In addition to cryo-ET and SAXS analysis on all PBd22-PEO14 vesicle compositions, single particle analysis (SPA) was performed on 0%, 50% and 100 mol% PBd22-PEO14 sample to confirm the polymer membrane structure. Copper Quantifoil grids (400 mesh, 2 by 2 µm) were glow discharged for 33 seconds at 10 mA using a Cressington208 carbon coater. 0%, 50% and 100 mol% PBd22-PEO14 samples were then placed directly on the grid using a FEI Vitrobot mkIV using a blot time of 6 seconds and a blot force of 6 at 4 °C and 100% relative humidity. Samples were vitrified using liquid ethane and were stored in liquid nitrogen until imaged. Samples were visualised using a a FEI GII Titan Krios microscope equipped with a Falcon 4 DED and selectris energy filter. Automated single particle data collection was carried out using EPU software (Version 2.11.0). Micrographs were collected at 105k with a pixel size of 1.2 Angstroms. An exposure time of 4.16 seconds gave a dose of 9.31 electrons per pixel per second, generating a total dose of 27 electrons per Angstroms 2 over 1001 EER frames. Micrographs were motion corrected using RELIONs own implementation and CTF estimated using CTFFind 4.1.