Label-free characterization of aqueous micelle nanostructure and dynamics via in-situ RSoXS

Micelles are fundamental to nanocarrier applications from drug delivery to environmental remediation. Their structure and dynamics are of critical importance to their properties and functions but are challenging to measure. Here we demonstrate a novel technique capable of such measurements based on resonant soft X-ray scattering (RSoXS), which uniquely probes organic materials using their intrinsic chemical bonds rather than laborious and disruptive labeling techniques. Our customized microfluidic cell enables RSoXS to be performed in liquid environments, allowing structure and dynamics to be measured in-situ. We have applied this technique to investigate three different molecular weights of a novel amphiphilic statistical copolymer designed for oil spill remediation. By applying a time-resolved dynamic flow experiment, we are able to investigate beyond the large aggregates seen by light scattering and electron microscopy. We can show that the unimeric bridged-core structure is retained despite aggregation at increased concentrations, which is crucial for its application. Further, the only structural dependence of the micelle is due to the molecular weight of the polymer used. Both the core radius and corona thickness are persistent at all concentrations.