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or functional groups such as carbonyl or hydroxyl groups
have been prepared for these purposes. As mentioned above,
some furanic-based monomers can be successfully used to
replace fossil fuel-based molecules. Moore and Kelly31,32 ini-
tially explored the scope and limitations of FDCA in polycon-
densation reactions. The authors synthesized a series of pol-
yesters based on FDCA and different diols and showed an
enormous potential of this furan-based compound. However,
owing to the limited availability of high-purity FDCA, the
research interest in this field declined in the following years.
Nevertheless, owing to the recent developments in the cata-
lytic routes toward high-purity FDCA, it is currently possible
to obtain high-purity FDCA in larger amounts. These devel-
opments sparked a significant increase in the amount of
research carried out toward FDCA-based polycondensates.
Gandini et al. have shown that FDCA or related compounds
are widely applicable in polymer chemistry.18–20,33–35 Fur-
thermore, recent studies concerning the properties of high-
molecular-weight polyesters, that is poly(ethylene-2,5-furan-
diacrboxylate)35,36 revealed that polycondensates based on
FDCA or other furanic derivatives could be interesting
replacements for fossil fuel-based polymeric materials. It
was shown that polyesters based on FDCA reveal higher
glass transition temperature (Tg), heat deflection tempera-
ture, and better barrier properties when compared with TPA
analogues.37 Furthermore, the strong dienic character of
FDCA19 extends its range of the applications in polymer
chemistry and material science. FDCA is very well suited for
DA reactions, leading to new possibilities in the reversible
curing of FDCA-derived polymers.18,20,38,39
Chloroform-d (CDCl3, 99.8% atom-d) was obtained from
Cambridge Isotope Laboratories. All chemicals were used as
received unless stated otherwise.
Synthesis of Dimethyl-2,5-furandicarboxylate (DM-FDCA)
FDCA (10 g, 0.064 mol) was reacted with methanol (118.7 g,
3.4 mol) in the presence of hydrochloric acid (1 mL) as a
catalyst. This reaction was allowed to continue for 18 h and
subsequently the catalyst was deactivated by adding 30 mL
of 0.5 N methanolic KOH solution. The solvent was evapo-
rated and the obtained white solid product was dissolved in
CHCl3. The solution was filtered and washed with demi-
water (2 ꢁ 200 mL) and brine (1 ꢁ 200 mL). Subsequently,
this solution was dried over MgSO4. Then, the solution was
filtered and the solvent evaporated using a rotary evaporator.
The obtained solids were recrystallized from CHCl3, affording
white crystals.
Yield: 80%. FTIR (m/cmꢂ1); 3118 (¼¼CH); 2964 (CAH); 1719
(C¼¼O); 1583, 1515 (C¼¼C); 1264 (CAO); 987, 834, 765
1
(¼¼CH). H-NMR (400 MHz, CDCl3, d, ppm): 3.94 (s, 6H), 7.23
(d, 2H). 13C-NMR (100 MHz, CDCl3, d, ppm): 52.36 (OCH3),
118.44 (furan ring C3 and C4), 146.67 (furan ring C2 and
C5), 158.29 (C¼¼O). Melting point ¼ 112 ꢀC, Tm,lit ¼ 107–
40
ꢀ
108 C. ELEM. ANAL. calc. C8H8O5: C, 52.18; H, 4.38; O, 43.44,
found: C, 52.24; H, 4.54; O, 43.18.
Synthesis of Poly(2,3-butylene-2,5-furancarboxylate)
A mixture of FDCA (5 g, 0.032 mol) or dimethyl-2,5-furandi-
carboxylate (5.9 g, 0.032 mol) and 2,3-butanediol (8.65 g,
0.096 mol) was reacted in a 100-mL three-necked round-
bottomed flask equipped with a vigreux column, a Dean–
Stark condenser, and a mechanical stirrer. The first step of
the polymerization was carried out at 180 ꢀC under argon
atmosphere in the presence of Irganox 1330 (1 wt % rela-
tive to the amount of furan-based monomer) and the catalyst
(0.1 wt % relative to the total amount of the monomers). Af-
ter the esterification/transesterification process by 1H-NMR
spectroscopy after 24 h, the second portion of catalysts (0.1
wt % relative to the initial total amount of the monomers)
was added. The polycondensation was continued under
reduced pressure for 4 h at 220 ꢀC. The analyses of the
obtained polyesters were performed on crude samples.
In this article, we present a series of novel, low-molecular-
weight amorphous polyesters based on FDCA and 2,3-buta-
nediol synthesized by bulk polycondensation. Furthermore, a
detailed study of the chemical structure using nuclear mag-
netic resonance (NMR), Fourier transform infrared spectros-
copy (FTIR), matrix-assisted laser ionization-desorption
time-of-flight mass spectrometry (MALDI-ToF-MS), electro-
spray ionization time-of-flight mass spectrometry (ESI-ToF-
MS), and electrospray ionization quadruple time-of-flight
mass spectroscopy (ESI-Q-ToF-MS-MS) an analysis of
the thermal properties has been performed. The relatively
low-molecular-weight, high Tg bio-based polyesters could be
successfully applied for (powder) coating applications.
METHODS
Size exclusion chromatography (SEC) was performed on a
Waters Alliance system equipped with a Waters 2695 separa-
tion module, a Waters 2414 refractive index detector at 35
ꢀC, a Waters 2487 dual absorbance detector, and a PSS SDV
5l guard column followed by 2 PSS SDV linearXL columns in
EXPERIMENTAL
Materials
FDCA was kindly supplied by Avantium. Meso-2,3-Butanediol
(99% (2R,3S)-butanediol) (23BD, fractionally distilled prior
to use), titanium n-butoxide (TiBO), tin (IV) ethylhexanoate
(Sn(Oct)2), zirconium(IV) butoxide (80 wt % solution in 1-
butanol) (ZrBO), 37 wt % aqueous solution of hydrochloric
acid (HCl), anhydrous magnesium sulfate (MgSO4), 4-dime-
thylaminopyridine (DMAP), and 0.1 and 0.5 N methanolic
solutions of potassium hydroxide (KOH) were purchased
from Sigma Aldrich. Irganox 1330 was obtained from CIBA
specialty chemicals. Methanol (MeOH), chloroform (CHCl3),
and tetrahydrofuran (THF) were obtained from Biosolve.
ꢀ
series of 5l (8 ꢁ 300) working at 40 C. THF stabilized with
butylated hydroxytoluene and 1 v/v % acetic acid was used
as eluent at a flow rate of 1.0 mL/min. The obtained molecu-
lar weights were calculated with respect to polystyrene stand-
ards (Polymer Laboratories, Mp ¼ 580 Da up to Mp ¼ 7.1 ꢁ
106 Da).
The acid value (AV) was determined by potentiometric titra-
tion. The measurements were carried out using a Metrohm
Titrino Plus 848 automatic buret equipped with a Metrohm
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JOURNAL OF POLYMER SCIENCE, PART A: POLYMER CHEMISTRY 2013, 51, 890–898
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