A closer look at the molecular structures in the two systems reveals that, while C12EO10 micelles respect Tanford's general theory of micelle formation with a core radius roughly corresponding to the contour length of the hydrophobic moiety of the surfactant, in TX-100, the core region has a thickness roughly twice longer than expected (Figures 6; SI Figure ). This implies a more disordered packing of the hydrophobic groups, with complex multilayering, and some degree of mixing between core and shell moieties, already occurring in smaller-sized micelles. It should be kept in mind that polyethylene oxides (PEO) exhibit a amphilphilic character with good solubility in both aqueous solutions and a variety of organic solvents including aromates such as toluene. Thus some intermixing may not be surprising. Interestingly, regardless of the size and shape of the micelles, the local core radii maintain similar values (Figure ). This implies that the more complex structures, such as the multilayered or toroidal micelles, emerge by the necessity of accommodating the more voluminous and disordered polar tails and, at the same time, maintaining the local packing of the hydrophobic groups.