a) b - École Polytechnique de Montréal

CHAPTER 4 - LOW PERCOLATION THRESHOLD CONDUCTIVE
DEVICE DERIVED FROM A FIVE-COMPONENT POLYMER BLEND
4.1 Abstract
In this work we report on the preparation of a solid, 3D, low percolation threshold conductive
device prepared through the control of multiple encapsulation and multiple percolation effects in
a 5 component polymer blend system through melt processing. Conductive polyaniline (PANI) is
situated in the core of the 5 component continuous system comprised of high-density
polyethylene(HDPE), polystyrene(PS), poly(methyl methacrylate)(PMMA) and poly(vinylidene
fluoride)(PVDF) and, in this fashion, its percolation threshold can be reduced to below 5%. The
approach used here is thermodynamically controlled and is described by Harkins spreading
theory. In this work the detailed morphology and continuity diagrams of binary, ternary,
quaternary and finally quinary systems are progressively studied in order to systematically
demonstrate the concentration regimes resulting in the formation of these novel multiple-
encapsulated morphological structures. Initially, onion-type dispersed phase structures are
prepared and it is shown that through the control of the composition of the inner and outer layers
the morphology can be transformed to a hierarchical-self-assembled, multi-percolated structure.
The influence of a copolymer on selected pairs in the encapsulated structure is also examined.
The conductivity of the quinary blend system can be increased from 10 -15 S cm -1 (pure PE) to 10 -
5 S cm -1 at 5 % PANI and up to 10 -3 S cm -1 for 10% PANI. These are the highest conductivity
values ever reported for these PANI concentrations in melt processed systems.
4.2 Introduction
Over the last 30 years the polymer-polymer blending of conventional polymers has received
significant attention since these materials can result in highly synergistic property sets. Although
a vast number of studies have been devoted to the study of immiscible polymer blends and of the
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