CONDUCTING POLYANILINE NANOPARTICLE BLENDS WITH EXTREMELY LOW PERCOLATION THRESHOLDS

Blends of HCl-doped polyaniline (PANI . HCl) nanoparticles with the following conventional polymers, poly(vinyl chloride), polystyrene, poly(methyl methacrylate), poly(vinyl acetate), and poly(vinyl alcohol) (PVA), were prepared by suspending preformed submicronic PANI . HCl particles in the solutions of the matrix polymers and sonicating the suspension for 1.5 h. The submicronic PANI . HCl particles were prepared by oxidative dispersion polymerization using poly(vinyl methyl ether) (PVME) stabilizer. The particles contained 4.4 wt % PVME and had a conductivity of 4.96 S/cm. They had an oblong shape (250 nm x 190 nm). Sonication breaks the particles to sizes less than 20 nm. The blend films exhibit an extremly low percolation threshold (f(p)) in every case. The volume fraction of PANI . HCl at the percolation threshold for the above mentioned matrices lies in the range 2.5 x 10(-4) to 4 x 10(-4). Transmission electron microscopy of PANI . HCl-PVA blend films directly cast on carbon-coated TEM grids reveals connectivity at compositions close to f(p). Self-assembly of the nanoparticles is evident from the TEM pictures.