The diffusion coefficients of R6G through the BBOA phases were measured using rectangular fluorescence recovery after photobleaching (rFRAP) . First, a phase-separated BBOA film (∼30 µm thick) containing trace amounts of R6G dye deposited on a glass slide was imaged using a confocal laser scanning fluorescence microscope, and regions of interest containing either the hydrophilic or hydrophobic phase were selected. Following a period of photobleaching of a central rectangular region with the scanning laser, images were taken periodically to track the fluorescence recovery in the bleached region, and from the recovery time, the diffusion coefficient of the R6G was determined. An example of a typical rFRAP experiment is provided in the supplementary material (Fig. ).