Self-assembly of block copolymers is driven by the immiscibility of different blocks, which can be defined by the product of the Flory-Huggins interaction parameter (χ) and the degree of polymerization (N). The χ value between PS and P4VP at 25 ℃ is reported to be 0.56. Also, the microphase separation between P4VP and PLA has been reported previously. Figure shows the SAXS curves of synthesized SVA before and after selective etching with 2M NaOH solution (MeOH/water = 50:50 v/v).