materials, such as paint formulations, biological cells, and foodstuffs, are macromolecular mixtures. These mixtures often show phase separation due to incompatibilities between the different macromolecules. An important feature of these aqueous mixtures is the presence of charges, which may promote, hinder or altogether change phase separation in ways that remain poorly understood. While in current applications phase separation is usually unwanted, actually utilizing it will enable new applications. Entirely new paint formulations or next-generation oil-free mayonnaise could, for instance, be texturized using novel macromolecular emulsions. These would consist of droplets composed of predominantly macromolecule A in a continuous phase rich in macromolecule B, sharing water as solvent. The preparation of such emulsions requires understanding of both the bulk phase behavior and the interface of these charged macromolecular mixtures.

To understand the effects of charge on phase behavior, theoretical descriptions for charged macromolecular mixtures will be developed that incorporate the effects of ions, which are neglected in current theories for phase separation. In combination with experiments, this will provide a fundamental understanding of phase separation in charged macromolecular mixtures.

Macromolecular emulsions require stabilization of the interface to prevent droplet coalescence. The design of appropriate stabilizers would benefit from knowledge of the structure of the macromolecular interface that separates the two (bulk) phases. However, this knowledge is at present very limited and this is even more the case for charged mixtures. To facilitate the design of new stabilizers, the concentration profiles and width of the macromolecular interface will be measured using synchrotron X-ray reflectivity experiments, in addition to accurately determining the interfacial tension. This will represent significant advances in the state of the art of X-ray reflectivity, enabling structural characterization of other soft interfaces such as biological membranes.

Details

Project number

722.017.005

Main applicant

Dr. M. Vis

Affiliated with

Technische Universiteit Eindhoven, Faculteit Biomedische Technologie, Institute for Complex Molecular Systems (ICMS)

Duration

01/01/2018 to 01/01/2021