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the monomer, side reactions (e.g., decarboxylation) taking
place during the polymer synthesis, or the presence of vari-
ous additives. It was also found that catalysts such as man-
the dimethyl ester of FDCA as raw material and low polycon-
densation temperatures (<230 8C) and less times (less than
3 h). The polyesters with 9 and 10 methylene groups were
prepared for the first time. Besides, although the synthesis
of POF and PDoF has been reported in the literature, their
physical and mechanical properties have not been studied in
such detail as in the current work.
7
ganese, cobalt, and germanium result in a strongly colored
8
PEF product. Furthermore, as was reported by de Jong
3
et al., there is a clear relationship between the amount of
FDCA and the amount of color formed.
Despite the fact that the use of 2,5-FDCA as monomer seems
to be associated with colored products, a number of success-
ful attempts have been reported for the preparation of furan
dicarboxylate polyesters. To avoid coloration, acid/diol molar
ratios ranging from 1/3 to 1/5 have been used in almost all
of the published works, whereas when terephthalic acid or
aliphatic dicarboxylic acids are used in similar reactions, the
ratio is just higher than the equimolecular (1/1.1). In such a
work, on the synthesis of poly(butylene 2,5-furandicarboxy-
MATERIALS AND METHODS
Materials
2,5-Furan dicarboxylic acid (purum 97%), 1,8-octanediol
(98%, m.p. 5 57–61 8C and b.p. 5 172 8C/20 mmHg), 1,9-non-
anediol (98%, m.p. 5 45–47 8C and b.p. 5 177 8C/15 mmHg),
1,10-decanediol (98%, m.p. 5 71–75 8C and b.p. 5 297 8C),
1,12-dodecanediol (99%, m.p. 5 79–81 8C and b.p. 5189 8C/
12 mmHg), and tetrabutyl titanate (TBT) catalyst of analytical
grade were purchased from Aldrich. All other materials and
solvents used were of analytical grade.
9
late) (PBF), Ma et al. reported a ratio between FDCA and
butanediol (BG) of 1/5 mol/mol. Except molar ratios, the
effect of polymerization reaction parameters such as the cat-
alyst amount, reaction time, and polycondensation tempera-
ture on the molecular weight of the produced PBF was
Synthesis of 2,5-Dimethylfuran Dicarboxylate
About 15.6 g of FDCA, 200 mL of methanol anhydrite, and
2 mL of concentrated sulfuric acid were transferred into a
random flask (500 mL), and the mixture was refluxed for
5 h. The excess of the methanol was distilled, and te solution
was filtered through a disposable Teflon membrane filter.
During filtration, dimethyl ester was precipitated as white
powder, and after cooling, 100 mL of distilled water was
added. The dispersion was partially neutralized by adding
1
0
studied extensively.
When high-boiling-point diols like isosorbide and 1,4-benze-
nedimethanol were used, the procedure for the preparation
of the corresponding polyesters of FDCA can be followed
1
1
only when its dichloride was used. This is because these
diols cannot be removed from the reactor during melt poly-
condensation procedure. In this case, high polycondensation
temperatures should be used, in which unfortunately the
5% Na CO (w/v) during stirring while pH was measured
2 3
continuously. The white powder was filtered, and the solid
product was washed several times with distilled water and
dried. The isolated white dimethyl ester was recrystallized
with a mixture of 50/50 (v/v) methanol/water. After cooling,
DMFD was precipitated in the form of white needles. The
reaction yield was calculated at 83%.
1
2
polyester will decompose. Storbeck and Ballauff proposed
earlier a similar procedure to prepare furan dicarboxylate
polyesters from three different dianhydrohexitols, namely,
1
1
,4:3,6-dianhydro-D-sorbitol, 1,4:3,6-dianhydro-D-mannitol, and
,4:3,6-dianhydro-L-iditol, which reacted with 2,5-furandicar-
bonyldichloride. All these polyesters were amorphous with
high glass transition temperatures ranging from 173 to 196
Polyester Synthesis
1
3
The polyesters were prepared by applying a variation of the
two-stage melt polycondensation method (esterification and
polycondensation) in a glass batch reactor. DMFD and the
appropriate diols at a molar ratio of diester/diol 5 1/2 were
charged into the reaction tube of the polyesterification appa-
ratus with 400 ppm TBT. The reaction mixture was heated
at 150 8C under argon atmosphere for 2 h, at 160 8C for
additional 2 h, and finally at 170 8C for 1 h. This first step
(transesterification) is considered to be complete after the
8C and high thermal stability.
The aim of this study is to prepare such biobased alipharo-
matic polyesters using 2,5-FDCA and diols with 8, 9, 10, and
12 methylene groups with a simple melt polycondensation pro-
cedure avoiding the use of acid chloride and the diol excess.
These polyesters are named as poly(octylene 2,5-furanoate)
(POF), poly(nonylene 2,5-furanoate) (PNF), poly(decylene 2,5-
furanoate) (PDeF), and poly(dodecylene 2,5-furanoate) (PDoF),
respectively. These diols are crystalline materials with high
molecular weight and also have high boiling points. Thus, to
remove them during the polycondensation stage, high tem-
perature is needed. However, in our previous attempts to
prepare such polyesters using polycondensation tempera-
tures of 260–290 8C, products with dark brown to black
collection of almost all the theoretical amount of CH OH,
3
which was removed from the reaction mixture by distillation
and collected in a graduate cylinder. After this stage, the cor-
responding bishydroxyalkylene-2,5-furan carboxylate mono-
mers have been formed. In the second stage, these
monomers reacted with DMFD in a molar ratio 1/1.05 at
150 8C under argon atmosphere for 2 h, at 160 8C for addi-
tional 2 h, and finally at 170 8C for 1 h. During this stage,
methanol was also removed as byproduct. After that time, in
the third step of polycondensation, a vacuum (5.0 Pa) was
applied slowly over a period of time of about 30 min. The
8
color were obtained. This is in accordance to Gruter et al.
who reported that with increasing the polymerization tem-
perature from 200 to 240 and 275 8C, the colorization of the
final polyester was increased. To avoid this coloration, in our
study, a different polymerization strategy was applied using
2
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JOURNAL OF POLYMER SCIENCE, PART A: POLYMER CHEMISTRY 2015, 53, 2617–2632