Comparison of the reflec on and SRS coefficient plots (Figure , le ) provides more detailed insight into phase separa on in the gel as a func on of film depth (nega ve x-posi on). In these plots, the reflec on intensity from exactly the same posi ons as the SRS drug, polymer and buffer coefficients are presented (grey line). The reflec on intensity distribu on evolves over me. The ini al onset of reflec on intensity increase appears in the gel phase at approximately -60 µm, -84 µm and -128 µm at 1, 2 and 5 min, respec vely (Figure ). The increased reflec on intensi es appear as a 'wave' that gradually progresses deeper into the gel-phase of the film, and represent the first sign of nano-(and then micro-) phase separa on. This phase separa on front trails the water-front (glass-gel interface) by about 27 µm and 37 µm, at 1 and 2 min respec vely. The elevated reflec on signal appears earlier (deeper) in the gel phase than any chemically-specific SRS evidence of phase separa on. This is because elas c sca ering of light already occurs with nano-scale phase separa on below the applied sampling resolu on of the SRS microscope in this experiment (approximated as three mes the pixel size of 414 nm). Once the phase separa on domain size has increased and is clearly evident with SRS, the elas c reflec on signal intensity decreases. The minimum phase-separated domain size required to generate a detectable confocal reflec on signal is not defined, but is likely on the order of tens of nanometers. As such, correla ve nonchemically specific confocal reflec on highly complements the chemically-specific SRS for in situ imaging of water-induced phase separa on in ASD films. In the Suppor ng Informa on (Figure ), a graphical representa on of the evolu on of three phenomena discussed above, namely the water penetra on front (glass-gel interface, detected with SRS), phase separa on front (detected with confocal reflec on imaging), and matrix swelling (matrix-dissolu on medium interface, detected with SRS), is presented (for the 20% drug loading, as well as higher drug loadings (vida infra)).