Figure shows the patterns of small-angle x-ray scattering (SAXS) from PPCx films at room temperature. The SAXS profile of PPC5 film at 25 o C shows multiple sharp peaks in the region of q = 0.05-0.40 Å -1 (Figure ). The scattering pattern most resembles that of multiple continuous cubic phases as revealed in the phase separation of BAB-type block copolymers. The SAXS profiles of both PPC10 and PPC15 films show three diffraction peaks at q = 0.15, 0.23 and 0.26 Å - 1 with a characteristic ratio of 1: √2: √3 (Figure & S15a), suggesting presence of body-centered cubic (BCC) phase separation. In contrast to PPC5, PPC10 and PPC15, the SAXS diffraction patterns of PPC25, PPC79, and PPC194 all appear similar to that of blank PCL. (Figure ) The disappearance of the diffraction peaks at q = 0.15, 0.23 and 0.26 Å -1 when x  25 suggests the domination of PCL phase and minimal phase separation between PPcy and PCL. These SAXS results suggest that shorter chain length of PCL leads to enhanced phase separation between PCL and PPcy in PPCx films.