Comb-shaped supramolecules of emeraldine base form of polyaniline due to coordination with zinc dodecyl benzenesulfonate and their plasticized self-organized structures

We show that the emeraldine base form of polyaniline (PANI) forms self-organized (mesomorphic) structures upon mixing with an amphiphilic oligomer zinc dodecyl benzenesulfonate, Zn-(DBS)(2) The number of Zn(DBS)(2) molecules vs the number of PhN repeat units of PANI was selected to be x = 0, 0.125, 0.25, 0.5, and 1.0, and the mixtures were denoted as PANI[Zn(DBS)(2)](x) according to their nominal compositions. PANI consists of alternating quinone diimine and benzene diamine groups. FT-IR and UV-vis spectroscopies reveal changes in the quinone diimine moieties upon adding Zn(DBS)(2), thus suggesting coordination to the iminic nitrogens to form comb-shaped supramolecules PANI[Zn-(DBS)(2)](0.5). Their structure formation was studied using small-angle X-ray scattering and electron microscopy. The competition between the attraction (coordination) and repulsion (dodecyl tails) leads to a self-organized lamellar phase with a long period of ca. 31 Angstrom. Further increase of Zn(DBS)(2) did not reveal clear changes in FT-IR and UV-vis but results in plasticization to render viscous fluid upon heating for x = 1.0, in contrast to the uncomplexed PANI which is infusible.