The presence of clusters of water in the DIPA-water mixture, indicated by the significant O-O coordination at low r in the MD ensembles (Figure ), supports the idea that nanoscale regions of water exist within the amine-water matrix, presumably in the form of reverse micelle-like structures. Several other MD studies have predicted a similar nano-phase separation tendency in amine-water mixtures. To look for direct experimental evidence for these inverse micelle-like structures, we carried out smallangle x-ray scattering (SAXS), a technique that is able to give information on structures between roughly 1 nm and 100 nm in size. Pure liquids are homogeneous down to the nanometer scale and, hence, do not exhibit a SAXS signal. Indeed, the SAXS signals of pure DIPA and pure water (Figure , xA = 1.0 and 0.0, respectively) have no intensity in the low-Q region. The only features of note in the scattering signal of the pure liquids are peaks at around 1 Å -1 for pure DIPA and 2 Å -1 for pure water, which are the beginning of the wide angle x-ray scattering structure function and encode information about the intermolecular distances. However, DIPA-water mixtures with intermediate compositions, measured in the monophasic region (Figure , xA = 0.5, 0.4, 0.3, 0.2, and 0.1, T = 26 °C) yield discernable low-Q SAXS features whose prominence grows with increasing water concentration. Water-lean DIPA-water mixtures, on the other hand, show no discernable low-Q scattering (e.g., xA = 0.77, Figure ) indicating mixture homogeneity. The SAXS measurements were all taken with the system in the monophasic region (compositions and temperatures shown in Figure ), so macroscopic phase separation is not a complicating factor. Considering the earlier PDF and MD results, we can hypothesize that this SAXS signal is caused by water segregating into the reverse micelles, and these are embedded within a larger, continuous solvent-rich phase.