Electrochemical deposition and characterization of copper crystals on polyaniline/poly(ethylene terephthalate) conductive textiles

Highlights

• Cu layers on conductive textiles were electroplated galvanostatically.

• Electrochemical characterizations of the electrodeposition process were detected. Granular and dendrite crystals were obtained as current density and time controlled.

• Chemical compositions of Cu–polymer surfaces were deduced from EDX and XPS analysis.

• Cu deposits displayed crystallographic structures with a preferred (1 1 1) orientation.

Abstract

Electrodeposition of copper was performed on the polyaniline/poly(ethylene terephthalate) conductive textiles in an aqueous electrolyte solution. The investigations of electrochemical deposition and dissolution processes of copper on and from textile electrodes were studied using cyclic voltammetry technique. Galvanostatic experiments give the evidence for reduction reactions of polyaniline layers and copper ions. The morphology observations by scanning electron microscopy show the nodular crystal and 3D branching microstructure of the coatings depend on the parameters current density and time of the copper electroreduction. Effects of current density and depositing time on the composition of the metallic-polymer layers on textile substrates were confirmed by energy dispersive X-ray and X-ray photoelectron spectroscopy. X-ray diffraction measurements for the copper films galvanostatically formed display the crystallographic structures with a preferred orientation.

Introduction

Numerous investigations to conducting polymers (CPs) modified textiles have attracted interest for the applications of these flexible materials in antistatic materials, gas sensors, biomechanical sensors, heating devices or microwave attenuation [1], [2], [3], [4], [5]. In the recent years the incorporation of metal particles into electronically CP layers have also attracted considerable attention due to the various possibilities of creating materials applied in electronic, catalytic, sensing, energy storaging and EMI shielding fields [6], [7], [8], [9].

CP can be deposited on textile surfaces chemically [10] or by indirect electrochemical deposition [11]. A respectable number of scientific papers including our previous reports [12], [13] have shown the chemical deposition produces a smooth layer of polymer on the fibers of the fabric, which facilitates uniform distribution of metal particles. So far, few researches have been worked on the issues that the formation of the layers including CP and metal deposits on textiles is performed by an indirect electrochemical deposition for the reason that the fabric substrate is insulating [14], [15]. Molina et al. covered polyester textile chemically with polypyrrole/PW₁₂O₄₀³⁻ or polypyrrole/AQSA and later electrochemically with polypyrrole or polyaniline [16], [17], [18].

Among a variety of methods for polymer metallization, electrodeposition via aqueous solutions is the most promising because of its convenience good economy, and the wealth of current plating knowledge [19]. Although metal electrocrystallization on CP layers is a field of research started in parallel with the investigations on chemical synthesis of CP coatings on textiles, metal particles electrodeposition in CP-modified textiles is still scarcely studied. Pasta et al. proposed gold nanoparticles electrodeposited on conductive textiles prepared by conformally coating SWNT on a polyester matrix to form a new anode material [20].

In this work copper has been deposited galvanostatically in the copper citrate complex anions on the surface of conducting fabrics (poly(ethylene terephthalate) (PET) covered with polyaniline (PANI) chemically). In electrodeposition practice, it is well known that certain complexing agents in the plating bath lead to significant changes in the properties and aspect of the deposit [21]. One of the aims of the present study is to investigate the possibilities for copper electrodeposition in the copper citrate complex on CP-modified conducting fabrics. On the other hand, different current densities were employed to obtain different growth velocities. Another objective of this study is to examine the initial and advanced stage of copper electrodeposition at a constant current, which is the mode of the industrial electroplating and therefore the process is of interest both from a fundamental and from a practical point of view. In some studies [22], [23], the role of the thickness and redox state of PANI layers for location of the electrodeposited copper particles on metal electrodes have been demonstrated. However, it turned out that there are no investigations on the electrochemical behavior and microscopic characteristics of copper deposits on PANI-coated fabric substrates by electrochemical reduction under galvanostatic conditions.