1 ISSN 1560-0904, Polymer Science, Series B © Pleiades Publishing, Ltd., 2017. Preparation of Conductive, Flexible and Transparent Films by In Situ Deposition of Polypyrrole Nanoparticles on Polyethylene Terephthalate 1 Mohammad Fallahian a , Behzad Pourabbas a, *, Mehdi Sharif b , Kamran Froutani a , Mehrnoosh Mahmoodian a , and Mahdi Mohammadizadeh a a Department of Polymer Engineering, Nanostructured Materials Research Centre, Sahand University of Technology, Tabriz, Iran b Departments of Chemical Engineering, Shiraz Branch, Islamic Azad University, Shiraz, Iran *e-mail: pourabas@sut.ac.ir Received July 28, 2016; Revised Manuscript Received December 26, 2016 Abstract—In this study polypyrrole (PPy) nanoparticles were deposited as a thin film on the modified surface of polyethyleneterephthalate (PET) by in situ chemical polymerization in the presence of sodium dodecyl- sulfate (SDS), sodium dodecylbenzenesulfonate (DBSNa) and mixture of them as the surfactant. The surface of PET was modified by KOH before deposition and was investigated for conductivity and adhesion of PPy nanoparticles to PET. Resulting conductive flexible films were characterized by UV–Vis spectroscopy, field- emission scanning electron microscopy, contact angle measurements and four-point-probe technique for conductivity. Direct morphological observation (FESEM) and electrical measurements indicated that the morphology, conductivity and the nature of deposited PPy films depend on surfactant, surface modification of PET and monomer concentration. In optimized process condition, uniform conductive films of PPy were obtained with good adhesion to PET. DOI: 10.1134/S156009041703006X INTRODUCTION In 1977, Shirakawa et al. [1] observed that almost insulating π-conjugated polyacetylene becomes con- ductive with a conductivity of about 10 3 S/cm by iodine doping. This unexpected discovery had broken the traditional concept that organic polymers can be only insulators and established a new kind of poly- mers, which called later as Synthetic Metals. Later on, many other types of conductive polymer with conju- gated π-electron structure such as polyaniline (PANI), polypyrrole (PPy), polythiophene (PTh), polyfuran (PFu), poly(p-phenylene) (PPP) and poly- carbazole (PCz) were synthesized and investigated [2, 3]. Although, a wide variety of electrically conducting polymers are now available polypyrrole (PPy) due to its outstanding physical and chemical properties [1] in addition to ease of synthesis, had become amongst the most extensively studied conducting polymers [4]. Technologically, PPy has very high potential for appli- cations inmolecular electronic devices [4], display devices [5], electrodes of lithium-ion batteries [6], electro-magnetic interference shielding materials [7],membranes, antistatic for mulations and sensors [8, 9]. Bleha et al. studied the composite polyethylene + PPy in order to use as a membrane [10]. In the flexible display technology, flexibility depends to the substrate properties. Three kinds of material which are consid- ered as a f lexible substrates are: thin glass films, metal foils and polymeric films [11]. Thin glass films are bendable with desired qualities of glass [12] but they are still too brittle to be used as a flexible substrate. Metal foils are excellent barrier materials to moisture and oxygen, perfect thermal conductivity without the problems of being brittle [13] however, they are chem- ically reactive, susceptible for corrosion and are too expensive materials in some cases to be used in large display panels. Plastic materials however, from the other hand, are the best candidates due to their rea- sonable tradeoffs in mechanical, optical, and chemical performance. They are inexpensive and useful mate- rial for in-line production via roll-to-roll (RTR) pro- cesses and they can be used in multilayer-engineered substrates in most practical applications such as in liq- uid crystal display (LCD), light-emitting diode (LED) devices and organic LEDs (OLED). Recently amor- phous thermoplastic materials such as cyclic olefin copolymers (COC) are being used for electronic devices applications which are transparent, light in 1 The article is published in the original. FUNCTIONAL POLYMERS