TRANSPORT-PROPERTIES OF POLYANILINE-CELLULOSE-ACETATE BLENDS

Transport properties of polyaniline (PANI)-cellulose acetate (CA) cond ucting blends have been investigated at various length scales and temp eratures. We report on the results of de and ac conductivity measureme nts, magnetoresistance and electron-spin resonance (ESR)performed on c omposite films with PANI weight fraction p ranging from the percolatio n threshold-p(c)similar or equal to 0.1%-to a few percent. Three diffe rent PANT doping agents have been tested, namely, camphor sulfonic aci d (CSA), di(i-octyl phosphate) (DiOP) and phenyl phosphonic acid (PPA) . The percolative behavior of sigma(dc) resembles that of published re sults on PANI/PIMA blends. The onset frequency omega(xi) of the disper sion in sigma(ac) appears to follow the scaling law: omega(xi)proporti onal to sigma(dc)(z), with z similar or equal to 1. The temperature de pendence is of the form of ln sigma(T)proportional to-(T-0/T)(gamma) t he exponent decreasing from 0.75 to 0.5 with increasing p. The microsc opic metallic character of transport is found in ESR and microwave mea surements. Spin-dependent conductivity is inferred from the (B/T)(2) u niversal behavior of magnetoresistance. Those results are discussed in conjunction with the ongoing debate on the nature of disorder in cond ucting polymers-homogeneous versus heterogeneous. [S0163-1829(98)01235 -1].