Colloidal silica nanoparticles
of an average diameter of 50 nm were purchased from Nissan Inc. Two
types of nanoparticles were prepared: (1) particles with grafted PMMA
with a graft density of 0.34 chains/nm2 and a molecular
weight of 120 000 g/mol, (2) particles with grafted polyaniline
acrylate polymer at a graft density of 0.34 chains/nm2 and
a molecular weight of 134 000 g/mol.
To create the grafted
polymers, poly(methyl methacrylate) (PMMA) and poly(acrylic acid N-hyroxysuccinimide) (PNAS) were synthesized by surface-initiated
reversible addition-fragmentation chain transfer polymerization (SI-RAFT).
The RAFT agent was 2-(dodecylthiocarbonothioylthio) propanoic acid
(DoPAT). All chemicals were used as received unless otherwise specified.
Methyl methacrylate (MMA, 99%, Acros) was purified by filtration through
an activated basic alumina column. Azobisisobutyronitrile (AIBN) was
recrystallized from methanol before use. Molecular weights and dispersity
were determined by monitoring monomer conversion through 1H NMR and gel permeation chromatography (GPC). THF was used as the
eluent for GPC at 30 °C and a flow rate of 1.0 mL/min. GPC was
calibrated with poly(methyl methacrylate) (PMMA) standards obtained
from Polymer Laboratories.
To synthesize free polyaniline acrylate,
DoPAT (5 mg, 0.014 mmol),
NAS (0.482 g, 2.84 mmol), and AIBN (140 μL in 0.01 M solution)
were dispersed in 4.75 mL of DMF and transferred into a dried Schlenk
flask. The mixture was degassed by three freeze–pump–thaw
cycles, back-filled with nitrogen, and then placed in an oil bath
at 65 °C. The polymerization solution was quenched in an ice
bath and exposed to air after 24 h. The polymer solution was precipitated
into diethyl ether and centrifuged at 6000 rpm for 5 min. The dispersion-precipitation
process was repeated four times. The polymer was then redissolved
in 5 mL of DMF and sparged with nitrogen for 15 min. N-Phenyl-p-phenylenediamine (1.05 g, 5.6 mmol) was
dissolved in 2 mL of DMF. The solution was then added to the polymer
solution where it was then transferred to an oil bath at 110 °C
for 24 h. The polymerization was quenched in an ice bath and precipitated
into diethyl ether and centrifuged at 6000 rpm for 5 min. The polymer
was then dissolved in THF, and the dispersion-precipitation process
was repeated until the supernatant was colorless. Polyaniline-acrylate-grafted
NPs were synthesized by a surface-initiated reversible addition-fragmentation
chain transfer polymerization (SI-RAFT).15 (link) A typical polyaniline-acrylate-grafted NP synthesis was: DoPAT-NP
(0.05 g, σ = 0.34 chains/nm2), NAS (0.30 g, 1.77
mmol), and AIBN (18 μL in a 0.1 M solution) were dispersed in
5 mL of DMF and transferred to a Schlenk flask. The remaining procedure
is identical to the free polyaniline acrylate synthesis.
of an average diameter of 50 nm were purchased from Nissan Inc. Two
types of nanoparticles were prepared: (1) particles with grafted PMMA
with a graft density of 0.34 chains/nm2 and a molecular
weight of 120 000 g/mol, (2) particles with grafted polyaniline
acrylate polymer at a graft density of 0.34 chains/nm2 and
a molecular weight of 134 000 g/mol.
To create the grafted
polymers, poly(methyl methacrylate) (PMMA) and poly(acrylic acid N-hyroxysuccinimide) (PNAS) were synthesized by surface-initiated
reversible addition-fragmentation chain transfer polymerization (SI-RAFT).
The RAFT agent was 2-(dodecylthiocarbonothioylthio) propanoic acid
(DoPAT). All chemicals were used as received unless otherwise specified.
Methyl methacrylate (MMA, 99%, Acros) was purified by filtration through
an activated basic alumina column. Azobisisobutyronitrile (AIBN) was
recrystallized from methanol before use. Molecular weights and dispersity
were determined by monitoring monomer conversion through 1H NMR and gel permeation chromatography (GPC). THF was used as the
eluent for GPC at 30 °C and a flow rate of 1.0 mL/min. GPC was
calibrated with poly(methyl methacrylate) (PMMA) standards obtained
from Polymer Laboratories.
To synthesize free polyaniline acrylate,
DoPAT (5 mg, 0.014 mmol),
NAS (0.482 g, 2.84 mmol), and AIBN (140 μL in 0.01 M solution)
were dispersed in 4.75 mL of DMF and transferred into a dried Schlenk
flask. The mixture was degassed by three freeze–pump–thaw
cycles, back-filled with nitrogen, and then placed in an oil bath
at 65 °C. The polymerization solution was quenched in an ice
bath and exposed to air after 24 h. The polymer solution was precipitated
into diethyl ether and centrifuged at 6000 rpm for 5 min. The dispersion-precipitation
process was repeated four times. The polymer was then redissolved
in 5 mL of DMF and sparged with nitrogen for 15 min. N-Phenyl-p-phenylenediamine (1.05 g, 5.6 mmol) was
dissolved in 2 mL of DMF. The solution was then added to the polymer
solution where it was then transferred to an oil bath at 110 °C
for 24 h. The polymerization was quenched in an ice bath and precipitated
into diethyl ether and centrifuged at 6000 rpm for 5 min. The polymer
was then dissolved in THF, and the dispersion-precipitation process
was repeated until the supernatant was colorless. Polyaniline-acrylate-grafted
NPs were synthesized by a surface-initiated reversible addition-fragmentation
chain transfer polymerization (SI-RAFT).15 (link) A typical polyaniline-acrylate-grafted NP synthesis was: DoPAT-NP
(0.05 g, σ = 0.34 chains/nm2), NAS (0.30 g, 1.77
mmol), and AIBN (18 μL in a 0.1 M solution) were dispersed in
5 mL of DMF and transferred to a Schlenk flask. The remaining procedure
is identical to the free polyaniline acrylate synthesis.
