The colour maps overlaying the filtered images in Figure give the probability of the bilayer measurement corresponding to a thicker polymersome-like phase. Blue indicates 0% likelihood that the membrane is in the polymersome-like phase, while red indicates 100% likelihood that the membrane is in the polymersome-like phase. Our analysis occasionally assigns 'thickness' to one leaflet only, rather than across two leaflets (bilayer), yielding anomalous results with the wrong colour assignation. Values are discarded by visual inspection of the measurement lines of Cannyfiltered images, removing erroneous values. For all vesicles, the colour map shows that the membrane thickness is consistent throughout the vesicle, so the absence of different membrane thicknesses suggests POPC and PBd22PEO14 are homogenously distributed within the membrane of vesicles in both thin and thick membrane populations.