Electronic supplementary information (ESI)
RESULTS AND DISCUSSION
Synthesis and characterization of dihydroxy compounds containing ester groups
In this study, three types of dihydroxy compounds each containing two ester groups
were utilized, a dihydroxy compound containing aliphatic–aliphatic ester group (CH–
Bu), a dihydroxy compound containing aromatic-aliphatic ester group (t-PHTH–Bu)
and a dihydroxy compound containing aromatic-aromatic ester group (t-PHTH–BPA).
The aliphatic-aliphatic and aromatic-aliphatic dihydroxy compounds were synthesized
from the reaction of cis/trans-1,4-cyclohexanedicarboxylic acid dichloride (CHAC) or
terephthaloyl chloride (t-PHTHC) with a 10 fold excess of 1,4-butanediol,
respectively. The aromatic-aromatic dihydroxy compound (t-PHTH–BPA) was
prepared by the reaction of terephthaloyl chloride with a 25% excess amount of the
stoichiometric quantity of BPA according to a previously published procedure.1,2
Bis(4-hydroxybutyl) cis/trans-1,4-cyclohexanedicarboxylate (CH–BuD) is a new
compound and was obtained in high yield as a light yellow viscous liquid. The other
two dihydroxy compounds, t-PHTH–BuD4,5,6-11 and t-PHTH–BPA,1-3 were already
known in the literature and were obtained as white solids in high yields. These
dihydroxy compounds were characterized by melting point, FT–IR, 1H–NMR and
13
C–NMR spectroscopy. The yield, the physical properties and the labeling of the
important IR bands of these dihydroxy compounds are summarized in Table S I. The
melting point (Tm) of t-PHTH–BPA diol is 197–199°C (lit value is 199–201°C2) and
the melting point of t-PHTH–BuD is 80°C (lit. value is 79–80ºC4,5). The melting point
of t-PHTH–BPA diol was much higher than that of t-PHTH–BuD, this may be due to
the extensive aromatic character of t-PHTH–BPA diol.
TABLE S I
FT–IR spectroscopy
The FT-IR spectra of dihydroxy compounds showed strong and broad absorption
bands from 3409 to 3426 cm-1 for the stretching vibrations of the alcoholic groups,
strong absorption bands from 1710 to 1736 cm-1 for the C=O stretching frequency of
the ester group, and from 1142 to 1282 cm-1 for the C–O–C stretching vibrations.
These IR data are conformed to the reported literature.1,2,10,12 and thus suggest the
formation of the postulated dihydroxy compounds containing ester groups.
NMR spectroscopy
1
H-NMR spectra: The 1H−NMR spectra of the dihydroxy compounds showed peaks
for all proton types present. The signal for the proton of the butyl hydroxyl group in
CH–BuD was observed at δ = 3.06 and that in t-PHTH–BuD at δ = 2.71 ppm,
respectively, while that of BPA in t-PHTH–BPA was observed at δ = 9.16 ppm. The
signal of the terminal aliphatic methylene protons of Bu moiety attached to the
hydroxyl group (–CH2OH) in both CH–BuD and t-PHTH–BuD were observed as
triplet at δ = 3.50 and 3.63 ppm, respectively. The signals for the terminal aliphatic
methylene protons of Bu moiety attached to the oxygen of the ester group (–
COOCH2–) in CH–BuD and in t-PHTH–BuD were observed at δ = 3.96 and 4.29
ppm, respectively. The signal of the tertiary aliphatic CH proton in CH–BuD attached
to the carbon of the C=O of the ester group (–CH–COO) was observed at δ = 1.91
ppm. The signals of the methylene protons of cis/trans-1,4-cyclohexylene ring and
those of the central protons of Bu unit were observed as masked unresolved multiplets
in the range δ =1.2–1.8 ppm. For the t-PHTH unit in t-PHTH–BuD and t-PHTH–
BPA, the signal of the terephthalate ring protons appeared as singlet at δ = 7.99 ppm
and at δ = 8.25 ppm, respectively. The signals of the aromatic protons of BPA unit
near the ester group were observed in the range δ = 7.1–7.3 ppm, while those next to
the alcoholic group were observed at δ = 6.65 ppm. The peak of the methyl protons of
BPA units was observed at δ = 1.57 ppm. These 1H–NMR data are conformed to the
reported literature2,5,8,10,11 and thus suggest the formation of the postulated dihydroxy
compounds containing ester groups.
13
C-NMR spectra: In the 13C–NMR spectra of the dihydroxy compounds, the signals
of the terminal methylene carbon atoms of Bu moiety attached to the hydroxyl group
(–CH2OH) of both CH–BuD and t-PHTH–BuD were observed at about δ = 62 ppm.
The signals of the terminal aliphatic methylene carbon atoms of Bu moiety attached to
the oxygen of the ester group (–COOCH2–) in CH–BuD and in t-PHTH–BuD were
observed at δ = 64.2 and 65.3 ppm, respectively. For cyclohexylene ring carbons of
CH–BuD, the signal of the tertiary aliphatic carbon atom (CH) attached to the carbon
of the C=O of the ester group (–CHCOO–) was observed at δ = 42.4 ppm. The signals
for cyclohexylene ring methylene carbon atoms appeared at δ = 25–28 ppm. For the tPHTH unit of t-PHTH–BuD and t-PHTH–BPA, the signals of the quaternary aromatic
ring carbon atoms next to the C=O of the ester groups appeared at δ = 134 ppm. The
other aromatic ring carbon atoms of both t-PHTH–BuD and t-PHTH–BPA appeared
at δ = 130 ppm. Interestingly, the signal of the quaternary carbon atoms of the
aromatic rings of the BPA in t-PHTH–BPA attached to the hydroxyl groups appeared
at a high δ value (δ = 156 ppm). Apparently, this peak (Table S II, entry 3, carbon 13)
lies a way enough from in the carbonyl carbon signal region of the aromatic or
aliphatic ester group and, therefore, does not mask with it. The signals of the carbon
atoms of the ring in ortho– and meta– positions to the alcoholic group appeared in the
range δ = 115 and 128 ppm, correspondingly. The signal of the quaternary aromatic
carbon atoms in para position to the hydroxyl group which is attached to the aliphatic
quaternary carbon atom appeared at δ = 148 ppm. The signal of the aliphatic
quaternary carbon atom (bearing the methyl groups) appeared at δ = 42.0 ppm, while
that of the methyl carbon atom appeared at δ = 31.2 ppm. The signal of the quaternary
carbon atom of the aromatic ring attached to the oxygen of the ester group appeared at
δ = 141 ppm. The signals of the carbon atoms of the ring in ortho– and meta–
positions to the ester group appeared at δ = 122 and 128 ppm, respectively. Finally,
the signal of the carbonyl carbon of the aromatic-aromatic ester of t-PHTH–BPA
appeared at δ = 164 ppm, aromatic-aliphatic ester of t-PHTH–BuD at about 166 ppm
and aliphatic-aliphatic ester (i.e., CH–BuD) at 175 ppm, which are the correct
positions for the carbonyl carbon atoms of these ester. These
13
C–NMR data are
conformed to the reported literature.1,2,5,8 and thus suggest the formation of the
postulated dihydroxy compounds containing ester groups. The 1H–NMR and
13
C–
NMR data for the various dihydroxy compounds prepared are reported in Table S II.
TABLE S II
Synthesis and characterization of monomers
The prepared dihydroxy compounds containing ester groups were reacted with PCF1315
to obtain the following diphenyl dicarbonate monomers: bis(4-hydroxybutyl)
cis/trans-1,4-cyclohexanedicarboxylate diphenyl dicarbonate (CH−Bu DPDC), bis(4hydroxybutyl) terephthalate diphenyl dicarbonate (t-PHTH−Bu DPDC) and 1,4-[di(4-hydroxy-diphenyl-2,2'-propane)]
terephthalate
diphenyl
dicarbonate
(t-
PHTH−BPA DPDC). To our knowledge, all these monomers are novel compounds;
therefore, they were characterized by melting point, FT–IR, 1H–NMR and
13
C–NMR
spectroscopy to confirm their structures. Their structures, yield, physical properties
and the labeling of the important IR bands are summarized in Table S II.
FTIR spectroscopy
The FT–IR spectra of the diphenyl dicarbonate monomers showed strong absorption
bands due to the C=O stretching vibrations of the carbonate group from 1759 to 1778
cm-1 and strong absorption bands due to the C=O stretching vibration of the ester
group from 1720 to 1739 cm-1. The FT–IR spectra also showed that the C=O
stretching frequency of aromatic-aromatic carbonate group (e.g., t-PHTH–BPA
DPDC) was the highest among the monomers. The absorption bands of the C–O–C
stretching vibrations were observed in the range from 1187 to 1253 cm-1. The yield,
melting points and the labeling of the important IR bands of monomers are
summarized in Table S I.
NMR spectroscopy
1
H–NMR spectra: In the 1H–NMR spectra of CH–Bu DPDC and t-PHTH–Bu DPDC
monomers, the signals of the terminal methylene protons of Bu moiety attached to the
ester group (–COOCH2–) were observed as triplets at δ = 4.11 and 4.32 ppm,
respectively, while those next to them (–COOCH2CH2–) in CH–Bu DPDC were
masked with CH ring protons, and in t-PHTH–Bu DPDC were observed at δ = 1.92
ppm. In the spectra of CH-Bu DPDC and t-PHTH–Bu DPDC monomers, the signals
of the terminal aliphatic methylene protons of Bu moiety attached to the carbonate
group (–OCOOCH2–) were observed as triplets at δ = 4.25 and 4.40 ppm,
respectively, while those next to them (–COOCH2CH2–) in CH–Bu DPDC were
masked with CH ring protons, and in t-PHTH–Bu DPDC were also observed at δ =
1.92 ppm. In the spectrum of CH–Bu DPDC, the signal of the tertiary aliphatic (CH)
protons attached to the carbon of the C=O of the ester group (–CH–COO–) was
observed at δ = 2.03 ppm, the signal of cyclohexylene ring methylene protons were
observed in the range δ = 1.3–1.9 ppm. In the spectrum of t-PHTH–Bu DPDC, the
signal of the aromatic terphthalate ring protons was observed at δ = 8.09 ppm.
Regarding the spectrum of t-PHTH–BPA DPDC the signal of the terephthalate
aromatic ring protons was observed at δ = 8.30 ppm, while the signals of BPA
aromatic ring protons were observed in the range δ = 7.1–7.5 ppm. The signal for the
methyl protons of BPA unit were observed at δ = 1.70 ppm. On the other hand, the
signals of the phenyl ring of phenyl carbonate group ortho, meta and para to the
carbonate group were observed in all monomers around δ = 7.15, 7.38 and 7.25 ppm,
correspondingly.
13
C–NMR spectra: In the
13
C–NMR spectra of CH–Bu DPDC and t-PHTH–Bu
DPDC, the signal for the terminal methylene carbon atoms of Bu attached to the ester
group (–COOCH2–) appeared at δ = 63.7 and 64.8 ppm, respectively, while that next
to them of CH–Bu DPDC (–COOCH2CH2–) appeared in the range δ = 25–29 ppm
and that of t-PHTH–Bu DPDC at δ = 25.2 ppm. The signal for the methylene carbon
atoms of Bu attached to the carbonate group (–OOCOCH2–) were observed at δ =
68.2 ppm for both monomers, while that next to them (–OOCOCH2CH2–) in CH–Bu
DPDC was observed in the range δ = 25–29 ppm and that in t-PHTH–Bu DPDC at δ
= 25.5 ppm. In the spectrum of CH–Bu DPDC, the signal of the tertiary aliphatic
(CH) carbon atom attached to the C=O of the ester group (-CH–COO) was observed
at δ = 42.5 ppm and the signals of cyclohexylene ring methylene carbons at δ = 25–29
ppm. In the spectrum of t-PHTH–Bu DPDC, the signal of the aromatic t-PHTH ring
carbons appeared at δ = 130 ppm and the signal of the quaternary aromatic ring
carbon attached to the C=O of the ester appeared at δ = 134 ppm. In the
13
C–NMR
spectra of CH-Bu DPDC, t-PHTH–Bu DPDC and t-PHTH–BPA DPDC, the signal for
the aliphatic-aliphatic, aromatic-aliphatic and aromatic-aromatic C=O of the ester
group appeared at δ = 175.0, 165.8 and 164.4 ppm, correspondingly. The
corresponding signals of the carbonate groups of these monomers appeared at δ =
153.7, 153.8 and 152.2 ppm, respectively. Regarding the spectrum of t-PHTH–BPA
DPDC the signal of the terphthalate aromatic ring carbon atoms appeared at δ = 130
ppm. The quaternary aromatic carbon of the terephthalate unit attached to C=O of
ester appeared at δ = 134 ppm, while that of BPA unit attached to the oxygen of the
ester appeared at 149 ppm. The peaks of the aromatic carbon atoms of BPA ortho and
meta to the ester group appeared at δ = 121 and 128 ppm, respectively. The signals of
the quaternary carbon atoms of the aromatic rings next to the aliphatic quaternary
carbon appeared at about 148 ppm. The signal of the aliphatic quaternary carbon atom
bearing the methyl groups appeared at δ = 42.7 ppm, while the signal of the methyl
carbon atoms appeared as at 31.0 ppm. The signals of the quaternary carbon atoms of
the aromatic rings of BPA next to the carbonate groups appeared at δ = 151 ppm. The
signals of the carbon atoms of the ring in ortho and meta positions to the carbonate
group appeared at δ = 121 to 128 ppm. On the other hand, the quaternary carbon atom
of the phenyl ring of the phenyl carbonate group of the three monomers attached to
carbonate group appeared at δ = 151 ppm. The carbon peaks of the phenyl ring ortho,
meta and para to the carbonate group in all monomers appeared at δ = 121, 129 and
126 ppm, correspondingly. The 1H–NMR and
13
C–NMR spectral data assigned to
protons and carbons of the various monomers are presented in Table S II.
Synthesis and characterization of poly(ester carbonate)s
FT–IR spectroscopy
The poly(ester carbonate)s prepared were analyzed by FT–IR. The IR spectra
showed two strong absorption bands due to the C=O stretching vibration; one for the
carbonate group and the other for the ester group. The spectra showed that the C=O
stretching frequencies of aromatic-aromatic polycarbonates were higher than those of
aromatic-aliphatic polymers which is in turn higher than those of aliphatic-aliphatic
polymers. The spectra showed strong absorption band due to the C=O stretching
vibration of the ester group around 1740 cm-1 for aromatic-aromatic ester, around
1720 cm-1 for aromatic-aliphatic ester and around 1730 cm-1 for aliphatic-aliphatic
ester. The absorption bands for aromatic-aromatic carbonate were above 1770 cm-1,
for aromatic-aliphatic carbonate around 1760 cm-1 and for aliphatic-aliphatic
carbonate below 1750 cm-1. Strong absorption bands for the C–O–C stretching
vibration for all polymers were observed in the range 1164 to 1270 cm-1. These IR
data, which are typical for the carbonate and ester groups, are in accordance with the
data reported in literature16,17 and, therefore, confirm the formation of the various
poly(ester carbonate)s in this work.
NMR spectroscopy
1
H–NMR spectra: The proton NMR spectra of aromatic-aliphatic and aliphatic-
aliphatic poly(ester carbonate)s confirm the formation of the polymers. The chemical
structures of the various polymers in all series essentially consisted of CH–Bu, tPHTH–Bu and t-PHTH–BPA units bonded to different alkylene or arylene units of
the dihydroxy compounds by a carbonate group. In their 1H–NMR spectra, the
polycarbonates of each series showed similar pattern of peaks for each of these units,
except for the aliphatic or the aromatic dihydroxy compound moieties attached to
them. The terminal methylene protons of Bu unit attached to the oxygen of the
carbonate group (–OOCOCH2–) in CH–Bu, t-PHTH–Bu units showed down field
effects, and their signals in polycarbonates was observed as multiplet in the range
from δ = 4.10 to 4.40 ppm, the signals of the methylene protons next to them
appeared as multiplet in the range from δ = 1.78 to 1.94 ppm. The signal of the
terminal methylene protons of Bu unit attached to the oxygen of the ester group (–
COOCH2–) was observed as multiplet in the range from δ = 4.03 to 4.33 ppm, the
signals of the methylene protons next to them appeared as multiplet in the range from
δ = 1.63 to 1.86 ppm. For poly(ester carbonate)s containing cyclohexylene units, the
signals due to cyclohexylene ring protons appeared as multiplets in the range δ = 1.2–
1.9 ppm. For poly(ester carbonate)s containing terephthalate units, the signal of the
aromatic protons appeared in t-PHTH–Bu and t-PHTH–BPA units as singlet at about
δ = 8.07 and 8.31 ppm, respectively. The signals of the other aromatic protons (BPA,
BIPH, HQ) of the diols employed appeared in the range δ = 7.0–7.7 ppm. The signals of
the aliphatic protons of Bu unit of BuD next to the carbonate group and that of those
next to them were observed at about δ = 4.40 and 1.86 ppm. The signals of the
aliphatic protons of DIGOL unit of the dihydroxy compound next to the carbonate
group were observed in the range δ = 4.03–4.40 ppm and those next to the ethereal
oxygen were observed in the range δ = 3.62–3.82 ppm, respectively. On the other
hand, the
1
H–NMR spectra of aromatic-aromatic poly(ester carbonate)s were
generally not indicative of formation of these polycarbonates. The signals of all
protons were collectively observed as asymmetric multiplets in the aromatic region of
the spectra.
13
C–NMR spectra: The
13
C–NMR spectra of poly(ester carbonate)s were quite
informative and showed signals due to all aliphatic carbon types. The polymers
synthesized exhibit a close similarity in the core structure, derived from the diphenyl
dicarbonate monomers, but differs in the alkylene or the arylene parts of the various
dihydroxy compounds. Therefore, the change in the pattern of
13
C–NMR spectra of
polymers could be correlated to the structure of the dihydroxy compounds. With the
exception of the alkylene and arylene moieties of the dihydroxy compounds, the
patterns of the 13C–NMR spectra for the CH–Bu unit, t-PHTH–Bu unit, and t-PHTH–
BPA unit, in all polycarbonates series were similar to those of their monomers. The
positions of the aliphatic and aromatic carbon signals of these units in the spectra of
all polymers containing these units were observed at chemical shifts close to those in
the monomers. All 1H–NMR and
13
C–NMR peaks were assigned to protons and
carbons of the various polymers synthesized in Series A, B, and C and their
assignments are presented in Tables S III, S IV and S V, respectively.
Table S III
Table S IV
Table S V
The 1H–NMR and
13
C–NMR signals of the terminal methylene groups of all
polycarbonates attached to the carbonate group were highly indicative for the
formation of the postulated polycarbonates. The attachment of the terminal methylene
group to the oxygen of the carbonate led to a downfield shift, which was reflected in
the chemical shifts in the proton spectra of the polycarbonates in the range δ = 4.10–
4.40 ppm and carbon spectra in the range, and δ = 67.4–69.1 ppm. This effect was
highly distinguished since the proton and carbon signals of the methylene carbon
attached to the ester or to the ethereal oxygen (–CH2OCH2–) appeared at smaller δ
values. This effect represents a strong spectral evidence of the formation of the
various poly(ester carbonate)s in this work. For example, this result was typically
demonstrated by the 1H–NMR spectra of Series B polymers, which showed peaks for
terminal proton signals at δ = 4.35–4.40 ppm attached to the carbonate group, at δ =
4.15–4.33 ppm attached to the ester group and at δ = 3.81 ppm attached to the ether
group. The corresponding peaks of the carbon atoms attached to the carbonate group,
ester group and ether group are less conformed to this trend and appeared at about δ =
68 ppm, 65 ppm and 67 ppm, correspondingly.
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