Amide-linked N-methacryloyl sucrose containing polymers

Article abstract of DOI:10.1016/j.carbpol.2014.03.050

1′,2,3,3′,4,4′,6-Hepta-O-benzyl-6′-N-methacryloyl- 6′-deoxysucrose 1, 6′-deoxy-6′-N-methacryloyloxyethylureido sucrose 2 and 6,6′-dideoxy-6,6′-N-dimethacryloyloxyethylureido sucrose 3 have been homo-polymerized and copolymerized with styrene by a free radical process, yielding polymer materials with pendant sucrose moieties, attached to the polymer backbone via amide linkages. The results demonstrated that varying the structural features of the monomers, greatly affected the thermal and rheological properties of the polymers. The polymer materials obtained have been characterized by NMR, MALDI-TOF, DSC, AFM and EWC (equilibrium water content). The efficient synthesis of the three novel, regioisomerically pure, N-methacryloylamide sucrose-containing monomers (1, 2 and 3) have been described.

Full text of DOI:10.1016/j.carbpol.2014.03.050

Carbohydrate Polymers 110 (2014) 38–46
Contents lists available at ScienceDirect
Carbohydrate Polymers
journal homepage: www.elsevier.com/locate/carbpol
Amide-linked N-methacryloyl sucrose containing polymers
Krasimira T. Petrova∗, Taterao M. Potewar, Osvaldo S. Ascenso, M. Teresa Barros
REQUIMTE, CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829-516 Caparica,
Portugal
a r t i c l e i n f o
a b s t r a c t
1ꢀ,2,3,3ꢀ,4,4ꢀ,6-Hepta-O-benzyl-6ꢀ-N-methacryloyl-6ꢀ-deoxysucrose 1, 6ꢀ-deoxy-6ꢀ-N-methacryloylo-
xyethylureido sucrose 2 and 6,6ꢀ-dideoxy-6,6ꢀ-N-dimethacryloyloxyethylureido sucrose 3 have been
homo-polymerized and copolymerized with styrene by a free radical process, yielding polymer mate-
rials with pendant sucrose moieties, attached to the polymer backbone via amide linkages. The results
demonstrated that varying the structural features of the monomers, greatly affected the thermal and
rheological properties of the polymers. The polymer materials obtained have been characterized by
NMR, MALDI-TOF, DSC, AFM and EWC (equilibrium water content). The efficient synthesis of the three
novel, regioisomerically pure, N-methacryloylamide sucrose-containing monomers (1, 2 and 3) have
been described.
Article history:
Received 27 May 2013
Received in revised form 4 March 2014
Accepted 19 March 2014
Available online 28 March 2014
Keywords:
Sucrose-containing monomers
N-methacryloyl monomers
Amide-linkage
© 2014 Elsevier Ltd. All rights reserved.
Free radical copolymerization
Poly(vinylsacharides)
1. Introduction
necessary for other potential applications. The design of polymers
and oligomers that mimic the complex structures and remarkable
Amphiphilic and hydrogel polymers are useful biomedical
materials. Self-assembly of amphiphilic polymers is a typical exam-
ple of advanced functional polymers. There have been reported
numerous examples of preparing nanoparticles from water-soluble
amphiphilic polymers as functional materials possessing potential
applications, including drug delivery, enzyme encapsulation and
nanoparticle catalysis (Caruso, Trau, Mohwald, & Renneberg, 2000;
Gaponik et al., 2003; Lu et al., 2001). If natural resources, such
as saccharides, are used for production of polymers, their appli-
cability would expand furthermore (Akiyoshi, Deguchi, Moriguchi,
Yamaguchi, & Sunamoto, 1993; Breslow & Zhang, 1996). The choice
of natural compounds as starting materials is based on the under-
standing that to minimize risks in designing new self-assembling
molecules, one must try to imitate and modify natural designs to
ensure biocompatibility.
It is known that a very important advantage of naturally derived
polymers as drug delivery systems over synthetic analogs is their
innate biocompatibility and biodegradability. However, to extract
proteins and polysaccharides from animals is often expensive and
with batch-to-batch variations. Due to the complexity of these
structures, it is difficult to introduce fine structural modification
to promote other specific functions in order to obtain properties
biological properties of proteins is an important task with both fun-
damental and practical implications (Liao, Yu, & Guan, 2009; Tew
et al., 2002).
It is in this sense that we aim to combine the advantages
from natural compounds and synthetic systems, namely, the bio-
compatibility and biodegradability of natural components and to
explore the potential structural versatility obtainable through syn-
thetic chemistry. Our group has been exploring strategies to design
synthetically simple, highly functional, and biocompatible novel
biomaterials from natural building blocks (Barros & Petrova, 2009;
Barros, Petrova, & Ramos, 2004, 2007).
Another feature that is expected to enhance the biocompatibility
and bio-recognition is the presence of amide linkage, which mimics
the repeating structural unit of proteins. N-methacryloyl polymers
have found various applications as stimuli-responsive polymers
(Luo, Zhao, & Li, 2012) affinity chromatography and protein recog-
nition (Corman & Akgol, 2012), drug-delivery systems (Chang,
Chen, Zhong, Chang, & Liang, 2012), etc. We aimed to combine this
functionality with pending sugar moieties, which have been shown
to bestow hydrophilic, biocompatible and biodegradable proper-
ties (Barros, Petrova, & Singh, 2010a; Varma, Kennedy, & Galgali,
2004). Particularly, sucrose is a carbohydrate feedstock of low
molecular weight which is ubiquitous in its availability and is of rel-
atively low cost. Since sucrose has eight chemically active hydroxyl
groups, we have developed its regioselective derivatization for the
selective synthesis of sucrose-containing linear polymers (Barros,
∗
Corresponding author. Tel.: +351 212948361; fax: +351 212948550.
E-mail address: k.petrova@fct.unl.pt (K.T. Petrova).
http://dx.doi.org/10.1016/j.carbpol.2014.03.050
0144-8617/© 2014 Elsevier Ltd. All rights reserved.

K.T. Petrova et al. / Carbohydrate Polymers 110 (2014) 38–46
39
Fig. 1. Structures of N-methacryloyl sucrose monomers 1–3.
Petrova, & Correia-da-Silva, 2011; Barros, Petrova, Correia-da-Silva,
& Potewar, 2011).
Several procedures for free-radical homopolymerization of
monomers 1–3 and copolymerization with styrene were described,
which produced linear hydrophobic and hydrophilic polymers
and cross-linked hydrogels. The experimental results demon-
strated how varying the structural features of the monomers
involved, greatly affected the thermal, mechanical and rheological
properties of the polymers. The resulted polymer materials were
characterized by NMR, MALDI-TOF, DSC and AFM. Their ability to
swell and absorb water has been studied as well.
The introduction of functional groups (mesogenic, chro-
mophoric, etc.) into side-chains of poly-methacrylates leads to
principally new materials which can be considered as binary sys-
tems, consisting of a polymer matrix with distributed functional
groups. The latter are anchored by only one end to the polymer
backbone, providing a relative independence in the motion of the
backbone and side-chains. As a result, comb-like polymers with
side-chain functional groups combine functional and polymeric
properties. Such systems are used as working elements in nonlin-
ear optics, holography, information storage and recording devices
(Moscicki, 1992; Yesodha, Pillai, & Tsutsumi, 2004).
2. Results and discussion
2.1. Synthesis of monomers
In our case, each structural unit of the polymer is an
amphiphile consisting of hydrophilic carbohydrate and hydropho-
bic vinylbenzyl (styryl) moieties. It has been shown that
monosaccharide-containing polystyrenes have a strong affinity for
organic solutes in water. The binding ability was assumed to be
attributable to the tightly coiled conformation induced by their
amphiphilic structures (Kobayashi, Sumitomo, & Ina, 1985).
Herein, the synthesis of three novel N-methacryloyl sucrose
monomers with different structural characteristics is reported
(Fig. 1). Monomer 1, which contains one polymerizable double
bond and sucrose with protected hydroxyl groups with benzyl
ether moieties, is expected to form hydrophobic linear polymers,
easily soluble in a variety of organic solvents. Monomer 2, also with
one polymerizable double bond, but with free hydroxyl groups,
yields linear hydrophilic and swellable in water polymers, soluble
in polar solvents; while monomer 3, which features two double
bonds and free hydroxyl groups, produces hydrophilic cross-linked
hydrogel also swellable in water, but insoluble in any solvent.
2.1.1. Synthesis of 1ꢀ,2,3,3ꢀ,4,4ꢀ,6-hepta-O-benzyl-6ꢀ-N-
methacryloyl-6ꢀ-deoxysucrose
1
In order to obtain 6ꢀ-amino-6ꢀ-deoxysucrose 10, a synthetic
strategy through the intermediate 1ꢀ,2,3,3ꢀ,4,4ꢀ,6-hepta-O-benzyl-
sucrose 7 (Barros et al., 2004) was used (see Supplementary
Data).
Compound 7 was treated with methanesulfonyl chloride in DCM
in the presence of Et3N and DMAP at 0 ◦C (Scheme 1). By using
1.1 equivalent of methanesulfonyl chloride, the reaction afforded
1ꢀ,2,3,3ꢀ,4,4ꢀ,6-hepta-O-benzyl-6ꢀ-O-mesyl-sucrose 8 in excellent
yield (95%). Next, compound 8 was treated with NaN3 in DMF
under microwave irradiation at 400 W, 120 ◦C for 10 min, to afford
1ꢀ,2,3,3ꢀ,4,4ꢀ,6-hepta-O-benzyl-6ꢀ-azido-6ꢀ-deoxysucrose 9 in 85%
yield. To reduce the azide group to amine, the azide 9 was treated
with Ph3P in THF/H2O at room temperature, but it did not react.
Then the reaction was carried out at elevated temperature and
Scheme 1. Synthesis of monomer 1.

40
K.T. Petrova et al. / Carbohydrate Polymers 110 (2014) 38–46
Scheme 2. Synthesis of monomer 2.
it proceeded smoothly at 70 ◦C to afford 1ꢀ,2,3,3ꢀ,4,4ꢀ,6-hepta-O-
benzyl-6ꢀ-amino-6ꢀ-deoxysucrose 10 in excellent yield (89%). Next,
the amine 10 was treated with methacryloyl chloride in DCM in the
presence of Et3N and catalytic amount of DMAP at 0 ◦C, followed
by stirring at room temperature. Thus, the desired monomer 1 was
obtained in 70% yield (Scheme 1). All the compounds were charac-
terized by IR, 1H NMR, 13C NMR spectroscopic and mass analysis.
The 1H NMR spectrum of compound 1 (see Supplementary Data)
showed the characteristic peaks: doublet at ı 5.62 ppm, singlet at
ı 5.59 ppm and singlet at ı 1.88 ppm. The 13C NMR spectrum of
compound 1 showed characteristic peaks at ı 168.38 (CO), 139.8
2.1.3. Synthesis of
6,6ꢀ-dideoxy-6,6ꢀ-N-dimethacryloyloxyethylureido sucrose 3
The compound 6,6ꢀ-diamino-6,6ꢀ-dideoxysucrose 18 has been
obtained as previously described (Barros, Petrova, Correia-da-Silva,
et al., 2011) via 6,6ꢀ-dibromo-6,6ꢀ-dideoxysucrose 16 and 6,6ꢀ-
diazido-6,6ꢀ-dideoxysucrose 17 (see Supplementary Data).
Then, by a similar procedure as described above, the diamine 18
was reacted with 2 equiv. of 2-isocyanatoethyl methacrylate in H2O
at room temperature to afford the monomer 3, 6,6ꢀ-dideoxy-6,6ꢀ-
N-dimethacryloyloxyethylureido sucrose (Scheme 3), as colorless
solid in 63% yield (see Supplementary Data).
(CO
C CH2), 119.5 (C CH2), 42.5 (CH2 NH ), 18.5 (CH3) ppm.
Thus, we have achieved the synthesis of monomer 1 from sucrose
4 in overall yield of 29% in 7 steps.
2.2. Synthesis and characterization of polymers
2.2.1. Polymerization methods
Using the novel sucrose monomers 1–3, several different types
of polymers have been synthesized by free radical homo- and
co-polymerization (See ESI, Schemes S7–S9 and Table 1). The poly-
merization conditions, reaction time, and the initial monomers
ratio have been optimized as previously described (Barros et al.,
2004; Barros & Petrova, 2009; Barros et al., 2007; Barros, Petrova,
& Singh, 2010a, 2010b).
As a result we obtained a number of copolymers with diverse
contents of pending sucrose moieties (estimated by 1H NMR), with
different chain length, reported by the mass average molecular
weight, Mw, number average molecular mass, Mn, and polydisper-
sity, Mw/Mn (measured by MALDI-TOF), and with different physical
properties such as glass transition temperatures, Tg (measured by
DSC), ability to swell and absorb water, and the surface morphol-
ogy of thin films, which has been examined by AFM (Atomic Force
Microscopy).
2.1.2. Synthesis of 6ꢀ-deoxy-6ꢀ-N-methacryloyloxyethylureido
sucrose 2
In continuation of our interest on new polymerizable sucrose
monomers, herein we present the regioselective synthesis of a new
hydrophilic sucrose monomer 2, 6ꢀ-deoxy-6ꢀ-N-methacryloyloxy
ethylureido-sucrose, in which the polymerizable double bond is
pendent from the sucrose core with a linker. It was designed with a
spacer in order to distance the acrylic group from the rigid sucrose
moiety, giving more flexibility and less steric hindrance for subse-
quent polymerization steps, as suggested in the literature (Anders
et al., 2006).
The
compound
1ꢀ,2,3,3ꢀ,4ꢀ,4,6-hepta-O-acetyl-6ꢀ-azido-6ꢀ-
deoxy-sucrose 13 was obtained as previously described (see
Supplementary Data) (Potewar, Petrova, & Barros, 2013). The next
step was deprotection of the acetyl groups, for which the azide 13
was treated with sodium methoxide in dry MeOH at room tem-
perature to afford 6ꢀ-azido-6ꢀ-deoxy-sucrose 14 in 85% as colorless
solid (Scheme 2). The spectroscopic data of this compound matches
the reported in literature (Singh, Maynard, Doyle, & Taylor, 1984).
When the azide 14 was treated with Ph3P in dioxane/MeOH at room
temperature, it afforded the desired 6ꢀ-amino-6ꢀ-deoxy-sucrose 15
(Sharma, Norula, & Mattey, 1982; Singh et al., 1984) in 86% as faint
pale yellow solid. Then 15 was treated with 2-isocyanatoethyl
methacrylate in H2O at room temperature to afford the monomer
2, 6ꢀ-deoxy-6ꢀ-N-methacryloyloxyethylureido sucrose, as colorless
solid in 82% yield (see Supplementary Data).
For the homo-polymerization of monomer
1 and its co-
polymerization with styrene (10 mol equiv.) have been used
homogeneous solution polymerization (see ESI, Scheme
S7). It has been examined in the presence of AIBN as
free-radical initiator in toluene at 70 ◦C, followed by pre-
cipitation in cold ethanol (which was miscible with the
monomers, the solvent, and by-products, such as oligomers),
to
produce
solid
polymers
poly(N-(methacrylamido)-
19
1ꢀ,2,3,3ꢀ,4,4ꢀ,6-hepta-O-benzyl-6ꢀ-amino-6ꢀ-deoxysucrose)
and poly(N-(methacrylamido)-1ꢀ,2,3,3ꢀ,4,4ꢀ,6-hepta-O-benzyl-6ꢀ-
amino-6ꢀ-deoxysucrose)-co-polystyrene 20. The sugar content in
Scheme 3. Synthesis of monomer 3.

K.T. Petrova et al. / Carbohydrate Polymers 110 (2014) 38–46
41
Table 1
Free radical homo- and co-polymerization with styrene of sucrose monomers 1–3.
a
sug
b
]
styr
]
[
]
sug
[
[
c
c
Polymer Monomers
Polymerization procedure;
Yield of solid polymer
Mn [g/mol]
MW [g/mol] Mw/Mn Tgd [◦C] Swelling in
0
styr
[
]
0
H2O [%]
19
20
21
22
23
1 (homo-polymer)
1 + styrene
Toluene/AIBN 70 ◦C, 24 h 14%
Toluene/AIBN 70 ◦C, 24 h 48%
H2O/Na2S2O8 70 ◦C, 24 h 18%
DMF/AIBN 70 ◦C, 24 h 14%
–
0.1
–
0.1
-
–
0.03
–
0.44
–
3230
3780
3280
4710
3740
4010
3540
5320
1.16
1.06
1.08
1.13
69
72
Hydrophobic
Hydrophobic
250
2 (homo-polymer)
2 + styrene
−27
64
160
3 (homo-polymeric H2O/Na2S2O8 70 ◦C, 24 h 20%
Not measured – insoluble
sample
Not measured – insoluble
sample
hydrogel)
3 + styrene
(dispersion
24
H2O + toluene/Na2S2O8 70 ◦C,
24 h 53%
0.1
0.09
copolymerization)
[a] Initial (feed) mol ratio of the monomers. [b] Mole ratio of the co-monomers in the copolymer, determined by 1H NMR. [c] Determined by MALDI-TOF. [d] Determined by
DSC.
the obtaining polymer 20 was 3 mol%. Both polymers were easily
soluble in a variety of organic solvents such as toluene, xylene,
benzene, hexane, dichloromethane, chloroform, etc.
In the last two procedures the bis-methacryloyl sucrose deriva-
tive 3 acted as cross-linker. Estimation of degree of cross-linking
was attempted by two different methods (Glavchev, Petrova, &
Devedjiev, 2002a, 2002b) – by IR spectrometry and the amount
of gel fraction after extraction in a Soxhlet extractor. The IR spectra
of the solid polymer samples 23 and 24 did not show any signals
corresponding to the vinyl groups of the monomers, which led
to conclusion that any unreacted monomers have been removed
during the work-up.
The degree of cross-linking by the amount of gel fraction can be
found as a ratio between the sample mass after extraction and the
initial sample mass, in percentages. In our case, four hours extrac-
tion in a Soxhlet extractor did not yield any soluble fractions for the
two samples, which corresponds to degree of cross-linking 100%.
Therefore, to further characterize the polymer 24, the residue of
unreacted monomers mixture, after isolating the solid polymer 24,
have been analyzed. By 1H NMR it was estimated to contain 11 mol%
of sugar monomer 3, and 89 mol% styrene. From this data, knowing
that the monomers feed ratio was sugar/styrene 1:10 and that the
yield of solid polymer was 53%, the monomers units contained in
the obtained polymer 24 have been calculated to be 8 mol% sugar
and 92 mol% styrene, or sugar/styrene ratio 0.09. Assuming that the
sugar and styrene units were randomly distributed in the polymer
chains, the length of the linear polymer segments was estimated to
be on the average around six styrene units.
Poly(6,6ꢀ-dideoxy-6,6ꢀ-N-dimethacryloyloxyethylureido
sucrose) 21 was obtained by precipitation polymerization (See
ESI, Scheme S8). Monomer 2 was dissolved in oxygen-free H2O
under argon atmosphere with sodium persulfate Na2S2O8 (1%)
as radical initiator, and heated at 70 ◦C for 24 h. The polymer was
separated from the resulting heterogeneous reaction mixture by
filtration, washed with cold methanol, and dried under vacuum.
The polymer 21 was obtained in 18% yield and was characterized
as amorphous solid.
The co-polymerization of monomer 2 with styrene has been
examined in the presence of AIBN as free-radical initiator and
in DMF as solvent, at 70 ◦C under an Ar atmosphere, fol-
lowed by precipitation in cold acetone to yield polymer 22
poly(6,6ꢀ-dideoxy-6,6ꢀ-N-dimethacryloyloxy ethylureido sucrose)-
co-polystyrene with 44 mol% sugar content and 14% yield of solid
polymer in respect to the initial monomer mixture. DMF was cho-
sen as media for the co-polymerization because it dissolves well
both monomers – the hydrophilic sugar monomer 2, as well the
hydrophobic styrene (homogeneous solution polymerization). In
these conditions was observed lower conversion of styrene, but
higher incorporation of the sugar monomer unit. The filtration and
washing of the precipitate with acetone, and repeated dissolution
and re-precipitation, assured the removal of unreacted monomers,
as they were soluble in acetone. The polymers 21 and 22 were
soluble in polar organic solvents, as DMF and DMSO.
2.2.2. 1H NMR
The copolymer compositions were determined by 1H NMR by
comparing the peak areas of the aromatic protons present in the
styrene unit with the 14 sucrose unit protons. In co-polymer 22
a higher incorporation of sugar (0.44 molar parts) than in the
co-polymer 20 (0.03 molar parts) by approximately one order of
magnitude was achieved. This result was expected based on the
structures of the monomers 1 and 2 – in monomer 2 the poly-
merizable double bond is positioned farther from the rigid sucrose
skeleton, thus providing more flexibility and facilitating its par-
ticipation in the co-polymerization. Even more, in monomer 1 the
hydroxyl groups of sucrose are protected with benzyl groups, which
make it bulkier and increase the steric hindrance. The value for
co-polymer 20 is in agreement with data previously obtained for
monomers with similar structural features, (Barros et al., 2004,
2010a) while the incorporation of sugar moieties in co-polymer
22 was found to be significantly improved.
Homo-polymeric
hydrogel
poly(6,6ꢀ-dideoxy-6,6ꢀ-N-
dimethacryloyloxyethylureido sucrose) 23 (See ESI, Scheme
S9) was prepared from monomer 3 by a similar technique used
for 21 by free-radical precipitation polymerization initiated by
sodium persulfate Na2S2O8 (1%) in oxygen-free H2O as solvent.
The resulted heterogeneous reaction mixture was filtered and
washed thoroughly with H2O and then cold methanol to remove
any residual monomer, to yield insoluble powder of cross-linked
hydrogel 23 (yield 20% from the monomer weight).
For the co-polymerization of
polymerization (Jung, Huh, Cheon,
3
with styrene, dispersion
Park, 2009) was per-
&
formed to yield the hydrogel 24, poly(6,6ꢀ-dideoxy-6,6ꢀ-N-
dimethacryloyloxyethylureido sucrose)-co-polystyrene. For this,
two solutions were prepared: water solution, containing the
hydrophilic sugar monomer and the radical initiator sodium per-
sulfate Na2S2O8 (1%); and toluene solution of styrene. Oil-in-water
emulsion was formed by combining the two solutions and dispers-
ing them by vigorous stirring. Then the emulsion was heated at
70 ◦C for 24 h while stirred vigorously. After cooling, the resulted
heterogeneous mixture was treated as described above, to yield the
cross-linked hydrogel 24 as insoluble white powder in 53% yield in
respect to the initial monomer mixture.
2.2.3. MALDI-TOF
MALDI-TOF measures the mass very accurately, and it gives
an absolute measurement of mass. Still, the choice of the most
suitable matrix for the sample and solution conditions have to
be optimized for unconventional polymers, as is the case of

42
K.T. Petrova et al. / Carbohydrate Polymers 110 (2014) 38–46
Fig. 2. AFM images of polymer films 19–22.
poly(vinylsacharides). The results obtained are summarized in
Table 1 (see SI for representative images).
the range 64–72 ◦C, while the homo-polymers consisting solely of
hydrophilic sugar monomers, 21 and 23, had much lower Tg (−20
and −27 ◦C, respectively). These results suggested that the presence
of large amount of sucrose moieties in the polymeric matrix pro-
moted a decrease in the polymer Tg, which indicated an increase
of the polymer chains flexibility and malleability.
The molecular weights of the co-polymers with styrene were
higher than the weights of the respective homo-polymers. This
difference could be due to steric reasons – the styrene units are
smaller and act as spacers between bulkier sugar units; or chemi-
cal reactivity reasons – the larger amount of the sugar co-monomer,
which is less reactive and also provides more possibilities for chain
transfer reactions in the reaction mixture, leads to slower reaction
and shorter chains. All the values of polydispersity obtained are
very low, varying between 1.06 and 1.16, which means that the
copolymers are very homogeneous.
2.2.5. Atomic force microscopy (AFM)
The surface morphology and size distribution of the polymer
samples were examined by AFM and representative images are
shown in Fig. 2 and in ESI. The polymer films were obtained by sus-
pending the polymer in a proper combination of good solvent/bad
solvent (solvent shifting technique), followed by depositing the
dilute dispersion onto freshly cleaved mica, then thorough dry-
ing. At these conditions, it was observed that the hydrophobic
polymers 19 (Fig. 2.1.) and 20 (Fig. 2.2.) showed less ability for
self-organization then the hydrophilic polymers 21 (Fig. 2.3.) and
22 (Fig. 2.4.). On the other side, the co-polymers with styrene 20
and 22 formed more uniform films then ones with high content of
sucrose moieties 19 and 21. The biggest and most uniformly shaped
nanoparticles, with size ranging from 70 to 140 nm, were observed
on the images of the hydrophilic polymer 21 film (Fig. 2.3).
2.2.4. Differential scanning calorimetry (DSC)
DSC main application is in studying phase transitions, such
as melting, glass transitions, or exothermic decomposition. These
transitions involve energy changes or heat capacity changes that
can be detected by DSC with great sensitivity, thus providing infor-
mation of the structure of the polymers. DSC traces of the six
polymer samples can be seen in the SI, and the polymers glass tran-
sition temperatures (Tg) obtained from the DSC thermograms are
presented in Table 1.
All the polymers synthesized were amorphous, bearing only
glass transition temperature and neither crystallization nor melting
temperatures were observed. The hydrophobic and styrene-
containing polymers 19, 20, 22 and 24 exhibited similar Tg in
2.2.6. Equilibrium water content
Equilibrium water content (EWC) of the hydrophilic polymer
samples 21 and 22, and the cross-linked hydrogels 23 and 24, was

K.T. Petrova et al. / Carbohydrate Polymers 110 (2014) 38–46
43
determined by immersing the samples in water at 25 ◦C for 24 h
to complete equilibration. The excess surface-adhered liquid was
removed by blotting and the swollen polymers were weighed using
an electronic microbalance. Then the samples were dried in a vac-
uum oven at 40 ◦C for 10 h until constant weight. The EWC was
calculated according to the following formula (Hou et al., 2006):
under nitrogen atmosphere. MALDI-TOF spectra of polymers were
recorded on Ultraflex III TOF/TOF Bruker equipped with laser type
smartbeam and detecting system fast MCP-Gating. AFM images
were acquired on a TT-AFM instrument from AFM Workshop in
a vibrating mode.
N-(methacrylamido)-1ꢀ,2,3,3ꢀ,4,4ꢀ,6-hepta-O-benzyl-6ꢀ-amino-
6ꢀ-deoxysucrose 1:
Ws − Wd
To a solution of 1ꢀ,2,3,3ꢀ,4,4ꢀ,6-hepta-O-benzyl-6ꢀ-amino-6ꢀ-
deoxysucrose 10 (0.400 g, 0.41 mmol) in CH2Cl2 (6 mL) under inert
atmosphere, was added Et3N (68 ␮L, 0.493 mmol), followed by cat-
alytic amount of 4-dimethylamino pyridine (DMAP). The reaction
mixture was cooled to 0 ◦C in ice-water bath and methacryloyl chlo-
ride (44 ␮L, 0.452 mmol) was added. Then the reaction mixture
was stirred for 20 min at 0 ◦C, followed by stirring at r.t. for 2 h.
After completion of the reaction, reaction mixture was quenched
with H2O and extracted with CH2Cl2 (2 × 10 mL). The combined
organic layer was dried over anhydrous Na2SO4 and concentrated
under reduced pressure to give crude product, which was further
purified by flash column chromatography (eluent, hexane/EtOAc;
3/1) to afford pure N-(methacrylamido)-1ꢀ,2,3,3ꢀ,4,4ꢀ,6-hepta-O-
benzyl-6ꢀ-amino-6ꢀ-deoxysucrose 1 (70%, 0.300 g) as a viscous
liquid.
EWC(%) =
× 100%
Wd
where Ws and Wd denote the weight of swollen and dried polymer
samples, respectively.
The results obtained (Table 1) demonstrated the polymer’s
ability to swell and absorb water, which is important feature in
many potential applications, as drug-delivery systems. The lin-
ear hydrophilic polymers 21 and 22 had higher EWC than the
cross-linked hydrogels 23 and 24, probably due to the restricted
flexibility of the later because of the dense bonding network. Also,
the styrene-containing polymers 22 and 24 absorbed less water
than the homo-polymers 21 and 23, due to the lower content of
free hydroxyl groups. The polymer particles were translucent under
swollen state, which is a typical feature of hydrogels. In general, the
highest EWC showed polymer 21, as high as 930%, which allowed
us to classify it as superabsorbent polymer.
[␣]D + 37.1 (c 1.0, CHCl3).
IR (NaCl): ꢀmax 3403, 3066, 3006, 2920, 2855, 1668, 1518, 1496,
1457, 1366, 1215, 1081 cm−1
.
3. Conclusions
1H NMR (400 MHz, CDCl3): ı ppm 7.27–7.11 (m, 35H, ArH), 6.43
(s, 1H, NH), 5.64 (s, 1H, CO CH), 5.61 (d, J = 2.4 Hz, 1H, H-1), 5.22
(s, 1H, CO CH), 4.90 (d, J = 11.0 Hz, 1H, PhCH2), 4.82–4.74 (m,
In summary, we have demonstrated the synthesis of different
types N-methacryloylamide sucrose-containing monomers, regioi-
somerically pure and in good yields. These amides have been
homo-polymerized and copolymerized with styrene by a free rad-
ical process, yielding polymer materials with pendant sucrose
moieties. The polymer materials obtained have been characterized
by NMR, MALDI-TOF, DSC, AFM and EWC (equilibrium water con-
tent), which showed that the structure of the resultant polymer was
coincident with the theoretic structure. We are currently investi-
gating a number of potential applications of these novel polymers
including water-absorbent materials, biocompatible polymers and
hydrogels, drug-delivery systems and solid supports for affinity
chromatography.
C
C
2H, PhCH2), 4.68–4.62 (m, 3H, 3H of PhCH2), 4.51–4.35 (m, 9H, 8H
of PhCH2, H-5ꢀ), 4.08–3.94 (m, 4H, H-3ꢀ, H-4ꢀ, H-3, H-5), 3.78–3.40
(m, 8H, H-2, H-4, H-1ꢀ, H-6, H-6ꢀ), 1.89 (s, 3H, CH3).
13CNMR (100 MHz, CDCl3): ı ppm 168.3 (CO amide), 139.8,
138.6, 138.3, 138.1, 138.0, 137.7 (Ar-Cquat), 128.3, 127.9, 127.7,
127.5 (Ar), 119.5 (
C
CH2), 105.2 (C-2ꢀ), 90.7 (C-1), 83.8 (C-3ꢀ), 83.5,
81.7, 79.7, 77.6 (C-2, C-3, C-4, C-4ꢀ, C-5ꢀ), 75.4 (CH2), 74.8 (CH2), 73.3
(CH2), 72.9 (CH2), 72.8 (CH2), 70.9 (C-5), 70.8 (C-6), 68.4 (C-1ꢀ), 42.6
(C-6ꢀ), 18.6 (CH3).
MALDI TOF MS calcd for C65H69NO11Na: [M-H+Na]+ 1062.231;
found 1062.414.
6ꢀ-Deoxy-6ꢀ-N-methacryloyloxyethylureido-sucrose 2:
To a cooled solution of 6ꢀ-amino-6ꢀ-deoxy-sucrose 15 (0.280 g,
0.820 mmol) in H2O (5 mL) at 0 ◦C, was added 2-isocyanato
ethyl methacrylate (0.116 mL, 0.820 mmol) and the mixture
was stirred at 0 ◦C for 2 h. The ice-water bath was removed;
the reaction mixture was allowed to warm to r.t. and then
stirred overnight. After completion of the reaction, reaction mix-
ture was washed with CH2Cl2 (thrice) and was concentrated
under reduced pressure to give crude oil which was puri-
fied by flash column chromatography (eluent; CH2Cl2/MeOH;
3/1) to afford 6ꢀ-deoxy-6ꢀ-N-methacryloyloxyethylureido-sucrose
2 (0.335 g, 82%) as colorless solid. m.p. 45–48 ◦C, dec. 150 ◦C to red
color.
4. Experimental
4.1. General
Reagents and solvents were purified by standard procedures
(Perrin, Armagedo, & Perrin, 1980). NMR spectra were recorded
at 400 MHz in CDCl3 or D2O, with chemical shift values (ı) in
ppm downfield from TMS (0 ppm) or the solvent residual peak
of D2O (4.79 ppm) as internal standard. Optical rotations were
measured at 20 ◦C on an AA-1000 polarimeter (0.5 dm cell) at
589 nm. The concentrations (c) are expressed in g/102 mL. Melt-
ing points were determined with a capillary apparatus with
heating plate Electrothermal type, in open capillary on Buchi
melting Point B-540 apparatus. FTIR spectra were recorded on
Perkin-Elmer Spectrum BX apparatus in KBr dispersions or on
NaCl cells. Mass Spectra were recorded on GC–TOF-MS (Gas
Chromatography–Time Of Flight–Mass Spectrometer) Micromass,
model GCT. The reactions under microwave irradiation were
performed using a monomodal microwave reactor MicroSynth Lab-
station (MileStone, USA) (www.milestonesrl.com) in open flasks
equipped with temperature control sensor and magnetic stirring.
Differential scanning calorimetry (DSC) measurements were car-
ried out on a Setaram DSC 131 scanning calorimeter equipped with
a thermal analysis data system. Samples of 10 mg were placed in
aluminum pans and sealed. The probes were heated two times,
from −20 ◦C to 80 ◦C at a rate of 10 ◦C/min and from 25 ◦C to 250 ◦C
[␣]D + 41.8 (c 0.4, H2O/CH3OH 1:1).
IR (KBr): ꢀmax 3419, 2927, 1715, 1651, 1575, 1556, 1322, 1299,
1170, 1057 cm−1
.
1H NMR (400 MHz, D2O): ı ppm 6.04 (s, 1H, CH2b), 5.63 (s,
1H, CH2a), 5.28 (s, 1H, H-1), 4.07–4.14 (m, 2H, H-3ꢀ, H-6ꢀ), 3.94 (t,
J = 8 Hz, 1H, H-4ꢀ), 3.65–3.74 (m, 5H, H-3, H-5, 2× H-6, H-6ꢀ), 3.56
(s, 2H, H-1ꢀ), 3.33–3.45 (m, 7H, H-2, H-4, H-5ꢀ, 2× CH2), 1.83 (s, 3H,
CH3).
13C NMR (100 MHz, D2O): ı ppm 170.0 (CO ester), 160.0 (CO
amide), 136.1 ( C(CH3) ), 127.2 ( CH2), 104.0 (C-2ꢀ), 92.4 (C-1),
80.2 (C-5ꢀ), 76.8 (C-3ꢀ), 76.0 (C-4ꢀ), 72.9 (C-3 and C-5), 71.4 (C-2),
69.8 (C-4), 64.7 (C-6ꢀ), 61.7 (C-1ꢀ), 60.8 (C-6), 43.1 ( CH2), 39.0
(
CH2), 17.7 (CH3).

44
K.T. Petrova et al. / Carbohydrate Polymers 110 (2014) 38–46
(20 mL), dried over anhydrous Na2SO4 and concentrated under
Anal. Calcd for C19H32N2O13: C, 45.97; H, 6.50; N, 5.64%. Found:
reduced pressure. The crude product was purified by flash col-
umn chromatography (eluent, hexane/EtOAc; 4/1) to afford pure
C, 45.89; H, 6.55; N, 5.59%.
6,6ꢀ-Dideoxy-6,6ꢀ-N-dimethacryloyloxyethylureido sucrose 3:
To a solution of 6,6ꢀ-diamino-6,6ꢀ-dideoxysucrose 18 (Barros,
Petrova, Correia-da-Silva, et al., 2011) (0.5 g, 1.47 mmol) in
water (6.5 mL) at 0 ◦C, was added 2-isocyanatoethyl methacry-
late (0.413 mL, 2.93 mmol, 2 equiv.), remaining at 0 ◦C for 1 h
and then stirred overnight at r.t. The resulting mixture was
washed with CH2Cl2, concentrated under vacuum and purified by
plate chromatography (SiO2 eluted with 70:30 CHCl3:MeOH) to
afford 6,6ꢀ-dideoxy-6,6ꢀ-N-dimethacryloyloxyethylureido sucrose
3 as colorless solid (0.612 g, 63%). m.p. 73–75 ◦C.
1ꢀ,2,3,3ꢀ,4,4ꢀ,6-hepta-O-benzyl-6ꢀ-azido-6ꢀ-deoxysucrose
9 (85%,
0.808 g) as colorless oil.
IR (NaCl): ꢀmax 3030, 2919, 2866, 2099, 1496, 1454, 1363, 1285,
1208, 1089 cm−1
.
[␣]D + 42.2 (c 1.0, CHCl3).
1H NMR (400 MHz, CDCl3): ı ppm 7.28–7.16 (m, 35H, ArH), 5.60
(d, J = 1.8 Hz, 1H, H-1), 4.90 (d, J = 10.7 Hz, 1H, PhCH2), 4.84–4.75 (m,
2H, PhCH2), 4.65–4.34 (m, 12H, H-3ꢀ, PhCH2), 4.10–3.94 (m, 4H, H-
3, H-4ꢀ, H-5ꢀ, 1H of H-6), 3.69–3.43 (m, 7H, H-1ꢀ, H-2, H-4, H-5, 1H
of H-6, 1H of H-6ꢀ), 3.17 (d, J = 12.3 Hz, 1H of H-6ꢀ).
[␣]D + 41.0 (c 0.8, CH3OH).
13C NMR (100 MHz, CDCl3): ı ppm 138.7, 138.4, 138.1, 138.0,
137.8, 137.7 (Ar-Cquat), 128.3, 127.8, 127.7, 127.6, 127.5 (Ar), 104.6
(C-2ꢀ), 90.2 (C-1), 83.6 (C-3ꢀ), 82.9, 81.8, 79.6, 79.3, 77.8 (C-2, C-3,
C-4, C-4ꢀ, C-5ꢀ), 75.5 (CH2), 74.8 (CH2), 73.4 (CH2), 73.3 (CH2), 72.8
(CH2), 72.7 (CH2), 72.6 (CH2), 70.8 (C-6), 70.6 (C-5), 68.7 (C-1ꢀ), 53.6
(C-6ꢀ).
IR (KBr): ꢀmax 3377, 1720, 1636, 1570, 1053 cm−1
.
1H NMR (400 MHz, D2O): ı ppm 6.00 (s, 1H, CH2a), 5.99 (s, 1H,
CH2a), 5.58 (s, 2H, CH2b), 5.19 (d, J = 2.92 Hz, 1H, H-1), 4.13–3.99
(m, 5H, H-3ꢀ, H-6, H-6ꢀ), 3.83 (t, J = 8.06 Hz, 1H, H-4ꢀ), 3.77–3.65 (m,
2H, H-5, H-5ꢀ), 3.61 (t, J = 9.52 Hz, 1H, H-3), 3.57–3.44 (m, 3H, H-1ꢀ,
H-2), 3.43–3.09 (m, 9H, H-4, 4× CH2), 1.77 (s, 6H, CH3).
MALDI-TOF MS: Calcd for C61H63N3O10Na ([M+Na]+):
1020.4411, found 1020.4406.
13C NMR (100 MHz, D2O) ı 169.6, 169.5 (CO ester), 160.2, 160.1
(CO amide), 135.7, 135.7 ( C(CH3) ), 126.9 ( CH2), 103.7 (C-2ꢀ),
92.0 (C-1), 79.8 (C-5ꢀ), 76.6 (C-3ꢀ), 76.0 (C-4ꢀ), 72.1 (C-3), 71.6 (C-5),
71.2 (C-2), 71.1(C-4), 64.5 (C-6ꢀ), 64.4 (C-6), 61.3 (C-1ꢀ), 43.1 ( CH2),
40.9 ( CH2), 38.7 ( CH2), 17.4 (CH3).
1ꢀ,2,3,3ꢀ,4,4ꢀ,6-hepta-O-benzyl-6ꢀ-amino-6ꢀ-deoxysucrose 10:
To
a
solution of 1ꢀ,2,3,3ꢀ,4,4ꢀ,6-hepta-O-benzyl-6ꢀ-azido-6ꢀ-
deoxysucrose 9 (0.500 g, 0.5 mmol) in THF:H2O (5.5 mL; 10:1), was
added Ph3P (0.395 g, 1.5 mmol) and reaction mixture was heated at
70 ◦C for 3 h. The progress of reaction was monitored by TLC. After
completion of the reaction (3 h), as indicated by disappearance of
starting material and appearance of a new more polar spot on TLC,
solvent was evaporated under reduced pressure to give crude prod-
uct, which was purified by column chromatography on activated
Al2O3 (eluent, 3% MeOH in CH2Cl2) to afford 1ꢀ,2,3,3ꢀ,4,4ꢀ,6-hepta-
O-benzyl-6ꢀ-amino-6ꢀ-deoxysucrose 10 (0.435 g, 89%) as colorless
oil.
MALDI-TOF MS: Calcd for C26H42N4O15 [M+Na]+: 673.2544,
Found 673.2539.
1ꢀ,2,3,3ꢀ,4,4ꢀ,6-Hepta-O-benzyl-6ꢀ-O-methanesulfonylsucrose
8:
To a solution of 1ꢀ,2,3,3ꢀ,4,4ꢀ,6-hepta-O-benzylsucrose 7 (Barros
et al., 2004) (1 g, 1.027 mmol) in CH2Cl2 (15 mL) under inert atmo-
sphere was added Et3N (0.158 mL, 1.13 mmol) and catalytic amount
of 4-dimethylamino pyridine (DMAP). The reaction mixture was
cooled to 0 ◦C in ice-water bath, then methanesulfonyl chloride
(85 ␮L, 1.08 mmol) was added dropwise and reaction mixture was
stirred for 30 min at 0 ◦C, followed by stirring at r.t. for 1.5 h.
After completion of the reaction, reaction mixture was quenched
with sat. solution of NH4Cl and extracted with CH2Cl2 (2 × 20 mL).
The combined organic layer was dried over anhydrous Na2SO4
and concentrated under reduced pressure to give crude prod-
uct, which was further purified by flash column chromatography
(eluent, hexane/EtOAc; 4/1) to afford pure 1ꢀ,2,3,3ꢀ,4,4ꢀ,6-O-
benzyl-6ꢀ-O-methanesulfonylsucrose 8 (95%, 1.028 g) as a viscous
liquid.
IR (NaCl): ꢀmax 3392, 3030, 2915, 2865, 1496, 1483, 1454, 1437,
1362, 1198, 1119, 1027 cm−1
.
[␣]D + 41.1 (c 1.0, CHCl3).
1H NMR (400 MHz, CDCl3): ı ppm 7.27–7.10 (m, 35H, ArH), 5.63
(d, J = 2.0 Hz, 1H, H-1), 4.90 (d, J = 10.8 Hz, 1H, PhCH2), 4.81–4.74
(m, 2H, PhCH2), 4.66–4.64 (m, 3H, PhCH2), 4.55–4.30 (m, 9H, 8H of
PhCH2 and H-5ꢀ), 4.17–3.95 (m, 4H, H-3, H-3ꢀ, H-4ꢀ, H-5), 3.62–3.29
(m, 6H, H-2, H-1ꢀ, H-4, H-6), 3.07–2.96 (m, 2H, H-6ꢀ).
13CNMR (100 MHz, CDCl3): ı ppm 138.5, 138.0, 137.9, 137.8,
137.7, 137.2 (Ar-Cquat), 128.5, 128.3, 127.8, 127.7, 127.6, 127.5
(ArCH), 104.7 (C-2ꢀ), 90.5 (C-1), 83.5 (C-3ꢀ), 82.1, 81.6, 79.3 (C-3,
C-4ꢀ, C-5ꢀ), 78.5 (C-4), 77.8 (C-2), 75.5 (CH2), 74.9 (CH2), 73.4 (CH2),
73.3 (CH2), 73.1 (CH2), 72.7 (CH2), 72.4 (CH2), 71.4 (C-6), 71.0 (C-5),
69.1 (C-1ꢀ), 41.6 (C-6ꢀ).
IR (NaCl): ꢀmax 3030, 2912, 2867, 1496, 1454, 1359, 1208, 1176,
1090 cm−1
.
[␣]D + 40.8 (c 1.0, CHCl3).
1H NMR (400 MHz, CDCl3): ı ppm 7.30–7.12 (m, 35H, Ar) 5.59 (d,
J = 3.2 Hz, 1H, H-1), 4.93–4.77 (m, 3H, PhCH2), 4.65–4.32 (m, 13H,
11H of PHCH2, 1H of H-6, H-3ꢀ), 4.23–4.17 (m, 2H, H-5ꢀ, H of 1H-1ꢀ),
4.10–3.94 (m, 3H, H-3, H-5, H-4ꢀ), 3.70 (d, J = 10.9, 1H, 1H of H-1ꢀ),
3.60–3.47 (m, 5H, H-2, H-4, H-6ꢀ, 1H of H-6), 2.88 (s, 3H, CH3).
13C NMR (100 MHz, CDCl3): ı ppm 138.7, 138.2, 138.1, 137.8,
137.6 (Ar-Cquat), 128.3, 128.0, 127.8, 127.7, 127.6 (Ar), 104.8 (C-2ꢀ),
90.5 (C-1), 83.5 (C-3ꢀ), 81.8 (C-3, C-5, C-4ꢀ), 79.6 (C-2), 78.1 (C-5ꢀ),
77.6 (C-4), 75.5 (CH2), 74.9 (CH2), 73.3 (CH2), 72.9 (CH2), 72.7 (CH2),
70.8 (C-5), 70.4 (C-6), 70.2 (C-1ꢀ), 68.6 (C-6ꢀ), 37.1 (CH3).
MALDI-TOF MS: Calcd for C62H66O13SNa ([M+Na]+): 1073.4122,
found 1073.4116.
MALDI-TOF MS: Calcd for C61H65NO10Na ([M+Na]+): 994.4506,
found 994.4501.
6ꢀ-Azido-6ꢀ-deoxy-sucrose 14:
To
a
solution of 1ꢀ,2,3,3ꢀ,4,4ꢀ,6-hepta-O-acetyl-6ꢀ-azido-6ꢀ-
deoxy-sucrose 13 (0.850 g, 1.285 mmol) in dry MeOH (15 mL) under
Ar at r.t. was added NaOMe (0.345 g, 6.42 mmol) and the mix-
ture was stirred at r.t. for 4 h. After completion of the reaction,
reaction mixture was neutralized by passing through a short bed
of Amberlite IR-120 (H+-form), washed with dry MeOH and the
filtrate was concentrated under reduced pressure to give crude
product, which was purified by flash column chromatography (elu-
ent; EtOAc/MeOH, 10/3) to afford 6ꢀ-azido-6ꢀ-deoxy-sucrose 14
(0.405 g, 85%) as colorless solid. m.p. 43–45 ◦C (EtOH) (not reported
in literature) dec. 70 ◦C
1ꢀ,2,3,3ꢀ,4,4ꢀ,6-Hepta-O-benzyl-6ꢀ-azido-6ꢀ-deoxysucrose 9:
To
a
solution
of
(1 g, 0.95 mmol) in DMF (25 mL)
1ꢀ,2,3,3ꢀ,4,4ꢀ,6-O-benzyl-6ꢀ-O-
methanesulfonylsucrose
8
[␣]D + 64.8 (c 0.6, H2O); Lit. (Singh et al., 1984) +68.0 (c 1.0, H2O).
IR (KBr): ꢀmax 3391, 2924, 2105, 1656, 1637, 1281, 1136,
was added NaN3 (0.250 g, 3.8 mmol) and reaction mixture was
subjected to microwave irradiation at 120 ◦C and 400 W for
10 min. After that the reaction was cooled to room temperature
and quenched with water (30 mL), followed by extraction with
Et2O (3 × 20 mL). The organic layer was again washed with water
1053 cm−1
.
1H NMR (400 MHz, D2O): ı ppm 5.50 (d, J = 3.66 Hz, 1H, H-1),
4.11 (d, J = 8.5 Hz, 1H, H-3ꢀ), 3.98 (t, J = 8.40 Hz, 1H, H-4ꢀ), 3.83–3.88

K.T. Petrova et al. / Carbohydrate Polymers 110 (2014) 38–46
45
(m, 1H, H-3), 3.76–3.78 (m, 2H, H-6), 3.63–3.70 (m, 3H, H-5, H-6ꢀ),
3.58 (s, 2H, H-1ꢀ), 3.43–3.48 (m, 2H, H-2 and H-5ꢀ), 3.33 (t, J = 9.36 Hz,
1H).
the solution was stirred at 70 ◦C for 24 h. The resulting polymer was
recovered by filtration, washed with methanol and dried under vac-
uum. The polymer 21 was obtained in 18% recovered yield (0.09 g)
and was characterized as amorphous solid.
13C NMR (100 MHz, D2O): ı ppm 104.2 (C-2ꢀ), 92.5 (C-1), 80.0
(C-3), 76.5 (C-3ꢀ), 75.7 (C-4ꢀ), 72.8 (C-5, C-5ꢀ), 71.4 (C-2), 69.7 (C-4),
61.4 (C-1ꢀ), 60.7 (C-6), 53.2 (C-6ꢀ).
Poly(6,6ꢀ-dideoxy-6,6ꢀ-N-dimethacryloyloxy
sucrose)-co-polystyrene 22:
ethylureido
MALDI-TOF MS: Calcd for C12H21N3O10 [M+Na]+: 390.3005,
Found 390.1119.
Co-polymerization of monomer 2 (0.500 g, 1.01 mmol) with
styrene (10 equiv., 1.15 mL, 10.1 mmol) was carried out in anhy-
drous DMF solution (0.1 M, 10 mL) in the presence of AIBN as
radical initiator (1% by weight with respect to the monomer mix-
ture, 15 mg). Dissolved oxygen was removed from the solutions by
three freeze-thaw cycles on the vacuum pump. It was then heated
at 70 ◦C until the polymerization was complete, the solution was
cooled to r.t. and the product precipitated in cold ethanol. The white
solid was filtered and washed several times with cold acetone. The
polymer 22 was dried under vacuum to yield 0.217 g, 14% as white
amorphous powder.
6ꢀ-Amino-6ꢀ-deoxy-sucrose 15:
To a solution of 6ꢀ-azido-6ꢀ-deoxy-sucrose 14 (0.367 g, 1 mmol)
in dioxane: MeOH (10 mL, 8:2) at r.t. was added Ph3P (1.05 g,
4 mmol) and the mixture was stirred at r.t. for 2 h. Then, NH4OH
(2.5 mL) was added and the mixture was stirred overnight. After
completion of the reaction, as indicated by disappearance of
starting material and appearance of a polar spot on TLC (eluent
EtOAc/MeOH; 5/3), the solvent was evaporated under reduced
pressure. The crude product was washed with EtOAc thrice and
decanted. The residue was dissolved in water, filtered off and the
filtrate was concentrated under reduced pressure to afford 6ꢀ-
amino-6ꢀ-deoxy-sucrose 15 (0. 296 g, 86%) as faint pale yellow solid.
m.p. 70–72 ◦C (H2O); Lit. (Suami, Ikeda, Nishiyama, & Adaghi, 1975)
132–135 ◦C.
Poly(6,6ꢀ-dideoxy-6,6ꢀ-N-dimethacryloyloxyethylureido
sucrose) 23:
Homo-polymeric hydrogel 23 synthesis was carried out by dis-
solving 3 (0.500 g, 0.769 mmol) in dist. H2O (0.1 M, 8 mL), and the
solution was sparged with Ar for 15 min. Sodium persulfate (1%,
5 mg) was added, and the solution was stirred at 70 ◦C for 24 h.
The resulted heterogeneous mixture was filtered and washed thor-
oughly with dist. water and then cold methanol to remove any
residual monomer, then dried under vacuum to yield 23 as insolu-
ble amorphous powder (0.250 g, 20%).
[␣]D + 58.8 (c 0.5, H2O); Lit. (Singh et al., 1984) +57.3 (c 1.0, H2O).
IR (KBr): ꢀmax 3446, 2924, 1654, 1457, 1340, 1138, 772 cm−1
.
1H NMR (400 MHz, D2O): ı ppm 5.29 (d, J = 3.69 Hz, 1H, H-1),
4.10 (d, J = 8.54 Hz, 1H, H-3ꢀ), 3.94 (t, J = 8.54 Hz, 1H, H-4ꢀ), 3.63–3.76
(m, 5H, H-3, H-5, H-5ꢀ, H-6), 3.56 (s, 2H, H-1ꢀ), 3.44 (dd, J = 3.66 and
10.24 Hz, 1H, H-2), 3.35 (t, J = 9.36 Hz, 1H, H-4), 2.87–2.89 (m, 2H,
H-6ꢀ).
Poly(6,6ꢀ-dideoxy-6,6ꢀ-N-dimethacryloyloxyethylureido
sucrose)-co-polystyrene 24:
13C NMR (100 MHz, D2O): ı ppm 104.1 (C-2ꢀ), 92.6 (C-1), 81.3
(C-5ꢀ), 76.8 (C-3ꢀ), 75.6 (C-4ꢀ), 72.8 (C-5), 71.4 (C-2), 69.6 (C-4), 61.6
(C-1ꢀ), 60.5 (C-6), 43.2 (C-6ꢀ).
Monomer 3 (0.500 g, 0.769 mmol) was dissolved in dist. H2O
(0.1 M, 8 mL) and sodium persulfate (1%, 5 mg) was added. Styrene
(10 equiv., 0.88 mL, 7.69 mmol) was dissolved in toluene (8 mL). The
two solutions were combined and sparged with Ar for 15 min; then
heated at 70 ◦C for 24 h while stirred vigorously. The resulted het-
erogeneous mixture was filtered and washed thoroughly with dist.
water and then cold methanol to remove any residual monomer,
then dried under vacuum to yield 24 as insoluble amorphous pow-
der (0.689 g, 53%).
MALDI-TOF MS: Calcd for C12H23NO10 [M+Na]+: 364.1220,
Found 364.1214.
Poly(N-(methacrylamido)-1ꢀ,2,3,3ꢀ,4,4ꢀ,6-hepta-O-benzyl-6ꢀ-
amino-6ꢀ-deoxysucrose) 19:
Homo-polymerization of monomer 1 (0.500 g, 0.48 mmol) was
carried out in anhyd. toluene solution (0.1 M, 4.8 mL) in the pres-
ence of AIBN as radical initiator (1% by weight with respect to the
monomer mixture, 5.0 mg). Dissolved oxygen was removed from
the solutions by three freeze-thaw cycles on the vacuum pump. It
was then heated at 70 ◦C until the polymerization was complete;
the solution was cooled to r.t. and the product was precipitated in
cold ethanol. The white solid was filtered and washed several times
with cold ethanol. The polymer was purified by repeated dissolu-
tion in toluene and reprecipitation in cold ethanol and dried under
vacuum to yield 0.070 g, 14% of polymer 19 as white powder.
Poly(N-(methacrylamido)-1ꢀ,2,3,3ꢀ,4,4ꢀ,6-hepta-O-benzyl-6ꢀ-
amino-6ꢀ-deoxysucrose)-co-polystyrene 20:
Acknowledgements
This work has been supported by Fundac¸ ão para a Ciência
e a Tecnologia through Grant No. PEst-C/EQB/LA0006/2011 and
PTDC/SAU-BMA/122444/2010. T.M.Potewar is grateful to Fundac¸ ão
para a Ciência e a Tecnologia for the pos-doctoral Grant No.
SFRH/BPD/65173/2009. O.S.Ascenso is grateful for the BI grant from
project PTDC/QUI/72120/2006.
Co-polymerization of monomer 1 (0.500 g, 0.48 mmol) with
styrene (10 equiv., 0.55 mL, 4.80 mmol) was carried out in anhyd.
toluene solution (0.1 M, 4.8 mL) in the presence of AIBN as radi-
cal initiator (1% by weight with respect to the monomer mixture,
10 mg). Dissolved oxygen was removed from the solutions by three
freeze-thaw cycles on the vacuum pump. It was then heated at 70 ◦C
until the polymerization was complete, the solution was cooled to
r.t. and the product precipitated in cold ethanol. The white solid was
filtered and washed several times with cold ethanol. The polymer
was purified by repeated dissolution in toluene and reprecipita-
tion in cold ethanol and dried under vacuum to yield 0.480 g, 48%
of polymer 20 as white powder.
Appendix A. Supplementary data
Supplementary data associated with this article can be
found, in the online version, at http://dx.doi.org/10.1016/
j.carbpol.2014.03.050.
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