The false color images in Figure also show that the water-induced surface-directed phase separa on of drug and polymer (and water) within the ASD does not develop in a uniform manner parallel to the original film-buffer. This suggests the process is highly sensi ve to experimental condi ons, and presumably is also par ally stochas c in nature. Nevertheless, the observa ons are consistent with the phenomenon of surface directed spinodal-decomposi on, first experimentally reported by Jones et al (1991) for unstable polymer blends in which one of the components has a preferen al a rac on to the surface. They observed composi on wave vectors normal to and propaga ng inwards from the interface, maintaining coherence for several wavelengths.