As tomography has shown that there are two bilayer thickness populations in 50 and 75 mol% PBd22-PEO14 samples, the thickness might be related to the vesicle diameter (i.e., curvature), since 𝜅 ∝ 𝑑 2 , where 𝜅 is the membrane bending rigidity and 𝑑 is the membrane thickness. To test this, vesicle diameter measurements were taken for every vesicle across 5 tomograms (188 vesicles in 50 mol% PBd22-PEO14 and 117 vesicles in 75 mol% PBd22-PEO14) and categorised into thin or thick bilayer populations based on visual inspection.