Collaborative Research: Sequence-Driven Assembly in Polyelectrolyte/Surfactant Complex Coacervates

Non-technical Abstract Molecules can arrange to form larger structures, a process that is key to both complex living tissues and new, advanced materials. For example, scientists have long studied how specific sequences of amino acids fold to create proteins that act as tiny machines. Similarly, surfactants (e.g., the molecules in soap) can assemble into spheres, layers, and tubes. In both cases, the assembled structure is important for their practical use. For example, long, tube-shaped surfactant structures help to thicken shampoos while also cleaning hair. However, the ability to form this tube-like structure is usually related to shape of the surfactant molecule itself. This project seeks to learn from the ways in which long, charged molecules with protein-like sequences attract oppositely-charged surfactants, and form materials with desired structures. This effort uses both experiments and computation and will benefit society and the U.S. by establishing a versatile class of biology-inspired materials for use across chemical, agricultural, and industrial applications. The research will also involve the interdisciplinary training of researchers with broad expertise in chemistry, engineering, and physics, via both student mentorship and engagement with K-12 students. Technical Abstract This project will establish how sequence-controlled polymers can be used for the rational design of surfactant-containing materials. This effort will leverage sequence-defined polypeptides to modulate the assembly of surfactants into a variety of different nano-scale structures. The resulting materials will be evaluated by optical and electron microscopy, as well as scattering and rheological methods, to determine the relationship between polypeptide sequence and assembled structure. These experimental aspects will be integrated with a modeling effort that connects molecular simulation, colloid science, and polymer field theory to obtain predictions of assembly in polyelectrolyte-surfactant complexes. The overarching goal is to establish a fundamental understanding of how sequenced polypeptides can be used to manipulate the nano-scale structure of bioinspired surfactant-based assemblies. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.