Chemical modifications of poly(vinyl chloride) to poly(vinyl azide) and "clicked" triazole bearing groups for application in metal cation extraction

Article abstract of DOI:10.1016/j.reactfunctpolym.2016.01.016

Chemical modification of poly(vinyl chloride) (PVC) by the replacement of chlorine atom presents a considerable interest in this work. In the first phase, PVC was partially azided with a sodium azide. Click-chemistry based on Copper (I)-catalyzed Huisgen'

Full text of DOI:10.1016/j.reactfunctpolym.2016.01.016

Reactive and Functional Polymers 100 (2016) 191–197
Contents lists available at ScienceDirect
Reactive and Functional Polymers
journal homepage: www.elsevier.com/locate/react
Chemical modifications of poly(vinyl chloride) to poly(vinyl azide) and
“clicked” triazole bearing groups for application in metal
cation extraction
b
b
c
b
Abid Ouerghui a,b,c, , Hichem Elamari , Mokthar Dardouri , Sana Ncib , Faouzi Meganem , Christian Girard
⁎
d,⁎⁎
a
Institut Supérieur de Biotechnologie de Beja, Avenue Habib Bourguiba, Beja 9000, Université de Jendouba, Tunisia
Laboratoire de Chimie Organique et Applications, Faculté des Sciences de Bizerte, Université de Carthage, 7021 Zarzouna, Bizerte, Tunisia
Laboratoire des Analyses Fines, Unité de Biologie Moléculaire et Génétique (B.M.G), Faculté des Sciences de Gafsa, Université de Gafsa, 2112 Sidi Ahmed Zarroug, Gafsa, Tunisia
Unité de Technologies Chimiques et Biologiques pour la Santé, UMR 8258 CNRS/U 1022 Inserm, Ecole Nationale Supérieure de Chimie de Paris, Chimie Paristech — PSL Research University,
b
c
d
11 rue Pierre et Marie Curie, 75005 Paris, France
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 10 August 2015
Received in revised form 10 December 2015
Accepted 28 January 2016
Available online 29 January 2016
Chemical modification of poly(vinyl chloride) (PVC) by the replacement of chlorine atom presents a considerable
interest in this work. In the first phase, PVC was partially azided with a sodium azide. Click-chemistry based
on Copper (I)-catalyzed Huisgen's reaction (CuAAC) was then used to form polymer-grafted 1,4-triazoles using
some synthesized substituted alkynes. In the second phase, the new synthesized polymers were used in
extraction studies of heavy metals (Cd, Cu, Ni and Pb). The obtained polymer-supported triazoles were character-
ized by infrared spectroscopy and thermal analysis (DSC). Evaluation of metallic cation extraction was done by
atomic absorption of the remaining solutions. Three polymers efficiently removed Ni Cu and Pb with extraction
yields between 50 and 90%. Two of the polymers studied had a high selectivity of extraction for Cadmium with a
good efficiency (around 80%).
Keywords:
Chemical modification
Poly(vinyl chloride)
Azidation
Polymer-supported 1,4-triazole
Metal extraction
© 2016 Elsevier B.V. All rights reserved.
1. Introduction
and moreover by the “Copper (I)-catalyzed azide/alkyne cycloaddition”
(CuAAC or Copper (I)-catalyzed Huisgen's reaction) in this field
The domain of applications of polyvinyl chloride (PVC) and its uses is
widespread and includes the following: windows, frames, flooring,
pipes, window blinds, wallpaper, hoses, cables and wires, coatings, plas-
tisols, packing, medical tubing and blood bags [1,2]. It's for this reason
that the chemical modifications of PVC for its recycling had been of
great interest in the recent years [3–6]. The extraction of heavy metals
presents the primary objective of the chemical modification of PVC
in this work, because pollution by these metals has become one of
the main problems for environmental protection [7,8]. The polymeric
membrane is one of the procedures used for removing heavy metals
nowadays [9–17]. Studies of metal extraction using polymers substituted
with chelating entities, ionic or not, have been developed [18–20]. The
preparation of some polymers was based on the use of “click-chemistry”,
[21–25]. Following our work on poly(styrene) scaffold, we were inter-
ested in the evaluation of PVC in order to make comparisons and to
propose another recycling possibility for this widely used polymer
[20].The use of the well known CuAAC, the Copper (I)-catalyzed
Huisgen's reaction, can give us the opportunity to introduced all
appendage we want to test for their chelating properties. Using PVC
after azidation, it is in fact possible to graft the chelating moieties by
using a properly substituted terminal alkyne to for the triazole link
between the polymer network and the chelating entity [26].The goal is
to test the ability of the introduced molecular units to chelate metals
for removal from aqueous solutions. This chelation can be made by
a single unit (pendant chelation), or by several ones due to the distribu-
tion and proximity onto the network. However, we can't rule out possible
chelation from the triazole link through its donating nitrogen (triazole
chelation), neither than chelation by both the chelating moiety and the
triazole (participative chelation) (Fig. 1) [27–29].We thus present in
this article the preparation of polymer-supported triazoles starting
from PVC, followed by its transformation in azido-PVC, and CuAAC with
selected alkynes. These polymers were then tested for extraction metals
salts (Cd2+, Pb2+,Cu2+ and Ni2+) from aqueous solutions.
⁎
Correspondence to: A. Ouerghui, Institut Supérieur de Biotechnologie de Beja, Avenue
Habib Bourguiba, Beja 9000, Université de Jendouba, Tunisia.
⁎⁎ Corresponding author.
E-mail addresses: abid_ouerghui2007@yahoo.fr (A. Ouerghui),
christian.girard@chimie-paristech.fr (C. Girard).
http://dx.doi.org/10.1016/j.reactfunctpolym.2016.01.016
1381-5148/© 2016 Elsevier B.V. All rights reserved.

192
A. Ouerghui et al. / Reactive and Functional Polymers 100 (2016) 191–197
Fig. 1. General scheme for the preparation of triazolic polymers and possible mono- and poly-chelation ways (pendant, triazole and participative).
2. Experimental
(1H) and 75.5 MHz for the carbon spectra (13C). Chemical shifts (δ)
are indicated after calibration on the residual undeuterated solvent
peak in part per million (ppm) and as follow: s (singlet), d (doublet), t
(triplet), m (multiplet). Coupling constants (J) are given in Hz. Differen-
tial scanning calorimetry (DSC) was performed on a DSC 1 STARe
System (METTLER TOLEDO) apparatus between 25 and 400 °C. Analtik
Jena Nova 400 (Japan) model atomic absorption spectrometer (AAS)
operating with an air–acetylene flame was used to measure residual
metal ion concentrations.
2.1. Materials and apparatus
2.1.1. Materials
Poly(vinyl chloride), with high molecular weight (MW
=
48,000 g·mol−1, 16 mmol of Cl·g−1, 99%), was purchased from Fluka.
Acyl chlorides (99%), propargyl amine (98%), substituted anilines, N,N-
dimethylaminopyridine (DMAP) (99%), triethyl and diisopropylethyl
(DIPEA) amines (99%), phenylacetylene (99%), sodium azide (99%)
and Copper (I) iodide (98%) were provided by Sigma-Aldrich and used
without further purification. Methylene chloride and dimethyl-
formamide (DMF) were bought from Acros Organics and used as
received. Tetrahydrofurane (THF) was from the same source, but dis-
tilled from benzophenone ketyl under nitrogen prior to use. CdCl2·H2O
(98%), NiCl2·6H2O (98%), Pb(NO3)2 (98%) and CuSO4·5H2O (98%) were
produced by Fluka, and used as such. Organic syntheses (Schemes 1
to 3) were conducted under nitrogen, otherwise stated, using standard
methods and procedures.
2.2. Organic synthesis
2.2.1. Chemical modification of PVC(A): synthesis of PVC-N3 (B)
Poly(vinyl chloride) (1 g, 16 mmol of Cl) was suspended in 50 mL
DMF and 1.60 g NaN3 (24.6 mmol, 1.54 eq.) was added. The reaction
mixture was slowly magnetically stirred at 100 °C for 2 h (Scheme 1).
The cooled mixture was filtered on sintered glass, washed with DMF
(2 × 40 mL), water (3 × 50 mL), and finally dried under vacuum at
70 °C for two days, the obtained polymer was not explosive under the
conditions studied. The isolated polymer weighted 1.07 g after purifica-
tion. The obtained polymer was not soluble in organic solvents (CHCl3,
CH2Cl2, MeOH, EtOH, Acetone and DMF), but have a low solubility
in THF. The effect of DMF washes on % N in the polymer B was tested
by control washes onto PVC (A). The percentage obtained was 0.033%
N, and was taken into account for the azide substitution. From the
results of elemental analysis the number of moles of substituted chlo-
rine by the azide group (N3) on the polymer mass was calculated as
23.77 mmol N·g−1, or 7.92 mmol N3·g−1).
2.1.2. Apparatus
Characterizations were made as described below. Melting points
(mp) were measured on a Kofler apparatus after calibration around
the observed fusion of the product. Elemental analysis of (C, H
and N) was performed by using Perkin Elmer Analyzer CHN Series II
2400 (France). Infrared analysis using the attenuated total reflectance
technique (ATR/FTIR) was made on a Nicolet IR 200 FTIR (France) spec-
trometer between 4000 and 400 cm−1. Only the main and relevant
absorption bands are indicated as vibrations (ν) and angular deforma-
tions (δ). Nuclear magnetic resonance spectroscopy (NMR) was record-
ed on a Bruker Avance 300 (France) at 300 MHz for the proton spectra
ATR/FTIR: ν = 2940 (νCH2), 2101 (νN3), 1636 (νC_C), 616 (νC–Cl
.
)
cm−1
Elemental analysis: % C = 33.197; % H = 4.795; % N = 33.334.
Scheme 1. Reaction scheme for the substitution of Cl in PVC (A) to obtain azido-PVC (B).

A. Ouerghui et al. / Reactive and Functional Polymers 100 (2016) 191–197
193
Scheme 2. Reaction for synthesis of alkynes 1a–dfrom acyl chlorides and propargylamine.
Corrected % N = 33.301.
6.85 Hz, 3H), 1,33 (m, 8H), 1.66 (m, 2H), 2.23 (m, 3H), 5.95 (s, 1H), 4.07
(dd, J = 5.20, 2.52 Hz, 2H) ppm. 13C NMR (75.5 MHz, CDCl3, δ): 13.91,
22.37, 25.25, 29.12, 31.41, 36.42, 71.44, 79.72, 172.86 ppm.
2.2.2. Synthesis of alkyne derivatives 1a–d (general method)
A stirred solution of 0.65 mL of propargyl amine (0.56 g, 10 mmol),
1.4 mL of triethylamine (1.0 g, 10 mmol, 1.0 eq.) and 24 mg of
DMAP (0.20 mmol, 2.0% mol) in 20 mL of CH2Cl2 was cooled to 0 °C
(Scheme 2). A solution of the acyl chloride (10 mmol, 1.0 eq.) in
20 mL of CH2Cl2 was then added drop wise. The reaction mixture was
then stirred at 0 °C for 0.5 h and over-night at room temperature. The
mixture was then extracted with 0.1 M aqueous solutions of HCl
(2 × 10 mL) and NaOH (2 × 10 mL), washed with water (3 × 20 mL),
dried over MgSO4, filtrated and the solvent evaporated under vacuum.
The resulting amides 1a–d were sufficiently pure to be used without
further purification.
2.2.2.4. N-prop-2-ynylbenzamide (1d). C10H9NO.MW = 159.19 g·mol−1
Yield = 79%. mp = 106 °C.ATR/FTIR: ν = 3286, 3049,2930, 2123, 1641,
1599, 1537 cm−1 1H NMR (300 MHz, CDCl3, δ): 2.33 (t, J = 2.56 Hz,
1H), 4.31 (dd, J = 2.54, 5.17 Hz, 2H), 6.31 (s, 1H), 7.56 (m, 1H), 7.48
(m, 2H), 7.82 (m, 2H) ppm. 13C NMR (75.5 MHz, CDCl3, δ): 29.80,
71.80, 79.61, 127.13, 128.62, 131.80, 133.79, 167.29 ppm.
.
.
2.2.3. Synthesis of polymer-supported triazoles (2a–e)
Coupling reactions onto the polymer using CuAAC were conducted
accordingly to the general procedure indicated below in round bottom
flasks equipped with a reflux condenser. Polymer 2e was synthesized
using commercially available phenylacetylene [26], the others with
the synthesized amides respectively (Scheme 3). To a suspension of
0.15 g of PVC-N3 (1.2 mmol of N3) in THF (10 mL) was added
4.5 mmol (3.7 eq.) of the alkyne, 1.0 mL of DIPEA (0.76 g, 6.0 mmol,
5.0 eq.) and 1.4 mg of Copper (I) iodide (7.3 × 10−3 mmol, 0.6 mmol
%). The suspension was slowly stirred at room temperature until
the complete disappearance of the IR band of the azide (2101 cm−1).
The resulting polymers 2a–e were filtrated and washed with
MeOH, CH2Cl2 (5 × 5 mL) and water (5 × 50 mL), and finally
dried under vacuum at 70 °C for two days. Since no residual azide
vibration was observed in infrared, reactions were considered as
quantitative.
2.2.2.1. N-prop-2-ynylacetamide (1a). C5H7NO. MW = 97.12 g·mol−1
Yield = 76%. mp = 82 °C. ATR/FTIR: ν = 3231, 2928, 2852, 2115,
.
1641 cm−1 1H NMR (300 MHz, CDCl3, δ): 2.05 (s, 3H), 2.27 (t, J =
.
2.57, 1H), 4.09 (dd, J = 5.25, 2.57 Hz, 2H), 5.72 (s, 1H) ppm. 13C NMR
(75.5 MHz, CDCl3, δ): 22.94, 29.19, 71.38, 79.67, 170.11 ppm.
2.2.2.2. N-prop-2-ynylbutyramide (1b). C7H11NO. MW = 125.17 g·mol−1
.
Yield = 67%. mp = 27 °C. ATR/FTIR: ν = 3294, 3049, 2928, 2117,
1641 cm−1. 1H NMR (300 MHz, CDCl3, δ): 0.98 (t, J = 7.37 Hz, 3H), 1.72
(sex, 2H), 2.22 (m, 3H), 4.08 (dd, J = 5.23, 2.56 Hz, 2H), 5.72 (s, 1H)
ppm. 13C NMR (75.5 MHz, CDCl3, δ): 13.74, 19.03, 29.11, 38.33, 71.44,
79.75, 172.75 ppm.
[4-(Acetamidomethyl)triazol-1-yl]polyvinylchloride (2a)
2.2.2.3. N-prop-2-ynylcaprylamide (1c). C11H19NO. MW
181.28 g·mol−1. Yield = 66%; mp = 64 °C. ATR/FTIR: ν = 3294, 2958,
2920, 2118, 1642 cm−1 1H NMR (300 MHz, CDCl3, δ): 0.91 (t, J =
=
ATR/FTIR: ν = 3283, 2946, 2865, 1650, 1551, 591 cm−1
.
[4-(Butyramidomethyl)triazol-1-yl] polyvinylchloride (2b)
.
ATR/FTIR: ν = 3316, 2938, 2873, 1642, 1535, 608 cm−1
.
Scheme 3. Cu(I)-catalyzed Huisgen's reaction of azido-PVC (B) with various alkynes (1a–e).

194
A. Ouerghui et al. / Reactive and Functional Polymers 100 (2016) 191–197
[4-(Caprylamidomethyl)triazol-1-yl] polyvinylchloride (2c)
ATR/FTIR: ν = 3308, 3059, 2938, 1650, 1535, 698 cm−1
.
[4-(Benzamidomethyl)triazol-1-yl] polyvinylchloride (2d)
ATR/FTIR: ν = 3291, 2962, 2889, 1642, 1551, 764 cm−1
(4-Phenyltriazol-1-yl) polyvinylchloride (2e)
.
ATR/FTIR: ν = 3141, 2954, 1617, 1429, 764, 690 cm−1
.
2.3. Characterizations by ATR/FTIR and thermal analysis (DSC) of PVC-N3
(B) and polymer-supported triazoles 2a–e
Infrared analyses using the attenuated total reflectance technique
(ATR/FTIR) was previously described in Figs. 2 and 3. Differential scan-
ning calorimetry (DSC) was presented in Fig. 4 and Table 1. The samples
(2.8 mg) were placed in 40 μL aluminum pans, and the DSC recorded
under argon between 25 and 400 °C at a speed of 10 °C min−1
.
2.4. Metal ion extraction method
Fig. 3. ATR/FT-IR spectra: polyvinyl chloride (A), PVC azide (B), [4-
(acetamidomethyl)triazol-1-yl]polyvinyl chloride (2a), [4-(butyramidomethyl)triazol-1-
yl] polyvinyl chloride (2b), [4-(caprylamidomethyl)triazol-1-yl] polyvinyl chloride (2c),
[4-(benzamidomethyl)triazol-1-yl] polyvinyl chloride, [4-(benzamidomethyl)triazol-1-
yl] polyvinylchloride (2d) and (4-phenyltriazol-1-yl)polyvinylchloride (2e).
Aqueous solutions of CdCl2·H2O, NiCl2·6H2O, CuSO4·5H20 and
Pb(NO3)2 were prepared at a concentration of 50 mg·L−1 in relation
with the metal cation, and were filtrated on filter paper prewashed
with distilled water before their use in the extraction of metals. The
polymer (45 mg) was incubated with 5 mL of the metal ion solution
at 25 °C for 48 h, (pH = 5–6). The suspension was filtrated on filter
paper prewashed with distilled water. The amount of remaining metal
ions in solution was evaluated by atomic absorption spectroscopy
(AAS) analysis of the filtrate after a 10 fold dilution in distilled water.
The atomic absorption spectrometer was calibrated with solutions of
with sodium azide (Scheme 1). Elementary analysis of PVC-N3 (B)
was performed to determine the percentage of the elements: % C =
33.197; % H = 4.765 and % N = 33.334. Using a control experiment
on PVC to evaluate the effect of DMF washed on the nitrogen content
gave us a value of % N = 0.033 The azide bearing polymer B isolated
from this reaction had a final loading of 7.92 mmol N3 g−1. The presence
of the azido group was confirmed by infrared spectroscopy on which its
strong characteristic absorption was seen at 2101 cm−1 (νN3). The sub-
stitution of Cl in PVC (A) by the nucleophile group was accompanied by
the elimination of HCl since a νC_C band is visible at 1636 cm−1. Both
reactions were not complete, because the IR spectrum of B (Fig. 2)
displayed a small residual vibration of C–Cl at 605 cm−1. The band
observed at 3351 cm−1 was attributed to the presence of residual
water molecules in the polymeric structure.
the metals studied: (0.5 to 5 mg·L−1) for Cd and Ni, (1 to 7 mg·L−1
)
for Cu and (5 to 15 mg·L−1) for Pb. Values of extraction percentages
were corrected for the amount of metallic ions absorbed onto cellulose
by the filter paper itself. These values were calculated after passing
solutions on the paper alone and were found to be of 0.34% (Ni2+),
1.10% (Cu2+), 2.06% (Pb2+) and 0.40% (Cd2+). The results, average of
three experiments, were expressed as percentages of extraction of the
metal, based on its initial concentration (Fig. 5).
3. Results and discussion
The substituted alkynes, needed for the grafting onto the polymer,
were prepared using usual procedures. The amides (1a–d) were
3.1. Characterization of PVC-N3 (B) and substituted alkynes (a–d)
PVC-N3 (B), now commercially available, was prepared following
the method of Yoshioka et al. [3]. The poly(vinyl chloride) was treated
Fig. 4. DSC diagrams of PVC azide (B), [4-(acetamidomethyl)triazol-1-yl]polyvinyl
chloride (2a), [4-(butyramidomethyl)triazol-1-yl] polyvinyl chloride (2b), [4-
(caprylamidomethyl)triazol-1-yl] polyvinyl chloride (2c), [4-(benzamidomethyl)triazol-
1-yl] polyvinyl chloride (2d) and (4-phenyltriazol-1-yl) polyvinylchloride (2e).
Fig. 2. ATR/FT-IR spectra of PVC (A) and PVC-azide (B).

A. Ouerghui et al. / Reactive and Functional Polymers 100 (2016) 191–197
195
Table 1
210 °C. This transition can be attributed to the decomposition of the
azido group of the polymer [20].
Loadings and DSC studies of synthesized polymers B and 2a–e.
Polymera
Loading (mmol·g−1
)
Texo (°C)
Tg (°C)
b
2a
2b
2c
2d
2e
B
4.48
3.97
3.25
3.50
4.38
7.92
–
–
–
–
–
210
132
131
126
123
119
90
3.3. Metal ion extraction
The results of extraction as determined by AAS, mean values of three
readings of each of three extraction experiments, were calculated as
percentages of extraction based on the initial concentration, and are
presented in Fig. 5.
As a first observation, the extraction of the metals by blanks A (PVC)
and B (PVC-N3) is low, the extraction yields do not go over a maximum
value of 10%; 10 4.06% and 8 1.54% respectively. Only the percent-
age of Cadmium extraction reached 15 0.18% with the polymer A. In a
second observation, the extraction of Nickel is very low with polymers
a
For structures, see Scheme 3.
mmol triazole for 2a–e and N3 for B.
b
synthesized using the corresponding acyl chlorides and coupling them
on propargylamine in the presence of a base and a catalyst (Scheme
2). The obtained yields were modest (66–79%) but the products were
pure enough to be used without further purification. The structure
of 1a–d was confirmed by characteristic signals in NMR (ca. δ = 2.25
(triplet, `C–H) ppm in 1H and 70, 80 (C`C), 170 (C_O) ppm in 13C)
and IR spectroscopy (ca. 3300 (ν`C–H), 2100 (νC`C), 1640 (νC_O) cm−1).
2c–e, the yield of extraction never exceeded 10
performance of extraction for this metal is obtained with polymers 2b
and 2a with yields of extraction of 22 5.95% and 19 1.84%
1.52%. The best
respectively. The extraction of Copper is better than the one of Nickel,
the extraction yields being of 63 8.72% (2a), 58 4.48% (2b), 54
8.83% (2c), and not exceeding 9 2.07% for the others polymers. The
average yield for this metal by polymers 2a–c is in the order 58
4.51%, this value being comparable with that found by Pellera et al.
using aqueous solutions using agricultural by-product for removal of
Copper [32]. The result of Lead extraction with polymers 2a–c reached
up to 74 7.87%, but only a maximum of 21 8.64% with the others.
Extraction yields of Pb by polymers 2a–c are a little better than those
obtained by Chaari et al., which have achieved an adsorption perfor-
mance around 65% using a Tunisian smectic clay [33].
The extraction of Cadmium is better than with the other metals, one
of the polymer-supported triazole 2a was found to extract Cadmium se-
lectively with a high efficiency of 92
comparable with those obtained by us using the same appendages
onto poly(styrene) [20]. The extraction yields for this metal by polymers
2d and 2e are good and similar around 83 0.75%, while polymer 2b
3.2. Characterization of polymer-supported triazoles (2f–j)
The reaction between alkynes 1a–d and azido-PVC (B) was
performed using a CuAAC procedure to obtain polymer-supported
1,2,3-triazoles 2a–d with various substituents onto the triazole in the
fourth position (Scheme 3). PVC-N3 (B) was treated with an excess of
the alkyne in the presence of a base (DIPEA) and cuprous iodide as a
catalyst, to increase both the reaction speed and yield. Another polymer
2e was synthesized using phenylacetylene which does not have an
amide bond in order to evaluate this influence of this link [26]. The
cycloadditions were followed by ATR/FTIR and considered as finished
when the azide vibration was not visible anymore. The yields of
the cycloadditions were difficult to evaluate using a mass increase on
the scale used. The reactions were considered as quantitative based on
the ATR/FTIR analysis and previous work.
Residual vibrations form the azido group of B or from the starting
alkynes 1a–e were not observed onto the IR spectra of polymers 2a–e
(Fig. 3). On these spectra, vibrations form amide bonds (NH, C_O),
with the exception of 2e, can be observed together with vibrations
coming from the triazole ring and its substituent, when compared to
the spectrum of the starting polymer B.
7.49%. These results are
(72
7.03%) and polymer 2c (52
7.86%) were a bit less efficient.
The results for Cadmium extraction found for those polymers (2a, 2b,
2d and 2e) are similar to those found by M'leyh et al. using natural
clays of Borj Chekir [34]. For the polymeric triazoles 2a–e, the average
extraction yields are in the following order: Cd2+ N Pb2+ N Cu2+ N Ni2+
.
These results are comparable to those obtained by Sprynskyy et al. with
the adsorption–diffusion column filled by the zeolite [35].
At the beginning of our work onto this set of alkynes, we became
interested on the possible chelations when the triazole formed was
bearing an amide function. Polymers described in the literature are
incorporating amine or pyridine sidearm's (“pendant” or “integrated
design”) or only “simple” triazoles (“triazole design”) in order to chelate
a metal ion before their reduction inside dendrimeric structures, as an
example. Catalysis was the ultimate goal for most of them [36–40].
For the study of our supported pendant amide triazole, we evaluated
the polymers 2a–e. The amino methyl substituent of the triazole ring
was linked under an amide form to alkyl chain, as well as a phenyl
ring, in order to evaluate the effect of steric hindrance and/or hydropho-
bicity. In this series, the polymer 2e was prepared to act as a blank, since
no amide function nor the amino methyl was included. From the results
The DSC curves of azido-PVC (B) and the polymers 2a–e are shown
in Fig. 4. The glass-transition temperatures (Tg) of the polymers were
determined from inflection points of DSC curves and are listed in
Table 1 [30,31]. The Tc and Tm temperatures are not easy to find. In
the case of PVC-N3 (B), an exothermic peak was also observed at
of Cadmium extraction by the polymers 2a (92
7.49%), 2b (72
7.03%) and 2c (52 7.86%), we can observe that the extraction yield
is dropping with the chain length increase. For the polymers 2d and
2e, they have the same extraction yield for Cadmium (around 83%),
suggesting that the amide function has no effect onto the chelation of
Cadmium, but a phenyl ring increases the extraction yield to almost
the level of the methyl substituant of the amide like in 2a. The extraction
yields of Cadmium by polymers A (15 0.18%) and B (7 2.69%) with
no amide neither triazole are low, which seems to confirm that the
triazole is responsible for the chelation of Cadmium by the polymers
studied.
Fig. 5. Percentages of metal cation extraction for the polymers 2a–e, in comparison to the
values found for PVC (A) and PVC-N3 (B) as blanks.

196
A. Ouerghui et al. / Reactive and Functional Polymers 100 (2016) 191–197
[7] J.K. Kiptoo, J.C. Ngila, N.D. Silavwe, Solid-phase extraction of Zn(II), Cu(II), Ni(II) and
For Lead, the tendance is reversed: if the alkyl chain increases in
size, the extraction of this metal increases from 2a (66 3.85%) to
2b (77 5.07%) and to 2c (81 1.48%). The results of Pb extraction
by the other polymers 2d (27 4.08%) and 2e (15 0.76%) are
Pb(II) on poly(vinyl chloride) modified with 3-ferrocenyl-3-hydroxydithio-
acrylicacid, and their subsequent determination by electrochemical atomic absorp-
tion spectrometry, Microchim. Acta (2008) 211–218.
[8] I.S. Ahamed, A.K. Ghonaim, A.A. Abdel Hakim, M.M. Moustafa, A.H. Kamal El-Din,
Synthesis and characterization of some polymers for removing of some heavy
metal ions of industrial wastewater, J. Appl. Sci. Res. 4 (2008) 1946–1958.
[9] N. Pont, V. Salvadó, C. Fontàs, Selective transport and removal of Cd from chloride
solutions by polymer inclusion membranes, J. Membr. Sci. 318 (2008) 340–345.
[10] M. Ulewicz, M. Bouchenska, U. Lesinsker, W. Walkowiak, Studies on removal of
Zn(II), Cd(II) and Pb(II) ions in polymer inclusion membrane transport with
calix[4]-crown-6 derivatives, Physicochem. Probl. Miner. Processing 39 (2005)
107–116.
much lower. We can observe that the polymer 2d gives a slightly bet-
ter performance than the one of polymer 2e. For this metal, the be-
havior is different than the one for Cadmium: the absence of an
amide in 2e when compared to the polymer 2d, while the two poly-
mers contain a phenyl group which suggests that the amide function
participates to a certain extent into the chelation of this metal. The
length of the side chain of the amide seems to have an importance,
but the relation between a higher hydrophobicity and chelation
properties is difficult to draw. It's possible that the chelate will be
more stable for ligand exchange if it forms a structure protected by
long alkane chains as substituant.
For the extraction of Copper, the extraction efficiency is similar to
the one for Cadmium. If the alkyl chain increases in size, the percent-
age of extraction decreases from 2a (63 8.72%), 2b (58 4.48%) to
2c (54
hability (A (11
(8 3.19%)) so it is difficult to draw a clear conclusion about the
[11] O. Kebiche-Senhadji, S. Tingry, P. Seta, M. Benamor, Selective extraction of Cr(VI)
over metallic species by polymer inclusion membrane (PIM) using anion (Aliquat
336) as carrier, Desalination 258 (2010) 59–65.
[12] R.T. Sobahi, Preparation of polystyrene based for polymer for carrier mediated heavy
metal ion extraction, Mansoura J. Chem. 32 (2005) 73–85.
[13] F.R. Muller, H. Handel, Tétraazamacrocycles lipophiles: synthèse et application à
l'extraction de Cu (II), Cd (II) et Pb (II), Tetrahedron Lett. 23 (1982) 2769–2772.
[14] F.R. Muller, H. Handel, R. Guglielmetti, Lipophilic tetraazamacrocyles: extraction of
metal ions by impregnated resin, Helv. Chim. Acta 66 (1983) 1525–1531.
[15] M. Ulewicz, U. Lesinska, M. Bochenska, W. Walkowiak, Facilitated transport of Zn(II),
Cd(II) and Pb(II) ions through polymer inclusion membranes with calix[4]-crown-6
derivatives, Sep. Purif. Technol. 54 (2007) 299–305.
[16] L.D. Nghiem, P. Momane, I.D. Potter, J.M. Perera, R.W. Cattral, S.D. Kolev, Extraction
and transport of metal ions and small organic compounds using polymer inclusion
membranes (PIMs), J. Membr. Sci. 281 (2006) 7–41.
8.83%). The other polymers have a very low complexing
2.82%), B (9 2.19%), 2d (6 1.70%) and 2e
complexation mechanism which can be, however, like the one en-
countered for Cadmium.
Last but not the least, none of the polymers studied have a selectivity
for Nickel. The extraction efficiency is staying below 20%, suggesting
that these polymers can be used as selective non-chelating polymers
for Ni.
[17] B. Wionczyk, W. Aposttoluk, K. Prochaska, C. Kozlowski, Properties of 4-(10-n-
tridecyl)pyridine N-oxide in the extraction and polymer inclusion membrane trans-
port of Cr(VI), Anal. Chim. Acta 428 (2001) 89–101.
[18] M. Rhazi, J. Desbrières, A. Tolaimate, M. Rinaudo, P. Vottero, A. Alagui, M. El Meray,
Influence of the nature of the metal ions on the complexation with chitosan.
application to the treatment of liquid waste, Eur. Polym. J. 38 (2002) 1523–1530.
[19] C.A. Kozlowski, W. Walkowiak, Applicability of liquid membranes in chromium(VI)
transport with amines as ion carrier, J. Membr. Sci. 266 (2005) 143–150.
[20] A. Ouerghui, H. Elamari, S. Ghammouri, R. Slimi, F. Meganem, C. Girard, Polystyrene-
supported triazoles for metal ions extraction and evaluation, React. Funct. Polym. 74
(2014) 37–45.
4. Conclusions
[21] Z. Tao, Z. Zhaohui, C. Xu, D. Xiaobin, P. Yuxing, Click chemistry in fields of materials
In this work, we made the first chemical grafting of chelating units
onto poly(vinyl chloride) using CuAAC procedure between the azided
polymer and selected alkynes. The synthesized polymers were charac-
terized by the way of FTIR, DSC and elemental analysis. They were
then evaluated for their ability to extract metallic ions from solutions;
namely Cd2+, Ni2+, Pb2+, and Cu2+. The polymers were found to
extract these ions with some selectivity, and seemed to have an affinity
following the order Cd2+ N Pb2+ N Cu2+ N Ni2+. The polymers 2a–c
were not very selective, but were able to chelate with some efficiency
of Cu2+, Pb2+, and Cd2+. Polymers 2d and 2e were very selective and
efficient for Cd2+ removal over the three other metals.
science, Prog. Chem. 20 (2008) 1090–1101.
[22] M.A. Tasdelen, G. Yilmaz, B. Iskin, Y. Yagci, Photoinduced free radical promoted
copper(I)-catalyzed click chemistry for macromolecular syntheses, Macromolecules
45 (2012) 56–61.
[23] M.A. Tasdelen, Poly(epsilon-caprolactone)/clay nanocomposites via “click”
chemistry, Eur. Polym. J. 47 (2011) 937–941.
[24] T. Liebert, C. Hansch, T. Heinze, Click chemistry with polysaccharides, Macromol.
Rapid Commun. 27 (2006) 208–213.
[25] J.-A. Shin, Y.-G. Lim, K.-H. Lee, Synthesis of polymers including both triazole and
tetrazole by click reaction, Bull. Kor. Chem. Soc. 32 (2011) 547–552.
[26] S. Moulay, Trends in chemical modification of poly(vinyl chloride), Khim. Chem. 11
(2002) 217–244.
[27] G. Izzet, J. Zeitouny, H. Akdas-Killig, Y. Frapart, S. Ménage, B. Douziech, I. Jabin, Y. Le
Mest, O. Reinaud, Dioxygen activation at a mononuclear Cu(I) center embedded in
the calix[6]arene-tren core, J. Am. Chem. Soc. 130 (2008) 9514–9523.
[28] D.C. Lacy, Y.J. Park, J.W. Ziller, J. Yano, A.S. Borovik, Assembly and properties of
heterobimetallic CoII/III/CaII complexes with aquo and hydroxo ligands, J. Am.
Chem. Soc. 134 (2012) 17526–17535.
These results, and the very good selectivity of 2d and 2e for
Cadmium (II), encourage us to pursue polymer modifications using
click chemistry in order to design new extractants. Further studies will
be reported in due course as well.
[29] R.L. Shook, A.S. Borovik, Role of the secondary coordination sphere in metal-mediated
dioxygen activation, Inorg. Chem. 49 (2010) 3646–3660.
[30] M. Koki, K. Demirelli, Y. Aydogdu, Thermophysical properties of blend of poly (vinyl
chloride) with poly (isobornyl acrylate), Int. J. Sci. Technol. 3 (2008) 37–42.
[31] M. Bazzar, M. Ghaemy, R. Alizadeh, Synthesis and characterization of new fluores-
cent polyimides bearing 1,2,4-triazole and 1,2-diaryl quinoxaline: study properties
and application to the extraction/elimination of metallic ions from aqueous media,
React. Funct. Polym. 73 (2013) 492–498.
[32] F.M. Pellera, A. Giannis, D. Kalderis, K. Anastasiadou, R. Stegmann, J.Y. Wang, E.
Gidarakos, Adsorption of Cu(II) ions from aqueous solutions on biochars prepared
from agricultural by-products, J. Environ. Manag. 96 (2012) 35–42.
[33] I. Chaari, E. Fakhfakh, S. Chakroun, J. Bouzid, N. Boujelben, M. Feki, F. Rocha, F.
Jamoussi, Lead removel from aqueous solutions by a Tunisian smectitic clay,
J. Hazard. Mater. 156 (2008) 545–551.
Acknowledgments
This project is financed by Tunisian 05/UR/12-05 and French UMR
8258 CNRS/U1022 INSERM grants. A.O. is grateful to EGIDE International
Program fellowship.
References
[1] S. Moulay, Chemical modification of poly(vinyl chloride)—still on the run, Prog.
Polym. Sci. 35 (2010) 303–331.
[2] D. Braun, Poly(vinyl chloride) on the way from the 19th century to the 21st century,
[34] A. M'leyeh, E. Srasra, A. Cheref, Proceedings of the International Symposium on
Environmental Pollution Control and Waste Management (EPCOWM’2002), 7–10
January 2002, Tunis, 2002 533–546.
J. Polym. Sci. A Polym. Chem. 42 (2004) 578–586.
[3] T. Kameda, M. Ono, G. Grause, T. Mizoguchi, T. Yoshioka, Chemical modification of
poly(vinyl chloride) by nucleophilic substitution, Polym. Degrad. Stab. 94 (2009)
107–112.
[35] M. Sprynskyy, Solid–liquid–solid extraction of heavy metals (Cr, Cu, Cd, Ni and Pb)
in aqueous systems of zeolite–sewage sludge, J. Hazard. Mater. 161 (2009)
1377–1383.
[4] T. Yoshinaga, M. Yamaye, T. Kito, T. Ichiki, M. Ogata, Upgrading of poly(vinyl
chloride) by chemical modifications using sodium sulfide, Polym. Degrad. Stab. 86
(2004) 541–547.
[36] R.M. Meudtner, S. Hecht, Responsive backbones based on alternating triazole-
pyridine/benzene copolymers: from helically folding polymers to
metallosupramolecularly crosslinked gels, Macromol. Rapid Commun. 29
(2008) 347–351.
[5] N. Bicak, D.C. Sherrington, H. Bulbul, Vinylamine polymer via chemical modification
of PVC, Eur. Polym. J. 37 (2001) 801–805.
[37] G. Zhang, Y. Wang, X. Wen, C. Ding, Y. Li, Dual-functional click-triazole: a metal che-
lator and immobilization linker for the construction of a heterogeneous palladium
catalyst and its application for the aerobic oxidation of alcohols, Chem. Commun.
48 (2012) 2979–2981.
[6] Y. Emad, M. Abdallh, H. Hassan, S. Nadia, S. Jumat, M.B. Abdullah, W. Yip-Foo, Optical
properties of pure and modified poly(vinyl chloride), Int. J. Ind. Chem. 4 (2013)
4–11.

A. Ouerghui et al. / Reactive and Functional Polymers 100 (2016) 191–197
197
[38] D. Astruc, Palladium catalysis using dendrimers molecular catalyst versus nanopar-
ticles, Tetrahedron Asymmetry 21 (2010) 1041–1054.
[39] W. Watanabe, T. Maekawa, Y. Miyazaki, T. Kida, K. Takeshita, A. Mori, Quadruple
click: a facile pathway leading to tetrakis(4-(1,2,3-triazolyl)methyl)-ethylene-
diamine derivatives as a new class of extracting agents for soft metal ions, Chem.
Asian. J. 7 (2012) 1679–1683.
[40] H. Li, J. Zhan, M. Chen, D. Tian, Z. Zou, Metal ions recognition by 1,2,3-triazolium
calix[4]arene synthesized via click chemistry, J. Incl. Phenom. Macrocycl. Chem. 66
(2010) 43–47.