a) b - École Polytechnique de Montréal

CONCLUSION AND RECOMMENDATIONS
In this dissertation, we developed the phase morphology of multi-component blends via melt-
processing, assisted by solvent etching, in order to generate novel conductive devices with an
ultra-low percolation threshold. This thesis evaluates and develops continuity evolution in cocontinuous,
double-percolated, triple-percolated, and quadruple-percolated morphologies to find
a way to considerably reduce the percolation threshold of all phases in the blend.
In order to achieve the aforementioned objective (reducing the percolation threshold of the
conductive polymer and other phases), a comprehensive systematic study on binary, ternary,
quaternary, and quinary blends with particular complete wetting morphology is investigated for
the first time. In this case, reduction of the continuity and/or electrical percolation threshold of
phases, particularly of a conductive polymer, is carried out by developing the novel and original
structures defined as multi-percolated structures. These special structures are constituted of
hierarchically ordered self-assembled continuous phases in polymer blends. Since the first
condition for the preparation of hierarchically ordered phase structures in a multi-component
blend is satisfying all Harkins equation sets, based on the various interfacial tensions for the
polymer pairs in the blend, the components must be precisely selected to meet the condition. For
this reason, polyaniline and four other commercial polymers with specific surface tensions,
polarities and interfacial tensions are precisely selected. The interfacial tensions between the
various components range from 1 mN/m for PVDF/PMMA to 26.9 mN/m for PANI/HDPE.
Morphological sample characterization is performed by both SEM and FIB-AFM techniques.
The polymer blends are prepared in a melt-blending process in an internal mixer at 50 rpm for 8
min at 200°C. Selective solvent extraction of phases either assists in better detection of phases in
order to collect qualitative data, or is employed to produce porous samples. A combination of
FIB treatment and AFM technique allows us to clearly distinguish the phases based on the
topographical contrast formed by the difference in the FIB etching rate of materials. In order to
study the effect of viscosity ratio on the ternary blends, both low molecular weight and high
molecular weight poly(methyl methacrylate) are selected.
In this thesis, fundamental studies are developed as models to prepare novel morphologies such
as onion morphology and multi-percolated morphologies. By employing a melt-processable
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