Referring to the above mentioned, predominantly applied FeCl3-catalyzed HCP-synthesis, which involves the addition of an aromatic co-monomer beside the phosphine building blocks, we examined the individual reactivities of the monomeric units benzene and PPh3 under the respective crosslinking conditions. For comparison, triphenylamine (NPh3) was additionally applied as monomer, owing to its close chemical similarities with PPh3 (Scheme 1). According to previous works, benzene (I) and NPh3 (II) own an appropriate nucleophilicity for the FeCl3-catalyzed crosslinking alkylation with FDA, resulting in solids, which are insoluble in water and organic solvents. Scheme 1: Reactivity of aromatic building blocks in the HCP-synthesis.