2. In a Schlenk 250 mL 19/24 cone (A), dry 5 cm of 4 A ˚ sieves:
3 cycles vac/N 2 , vacuum and hot gun for 5 min, cooling under
vacuum. Then add up to 220 g of ε-caprolactone (20 g lost on
sieves).
3. In a 25 mL Schlenk (B), dry 1 cm of sieves (same procedure as
above), and add between 10 and 20 mL of HEVE.
4. Prepare 1 dry, cooled 250 mL Schlenk (C) 14/20 cone, with
one magnetic stirrer, by assembling hot parts from oven, cooling under vacuum, and run 3 cycles vac/N 2 . Replace glass
stopper with rubber stopper under nitrogen flow.
5. In a three-neck round-bottom flask equipped with a rubber
septum, a nitrogen/vacuum inlet, and a thermometer, transfer
the required amounts of dry DCM (from half to same as
monomer) and ε-CL using a double-tipped needle.
6. In the glove box under argon atmosphere, place the required
amount of trimethylaluminum (1 M solution in toluenecatalyst) in a Schlenk tube under magnetic stirring, then slowly
add a solution of HEVE in toluene, and keep the mixture under
stirring for 10 min.
7. Inject the catalyst precursor through the septum with a
nitrogen-flushed syringe to the Schlenk containing the ε-CL
(ε-CL/HEVE ratio 12.5:1). Leave the reaction proceed under
vigorous stirring overnight, under a static atmosphere of nitrogen at room temperature.
8. Disconnect the flask from the nitrogen inlet and gently pour
the content to a cold 1:1 methanol/water bath. Maintain
under vigorous stirring for at least 2 h until polymer particles
are clearly visible. The bath size needs to be 3–5 times the total
volume of the reagents.
9. Filter the methanol suspension gently on a Buchner filtration
device and recover the solid VPCL (MW ¼ 1.5 kDa).
10. Dry the solid VPCL overnight in vacuum oven at 30
C.
3.2 Synthesis
of VPCLF
1. Transfer the required amount of previously synthesized VPCL
and K 2 CO 3 in a three-neck round-bottom flask, equipped with
a magnetic stirrer, a reflux condenser, a rubber septum, and a
nitrogen/vacuum inlet, and place in a water bath.
2. Apply three cycles of vacuum/nitrogen to the flask to remove
traces of moisture and oxygen, and then transfer dry DCM
using a double-tipped needle.
3. After complete dissolution of the polymer, add the desired
amount of fumaryl chloride dissolved in dry DCM via injection
through the rubber septum to the suspension under vigorous
stirring. The reaction is kept overnight at 50
C under reflux
under a static nitrogen atmosphere.
58
Alfredo Ronca et al.
3 cycles vac/N 2 , vacuum and hot gun for 5 min, cooling under
vacuum. Then add up to 220 g of ε-caprolactone (20 g lost on
sieves).
3. In a 25 mL Schlenk (B), dry 1 cm of sieves (same procedure as
above), and add between 10 and 20 mL of HEVE.
4. Prepare 1 dry, cooled 250 mL Schlenk (C) 14/20 cone, with
one magnetic stirrer, by assembling hot parts from oven, cooling under vacuum, and run 3 cycles vac/N 2 . Replace glass
stopper with rubber stopper under nitrogen flow.
5. In a three-neck round-bottom flask equipped with a rubber
septum, a nitrogen/vacuum inlet, and a thermometer, transfer
the required amounts of dry DCM (from half to same as
monomer) and ε-CL using a double-tipped needle.
6. In the glove box under argon atmosphere, place the required
amount of trimethylaluminum (1 M solution in toluenecatalyst) in a Schlenk tube under magnetic stirring, then slowly
add a solution of HEVE in toluene, and keep the mixture under
stirring for 10 min.
7. Inject the catalyst precursor through the septum with a
nitrogen-flushed syringe to the Schlenk containing the ε-CL
(ε-CL/HEVE ratio 12.5:1). Leave the reaction proceed under
vigorous stirring overnight, under a static atmosphere of nitrogen at room temperature.
8. Disconnect the flask from the nitrogen inlet and gently pour
the content to a cold 1:1 methanol/water bath. Maintain
under vigorous stirring for at least 2 h until polymer particles
are clearly visible. The bath size needs to be 3–5 times the total
volume of the reagents.
9. Filter the methanol suspension gently on a Buchner filtration
device and recover the solid VPCL (MW ¼ 1.5 kDa).
10. Dry the solid VPCL overnight in vacuum oven at 30
C.
3.2 Synthesis
of VPCLF
1. Transfer the required amount of previously synthesized VPCL
and K 2 CO 3 in a three-neck round-bottom flask, equipped with
a magnetic stirrer, a reflux condenser, a rubber septum, and a
nitrogen/vacuum inlet, and place in a water bath.
2. Apply three cycles of vacuum/nitrogen to the flask to remove
traces of moisture and oxygen, and then transfer dry DCM
using a double-tipped needle.
3. After complete dissolution of the polymer, add the desired
amount of fumaryl chloride dissolved in dry DCM via injection
through the rubber septum to the suspension under vigorous
stirring. The reaction is kept overnight at 50
C under reflux
under a static nitrogen atmosphere.
58
Alfredo Ronca et al.