Liquid worm-like and proto-micelles: Water solubilization in amphiphile-oil solutions

Noncovalent interactions determine the structure-property relationship of materials. Self-assembly originating from weak noncovalent interactions represents a broad variety of solution-based transformations spanning micellization and crystallization, which, nevertheless, conforms to neither colloid nor solution sciences. Here, we investigate the weak self-assembly in water-amphiphile-oil solutions to understand the connection between the amphiphilic molecular structure and water solubilization in oil. X-ray and neutron scattering, converged with large-scale atomistic molecular dynamics simulations, support the fact that the amphiphiles assemble into liquid worm-like micelles and loose inverted proto-micelles. The inverted proto-micelles are energetically ready to accommodate a higher amount of water. These structures arise from a balance of intermolecular interactions controlled by the amphiphile tail-group structures. Thus, by linking the aggregate morphology to the molecular structure, this work provides insights on the molecular design for control of water solubility and dispersion in oil.