Comb-Shaped Supramolecules of Emeraldine Base Form of Polyaniline Due to Coordination with Zinc Dodecyl Benzenesulfonate and Their Plasticized Self-Organized Structures

Abstract

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 Å. 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.