Fig. 1: Polycondensation mechanism and structure of RF-base resins.

a Polycondensation mechanism; b crosslinking structure; and c π-conjugated and π-stacked D–A architecture. In b, all aromatic units are substituted by linkers. The structure contains 136 carbons (6 × 16 aromatics + 40 linkers), and the linker/aromatic ring ratio (= 40/16) is 2.5.