Structured electrically conductive polyaniline/polymer blends

This paper describes electrically conductive polymer blends consisting of p olyaniline (PANI) dispersed in a polymer matrix. Melt blending of previousl y mixed, coagulated and dried aqueous dispersions of PANI and the polymer m atrix lead to high conductivities at extremely low PANI concentrations (sim ilar to0.5 wt% PANI) In these blends the surface properties (surfactants us ed) of ate PANI and the polymer particles play a major role in the structur ing process, in addition to the very small size of the PANI particles. In a nother approach i.e. conventional melt blending of PANI powder with a given polymer powder the success of generating an efficient conductive network d epends on the PANI/polymer interaction level. A high interaction level for example similar solubility parameters) leads under dynamic hot blending con ditions to the formation of conductive networks, but still at relatively hi gh PANI concentration >10 wt% PANI). To further reduce the PANI conductivit y threshold concentration, ternary PANI/ polymer/polymer blends can be desi gned in which PANI is selectively attracted to the minor polymer component, thus generating double-percolation structures. The threshold PANI concentr ation in the ternary blends may be reduced by a factor of similar to2 compa red to the binary blends. Further reduction ran be expected in special tern ary blends designed so that the PANI particles will mostly locate at the in terfaces, rather than within the dispersed minor polymer particles. The ble nding method of aqueous dispersions is limited to matrix polymers which can be synthesized by emulsion polymerization. Thus, the conventional melt ble nding procedure and also the formation of ternary blend systems are particu larly beneficial for condensation type polymers, whereas melt blending of P ANI/polymer powders prepared by the aqueous dispersions method is beneficia l for the addition-type polymers. Copyright (C) 2000 John Wiley & Sons, Ltd .