Optical properties of biocompatible polyaniline nano-composites

Polyaniline (PANI) is an electro-active polymer of great interest thanks to its outstanding physical and chemical properties which make it suitable for various applications in optics, bioelectronics, biosensors, diagnostics and therapeutic devices. Unfortunately, PANI is infusible and insoluble in most common solvents and, thus, very difficult to process. In the attempt of improving processability, yet preserving its interesting properties, PANI has been synthesized in the form of particles and dispersed into a hydrogel matrix. The synthesis of PANI-hydrogel composites proceeds via gamma-irradiation of PANI dispersions as obtained by 'in situ' polymerization of aniline in the presence of water-soluble, polymeric stabilizers. The chosen stabilizers are able to undergo to chemical cross-linking when exposed to ionizing radiations, so forming the highly hydrophilic network that entrap PANI particles. The presence of a hydrogel matrix induces biocompatibility to the final composite material which, in a typical bottom-up approach, may become suitable for the development of biocompatible, optoelectronic devices. Some morphological and optical features of these novel soft, functional nano-composites are here presented. (c) 2006 Elsevier B.V. All rights reserved.