Spectroscopic study of the polymerization of intercalated anilinium ions in different montmorillonite clays

The polymerization of the intercalated aniline ions was studied in three different clays, Swy2-montmorillonite (MMT), synthetic mica-montmorillonite (Syn1) and pillarized Swy2-montmorillonite (PILC). PANI is formed between the MMT and Syn1 clay layers, being confirmed by the shift of d001 peak in the X-ray pattern. X-ray Absorption near to Si K edge (Si K XANES) data show that the structures of clays are preserved after the polymerization process and in addition to the SEM images show that morphologies of the clays are maintained after polymerization, indicating no polymerization in their external surface. UV–vis–NIR and resonance Raman data display that the PANI formed in Syn1 galleries has higher amount of phenazinic rings than observed for PANI intercalated in montmorillonite (MMT) clay. No polymer formation was detected in the PILC. N K XANES and EPR spectroscopies show the presence of azo and radical nitrogen in intercalated PANI chains. Hence, the results are rationalized considering the structural differences between the clays for understanding the role of the anilinium polymerization within the clays galleries.

► We characterize the polymerization of aniline into three different clays.
► Many spectroscopic and textural techniques were used for the first time in these samples.
► The formation of new segments in the intercalated PANI chains is related to the acidic clay sites.