Catalytic Synthesis and Characterization of Biodegradable ...

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Synthesis of Triblock Copolymers of TEMPO‐Acrylamide
and Lactate by RAFT Polymerization
on an indium tin oxide (ITO) electrode as working electrode and Ag/Ag + as reference
electrode. Cyclic voltammograms were recorded on a CHI 630 potentiostat with different
scanning rate.
Synthesis of Hydroxyl-capped PLA
After recrystallization in ethyl acetate for three times, lactide (1 mol) was added to a
flame-dried and nitrogen-purged glass ampoule, into which a 150 mL toluene solution of
BDO (7.2 mmol) and Sn(Oct)2 (0.3% of the BDO, mol/mol) was then transferred. The
reaction vessel was immersed into a thermostatic oil bath maintained at 120 o C, under
magnetic stirring for 24 h. The reaction product was precipitated into ethanol, filtered and
dried at 40 o C in vacuum for 48 h.
Synthesis of Macromolecular CTA: CPAD-PLA-CPAD
Typically, PLA 5 g (0.5 mmol), CPAD 0.28 g (1mmol), DCC 0.42 g (2 mmol) and DMAP
0.025 g (0.2 mmol) were dissolved in 20 mL anhydrous methylene chloride. The solution was
stirred at room temperature for 48 hours. After filtration of the precipitate, the solution was
poured into 200 mL cold ethyl ether, yielding pink precipitate. The pink precipitate was
redissolved in methylene chloride and precipitated again in cold ethyl ether. After washing
with additional two times with ethyl ether, the pink product CPAD-PLA-CPAD was finally
obtained, Yield 92%.
Synthesis of PTAm-b-PLA-b-PTAm
Typically, 0.20 g CPAD-PLA-CPAD (0.02 mmol), 0.29 g (1.4 mmol) TAP monomer and
1.6 mg AIBN (0.01 mmol) ware dissolved in 2 mL THF. The mixture was deaerated by
applying three times freeze-pump-thaw cycle. Afterwards, the tube was immerged in 90 o C
oil bath and stirred for 12 hours. After cooling to room temperature, the mixture was
precipitate in cold ethyl ether. The slight pink precipitate was collected and washed twice
with ethyl ether. The product was obtained after vacuum drying for 24 h with a yield of 81%.
In order to obtain PTAm-b-PLA-b-PTAm, an oxidation step was needed. Typically, 110 mg of
the aforementioned PTAP-b-PLA-b-PTAP dissolved in 5 mL THF and stirred in ice-cold bath,
to which 500 mg of m-chloroperbenzoic acid (mCPBA) was added. The mixture was allowed
to move to the room temperature and stirred for further 4 hours. The final product was
obtained by precipitate the mixture into 120 mL ethyl ether/n-hexane (v/v, 1:1), Yield: 92%.