Synthesis and characterization of novel methacrylate copolymers based on sulfonamide and coumarine: Monomer reactivity ratios, biological activity, thermal stability, and optical properties

Article abstract of DOI:10.1002/pola.24220

The free radical copolymerization of 2-oxo-2-[(4-sulfamoylphenyl)amino] ethyl-2-methylpropenoate (SAEMA) with 4-methyl-2-oxo-2H-chromen-7-yl-2- methylpropenoate (MCMA) has been carried out in 1, 4-dioxane at 65 °C ± 1 °C and the copolymers were analyzed by Fourier-transform infrared,¹H-NMR,¹³C-NMR and gel permeation chromatography.¹H-NMR and elemental analysis was used to determine the molar fractions of SAEMA and MCMA in the copolymers. The monomer-reactivity ratios were calculated according to the general copolymerization equation using Kelen-Tuedos and Fineman-Ross linearization methods. The reactivity ratios indicated a tendency toward random copolymerization. The polydispersity indices of the polymers, determined with gel permeation chromatography, suggested a strong tendency for chain termination by disproportionation. The thermal behaviors of copolymers with various compositions were investigated by differential scanning calorimetry and thermogravimetric analysis. The glass-transition temperature of the copolymers increased with increasing MCMA content in the copolymers. Also, the apparent thermal decomposition activation energies were calculated by the Ozawa method with a Shimadzu TGA 60 thermogravimetric analysis thermobalance. All the products showed moderate activity against different strains of bacteria and fungi. The photochemical properties of the polymers were investigated by UV spectra.

Full text of DOI:10.1002/pola.24220

Synthesis and Characterization of Novel Methacrylate Copolymers based
on Sulfonamide and Coumarine: Monomer Reactivity Ratios, Biological
Activity, Thermal Stability, and Optical Properties
_
¨
IBRAHIM EROL, GULAY SANLI, MELTEM DILEK, LEVENT OZCAN
Department of Chemistry, Faculty of Science and Arts, University of Afyon Kocatepe, Afyonkarahisar, Turkey
Received 13 April 2010; accepted 29 June 2010
DOI: 10.1002/pola.24220
Published online in Wiley Online Library (wileyonlinelibrary.com).
ABSTRACT: The free radical copolymerization of 2-oxo-2-[(4-sulfa-
moylphenyl)amino]ethyl-2-methylpropenoate (SAEMA) with 4-
methyl-2-oxo-2H-chromen-7-yl-2-methylpropenoate (MCMA) has
been carried out in 1, 4-dioxane at 65 ꢀC 6 1 ꢀC and the copoly-
mers were analyzed by Fourier-transform infrared, 1H-NMR, 13C-
NMR and gel permeation chromatography. 1H-NMR and elemen-
tal analysis was used to determine the molar fractions of SAEMA
and MCMA in the copolymers. The monomer-reactivity ratios
were calculated according to the general copolymerization equa-
investigated by differential scanning calorimetry and thermo-
gravimetric analysis. The glass-transition temperature of the
copolymers increased with increasing MCMA content in the
copolymers. Also, the apparent thermal decomposition activa-
tion energies were calculated by the Ozawa method with a Shi-
madzu TGA 60 thermogravimetric analysis thermobalance. All
the products showed moderate activity against different strains
of bacteria and fungi. The photochemical properties of the poly-
C
V
mers were investigated by UV spectra. 2010 Wiley Periodicals,
tion using Kelen-Tudo˜ s and Fineman-Ross linearization methods.
¨
Inc. J Polym Sci Part A: Polym Chem 48: 4323–4334, 2010
The reactivity ratios indicated a tendency toward random copoly-
merization. The polydispersity indices of the polymers, deter-
mined with gel permeation chromatography, suggested a strong
tendency for chain termination by disproportionation. The ther-
mal behaviors of copolymers with various compositions were
KEYWORDS: activation energy; biological activity; biomaterials;
coumarin methacrylate; differential scanning calorimetry (DSC);
functionalization of polymers; monomer reactivity ratios; radical
polymerization; suflonamide methacrylate
INTRODUCTION Functional groups give a polymer structure
a special character substantially different from the inherent
properties of the basic polymer chain.1 In recent years, some
comprehensive work has been published on functional
monomers and their polymers.2–5 Sulfonamide is a generic
name for derivatives of para-aminobenzene sulfonamide. The
importance of sulfonamide nucleus is well established in the
pharmaceutical chemistry and drug design. A considerable
number of sulfonamides are well known as antibacterial,6
anticancerous,7 carbonic anhydrase inhibitors,8 and also as
anti-inflammatory agents.9 Just how good a drug the sulfona-
mide is depends on the nature of the group attached to the
amido nitrogen. Although many thousands of derivatives
have been synthesized only a few had the proper combina-
tion of high antibacterial activity and low toxicity to human
beings that is necessary for an effective drug.10 The antibac-
terial activity of sulfonamides set in motion for other chemi-
cals, related to sulfonamides that have even better chemo-
therapeutic effects. Literally thousands of chemical variations
were played on the sulfanilamide theme; the structure of
sulfanilamide was varied in almost every imaginable way. In
previous reports, a new class of pH-sensitive polymers con-
taining a sulfonamide group was shown to demonstrate a
sharp transition in solubility and swelling around pH 7.411–19
and its reversibility.20
Coumarin-containing polymers have been well studied and
widely applied in many fields, such as biochemicals, electro-
optical materials, organic-inorganic hybrid materials, liquid
crystalline materials, and light harvesting/energy transfer-
ring materials.21–25 However, most reported coumarin-con-
taining polymers were linear polymers. And the coumarin
functional group was introduced as a pendent group or ter-
minal group of the polymer chain.26–29 A recent review arti-
cle highlighted the photochemistry of 7-hydroxycoumarin
and various derivatives that are known to undergo photodi-
merization (2p þ 2p cycloaddition) reactions when irradi-
ated with ultraviolet-A (UVA) sources (320–400 nm).30 Some
photodimerized coumarins have reversible cleavage potential
at wavelengths below 290 nm, shifting the equilibrium to-
ward the monomeric coumarin species.
Knowledge of the copolymer composition is an important
step in the evaluation of its utility. The copolymer composi-
tion and its distribution depend on monomer reactivity
ratios. The most common mathematical model of copolymer-
ization is based on finding the relationship between the
Correspondence to: I. Erol (E-mail: iberol@hotmail.com)
C
V
Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 48, 4323–4334 (2010) 2010 Wiley Periodicals, Inc.
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JOURNAL OF POLYMER SCIENCE: PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
SCHEME 1 Synthesis of the MCMA
monomer.
composition of copolymers and the composition of the
monomer feed in which the monomer-reactivity ratios are
the parameters to be determined.31,32 The calculation of the
monomer-reactivity ratios requires the mathematical treat-
ment of experimental data on the composition of copolymers
and monomer in feed mixtures. The most fundamental quan-
tity characterizing a copolymer is its composition on a molar
basis, which eventually is used for the determination of the
relevant monomer reactivity ratios. Spectroscopic methods,
preferably 1H-NMR spectroscopy,33,34 and elemental analysis
are probably the most widely used methods for the analysis
of copolymers and the determination of reactivity ratios r1
and r2.
Instrument and Measurements
Infrared spectra were obtained with a Perkin–Elmer 460
Fourier-transform infrared (FT-IR) spectrometer with KBr
pellets in the 4000 to 400 cmꢁ1 range, and 10 scans were
taken at a 4 cmꢁ1 resolution. 1H-NMR and 13C-NMR spectra
in DMSO and CD2Cl2 solutions were recorded on a Bruker
GmbH DPX-400 400 MHz FT-NMR spectrometer with tetra-
methylsilane as an internal reference. The molecular weights
[weight average molecular weight (Mw) and number average
molecular weight (Mn)] of the polymer were determined
with a Waters 410 gel permeation chromatograph equipped
with a refractive index detector and calibrated with poly-
styrene standards. Thermal data were obtained with a Shi-
ꢁ1
ꢀ
madzu DSC-60H instrument at a heating rate of 10 C min
Thermogravimetric analysis (TGA) has been widely used to
investigate the decomposition characteristics of many mate-
rials. Some methods have already been established to evalu-
ate the kinetic parameters from thermogravimetric data.35,36
In previous study,16 Han Bae et al. described the synthesis
and characterization of the methacrylamide monomer based
on the sulfonamide and its homopolymer.
and with a Labsys TGA thermobalance at a heating rate
of 10 ꢀC minꢁ1 in a N2 atmosphere. Elemental analyses
were carried out with an Elementar CHNS microanalyzer.
UV-vis absorption spectra were measured using a Shimadzu
UV-1700 Pharma spectrophotometer. The photoluminescence
were recorded on
spectrophotometer.
a Varian Cary Eclipse Fluorescence
In this work, we have synthesized two new methacrylate
monomers. One of them has sulfonamide group in side chain.
Almost all the polymers bearing sulfonamide published in
the literature are as methacrylamide. We have synthesized
and characterized a new monomer and its polymer as meth-
acrylate having pendant sulfonamide. The other monomer
that we have synthesized is methacylate containing coumar-
ine ring. As far as we know, in the literature, an acrylate
monomer bearing coumarine has been synthesized37 but a
methacrylate has not. It is thought that methacrylate poly-
mers bearing two important groups such as coumarine and
sulfonamide and their copolymerization acts will be interest-
ing for polymer chemistry. In addition, the effects of the co-
polymer composition/thermal behavior relationships, and an
investigation of the biological activity and optical properties
are presented and discussed.
Syntheses
Synthesis of 4-Methyl-2-oxo-2H-chromen-7-yl-2-
methylpropenoate Monomer (MCMA)
The synthesis of 4-methyl-2-oxo-2H-chromen-7-yl-2-methyl-
propenoate (MCMA) monomer was carried out according to
the usual method.38 Scheme 1 shows the reaction leading to
the fꢀormation of monomer. The melting point of MCMA was
110 C, and yield was about 82%.
IR (neat), cmꢁl: 1734 (broad, C¼¼O of methacrylate and of
coumarin group), 3082 (ACH stretching vibration of the
aromatic ring), 2990 (ACH3 on coumarin and methacrylate),
1634 (C¼¼C), 1240 (asymmetric CAOAC), 1142 (symmetric
CAOAC), 890 (ACH bending mode of vinyl group).
1H-NMR (d, ppm from TMS in CDCl3): 6.4–7.8 (aromatic pro-
tons, 4H); 5.6 (CH2¼¼, 1H); 6.2 (CH2¼¼, 1H); 2.5 (CH3A, on
coumarin, 3H); 1.9 (CH3A, on methacrylate, 3H).
13C-NMR (d, ppm from TMS in CDCl3): 165.5 and 160.6
(C¼¼O of methacrylate and coumarine moiety respectively);
135.7 (¼¼C); 128.0 (CH2¼¼); 156-119 (Aromatic carbons);
19 (CH3 in olefinic and on coumarine carbon).
EXPERIMENTAL
Materials
Methacryloyl chloride, sodium methacrylate, 4-methyl-7-
hydroxy coumarin, sulfonamide (Aldrich) were used as
received. Ethanol, methanol, chloroform, n-hexane, and ben-
zene were freshly distilled over molecular sieves before use.
Then 1,4-dioxane, acetonitrile, and potassium carbonate
(Merck) were used as received. Azobisizobutyronitrile
(AIBN) was recrystallized from a chloroform-methanol mix-
ture. All the other chemicals were analytical grade and com-
mercial products, and they were used without any further
purification.
Synthesis of 2-Chloro-N-(4-sulfamoylphenyl)acetamide
(ClSPA)
Synthesis of the 2-chloro-N-(4-sulfamoylphenyl)acetamide
was carried out according to the usual method.38 The syn-
thesis route is shown in the Scheme 2.
IR (neat), cmꢁl: 1684 (C¼¼O for amide), 1160–1300 (SO2),
3187 (ANHA), 680 (C-Cl).
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SCHEME 2 Synthesis of the 2-chloro-N-(4-sulfamoylphenyl)acetamide.
Synthesis of 2-Oxo-2-[(4-sulfamoylphenyl)amino]ethyl-2-
methylpropenoate (SAEMA) Monomer
uum to constant weight at room temperature and kept in
desiccators under vacuum until use.
The synthesis of monomer is shown in Scheme 3. Synthesis
of 2-oxo-2-[(4-sulfamoylphenyl)amino]ethyl-2-methylprope-
noate(SAEMA) was as follows: 2-chloro-N-(4-sulfamoylphe-
nyl)acetamide (ClSPA) (1 mol) and sodium methacrylate (1.1
mol) were stirred in 75 mL acetonitrile at 75 ꢀC in a reflux
condenser for 24 h in the presence of 100 ppm hydro-
quinone as inhibitor. Then the solution was cooled to room
temperature and neutralized with a 5% KOH solution. The
organic layer was washed several times with water and
the water layer was washed with diethyl ether a few times.
The acetonitrile layer and diethyl ether layer were collected
and dried over anhydrous MgSO4 overnight. Acetonitrile and
diethyl ether were evaporated. The organic layers were
collected and the residue was crystallized from methanol.
Yield: 80%. The reactions path is shown in Scheme 3.
Copolymerization
Copolymerizations of SAEMA with MCMA, with five different
feed compositions, were carried out in DMSO at 65 ꢀC with
AIBN (1%, based on the total weight of the monomers) as
an initiator. Appropriate amounts of SAEMA with MCMA and
DMSO was mixed in a polymerization tube, purged with N2
for 20 min, and kept at 65 ꢀC in a thermostat. The reaction
time (ꢂ3.5 h) was selected to give conversions less than
10 wt % to satisfy the differential copolymerization equa-
tion. The conversion of the monomer to the polymer was
determined by a gravimetric method. After the desired time,
the copolymerization was stopped. These copolymers were
poured into excess ethanol to precipitate, were filtered, were
purified by repeated reprecipitation from a solution of each
polymer in DMF by ethanol, and were dried in a vacuum
oven at 60 ꢀC to a constant weight. The amounts of mono-
meric units in the copolymers were determined by elemental
analysis (N and S content of SAEMA units) and 1H-NMR
analysis.
IR (neat), cmꢁl: 1724 (C¼¼O for ester), 1684 (C¼¼O, for
amide), 1160–1300 (SO2), 3187 (NHA), 3082 (CHA, of the
aromatic ring), 2980 (CAHA, aliphatic stretching vibration),
1630 (C¼¼C), 895 (CAH bending mode of vinyl group).
1H-NMR (d, ppm from TMS in CDCl3): 7.3–7.8 (aromatic pro-
tons, 4H); 5.6 (CH2¼¼, 1H); 6.2 (CH2¼¼, 1H); 10.8 (ANHA,
1H); 1.9 (CH3A, in olefinic carbon, 3H); 7.4 (SO2NH2), 4.8
(OCH2A, 2H).
Antimicrobial Screening
The biological activities of the monomers and their homo-
polymers and copolymers were tested against different
microorganisms with DMSO as the solvent. The sample con-
centration was 100 lg. In this study, Staphylococcus aureus
ATCC 29,213, Escherichia coli 0157:H7, Pseudomonas aerugi-
nasa ATCC 27,853, Proteus vulgaris, Salmonella enteridis, and
Klebsiella pneumoniae were used as bacteria. Candida
albicans CCM 31 was a fungus. YEPD medium cell culture
was prepared as described by Connerton.39 Ten milliliters of
YEPD medium were inoculated with each cell from plate
cultures. Yeast extract 1% (w/v), bactopeptone 2% (w/v),
and glucose 2% (w/v), was obtained from Difco. Microorgan-
isms were incubated at 35 ꢀC for 24 h. About 1.5 mL of
these overnight stationary phase cultures were inoculated
onto 250 mL of YEPD and incubated at 35 ꢀC until OD600
reached 0.5.
13C-NMR (d, ppm from TMS in CDCl3): 167.0 and 165.4
(C¼¼O of amide and ester); 129.6 (¼¼C); 125.1 (CH2¼¼); 110–
150 (aromatic carbons); 65 (OCH2); 18 (CH3 in olefinic
carbon).
Polymerization of the Monomers
Polymerization of SAEMA and MCMA were carried out in
glass ampoules under N2 atmosphere in DMSO solution with
AIBN (1% based on the total weight of monomers) as an ini-
tiator. The reacting components were degassed by threefold
freeze-thawing cycles and then immersed in oil bath at
65 ꢀC for a given reaction time. The polymers were sepa-
rated by precipitation in ethanol and reprecipitated from
DMF solution. The polymers were finally dried under vac-
SCHEME 3 Synthesis of the SAEMA
monomer.
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JOURNAL OF POLYMER SCIENCE: PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
FIGURE 1 1H-NMR spectra of (a) poly(MCTMA)
and (b) poly(SAEMA).
The antibiotic sensitivity of the polymers was tested with
the antibiotic disk assay as described.40 Nutrient agar (NA)
was purchased from Merck. About 1.5 mL of each prepared
different cell culture were transferred into 20 mL of NA and
mixed gently. The mixture was inoculated into the plate. The
plates were rotated firmly and allowed to dry at room
temperature for 10 min. Prepared antibiotic discs (100 lg)
were placed on the surface of the agar medium.41 The plates
were kept at 5 ꢀC for 30 min and then incubated at 35 ꢀC
for 2 days. If a toxic compound leached out from the disc, it
means that the microbial growth is inhibited around the
sample. The width of this area expressed the antibacterial or
antifungal activity by diffusion. The zones of inhibition of
microorganism growth of the standard samples monomers,
homopolymers and copolymers, were measured with a milli-
meter ruler at the end of the incubation period.
of some characteristic signals of the double bond in the
spectra and this fact was effectively observed in our case.
Thus, two bands vanished in the IR spectrum: the absorption
band at 923 cmꢁ1 assigned to the C-H bending of geminal
¼¼CH2 and the stretching vibration band of C¼¼C at 1600
1
cmꢁ1. The H-NMR spectrum of the monomers are presented
in Figure 1 and are good agreement with the structure.
From 1H-NMR spectroscopy the formation of the polymers
are also clearly evident from the vanishing of two singlet at
5.6 and 6.2 ppm of the vinyl protons and the appearance of
the broad signal at 1.5 and 2.2 ppm assigned to an aliphatic
ACH2A group. In the proton decoupled 13C-NMR spectrum
of poly(SAEMA) (Fig. 2), chemical shift assignments were
made from the off-resonance decoupled spectra of the poly-
mer. Resonance signals at 168 and 165 ppm correspond
to ester and amide group present in polymer. The signal due
to carbon of the aromatic ring attached to the NH group
shifts toward downfield and is observed at 142 ppm. The
other aromatic carbons are observed at 125 to 135 ppm.
The a-methyl group of polymer shows resonance signals at
18 ppm.
RESULTS AND DISCUSSION
Structural Characterization of the Monomers
and their Polymers
During the polymerization of the both monomers, the IR
band at 1630 cmꢁ1 (C¼¼C) disappearance and ester carbonyl
stretching for polymers shifted to about 1740 cmꢁ1. The
main evidence of the polymer is certainly the disappearance
Characterization of the Copolymers
The copolymeric units of SAEMA with MCMA can be repre-
sented according to Scheme 4.
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ARTICLE
FIGURE
2
13C-NMR spectra of
poly(SAEMA).
Solubility
1200 cmꢁ1. The CAH and C¼¼C out of plane bending vibra-
tions of the aromatic nuclei are observed at 790 and
565 cmꢁ1, respectively.
The solubility of the homopolymers and copolymers was
tested via the mixing of 10 mg of each polymer with 3 mL
of various solvents in test tubes. After the closed tubes
were set aside for 1 day, the solubility was observed. The
homopolymers and copolymers were soluble in 1,4-dioxane,
dimethylacetamide, dimethylformamide, dimethyl sulfoxide
(DMSO), tetrahydrofuran, but were insoluble in n-hexane,
n-heptane, ethanol, and methanol solvents.
1H-NMR Spectrum
The 1H-NMR spectrum of the copolymer poly(SAEMA-co-
MCMA) (0.70:0.30) is shown in Figure 4(a). The chemical
shift assignments for the copolymers were based on the
chemical shifts observed for the respective homopolymers.
The resonance signals at 10.50 ppm correspond to the NH
protons of the SAEMA unit. The aromatic protons show sig-
nals between 7.82 and 7.35 ppm.
Spectroscopic Characterization
FT-IR Spectrum
The FT-IR spectrum of the copolymer, poly-(SAEMA-co-
MCMA) (0.48:0.52), is shown in Figure 3. The peak at 3340
cmꢁ1 which is attributed to N-H stretching of the amide
group. The peak at 3050 cmꢁ1 corresponds to the CAH
stretching of the aromatic system. The symmetrical and
asymmetrical stretching due to the methyl and methylene
groups is observed at 2983, 2938, and 2863 cmꢁ1. The
shoulder at 1740 and a peak at 1680 cmꢁ1 are attributed to
the ester and amide carbonyl stretching of SAEMA and ester
and lactone carbonyl stretching of MCMA. The ring breathing
vibrations of the aromatic nuclei are observed at 1600,
1504, and 1470 cmꢁ1. The asymmetrical and symmetrical
bending vibrations of methyl groups are seen at 1460 and
1385 cmꢁ1. The CAO stretching is observed at 1165 and
The spectrum shows a signal at 4.8 ppm, which are due to
AOCH2A group at SAEMA units. The methyl protons on
MCMA show signal at 2.6 pmm. The backbone methylene
groups show signals at 2.24 to 2.60 ppm. The signals
obtained at 1.10 and 1.42 ppm are due to the a-methyl pro-
tons of both the monomer units.
13C-NMR Spectrum
The proton decoupled 13C-NMR spectrum of the copolymer
poly(SAEMA-co-MCMA) (0.70:0.30) is shown in Figure 4(b).
The amide and ester carbonyl of SAEMA appeared at 168.1
and 166 ppm, respectively, while the ketone and ester
carbonyl of MCMA appeared at 165.6 and 163.1 ppm. The
aromatic carbons in copolymer appeared at 115 to 150 ppm.
SCHEME 4 The structure monomeric
units of the copolymer.
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JOURNAL OF POLYMER SCIENCE: PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
The methyl carbons on the coumarin appeared at 25.6 ppm.
The a-methyl carbon atoms of both monomeric units give a
series of resonance signal at 18.2 ppm.
Copolymer Compositions
The copolymerization of MCTMA with IAOEMA in a 1,4-diox-
ane solution was studied for SAEMA molar fractions of
approximately 0.90 to 0.10 in the feed. The number of mono-
meric units in the copolymers was determined by 1H-NMR
spectroscopy and by elemental analysis. Thus, the mole frac-
tion of SAEMA in the copolymer was determined from the
ratio of the integrated values of the intensities of the aro-
matic protons (7.3–7.8) and the methylenoxy (4.8) of SAEMA
and aromatic protons (6.4–7.8 ppm) of MCMA units.
FIGURE
3 FT-IR
spectrum
of
poly(SAEMA-co-MCMA)
Let m1 be the mole fraction of SAEMA and m2 ¼ (1 ꢁ m1)
(0.70:0.30).
that of the MCMA unit.
Integrated intensities of aromatic protons and NH2 protons
Integrated intensities of methylenoxy protons
The methylenoxy group in SAEMA unit show signal at
66.3 ppm. The signals due to the backbone methylene
carbon atoms are observed at 43.2 and 45.0 ppm, while that
of the tertiary carbons is observed at 45.1 and 48.3 ppm.
4m1 þ 2m1 þ 4m2
¼
¼ C (1)
2m1
FIGURE 4 (a) 1H-NMR and (b) 13C-NMR spec-
tra of poly(SAEMA-co-MCMA) (0.70:0.30).
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TABLE 1 Monomer Compositions in Feed and in the Copolymer
Feed Composition
Copolymer Composition
(mol Fraction)
Intensty of
(mol Fraction)
Conv.
(%)
Methylenoxy
Protons
Sample
SAEMA (M1)
MCMA (M2)
SAEMA (m1)
MCMA (m2)
1
2
3
4
5
a
0.10
0.25
0.50
0.70
0.85
0.90
0.75
0.50
0.30
0.15
9.50
7.50
8.90
8.40
9.20
0.55
1.25
2.05
3.12
4,34
0.20
0.36
0.48
0.60
0.70
0.80, 0.81a
0.64, 0.65a
0.52
0.40, 0.39a
0.30
Determined by elemental analysis (N content).
Determination of the Monomer Reactivity Ratios
On simplification
The monomer reactivity ratios for the copolymerization of
SAEMA with MCMA were determined from the monomer
feed ratios and the copolymer composition. The plot of the
mole fraction of SAEMA in feed (M1) versus that of SAEMA
in copolymer (m1) is shown in Figure 5. The Fineman-Ross
(FR)44 and Kelen-Tudos (KT)45 methods were used to deter-
mine the monomer reactivity ratios. According to the FR
method, the monomer reactivity ratios can be obtained as
follows:
4
m1 ¼
(2)
2C ꢁ 2
where m1 and m2 are the copolymer molar compositions.
With eq 2, the molar fractions of SAEMA in the copolymers
were determined by the measurement of the integrated peak
heights of the total aromatic, methylenoxy, and NH2 protons
signals of SAEMA units. The results are presented in Table 1.
G ¼ Hr1 ꢁ r2
(3)
Molecular Weights
The molecular weights of the polymers were determined by
GPC with polystyrene and tetrahydrofuran as the standard
solvent, respectively. The Mw and Mn values and polydisper-
sity indices (Mw/Mn) of the polymer samples are presented
in Table 2. The polydispersity index of the polymers ranges
from 1.61 to 1.82. The theoretical values of Mw/Mn for the
polymers produced via radical recombination and dispro-
portionation are 1.5 and 2.0, respectively.42 In the homopoly-
merization of SAEMA, the growing chains terminate by
disproportionation. The polydispersity indices of poly
(SAEMA) and poly(MCMA) suggest that in both cases chain
termination by disproportionation outweighs coupling, and
the tendency for termination by disproportionation is greater
for MCMA than for SAEMA. The values of Mw/Mn in copoly-
merization are also known to depend on chain termination
in the same way as in homopolymerization.43
where r1 and r2 correspond to the SAEMA and MCMA mono-
mers, respectively. The parameters G and H are defined as
follows:
G ¼ F=ðf ꢁ 1Þ=f and H ¼ F2=f
(4)
with
F ¼ M1=M2 and f ¼ m1=m2
(5)
where M1 and M2 are the monomer molar compositions
in the feed and m1 and m2 are the copolymer molar
compositions.
TABLE 2 Molecular Weights, Polydispersity Index, and Tg
Values of Polymers
Sample
Mw ꢃ 104 Mn x 104 Mw/Mn Tg
Poly(SAEMA)
8.12
9.50
4.69
5.22
1.73
1.82
170
198
Poly(MCMA)
Poly(SAEMA-co-MCMA)
20/80
36/64
48/52
60/44
70/30
5.48
7.88
7.84
7.40
6.80
3.10
4.60
4.67
4.48
4.22
1.77
1.71
1.68
1.65
1.61
190
186
183
180
177
FIGURE 5 Copolymer composition diagram for poly(SAEMA-
co-MCMA) system. M1, feed composition in mole fraction for
SAEMA; m1: Copolymer composition in mole fraction for
SAEMA.
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ization kinetics and that the reactivity of a polymer radical is
determined only by the terminal monomer unit.
The values of r1 and r2 is less than 1, which indicates that
the system copolymerizes statistically. The reactivity of grow-
ing radicals with SAEMA unit, as measured by 1/r2 seems to
be higher toward MCMA monomer than its own monomer.
The r1 and r2 values strongly suggest that the copolymer
chain contains a greater number of MCMA units and less
SAEMA units than in the feed. Taking into account the micro-
structures of these copolymer systems, we know that the
intermolecular hydrogen bonding between the carbonyl
group of MCMA and the amide group of SAEMA has a larger
probability of occurring than the self-association through
hydrogen bonding of pure MCMA.46,47 The microstructure of
a polymeric material plays an important role in the behavior
of the material toward a variety of biological systems and
could be especially important in copolymerizations with
monomers of different reactivities.48
Glass Transition Temperatures
The glass transition temperatures (Tg’s) were determined
with a Shimadzu DSC-60 instrument.
Samples (about 5–8 mg) held in sealed aluminum crucibles
at a heating rate of 20 ꢀC/min under a dynamic nitrogen
flow (5 L hꢁ1) were used for the measurements. From DSC
measurements, Tg was taken as the midpoint of the transi-
tion region. Tg of is poly(MCMA) 198 ꢀC, and that of poly
ꢀ
(SAEMA) is 170 C. The Tg values of the copolymers increase
with an increase in the MCMA content in the copolymers.
The results clearly indicate that the Tg values of the copoly-
mers depend on the compositions of the comonomers and
increase with increasing MCMA content in the polymer chain.
The observed Tg values increase with increasing MCMA and
present a striking positive deviation with respect to linearity,
which can be associated with lower free volume, mobility,
and flexibility than those of a mixture of MCMA and SAEMA
units. The Tg values of the copolymers are indicated in the
Table 2.
FIGURE 6 (a) FR plots and (b) KT plots for determining the
monomer reactivity ratios in the copolymerization of SAEMA
(M1) and MCMA (M2).
Alternatively, the reactivity ratios can be obtained with the
KT method, which is based on the following equation:
g ¼ ðr1 þ r2=aÞn ꢁ r2=a
where g and n are functions of the parameters G and H
g ¼ G=ða þ HÞ and n ¼ H=ða þ HÞ
(6)
Decomposition Kinetics
The thermal stabilities of the polymers were investigated ꢁb1y
TGA in a nitrogen stream at a heating rate of 20 ꢀC min
.
(7)
In Figure 7, the TGA thermograms of the polymers are
shown. It is clear that one degradation stages are observed
for poly(SAEMA) and poly(MCMA). The initial decomposition
temperatures of poly(SAEMA) are around 318 ꢀC, and
and a is a constant equal to (Hmax ꢄ Hmin
)
1/2, Hmax, and Hmin
being the maximum and minimum H values, respectively,
from the series of measurements. From a linear plot of g as
a function of n, the values of g for n ¼ 0 and n ¼ 1 can be
used to calculate the reactivity ratios according to the follow-
ing equations:
TABLE 3 Copolymerization Parameters for the Free-Radical
Copolymerization of SAEMA with MCMAa
Methods
r1
r2
r1r2
1/r1
1/r2
n ¼ 0ꢁ! g ¼ ꢁr2=a and n ¼ 1ꢁ! g ¼ r1
(8)
F-R
0.26 6 0.015
0.28 6 0.08
0.27 6 0.095
0.30 6 0.014
0.36 6 0.011
0.33 6 0.013
0.078
0.100
0.090
3.85
3.75
3.70
3.33
2.78
3.03
The graphical plots concerning the methods previously
reported are given in Figure 6(a,b), whereas the reactivity
ratios are summarized in Table 3. In all cases and for all
graphical methods, the plots are linear, and this indicates
that these copolymerizations follow conventional copolymer-
K-T
Average
a
r1 and r2 are the monomer reactivity ratios for SAEMA and MCMA,
respectively.
4330
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ARTICLE
TABLE 4 Some TGA Result of the Copolymers
The Temperature (%) for a Weight Loss of the Residue (%)
IDT
(%)a
At
450 ꢀC
Polymer
20 ꢀC
50 ꢀC
70 ꢀC
Poly(SAEMA)
Poly(MCMA)
317
301
331
349
440
392
–
48
8
416
Poly(SAEMA-co-MCMA)
(20/80)
(48/52)
(70/30)
305
308
311
347
317
323
373
377
435
404
497
–
20
34
42
a
Initial decomposition temperature.
FIGURE 7 TGA curves for homoplymers and some copolymers.
with Ozawa plots, which are widely used. Degradations were
ꢀ
performed in the scanning mode, from 35 to 500 C, under a
nitrogen flow (20 mL minꢁ1), at various heating rates (7.0,
independent of the side-chain structures. The initial decom-
position temperatures for poly(MCMA) are observed at
10.0, 15.0, and 20.0 C minꢁ1). In Figure 8, the TGA thermo-
ꢀ
grams of poly (SAEMA-co-MCMA) (0.70:0.30) are shown.
Samples (5–8 mg) held in alumina open crucibles were used,
and their weights were measured as a function of the
temperature and stored in a list of data of the appropriate
built-in program of the processor. The TGA curves were
immediately printed at the end of each experiment, and the
weights of the sample were then transferred to a personal
computer at various temperatures.
ꢀ
around 300 C. One degradation stages for all copolymer are
observed. Some degradation characteristics of the copoly-
mers are given in Table 4 by comparison with those of the
homopolymers. The thermal degradation of poly(n-alkyl
methacrylate)s typically produces the monomer as a result
of depolymerization. The formation of cyclic anhydride-type
structures by intramolecular cyclization is another main pro-
cess in the degradation of these polymers. The latter pro-
duces some low-molecular-weight products, depending on
the chemical structures of the side chain of poly(methacrylic
esters). For the study of the kinetics of the thermal degrada-
tion of polymers, we can select isothermal thermogravimetry
(ITG) or thermogravimetry (TG) at various heating rates.49
ITG is superior for obtaining an accurate activation energy
for thermal degradation, although it is time-consuming. For
the thermal degradation of polymers, in which depolymeriza-
tion is competing with cyclization or crosslinking due to the
side groups, TG at various heating rates is much more con-
venient than ITG for the investigation of thermal degradation
kinetics. Therefore, in this work, TG curves at various heat-
ing rates were obtained, and the activation energies (DEd)
for the thermal degradation of the polymers were calculated
According to the method of Ozawa,50 the apparent thermal
decomposition activation energy (Ed) can be determined from
the TGA thermograms at various heating rates, such as those
in Figure 9, and with the following equation:
ꢀ
ꢁ
R
d log b
Ed ¼ ꢁ
(9)
b dð1=TÞ
where R is the gas constant; b is a constant (0.4567); and b
is the heating rate (ꢀC/min). According to eq 9, the activation
energy of degradation can be determined from the slope of
the linear relationship between log b and the reciprocal
of the temperature, as shown in Figure 8; the DEd values for
the polymers are given in Table 5. DEd calculated from the
FIGURE 8 Thermal degradation curves
of poly(SAEMA-co-MCMA) (0.48:0.52)
at different heating rates.
NOVEL METHACRYLATE COPOLYMERS, EROL ET AL.
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JOURNAL OF POLYMER SCIENCE: PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
Antimicrobial Activity of the Polymers
The homopolymers and copolymers thus obtained, were
tested against different microorganisms that are commonly
employed in biodegradability examinations. The results were
standardized against penicilin G and teicoplanin under the
same conditions. All the compounds exhibited moderate
activity comparable to that of the standard drugs. The data
reported in Table 6 and are the average data of three experi-
ments. The results show that the investigated polymers have
good biological activity comparable with that of standard
drugs such as penicilin G and teicoplanin. The results sug-
gest that the monomers, polymers, and the some copolymers
have good biological activity on the E. coli microorganisms in
comparison with standard drugs. Consequently, the peculiar
chemical structure of these copolymers with sulfonamides
with mutual lipophilic and hydrophilic groups may have the
proper combination of surface activity and bacterial effect.
Although the lipophilic portion of the surfactant is important
to biological function in general, the polar group contributes
to biocidal activity. Thus, the activity of these compounds
may allow to design surfactant and antimicrobial systems
specifically effective against certain microorganisms and for
FIGURE 9 Ozawa plots of the logarithm of the heating rate
(log b) versus the reciprocal of the temperature (1/T) at differ-
ent conversions for poly(SAEMA-co-MCMA) (0.48:0.52).
Ozawa method is superior to other methods for complex
degradation because it does not use the reaction order in
the calculation of the decomposition activation energy.51
Therefore; DEd calculated from the Ozawa method is supe-
rior to the former methods for complex degradation.
TABLE 5 The Apparent Activation Energies of Investigated Copolymers under Thermal Degradation in N2
Activation Energy (kJ/mol) Conversion (%)
Sample
10
20
30
40
50
60
70
80
90
Poly(SAEMA)
162.8
116.4
121.4
129.4
132.6
139.5
154.7
163.4
92.0
166.7
78.4
160.8
86.6
156.7
90.8
–
–
–
–
Poly(MCMA)
98.4
105.8
119.2
149.8
–
100.2
84.0
87.3
Poly(SAEMA 20%-co-MCMA)
Poly(SAEMA 36%-co-MCMA)
Poly(SAEMA 48%-co-MCMA)
Poly(SAEMA 60%-co-MCMA)
Poly(SAEMA 70%-co-MCMA)
96.7
112.2
121.1
139.2
138.8
158.2
98.0
125.8
133.5
139.1
141.6
147.9
119.0
–
–
–
–
–
–
–
–
–
–
114.6
137.0
136.2
153.5
117.2
133.6
134.2
163.3
–
–
–
–
–
TABLE 6 Antimicrobial Effects of the Compounds (mm of Zones)
Pseudomonas
aeruginasa
Escherichia
coli
Proteus
vulgaris
Salmonella
enteridis
Klebsiella
Staphylococcus
aureus
Candida
albicans
Compounds
pneumoniae
SAEMA
27
23
35
34
25
23
19
17
28
26
29
24
28
25
Poly(SAEMA)
Poly(SAEMA-co-MCMA)
20/80
23
25
27
–
24
28
31
33
34
12
18
–
17
–
–
19
–
21
22
24
–
–
36/64
14
16
–
23
–
48/52
19
20
22
9
22
24
25
18
25
–
60/70
24
–
70/30
28
16
18
–
17
16
22
–
26
17
12
–
Penicillin G
Teicoplanin
DMSO
35
15
–
11
–
Compound concentration: 100 lg/disc; the symbol (–) reveals that the compounds have any activity against the microorganisms. DMSO, dimethyl-
sulfoxide (control).
4332
WILEYONLINELIBRARY.COM/JOURNAL/JPOLA

ARTICLE
energy of the decomposition of the investigated polymers
was calculated by the Ozawa method with the TGA data. The
polymers have good biological activity comparable with that
of standard drugs such as penicilin G and teicoplanin.
The authors are indebted to Dr. Zeki Gu¨rler for the biological
activity studies.
REFERENCES AND NOTES
1 Kim, B. Y.; Ratcliff, E. L.; Armstrong, N. R.; Kowalewsk, T.;
Pyun, J. Langmuir 2010, 26, 2083–2092.
2 Yactine, B.; Ratsimihety, A.; Ganachaud, F. Polym Adv Tech-
nol 2010, 21, 139–149.
3 Fresvig, T.; Ludvigsen, P.; Steen, H.; Reikeras, O. Med Eng
Phys 2008, 30, 104–108.
4 Ishio, M.; Terashima, T.; Ouchi, M.; Sawamoto, M. Macro-
FIGURE 10 Emission spectra of polymers in DMF, kex ¼ 320 nm.
molecules 2010, 43, 920–926.
5 Erol, I. J Fluorine Chem 2008, 129, 613–620.
6 Joshi, S.; Khosla, N.; Khare, D.; Tiwari, P. Acta Pharm 2002,
probably certain health care, food services, and other practi-
cal applications.
52, 197–206.
7 Sondhi, S. M.; Johar, M.; Singhal, N.; Dastidar, S. G.; Shukla,
Photophysical Properties
R.; Raghubir, R. Monatsh Chem 2000, 131, 511–520.
UV-vis absorption spectra of the copolymers were recorded
in DMF solutions. In these measurements 7 ꢃ 10ꢁ5 M solu-
tions of each polymer was used. Obviously the spectrum of
these structures two intense absorption bands at 272 and
313 nm. Of these absorption bands kmax ¼ 272 nm corre-
sponds to the sulfonamide structure and kmax ¼ 313 nm
corresponds to the coumarin chromophore. As expected an
increase in the quantity of the coumarin leads an increased
coumarin absorption and decreased sulfonamide absorption.
Fluorescence emission spectra for 7 ꢃ 10ꢁ5 M solutions of
polymers are shown in Figure 10. Excitation of the polymer
series at kex ¼ 320 nm (maximum absorption wavelength
for coumarin) showed a strong fluorescence peak at about
385 to 386 nm, which was the charactesistic fluorescence
peak of the coumarine chromophore.52 Furthermore, it
showed that there was an apperent increase in the fluores-
cence intensity from the 30% coumarine to the 80% cou-
marine containing polymers.
8 Spuran, C. T.; Scozzafava, A.; Casini, A. Med Res Rev 2003,
23, 146–189.
9 Li, J. J.; Anderson, G. D.; Burton, E. G.; Cogburn, J. N.; Collins,
J. T.; Garland, D. J.; Gregory, S. A.; Huang, H. C.; Isakson P. C.
J Med Chem 1995, 38, 4570–4578.
10 Bell, P. H.; Roblin, R. O.
J Am Chem Soc 1942, 64,
2905–2917.
11 Kang, S. I.; Bae, Y. H. Macromolecules 2001, 34, 8173–8178.
12 Kang, S. I.; Bae, Y. H. J Contr Release 2002, 80, 145–155.
13 Kang, S. I.; Na, K.; Bae, Y. H. Macromol Symp 2001, 172,
149–156.
14 Sakata, M.; Todokoro, M.; Kai, T.; Kunitake, M.; Hirayama,
C. Chromatographia 2001, 53, 619–623.
15 Park, S. Y.; Bae, Y. H. Macromol Rapid Commun 1999, 20,
269–273.
16 Sethuraman, V. A.; Lee, M. C.; Bae, Y. H. Pharm Res 2008,
CONCLUSIONS
25, 657–666.
The synthesis of new methacrylate monomers (SAEMA) hav-
ing pendant sulfonamide and MCMA pendant coumarine ring
moieties have been reported for the first time. The structure
of monomers and their polymers were characterized by
spectroscopic methods. Copolymers of SAEMA with MCMA
were prepared by free-radical polymerization in 1,4-dioxane
at 65 ꢀC. The reactivity ratios of the copolymers were esti-
mated with linear graphical methods. The reactivity values
r1 and r2 are smaller than 1, and this indicates that the sys-
tem copolymerizes statistically. GPC data imply that the poly-
dispersity index of the copolymers is nearly equal to 2, and
this implies a strong tendency for chain termination by
disproportionation. Tg of the copolymers increased with
increasing MCTMA content in the copolymers. The activation
17 Kang, H. C.; Bae, Y. H. Adv Funct Mater 2007, 17,
1263–1272.
18 Sethuraman, V. A.; Na, K.; Bae, Y. H. Biomacromolecules
2006, 7, 64–70.
19 Na, K.; Lee, K. H.; Bae, Y. H. J Contr Release 2004, 97,
513–525.
20 Mal, N. K.; Fujiwara, M.; Tanaka, Y. Nature 2003, 421,
350–353.
21 Brun, M. P.; Bischoff, L.; Garbay, C. Angew Chem Int Ed
2004, 43, 3432–3436.
22 Zhao, L.; Loy, D. A.; Shea, K. J. J Am Chem Soc 2006, 128,
14250–14251.
NOVEL METHACRYLATE COPOLYMERS, EROL ET AL.
4333

JOURNAL OF POLYMER SCIENCE: PART A: POLYMER CHEMISTRY DOI 10.1002/POLA
23 Jackson, P. O.; O’Neill, M.; Duffy, W. L.; Hindmarsh, P.;
37 Degutis, J.; Undzenas, A.; Urbonavicius, A. U.S.S.R. Patent
Kelly, S. M.; Owen, G. J. Chem Mater 2001, 13, 694–703.
466227, 1975.
38 Erol, I.; Soykan, C. J Macromol Sci Pure Appl Chem 2002,
24 Kim, C.; Trajkovska, A.; Wallace, J. U.; Chen, S. H. Macro-
A39, 405–417.
molecules 2006, 39, 3817–3823.
39 Connerton, I. F. In Analysis of Membrane Proteins; Gould,
25 Tian, Y.; Akiyama, E.; Nagase, Y.; Kanazawa, A.; Tsutsumi, O.;
G. W., Ed.; Portland: London, 1994; p 177.
Ikeda, T. J Mater Chem 2004, 14, 3524–3531.
40 Chan, E. C. Z.; Pelczar, M. J.; Krieg, N. R. In Agar Diffusion
Method in Laboratory Exercise in Microbiology; Chan et al.,
Ed.; Mc-Graw-Hill: New York, 1993; p 225.
26 Jiang, J.; Qi, B.; Lepage, M.; Zhao, Y. Macromolecules 2007,
40, 790–792.
27 Kiskan, B.; Yagci, Y. J Polym Sci Part A: Polym Chem 2007,
41 Desai, J. A.; Dayal, U.; Parsania, P. H. J Macromol Sci Pure
45, 1670–1676.
Appl Chem 1996, A33, 1113–1122.
28 Trenor, S. R.; Long, T. E.; Love, B. J. Macromol Chem Phys
42 Teramachi, S.; Hasegawa, A.; Akatsuka, M.; Yamashita, A.;
2004, 205, 715–723.
Takemoto, N. Macromolecules 1978, 11, 1206–1210.
29 Trenor, S. R.; Shultz, A. R.; Love, B. J.; Long, T. E. Chem
43 Melville, H. W.; Noble, B.; Watson, W. F. J Polym Sci 1949,
Rev 2004, 104, 3059–3078.
4, 629–637.
30 Arshady, R.; Kenner, G. W.; Ledwith, A. Macromol Chem
44 Fineman, M.; Ross, S. D. J Polym Sci 1950, 5, 259–262.
Phy 1981, 182, 41–46.
45 Kelen, T.; Tudos, F. J Macromol Sci Pure Appl Chem 1975,
31 Ham, G. E. Copolymerization, High Polymers; Interscience:
9, 1–27.
New York, 1964; Vol. 18.
46 Kuo, S. W.; Kao, H. C.; Chang, F. C. Polymer 2003, 44, 6873–6882.
32 Liang, K.; Dossi, M.; Moscatelli, D.; Hutchinson, R. A. Macro-
47 Chen, J. K.; Kuo, S. W.; Kao, H. C.; Chang, F. C. Polymer
molecules 2009, 42, 7736–7744.
2005, 46, 2354–2364.
33 Rajendrakumar, K.; Dhamodharan, R. Eur Polym J 2009, 45,
48 Aguilar, M. R.; Gallardo, A.; Fernandez, M. M.; San Roman,
2685–2694.
J. Macromolecules 2002, 35, 2036–2041.
34 Houchin, M. L.; Topp, E. M. J Appl Polym Sci 2009, 114,
49 De Silva, M. E. S. R.; Dutra, E. R.; Mano, V.; Machado, J. C.
2848–2854.
Polym Degrad Stab 2000, 67, 491–495.
35 Konaganti, V. K.; Madras, G. Polym Degrad Stab 2009, 94,
50 Ozawa, T. Bull Chem Soc Jpn 1965, 38, 1881–1886.
51 Regnier, N.; Guibe, C. Polym Degrad Stab 1997, 55, 165–172.
52 Sherman, W. R.; Robins, E. Anal Chem 1968, 40, 803–805.
1325–1335.
36 Patel, H. J.; Patel, M. G.; Patel, R. J.; Patel, K. H.; Patel, R. M.
Iran Polym J 2008, 17, 635–644.
4334
WILEYONLINELIBRARY.COM/JOURNAL/JPOLA