Synthesis and characterisation of a high dielectric constant and ac-conducting PANI/[Co(NH3)3(C4H4N2)3]Cl3 nanocomposite

Abstract

In this study we have synthesised polyaniline/[Co(NH3)3(C4H4N2)3]Cl3 nanocomposite by in-situ chemical polymerisation method in non-aqueous dimethyl sulphoxide medium. The filler photoadduct was synthesised by irradiating aqueous solution mixture of hexaminecobalt(III) chloride metal complex and pyrazine, which was subsequently reduced in size by high energy ball milling prior to incorporation into the polyaniline matrix. The optical, structural, thermal and dielectric properties of the as synthesised nanocomposite were studied. The energy band gap as obtained from Tauc plot was observed higher for nanocomposite as compared to polyaniline. FTIR and XRD results show presence of photoadduct nanoparticles in the polyaniline matrix and successful interactions between them. The crystallite size as obtained from XRD confirms the nano dimensions of both photoadduct (26 nm) and nanocomposite (18 nm) with photoadduct retaining its structure in the nanocomposite. Presence of modified agglomerate regions in nanocomposite have been confirmed from FESEM which facilitates better charge separation in the material as observed from dielectric measurements. TG of nanocomposite shows better thermal stability as compared to both polyaniline and photoadduct owing to the strong interactions between the photoadduct nanoparticles and polyaniline matrix. The dielectric measurements (έ, ἒ, tanδ and σac) were studied as a function of frequency and their variation with frequency is explained by “Maxwell–Wagner” model. The nanocomposite shows higher value of dielectric constant (106) and higher value of ac-conductivity (109) as compared to pure PANI. The high value of dielectric constant and ac-conductivity of the nanocomposite makes the material suitable for energy storage applications and an effective electromagnetic interference shielding material both at low and high frequency.