Supplementary Material
Crystallization and Melting of Poly(glycerol adipate) Based Graft Copolymers
with Single and Double Crystallizable Side Chains
Dirk Pfefferkorn,† Martin Pulst,† Toufik Naolou,† Karsten Busse,† Jens Balko,‡ Jörg Kressler*,†
†
Department of Chemistry, Martin Luther University Halle-Wittenberg, D-06099 Halle(Saale),
Germany
‡
Department of Physics, Martin Luther University Halle-Wittenberg, D-06099 Halle(Saale),
Germany
*
Corresponding author E-mail: joerg.kressler@chemie.uni-halle.de
Polymer Synthesis
Synthesis of Poly(glycerol adipate) PGA. Ploy(glycerol adipate) was synthesized
enzymatically using glycerol and divinyl adipate as monomers according to the procedure
described by Kallinteri et al.1
Synthesis of alkyne modified poly(glycerol adipate) PGA-alkyne. PGA (1.5 g, 7.41
mmol with respect to OH groups) and 5-hexynoic acid (2.1 ml, 18.5 mmol) were dissolved into
20 ml dichloromethane (DCM) and added to an oven dried 100 ml two-necked round bottom
flask. The mixture was cooled using an ice bath. Afterwards, a solution of 4-(dimethylamino)pyridin (DMAP) (293 mg, 0.96 mmol) and dicyclohexylcarbodiimid (DCC) (3.44ml, 14.85
mmol) dissolved into 10 ml of DCM was dropwise added to the polymer solution over 20 min.
The mixture was stirred at room temperature for 24 h and yields finally a brownish solution. The
solution was then filtered to remove the resulting precipitate. The organic solution was then
extracted three times using distilled water. The organic layer was dried by anhydrous sodium
sulfate. The polymer was further purified by precipitation into cold n-hexane two times followed
by drying at 40°C. The 1H NMR spectrum of PGA-alkyne in CDCl3 is given in the Figure S1.
The integral ratio between peak a and peak d is 4 : 0.97 which means nearly quantitative
coupling.
Synthesis of Poly(glycerol adipate)-g-Poly(ethylene oxide) PGA-g-PEO. PGA-alkyne
(150 mg, 0.51 mmol with respect to alkyne group) and azide-terminated poly (ethylene glycol)
monomethylether (1.2 mg, Mn=2000 g/mol, 0.56 mmol) were dissolved into 3.5 ml anhydrous
dimethylformamide (DMF) and then loaded 10 ml oven dried Schlenk flask. Degassing was
carried out by bubbling nitrogen for 15 min. This was followed by addition of (21 mg, 0.15
mmol) of CuBr and (0.031 ml, 0.15 mmol) of N,N,N′,N′′,N′′-pentamethyldiethylenetriamine
(PMDETA). Further degassing was carried out again using nitrogen for 10 min. The solution was
kept for 37 h at room temperature. The reaction was quenched by open the rubber septum for 30
min. The solution was then diluted using tetrahydrofurane (THF), and purified using a silica gel
column in order to remove cupper bromide. This was followed by removing solvent using rotary
evaporation at 40 °C under vacuum. The residue was redissolved using 10 ml methanol followed
by dialysis against water for four days using regenerated cellulose membrane MWCO= 3500 Da.
The polymer was finally dried by freeze drying.
Figure S2 shows the 1H NMR spectrum of PGA17-g-PEO44 in CDCl3. The grafting
efficiency was calculated by calculating the integrate ratio between peak m and peak d which was
3 : 0.97. Thus, the reaction was almost quantitative within the experimental error of 1H NMR
spectrascopy. Furthermore, the comparison between the FT-IR spectra of PGA17-alkyne and
PGA17-g-PEO44 reveals a complete disappearance of alkyne vibration of PGA17-alkyne at 650,
2115, and 3290 cm-1 as a result of the coupling reaction Figure S3.
Synthesis of poly(glycerol adipate)-g-poly(ε-caprolactone) PGA-g-PCL. The typical
procedure to synthesize PGL-g-PCL is described here briefly; PGA (Mn= 3400 g/mol, 1 mmol
with respect to hydroxyl group), ε-caprolactone (25 mmol) and stannous octoate (0.027 ml) were
dissolved in 10 ml of anhydrous THF and charged in 25 ml oven dried Schlenk tube. The solution
was degassed and stirred for 20 h. The solution was then concentrated and precipitated into 200
ml of methanol. Precipitation in methanol was repeated many times in order to remove the
inevitably generated homopolymer poly(ε-caprolactone).2
Synthesis of alkyne-modified poly(glycerol adipate)-g-poly(ε-caprolactone), PGA-g(PCL-alkyne). PGA-g-PCL (Mn= 32000 g/mol, 0.52 mmol) and 5-hexynoic acid (0.13 ml, 1.15
mmol) were dissolved into 25 ml of anhydrous dichloromethane (DCM) and added to 100 mL
round bottom flask. The solution was then cooled using ice bath. A solution of 1-ethyl-3-(3dimethylaminopropyl)carbodiimide (EDCI) (1.15 mmol) and DMAP (0,23 mmol) dissolved into
7 ml DCM was then dropwise added to the cooled solution. The mixture was stirred for 24 h at
ambient temperature. The resulting solution was filtered to remove the precipitate. The polymer
solution was then precipitated two times into cold diethyl ether and dried under vacuum at room
temperature.
Synthesis of PGA-g-(PCL-b-PEO) using “click” chemistry. Briefly, PGA-g-PCL
(Mn=32000 g/mol, 0.29 mmol), azido-terminated poly(ethylene oxide) monomethylether (mPEO-N3) (Mn= 2000 g/mol, 0.3 mmol), and PMDETA (0.2 mmol) were dissolved into anhydrous
DMF and added to 25 ml Schlenk tube. The tube was degassed for 10 min. Then (0.2 mmol) of
CuBr was added. The solution was agitated for 48 h at ambient temperature. The polymer
solution was passed then through alumina column to remove CuBr. The resulting solution was
concentrated and dialyzed against water for 4 days using dialysis membrane of MWCO= 3500
g/mol. The product was dried by freeze-drying.
Synthesis of -Hydroxy--Alkyne End Functional Poly(ε-caprolactone) (AlkynePCL).The polymer was synthesized according to the procedure described by Hoogenboom et al. 3
The reaction was carried out at 85 °C.
Synthesis of Poly(ε–caprolactone)-b-Poly(ethylene oxide) PCL-b-PEO. Alkyne-PCL
(Mn=1800 g/mol, 0.4 mmol), mPEO-N3 (Mn= 2000 g/mol, 0.4 mmol) were dissolved into 20 ml
anhydrous DMF and added to oven dried Schlenk tube. The tube was purged with nitrogen for 10
min. CuBr (16 mg, 117 mmol), PMDETA (0.024 ml, 117 mmol) were then added. The solution
was purged again with nitrogen for 10 min. afterwards; the solution was kept at room temperature
for 2 d. At the end resulting solution was passed through alumina column in order to remove
copper bromide. The resulting solution was dialyzed against acetone for 2 d using dialysis
membrane of MWCO= 2000 g/mol. Finally, the resulting polymer was dried in an oven at 50 °C
under vacuum.
FigureS1. 1H NMR of PGA17-alkyne in CDCl3 at 400 MHz.
Figure S2. 1H NMR spectrum of PGA17-g-PEO44 in CDCl3 at room temperature and 400 MHz.
Figure S3. FT-IR spectra of PGA17-alkyne and PGA17-g-PEO44.
Figure S4. The WAXD pattern of PEO44 and PGA17-g-PEO44.
Figure S5. SAXS traces of PCL16.
Figure S6. The SAXS patterns of PGA17-g-PCL15.
Figure S7. The SAXS patterns of PGA17-g-PCL25.
References
(1)
Kallinteri, P.; Higgins, S.; Hutcheon, G. A.; St Pourçain, C. B.; Garnett, M. C.
Biomacromolecules 2005, 6, 1885–1894.
(2)
Aoi, K.; Aoi, H.; Okada, M. Macromol. Chem. Phys. 2002, 203, 1018–1028.
(3)
Hoogenboom, R.; Moore, B. C.; Schubert, U. S. Chem. Commun. (Cambridge, U. K.)
2006, 4010–4012.