The use of new “tailor-made” reactive statistical copolymers
for the synthesis of sterically stabilized
polypyrrole colloids is described. These copolymer stabilizers are
readily prepared by free-radical
copolymerization of (bi)thiophene-based vinylic monomers with
various hydrophilic vinyl monomers such
as 2-(dimethylamino)ethyl methacrylate, 2-vinylpyridine,
N-vinylpyrrolidone or oligo(ethylene
oxide)
methacrylate. Monitoring the oxidation of the bithiophene graft
sites using visible absorption spectroscopy
provided evidence for stabilizer grafting. Relatively high
stabilizer efficiencies were obtained and the
resulting spherical polypyrrole particles contained 14 to 48%
stabilizer by mass and had reasonably narrow
size distributions in the 50−100 nm range. Pressed pellet
conductivities were as high as 4 S cm-1.
X-ray
photoelectron spectroscopy studies indicated that the polypyrrole
particles were coated with an overlayer
of grafted stabilizer, as expected from steric stabilization theory.
This route to polypyrrole particles is
believed to be completely general and is expected to allow the rational
design of steric stabilizers containing
a wide range of functional comonomers. This should be useful for
the improved design and performance
of immunodiagnostic assays based on polypyrrole “marker”
particles.
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