a) b - École Polytechnique de Montréal

CoPA/LLDPE/PANI blend and a poor-quality PANI network in a (PS+DOP)/LLDPE/PANI
blend. They concluded and reported formation of a host matrix containing two co-continuous
immiscible thermoplastic polymer phases and developed a model predicting that doped PANI
can generate a network at the interface of CoPA/LLDPE blend and disperse in a
(PS+DOP)/LLDPE blend due to their solubility properties. Zilberman et al.(Zilberman et al.,
1997) measured the stability of conductivity of 80%PS/20%PANI-DBSA blend at 80ºC in a
vacuum and at 50ºC in 60% RH based on exposure time. It was noted that after four hours, the
conductivity decreased from 0.25 S/cm to about 0.1 S/cm in both states. Fraysse et al.(Fraysse,
Planes, & Dufresne, 2000) could decrease the percolation threshold of PANI sharply in a
PANI/PMMA blend prepared by melt dispersion to 0.5 wt% of PANI. TEM micrographs showed
that connectivity of the PANI-CSA network in PANI-CSA/PMMA blend decreases rapidly for a
volume fraction less than 0.5% (Figures 2-27a and 2-27b)(Reghu et al., 1994; C. Y. Yang, Y.
Cao, Paul Smith, & A. J. Heeger, 1993a).
A typical scenario for a percolating medium with “links” (PANI-CSA fibrils), “nodes” ((crossing
points of the links), and “blobs” (dense, multiply connected regions)(Stauffer & Aharony,
1994b)) is illustrated in these figures. Numerous links with diameters of about 100-500 Å are
clearly exhibited in the sample containing 0.5% PANI-CSA (Figure 2-27a), while rather few
links between the nodes and blobs are observed in sample containing 0.25% PANI-CSA (Figure
2-27b). They showed that the relationship between conductivity and volume fraction of PANI-
CSA was critically dependent upon the nature of mass distribution among the links, nodes, and
blobs in the samples. They found various parameters involved in this distribution including the
molecular weight of the polymers, the viscosity of the polyblend solution, the solvent, and the
drying temperature.
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