Surface modification of silver microparticles with 4-thioaniline

Silver microparticles have been prepared by chemical reduction method onto a rotating copper disc. It was found that in the presence of polyvinylpyrrolidone (PVP) in the initial AgNO₃ aqueous solution the radius of the Ag particles decreased from 1.18 to 0.48 μm and the formation of dendritic clusters with the fractal dimension of 1.61 occurred. The two-stage modification of the surface of synthesized silver particles with bifunctional 4-thioaniline (TAn) and further grafting of polyaniline (PAn) chains to the end amino-group of formed self-assembled surface layer were carried out. The modified surfaces were studied by scanning electron microscopy and X-ray diffraction methods, the physico-chemical properties of the formed products have been investigated. The obtained results indicate that the highest thermal stability is displayed by the silver particles produced in the presence of PVP, while the sample with grafted polyaniline exhibits the lowest thermal stability among the investigated samples. The reactivity of TAn has been examined by cyclic voltammetric method. In contrast to aniline, the electrochemical oxidation of TAn did not result in the formation of an electroconductive film on Pt electrode. It was found that oxidative condensation of aniline is suppresses by the TAn: when the molar ratio of aniline/TAn is 2:1 the formation of an electrochemically active product is stopped. The phenomenon of inhibition of the oxidative polymerization of aniline with TAn is related to an impossibility of growing of polymeric chains in the result of the “head-to-tail” type of bonding of the thioaniline links.