Supporting Information:
Synchronous and Separate Homo-Crystallization
of Enantiomeric Oligomeric Poly(L-3-hydroxybutanoic acid)
/Poly(D-3-hydroxybutanoic acid) Blend
Hideto Tsuji,* Soma Noda, and Satoru Shimizu
1
Department of Environmental and Life Sciences, Graduate School of Engineering,
Toyohashi University of Technology,
Tempaku-cho, Toyohashi, Aichi 441-8580, Japan
Email: tsuji@ens.tut.ac.jp
* To whom correspondence should be addressed
1
Synthesis of P(L-3HB) and P(D-3HB)
P(L-3HB) and P(D-3HB) were synthesized by polycondensation of L-3-hydroxybutanoic acid [or
(S)-3-hydroxybutyric
D-3-hydroxybutanoic
acid]
(≥
97.0%,
Kanto
Chemical
Co.,
Inc.,
Tokyo,
Japan)
and
acid (D-3HB) [or (R)-3-hydroxybutyric acid] (≥ 97.0%, Sigma-Aldrich Co.),
respectively, using 5wt% p-toluenesulfonic acid (monohydrate, guaranteed grade, Nacalai Tesque inc.,
Kyoto, Japan) as the catalyst, as reported previously.1–3
The reaction was performed at 130°C under
atmospheric pressure for 5 h. The synthesized polymers were purified by extraction using methanol
(guaranteed grade, Nacali Tesque Inc.). The purified polymers were dried under reduced pressure for
at least 6 days.
As shown in Table 1, after polycondensation of L- and D-hydroxybutanoic acid at 130°C for 5 h
under atmospheric pressure, Mw values were increased to 1.3 and 1.8103 gmol-1, respectively.
However, further polycondensation under atmospheric or reduced pressure did not increase Mw values,
meaning 5 h of polycondensation was sufficient to reach saturated Mw values at 130°C.
1
H NMR
measurements were performed on the synthesized and purified P(L-3HB) and P(D-3HB), together
with that of one of the monomers, as-received D-3HB.
The methine multiplet, methylene multiplet,
and methyl doublet peaks of D-3HB were observed at 4.2–4.3, 2.4–2.6, and 1.2–1.3 ppm, respectively,
whereas the methine, methylene, methyl multiplet peaks of P(L-3HB) and P(D-3HB) were seen at
5.2–5.3, 2.4–2.7, and 1.2–1.3 ppm, respectively, which are in agreement with the previously reported
values for P(D-3HB).4,5
The higher chemical shift values of methine group of P(L-3HB) and
P(D-3HB) compared with that of monomer D-3HB are consistent with the result reported for PLLA.6
Also, the positive and negative values of P(L-3HB) and P(D-3HB) (Table 1) are in agreement with the
reported result.7 The lower absolute []25589 value of P(D-3HB) compared with that of P(L-3HB) can
be ascribed to the relatively higher molecular weight of the former, as reported previously.7 The
aforementioned results indicate the synthesis of P(L-3HB) and P(D-3HB) in the present study.
Sample preparation
2
The samples of neat P(L-3HB) and P(D-3HB)
physical measurements and observation were prepared by casting 1 g dL-1 solutions of the polymers
using dichloromethane as the solvent, and subsequent solvent evaporation at room temperature,
followed by drying under reduced pressure for at least 6 days.
For preparation of a blend sample, the
separately prepared solutions of P(L-3HB) and P(D-3HB) were mixed vigorously before solution
casting.
We call thus prepared samples solution-crystallized samples.
For preparation of
melt-crystallized samples, solution-crystallized neat P(L-3HB) and P(D-3HB), and their blend samples
were sealed in test-tubes under reduced pressure, melted at 150°C for 3 min, crystallized at
crystallization temperature (Tc) of 60°C for 3 h, and quenched at 0°C for 5 min.
Table S1. Thermal properties and crystallinity of neat P(L-3HB), P(D-3HB), their blend, and HMW
P(L-3HB).
Code
P(L-3HB)
P(D-3HB)
Blend
HMW P(D-3HB)
Crystallization procedure
Tma)
(°C)
ΔHma)
(J g-1)
Xcb)
(%)
Solution
101.8, 107.7
61.8
73.0
Melt (Tc = 60°C)
94.9, 104.9
43.4
73.9
Solution
105.7, 121.8
75.6
74.6
Melt (Tc = 60°C)
101.8，118.2
83.3
76.9
Solution
92.5, 104.4, 116.3
80.4
79.1
Melt (Tc = 60°C)
92.7, 103.4, 116.0
58.6
78.9
As-received
176.3
85.8
76.4
a)
Melting temperature and enthalpy (Tm and ΔHm, respectively) were obtained by DSC measurements.
b)
Crystallinty estimated by WAXD measurements.
Table S2. Front constant (G0) and nucleation constant (Kg) of neat P(L-3HB), P(D-3HB), and their
blend.
Code
P(L-3HB)
P(D-3HB)
Blend
G0
(m min-1)
5.29×1021
6.10×1018
2.69×1019
Kg
(K2)
1.38106
1.12106
1.23106
3
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2.
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3.
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4.
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5.
Nduko, J. M., Matsumoto, K., Ooi, T., Taguchi, S. Appl. Microbiol. Biotech., 98, 2453–2460
(2014).
6.
Espartero, J. L., Rashkov, I., Li, S. M., Manolova, N., Vert, M., Macromolecules, 29, 3535–3539
(1996).
7.
Marchessault, R. H., Okamura, K., Su, C. J. Macromolecules, 3, 735–740 (1970).
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