Synthesis and solid‐state properties of comb‐like ionenes

A series of comb‐like ionenes with aliphatic side chains of different length and organic main chain spacer groups of different size have been synthesized by the step‐growth polymerization of long aliphatic chain‐substituted diamines with α,ω‐dibromoalkanes. Highly ordered films of layered structure have been obtained by solution casting. The long side chains crystallize with an interdigitating hexagonal packing perpendicular to the film plane. The perfection of the side chain packing is related to the size of the spacer group in the main chain as well as to the valence of the counterions, but also depends on the thermal history of the samples. It is in all cases comparable to the quality of aliphatic chain packing in LB multilayers of surfactants. The comb‐like ionenes exhibit liquid‐crystalline textures above their side chain melting transition.