Plasticizer Effect and Electronic Diffusive Behavior of Polyaniline-Modified Clay in Polystyrene Nanocomposites Camila P. Pinto, 1 Wagner M. Pachekoski, 2 Carla Dalmolin, 1 Daniela Becker 1 1 State University of Santa Catarina, Technological Science Centre Rua Paulo Malschitzki 200, Campus Universit  ario – Zona Industrial Norte, Joinville, SC, Brazil 89204-710 2 Federal University of Santa Catarina, Campus Joinville R. Dr. Jo ~ ao Colin 2700, Santo Ant ^ onio, Joinville, SC, Brazil 89218-035 Montmorillonite clay (MMT) was modified with polyani- line (Pani) and used to produce nanocomposites in a polystyrene (PS) matrix. MMT/Pani particles were evalu- ated by Infrared Spectroscopy (FT-IR), where groups of both MMT and Pani were found; and by XRD, where an increase in the interlamellar distance was detected, changes on the resistive electrical behavior of MMT to a diffusive one for MMT/Pani were identified by Electrochemical Impedance Spectroscopy (EIS). Nano- composites of PS with MMT-Pani were produced by melt intercalation in the proportions of 1%, 3%, 5%, and 10%. They were characterized by Transmission Electron Microscopy (TEM), Differential Scanning Calorimetry (DSC), Thermogravimetry (TG), and EIS. Main results showed a decrease in the glass transition temperature and in the onset temperature according to the amount of MMT-Pani. Analyses by EIS demonstrated a capacitive behavior (polarization) for nanocomposites containing smaller amounts of MMT-Pani and diffusive behavior for the largest proportions, which were explained by a model of electronic diffusion in the Pani polymeric chain due to the chain intercalation observed by TEM in sam- ples with higher concentration of MMT-Pani. Therefore, the results suggest that the addition of MMT-Pani alters some properties of the polystyrene matrix, changing its degradation and transition temperature, and its electrical behavior. POLYM. COMPOS., 00:000–000, 2017. V C 2017 Society of Plastics Engineers INTRODUCTION Blending of insulating polymeric matrices and electri- cally conducting polymers has been receiving great atten- tion in recent years due to a combination of conventional properties of traditional polymers such as easy processability, low density, environmental stability, and corrosion resis- tance, with the electrical properties of the conducting ones [1]. These conducting polymers are a class of functional materials in which the polymeric chains are constituted by alternated single and double carbon-carbon bonds. This highly conjugated configuration enables reversible electro- chemical and physical properties that can be achieved through switchable doping/de-doping processes [2, 3]. Polyaniline (Pani), among other conducting polymers, exhibits some interesting characteristics, such as a wide conductivity range, unique redox reversibility, good envi- ronmental stability, biocompatibility, and optical proper- ties. In addition, it can be produced as a bulk powder, films or fibers through an easy and low-cost synthesis [3, 4]. These unique properties can be enhanced by producing a nanostructured material, where the highly ordered poly- meric chains are responsible for higher conductivities and faster doping/de-doping processes [5]. Unfortunately, Pani applications are limited because of its poor processability. The production of polymeric blends with Pani or adding a Pani-modified particle or fiber to produce polymeric com- posites arises as alternatives for Pani applications [6–13]. One strategy to produce Pani-modified particles for nanocomposites is through intercalation polymerization. Polymeric chains are confined inside the nanosized galler- ies of inorganic layered materials such as montmorillonite clays (MMT). This constrained environment is expected to lead to a high degree of chain ordering, increasing the doping and de-doping processes capacity and reversibility, high anisotropy and, consequently, enhanced electrical conductivity. This confinement is possible, in part, due to the clay’s ability to exchange ions, since its negative charged layers form galleries occupied by hydrated cati- ons, such as Na 1 , to maintain the electrical neutrality. These cations can be exchanged by charged monomers, Correspondence to: D. Becker; e-mail: daniela.becker@udesc.br Contract grant sponsor: Brazilian research funding agencies FAPESC, CAPES, and CNPq. DOI 10.1002/pc.24594 Published online in Wiley Online Library (wileyonlinelibrary.com). V C 2017 Society of Plastics Engineers POLYMER COMPOSITES—2017