Toward homogeneous nanostructured polyaniline/resin blends.

The high interest in applications of conducting polymers, especially polyaniline (PANI), makes it important to overcome limitations for effective usage due to poor processability and solubility. One promising approach is to make blends of PANI in polymeric resins. However, in this approach other problems related to the difficulty of achieving a homogeneous PANI dispersion arise. The present article is focused on this general problem, and we discuss how the synthesis method, choice of dopant and solvent as well as interfacial energies influence the dispersibility. For this purpose, different synthesis methods and dopants have been employed to prepare nanostructures of polyaniline. Dynamic light scattering analysis of dispersions of the synthesized particles in several solvents was employed in order to understand how the choice of solvent affects PANI aggregation. Further information on this subject was achieved by scanning electron microscopy studies of PANI powders dried from various solutions. On the basis of these results, acetone was found to be a suitable dispersion medium for PANI. The polymer matrix used to make the blends in this work is a UV-curing solvent-free resin. Therefore, there is no low molecular weight liquid in the system to facilitate the mixing process and promote formation of homogeneous dispersions. Thus, a good compatibility of the components becomes crucial. For this reason, surface tension and contact angle measurements were utilized for characterizing the surface energy of the PANI particles and the polyester acrylate (PEA) resin, and also for calculating the interfacial energy between these two components that revealed good compatibility within the PANI/PEA blend. A novel technique, based on centrifugal sedimentation analysis, was employed in order to determine the PANI particle size in PEA resin, and high dispersion stability of the PANI/PEA blends was suggested by evaluation of the sedimentation data.