The MF precondensate prepared as described
above was used to synthesize both imprinted (MIPs) and nonimprinted
(NIPs) monolithic MF polymers by the one-pot synthesis route shown
inFigure 1 b. In this
procedure, the MF precondensate (780 μL) was mixed with NIP
or MIP porogen solution (600 μL) and formic acid (35 μL)
in a 2 mL GC glass vial, then ultrasonically agitated as above to
prepare homogeneous solutions. The sonicated vials were capped with
PTFE-lined septa, shaken vigorously, and given an additional 30 s
ultrasonic treatment. Pretreated capillariesC3 cut into
50 cm long pieces were then filled with the MF precursor solution
by inserting one end through the pre-pierced septa of the precursor-containing
vial and the other end likewise into an empty septum-capped vial.
Slight N2 overpressure applied to the vial containing the
precursor solutions caused a slow flow, keeping the capillary inlet
submerged so that gas bubbles did not enter into the capillary. After
several drops of precursor solution had exited from the capillary
outlet, N2 pressure was released by piercing the septum
of the pressurized vial by a hypodermic needle. The filled capillary
was thereafter withdrawn from both vials and capped by piercing the
ends into silicone GC septa. Both the capped capillaries and the left-over
solutions in the source vials were transferred to a Binder ED53 convective
oven (Tuttlingen, Germany) where polymerization took place under static
conditions for 4 h at 80 °C. The capillaries were thereafter
allowed to cool to ambient temperature.
The polymerized capillaries
were detached from the septa and cut into monolith columns of 70 mm
length. The glass vials were disintegrated with minimal force to render
the bulk monolithic materials formed therein as intact as possible,
then parting it into roughly cubiform pieces with 2–3 mm sides,
which were transferred to cellulose extraction thimbles. Unreacted
precondensate, mesoporogen/template, co-porogen, solvents, and reaction
by-products were flushed from the capillaries by pumping with methanol
for 24 h at 20 μL/min. The parted bulk monoliths were Soxhlet-extracted
for 24 h with methanol. Cleaning of the capillary monoliths was followed
by flushing with at least ten column volumes of 70:30% (v/v) acetonitrile/water,
which was also used to store the capillary MIP and NIP monoliths in
a refrigerator at +4 °C. The Soxhlet-extracted bulk monolithic
materials were finally dried under reduced pressure (≈100 Pa)
in a Gallenkamp (Loughborough, UK) vacuum oven at 40 °C overnight,
followed by crushing and sieving (37–74 μm) prior to
further characterization.
above was used to synthesize both imprinted (MIPs) and nonimprinted
(NIPs) monolithic MF polymers by the one-pot synthesis route shown
in
procedure, the MF precondensate (780 μL) was mixed with NIP
or MIP porogen solution (600 μL) and formic acid (35 μL)
in a 2 mL GC glass vial, then ultrasonically agitated as above to
prepare homogeneous solutions. The sonicated vials were capped with
PTFE-lined septa, shaken vigorously, and given an additional 30 s
ultrasonic treatment. Pretreated capillaries
50 cm long pieces were then filled with the MF precursor solution
by inserting one end through the pre-pierced septa of the precursor-containing
vial and the other end likewise into an empty septum-capped vial.
Slight N2 overpressure applied to the vial containing the
precursor solutions caused a slow flow, keeping the capillary inlet
submerged so that gas bubbles did not enter into the capillary. After
several drops of precursor solution had exited from the capillary
outlet, N2 pressure was released by piercing the septum
of the pressurized vial by a hypodermic needle. The filled capillary
was thereafter withdrawn from both vials and capped by piercing the
ends into silicone GC septa. Both the capped capillaries and the left-over
solutions in the source vials were transferred to a Binder ED53 convective
oven (Tuttlingen, Germany) where polymerization took place under static
conditions for 4 h at 80 °C. The capillaries were thereafter
allowed to cool to ambient temperature.
The polymerized capillaries
were detached from the septa and cut into monolith columns of 70 mm
length. The glass vials were disintegrated with minimal force to render
the bulk monolithic materials formed therein as intact as possible,
then parting it into roughly cubiform pieces with 2–3 mm sides,
which were transferred to cellulose extraction thimbles. Unreacted
precondensate, mesoporogen/template, co-porogen, solvents, and reaction
by-products were flushed from the capillaries by pumping with methanol
for 24 h at 20 μL/min. The parted bulk monoliths were Soxhlet-extracted
for 24 h with methanol. Cleaning of the capillary monoliths was followed
by flushing with at least ten column volumes of 70:30% (v/v) acetonitrile/water,
which was also used to store the capillary MIP and NIP monoliths in
a refrigerator at +4 °C. The Soxhlet-extracted bulk monolithic
materials were finally dried under reduced pressure (≈100 Pa)
in a Gallenkamp (Loughborough, UK) vacuum oven at 40 °C overnight,
followed by crushing and sieving (37–74 μm) prior to
further characterization.
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