The conducting properties of composites prepared by deposition of polyaniline layers on the surface of porous polyethylene films from dispersions and by polymerization in situ were studied.Conducting polymers such as polyacetylene, polyaniline (PANI), polypyrrole, polythiophene, and their derivatives are novel promising materials attracting researchers' attention [1,2]. They are used in membrane processes, electric batteries, and new types of electronic and optoelectronic devices, and also as sensitive elements in modern sensor systems, antistatic agents, and microwave absorbers. Due to relatively high intrinsic conductivity and chemical stability, and also to diverse and simple preparation procedures, polyaniline is the most promising conducting polymer [3,4]. However, low strength, brittleness, and very poor solubility hinder utilization and treatment of PANI. These disadvantages can be effectively overcome by preparing composites containing PANI as conducting component [5,6]. Development of methods for preparing composites consisting of conducting layers on various supports is an urgent problem. When the composites are used as membranes, the resistance of the supports to the mass transfer should be minimal, and porous materials containing through channels meet this requirement.In this work we used porous polyethylene (PE) supports, because they exhibit good mechanical properties and high chemical resistance with respect to organic solvents, acids, and alkalis.We studied the electrical and mechanical properties of composites consisting of PANI layers deposited on porous PE film supports. Since in service these composites can be exposed to thermal treatment, we also studied their thermal-deformation behavior and structural transformations. EXPERIMENTAL The required porous films were prepared from high-density polyethylene (M w 1.4 0 10 5 , M w /M n 6 38, and mp 132oC). The porous structure was formed by uniaxial extension of the film prepared by extrusion of the melt with subsequent annealing [7]. The total porosity of the resulting 20-mm films was 40%. These porous films contained through channels (180 3 360 nm in diameter) [7, 8] and had developed rough surface [9, 10] providing high adhesion of the films to the layers deposited. The PE/PANI composites were prepared by two procedures: by chemical oxidative polymerization from aniline solutions directly on the porous film surface [PE/PANI(in situ)] and by deposition of a polyaniline dispersion on the film surface [PE/PANI (disp.)].To prepare the PE/PANI(in situ) systems, the porous PE film was immersed into the reaction mixture containing aniline hydrochloride (0.2 M), ammonium peroxodisulfate (0.25 M), and excess hydrochloric acid (1 M). The polymerization time was varied from 8 min to 2 days. Then, the resulting film was dried in a vacuum at room temperature. The polymerization was carried out at 5 and 20oC.The colloidal PANI dispersion was prepared as follows. To a solution of dodecylbenzenesulfonic acid (0.1 M, 100 ml), we successively added aniline (0.01 m...