Synthesis and Characterization of Ag2S Layers Formed on Polypropylene

Hindawi Publishing Corporation Journal of Chemistry Volume 2013, Article ID 987879, 11 pages http://dx.doi.org/10.1155/2013/987879 Research Article Synthesis and Characterization of Ag2S Layers Formed on Polypropylene Valentina Krylova and Nijolė Dukštienė Faculty of Chemical Technology, Kaunas University of Technology, Radvilėnų Street 19, 50254 Kaunas, Lithuania Correspondence should be addressed to V. Krylova; Received 29 June 2012; Revised 20 August 2012; Accepted 28 August 2012 Academic Editor: Peter Chang Copyright © 2013 V. Krylova and N. Dukštienė. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Silver sulphide, Ag2 S, layers on the surface of polypropylene (PP) �lm was formed by chemical bath deposition method (C�D). Film samples were characterised by X-ray photoelectron spectroscopy (XPS), attenuated total re�ection Fourier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction analysis (XRD). e surface morphology, texture, and uniformity of the silver sulphide layers were formed on PP surface dependent on the number of polymer immersions in the precursor solution. XPS analysis con�rmed that on the surface of the polypropylene �lm, a layer of Ag2 S was formed. ATR-FTIR and FTIR spectra analysis showed that the surface of Ag2 S layers is slightly oxidized. All prepared layers gave multiple XRD re�ections, corresponding to monoclinic Ag2 S (acanthite). e Ag2 S layer on polypropylene was characterized as an Ag+ ion selective electrode in terms of potential response and detection limit. e electrode was also tested as an end-point electrode for argentometric titration of thiamine hydrochloride. 1. Introduction Polymers modi�ed by thin electrically conductive or semiconductive �lms of binary inorganic compounds, particularly of metal chalcogenides [1–4] represent a new class of materials—composites. e application of these composites is determined by their properties, wheares the latter depend signi�cantly on the preparation method, even the chemical composition and structure of composites slightly change [5, 6]. In the last few years, there is a growing interest in Ag2 S �lms because of their unique electrical [7, 8], optical [9], photovoltaic [10], and thermoelectric properties [11, 12]. ese unique properties suggest potentially broad applications of Ag2 S �lms in various devices such as solar cells, super ionic conductors and semiconductors, photo detectors, photo thermal conversion, electroconductive electrodes, microwave shielding coating, gas sensors functioning at temperatures tending to room temperature, polarizer’s of infrared radiation, and active absorbents of radio waves [5, 6, 13–15]. e properties of Ag2 S �lms can be successfully utilized by deposition its layers (either by in situ or ex situ methods) onto polymer surface, since a polymer can be easily designed into almost any shape required by a particular application. Additionally, the polymer can also act as the controlled environment for the growth of the �lm layers. Furthermore, the Ag2 S/polymer composites may exhibit new properties that differ from those of single Ag2 S �lms, arising from the spatial orientation and network arrangement. erefore, the ability to prepare such composites on a large scale is an important goal of materials science. e properties of Ag2 S/polymer composites are very sensitive to preparation technique and signi�cantly depend on the nature of polymer on which Ag2 S layers are formed. Recently, there have been a number of papers suggesting different methods for the incorporation of silver sulphide nanocrystals in different polymer matrices and their characterization. e well-dispersed Ag2 S nanoparticles 2 incorporated in polyvinylpyrrolidone (P�P)/�bre matrices using the electrospinning technique [16]. Kumar et al. [17] have applied a sonochemical method for the preparation of Ag2 S nanoparticles in the presence of polyvinyl alcohol. Composite thin �lms consisting of nanosized Ag and Ag2 S particles dispersed in nylon 11 thin �lms have been prepared by using a thermal relaxation technique [18]. Wang et al. developed a gas/solid reaction method based on surface initiated atom transfer radical polymerization (ATRP) for fabricating nanoparticles/polymer composite thin �lms, while preventing the aggregation of nanoparticles; thus the reaction may happen on the surface of composite thin �lms [19]. is present study focuses on the deposition of Ag2 S layers on the polypropylene (PP) by the chemical bath deposition method (CBD). PP �lm is characterized by many excellent properties than other polymers. is is a low density, high thermal resistance, high strength at high �exibility, resistance to cracking under stress and a very good chemical stability [20]. e CBD method is relatively simple and inexpensive, and highly reproducible technique. e technology is based on slow controlled precipitation of the Ag2 S through the reaction between Ag+ and sulphur compounds as the sulphur source. In the past decade, Ag2 S thin �lms by CBD method have been successfully prepared on silica [21], glass [22], biopolymer matrix [23], indium doted tin oxide (ITO) �lm [24], and polyamide (nylon) surfaces [25]. e sulphur precursors were usually thiourea [24], the elemental sulphur dissolved in a concentrated NaOH solution [26], thioacetamide [27], sodium sulphide [25], sodium thiosulphate [3], dimethylthiourea [6] and toxic carbon disulphide (CS2 ) in ethanol [28]. e most pronounced role in the formation of the Ag2 S particles and consequently deposits has been played by the complexing agents. An ethylenediaminetetraacetate disodium salt (EDTA) [8] and ammonia solution [21] acting as a complexant for Ag ions or as a catalyst is usually employed to control the reaction rate. e commonly accepted underlying mechanism involves alkaline solution (pH 6−10) as ammonia for pH adjustment [8] and higher temperature 30−80∘ C [21]. However, the adding of complexing agent increases experimental parameters whereas the nonaqueous medium is expensive or toxic generally. In this paper we report on the depositing of Ag2 S layers by CBD from an acidic aqueous solution containing silver nitrate and an excess of sodium thiosulphate at 20∘ C temperature. e replacement of complexing agents with excess of sodium thiosulphate results to the simpler reaction mechanism. A reaction mechanism for depositing continuous Ag2 S layer has been examined, and the optimal precursor’s concentrations in solution are suggested. e chemical composition, structural, and morphological properties of Ag2 S layer formed on polypropene surface have been investigated. e Ag2 S layer formed on polypropene was also tested as an indicator electrode for argentometric titration of thiamine hydroc (...truncated)