In 50 mol% and 75 mol% PBd22-PEO14 / POPC hybrid vesicles, two thickness populations were found using cryo-ET: vesicles could be categorised by a visibly thick or thin membrane and homogeneity within these populations were confirmed using an automated analysis. SAXS confirms that the hybrid PBd22-PEO14 samples comprise two populations: a thin membrane with an electron density profile similar to a lipid bilayer and a thick membrane with an electron density profile similar to a pure polymer membrane. An FFT of the cryo-ET images also confirmed the peak positions found in the SAXS electron density profile.