Since phase separa on in both liquid and gel phases has been extensively studied with various light sca ering techniques, such as dynamic light sca ering , we further characterized the phase behavior in the gel phase of the film, as well as the dissolu on medium, by employing correla ve confocal reflec on imaging with a 640 nm laser. While more advanced light sca ering techniques can provide more comprehensive informa on, such as par cle size on the nano-to micro-scale and density , the confocal reflec on imaging provides a simple approach to visualize the onset and propaga on of phase separa on (without chemical specificity) beyond the resolu on limit of the chemically-specific SRS imaging. The resul ng correla ve reflec on images are presented in greyscale in Figure (far right column, represen ng exactly the same sample area as the false-color SRS images). Prior to buffer exposure, there is no significant reflec on signal from the film (except for at the edge of the film), consistent with a singlephase film (outside the film area, the reflec on signal from the glass/air interface disappears once the buffer is added). From 1 min onwards, the films exhibit a reflec on response visible as grey/white regions in the grey-scale images in Figure (right), indica ve of nano-and micro-scale phase separa on.