ORIGINAL PAPER Electrical, optical, and structural characterization of polymer blend (PVC/PMMA) electrolyte films V. Balasubramanyam Achari & T. J. R. Reddy & A. K. Sharma & V. V. R. Narasimha Rao Received: 15 December 2006 / Accepted: 2 April 2007 / Published online: 25 July 2007 # Springer-Verlag 2007 Abstract Ion-conducting solid polymer blend electrolytes based on polyvinyl chloride (PVC)/poly methyl methacry- late (PMMA) complexed with sodium perchlorate (NaClO 4 ) were prepared in various concentrations by solution cast technique. The features of complexation of the electrolytes were studied by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. DC conductivity of the films was measured in the temperature range 303–398 K. Transference number measurements were carried out to investigate the nature of charge transport in the polymer blend electrolyte system. The electrical conductivity increased with increasing dopant concentra- tion, which is attributed to the formation of charge transfer complexes. The polymer complexes exhibited Arrhenius type dependence of conductivity with temperature. In the temperature range studied, two regions with different activation energies were observed. Transference number data showed that the charge transport in this system is predominantly due to ions. Optical properties like absorp- tion edge, direct band gap, and indirect band gap were estimated for pure and doped films from their optical absorption spectra in the wavelength region 200–600 nm. It was found that the energy gap and band edge values shifted to lower energies on doping with NaClO 4 salt. Keywords Polymer blend electrolyte . DC conductivity . Activation energy . Absorption edge and energy gap Introduction In recent years, studies on the electrical and optical properties of polymers have attracted much attention in view of their applications in electronic and optical devices [1, 2]. The electrical properties are aimed to understand the nature of the charge transport prevalent in these materials while the optical properties are aimed at achieving better reflection, antireflection, and polarization properties. Elec- trical and optical properties of the polymers can be suitably modified by the addition of dopant depending on their reactivity with the host matrix. Among the first and most studied host matrices for solid polymer electrolytes is polyethylene oxide (PEO), which dissolves high concen- trations of a wide variety of salts to form polymeric electrolytes [3]. Investigations on polymer electrolytes have focused primarily on the enhancement of ionic conductiv- ities at room temperature. Several methods, such as copolymerization, plasticization, blending, and addition of ceramic fillers/additives have been used to modulate the conductivity of the polymer electrolytes. Among the polymer electrolytes, PMMA-based electrolyte has a special significance in view of its well-known chemistry and cheaper method of processing as laminates. To get PMMA amenable, choice of blending with PVC has been suggested [4]. Although there are many polymer blends, those containing PVC are among the most important from both scientific and commercial point of views [5, 6]. A relatively small number of studies have been reported on the development of PVC/PMMA-based polymer electrolyte systems [7–9]. The present work aims to investigate the PVC/PMMA matrix to improve its electrical and optical performance. Because Na+ is a fast conducting ion in a number of crystalline and amorphous materials, its incorporation in a Ionics (2007) 13:349–354 DOI 10.1007/s11581-007-0124-9 Paper presented at the Third International Conference on Ionic Devices (ICID 2006), Chennai, Tamil Nadu, India, Dec. 7–9, 2006. V. B. Achari : T. J. R. Reddy : A. K. Sharma (*) : V. V. R. N. Rao Department of Physics, S.V. University, Tirupati 517 502, India e-mail: profaks_svu@rediffmail.com