Role of Atmospheric Oxygen for the Polymerization of Interleaved Aniline Sulfonic Acid in LDH

New polymer/inorganic hybrid materials have been prepared by a two-step soft chemistry route including the intercalation of aniline sulfonic acid between the sheets of a layered double hydroxide (LDH), Cu2Cr(OH)6Cl·nH2O, and its in situ polymerization at temperatures below 473 K in air atmosphere. A combination of techniques, including X-ray diffraction, X-ray absorption spectroscopy at Cu, Cr, and S K-edge, electron spin resonance, and infrared spectroscopies, was used for their characterization. For the first time, a pure nanocomposite was successfully obtained. The interleaved polymer is found to be present under its emeraldine salt form. In situ ESR measurements enable determination of the thermal condition for the polymerization, showing the kinetic factor of the process. Like other lamellar nanocomposites, the atmospheric oxygen plays a major role for the polymerization process, although, here it is crucial, since no redox chemistry or external oxidizing agents are employed. The monomer confinement and its matching with the layer charge density of the host framework are found to be of great importance.