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

Micelles are key to applications from drug delivery to commercial paints. Their nanostructure and dynamics are of critical importance to their macroscopic properties and functions, but are difficult to measure. Here we demonstrate a novel technique capable of such measurements based on Resonant Soft X-ray Scattering (RSoXS), which is uniquely capable of probing organic materials using their intrinsic chemical bonds rather than laborious and potentially disruptive labeling. Our customized nanofluidic cell enables RSoXS to be performed in liquid environments, allowing structure and dynamics to be measured in-situ for the intended application. We first apply the technique to a model system, Pluronic F127 micelles. Resonant energy contrast tuning allows the internal structure and composition to be measured quantitatively. We further investigate a novel amphiphilic statistical copolymer, “polysoap”, designed for oil spill remediation. Dynamic dual flow reveals an unexpected concentration dependence of the corona, which was not observed with traditional visible light scattering. We further show that despite aggregation, the unimeric core structure is retained, crucial for its application.