ISSN 0965-545X, Polymer Science, Ser. A, 2011, Vol. 53, No. 9, pp. 800–810. © Pleiades Publishing, Ltd., 2011. Original Russian Text © I.G. Sushchenko, T.K. Meleshko, I.V. Gofman, T. E. Sukhanova, M.E. Vylegzhanina, I.V. Abalov, E.N. Vlasova, E.N. Popova, V.E. Yudin, A.V. Yakimanskii, 2011, published in Vysokomolekulyarnye Soedineniya, Ser. A, 2011, Vol. 53, No. 9, pp. 1552–1563. 800 INTRODUCTION An urgent direction in the synthesis of new high- tech polymer materials with special properties is the study of processes of formation of composite systems from diverse polymers that can combine the attractive properties of each component in one material. Among polymers showing promise for the development of polymer composites, aromatic polyimides and polya- niline (PANI) are of indubitable interest. PANI, which is one of the most interesting poly- conjugated polymers, shows not only high conductiv- ity but also other valuable properties: Specifically, it is an efficient material for membrane preparation [1]. However, the brittleness of one-component PANI films significantly impedes their use in practice. A pos- sible way of improving mechanical characteristics of such films may involve the obtainment of PANI com- posites with matrix PIs [2, 3], which possess good film-forming and membrane properties [4]. It is expected that the nanosized stiff fragments of such an active component as PANI can interact with the PI matrix, cause its nanostructuring, cause nanopore for- mation, etc., thereby significantly affecting the mor- phology of the films. Film composites of PANI and PI, which are solu- ble in amide solvents, are prepared through mixing of their solutions followed by film formation via solvent removal from the layer of the mixed polymer solution in a common solvent deposited on a substrate [3]. The main problems encountered in the preparation of the homogeneous polymer mixture are the compatibility and phase stability of blends. For most polymers, spontaneous mutual dissolution cannot be attained. Usually, the mixing of two chemically dissimilar poly- mers gives rise to a two-phase system. If the content of one component in a mixture is no less than 80 wt %, such a system is the dispersion of one polymer in the matrix of the other polymer. In this case, term “com- patibility” is not related to the mutual solubility of components. It is believed that “compatible” poly- mers also form heterophase mixtures with the accept- able set of properties because a high viscosity of poly- mer mixtures ensures a high stability of these het- erophase thermodynamically unstable systems [5, 6]. It is known that PANI, because of a relatively high stiffness of the polymer chain and an appreciable intensity of intermolecular interaction, features poor solubility and high aggregation in solution. Therefore, the formation of homogeneous films of polymer blends is difficult. The incorporation of substituents into the benzene rings of PANI improves the solubility of the polymer, including the solubility in amide sol- vents. In this respect, carboxy-derivatives of PANI are especially promising because they may be involved in thermal decarboxylation and may serve as soluble pre- cursors of PANI [7]. Such polymers, like PANI, pos- sess poor film-forming ability. Film articles (not coat- ings) can be formed from these polymers through the Film Composites of Polyimide with Polyaniline and Poly(aniline-co-anthranilic acid) I. G. Sushchenko, T. K. Meleshko, I. V. Gofman, T. E. Sukhanova, M. E. Vylegzhanina, I. V. Abalov, E. N. Vlasova, E. N. Popova, V. E. Yudin, and A. V. Yakimanskii Institute of Macromolecular Compounds, Russian Academy of Sciences, Bol’shoi pr. 31, St. Petersburg, 199004 Russia e-mail: meleshko@hq.macro.ru Received December 27, 2010; Revised Manuscript Received April 21, 2011 Abstract—New two-component composite polymer films are prepared and studied in terms of thermal sta- bility and stress–strain properties. The matrix component of the composite is polyimide based on 3,3',4,4'-(1,3-diphenoxybenzene)tetracarboxylic dianhydride and 4,4'-bis(4''-aminophenoxy)diphenyl sul- fone. Another component is polyaniline or the copolymer poly(aniline–co-2-aminobenzoic acid). Compos- ite films are cast from mixed solutions of individual polymers in N-methyl-2-pyrrolidone. Interpolymer interactions in polyimide composites with polyaniline or the copolymer of aniline and 2-aminobenzoic acid are investigated via viscometry and IR spectroscopy. The thermal treatment of composite films with poly(aniline-co-2-aminobenzoic acid) results in decarboxylation of the copolymer and formation of polyim- ide–polyaniline composite films. The morphology, microphase structure, and porosity of the composite films are different from those of the films cast from solutions of polyimide–polyaniline mixtures. DOI: 10.1134/S0965545X11090124 POLYMER BLENDS