Investigations on electrical properties of poly(vinyl alcohol) doped with 1-methyl-3-n-decyl-imidazolium bromide ionic liquid Ahmad I. Ayesh a, * , Mahmoud A. Mohsin b , Mohammad Y. Haik c , Yousef Haik c, d a Department of Physics, United Arab Emirates University, P.O. Box 17551 Al Ain, United Arab Emirates b Department of Chemistry, University of Sharjah, P.O. Box 27272 Sharjah, United Arab Emirates c Department of Mechanical Engineering, United Arab Emirates University, Al Ain, United Arab Emirates d Center for Research Excellence in Nanobiosciences, University of North Carolina at Greensboro, Greensboro, United States article info Article history: Received 24 November 2011 Received in revised form 29 February 2012 Accepted 2 March 2012 Available online 13 March 2012 Keywords: Poly(vinyl alcohol) 1-methyl-3-n-decyl-imidazolium bromide Ac impedance spectroscopy FTIR spectroscopy Electrical conductivity Ionic liquid abstract Thin films of poly(vinyl alcohol) (PVA) that are 100e500 mm thick were prepared by solution casting method. Various ratios of 1-methyl-3-n-decyl-imidazolium bromide ionic liquid [MDIM] (þ) Br () , were used as dopants (plasticizers) to control the conductivity of the PVA thin films. Fourier transform infrared spectroscopy (FTIR) was used to indicate the detailed interaction of PVA with proton of the dopant in the blends. Ac impedance spectroscopy was used to investigate the impedance of the films within a frequency range of 10e10 6 Hz as a function of temperature between 298 and 425 K. Each film with a precise doping concentration was sandwiched between two stainlessesteel electrodes. The results showed that the electrical conductivity can be engineered by controlling the [MDIM] (þ) Br () doping concentration. Therefore, those films have potential to be used in flexible and cheap organic device applications. Ó 2012 Elsevier B.V. All rights reserved. 1. Introduction Poly(vinyl alcohol) (PVA) is a synthetic polymer produced from the hydrolysis of poly(vinyl acetate). It is readily soluble in water and its solubility is influenced by a number of factors like; the degree of hydrolysis, molecular weight, and particle size distribu- tion. It is one of the hydrogels often used in biomedical applications due to its excellent adhesion and emulsifying characteristics. PVA is well suited for making biodegradable blends with natural polymers due to its good film-forming capability and water solubility. On the other hand, ionic liquids (IL), also known as plasticizers, have been widely used as organic solvents and supporting electrolytes in many scientific fields due to their excellent properties such as high conductivity, non-volatility and non-flammability. Addition of a plasticizer (dopant) to PVA is necessary to overcome the brittle- ness of the polymer films, improve flow and flexibility, increase toughness to impact resistance, and customizes the electrical conductivity of the blends [1e4]. PVA has high concentration of polar groups and high chain flexibility depending on the molar mass of the polymer. PVA is described as a proton conducting material with low conductivity [5,6], thus, its conductivity can be remarkably enhanced by doping with suitable impurities [7,8]. This generated great potential of using PVA and its derivatives for devices [9,10] especially in medical applications [11e 13]. Ionic liquids molecular structures were synthesized to composed of a weakly bounded anions and usually long chain of organic cations. They have good thermal stability, low flammability, high electrochemical stability, and high ionic and thermal conductivity. These are a special class of salts that have melting points at or close to ambient temperature. They are miscible with water or organic solvents and being applied as solvents, separation media, electrolytes, and lubricants in many applications. Generally, the ac impedance measurements can be used to obtain an insight into the polarization mechanisms, structural transition, and homogenous electrical properties inside a solid [14]. The analysis allows discriminating the resistance of the bulk composite film from the contribution of its capacitance as well as the charge transfer. Equivalent circuits can be used to simulate the ac measurements and it demonstrates the effects of blocking elec- trodes, grain boundaries, etc [15]. * Corresponding author. Tel.: þ971 3 7136315; fax: þ971 3 7671291. E-mail address: ayesh@uaeu.ac.ae (A.I. Ayesh). Contents lists available at SciVerse ScienceDirect Current Applied Physics journal homepage: www.elsevier.com/locate/cap 1567-1739/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.cap.2012.03.004 Current Applied Physics 12 (2012) 1223e1228