Synthesis and characterization of monoallyl-end-capped diethylene oxide-based polyurethane surfactant

Article abstract of DOI:10.1080/15533174.2013.790441

Diethylene glycol monoallyl ether (DGME) was synthesized by reaction of diethylene glycol with allyl chloride. Then, a novel non-ionic functional polyurethane surfactant (PUS) was synthesized by the polycondensation of hexamethylene diisocyanate (HMDI) with polypropylene glycol (PPG-1000) and DGME. Next, a series of polyvinyl acetate (PVAc), polybutyl acrylate (PBA), and polystyrene (PSt) latexes have been successfully synthesized, each one throughout by the emulsion copolymerization in the presence of a PUS. This polymeric surfactant exhibited excellent surface activity, and the surface tension decreased with an increase in the concentration of the polyurethane surfactant.

Full text of DOI:10.1080/15533174.2013.790441

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Synthesis and Characterization of Monoallyl-End-
Capped Diethylene Oxide-Based Polyurethane
Surfactant
a
a
a
Hamid Javaherian Naghash , Mohammad Iravani & Rouhollah Akhtarian
a
Department of Chemistry , Shahreza Branch of Islamic Azad University , Shahreza ,
Isfahan , I. R. Iran
Accepted author version posted online: 28 Oct 2013.Published online: 04 Mar 2014.
To cite this article: Hamid Javaherian Naghash , Mohammad Iravani & Rouhollah Akhtarian (2014) Synthesis and
Characterization of Monoallyl-End-Capped Diethylene Oxide-Based Polyurethane Surfactant, Synthesis and Reactivity in
Inorganic, Metal-Organic, and Nano-Metal Chemistry, 44:7, 927-934, DOI: 10.1080/15533174.2013.790441
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Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 44:927–934, 2014
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2013.790441
Synthesis and Characterization of Monoallyl-End-Capped
Diethylene Oxide-Based Polyurethane Surfactant
Hamid Javaherian Naghash, Mohammad Iravani, and Rouhollah Akhtarian
Department of Chemistry, Shahreza Branch of Islamic Azad University, Shahreza, Isfahan, I. R. Iran
diblock copolymers of 2-(dimethylamino) ethyl methacrylate
Diethylene glycol monoallyl ether (DGME) was synthesized by and 2-(diethylamino) ethyl methacrylate exhibited surprisingly
reaction of diethylene glycol with allyl chloride. Then, a novel non- high surface activities (37.5 mN/m), which were comparable
ionic functional polyurethane surfactant (PUS) was synthesized
to that found for the corresponding 2-(dimethylamino) ethyl
by the polycondensation of hexamethylene diisocyanate (HMDI)
methacrylate/ 2-(diethylamino) ethyl methacrylate diblock pre-
with polypropylene glycol (PPG-1000) and DGME. Next, a se-
cursor (34.6 mN/m). Recently, the synthesis of diblock and tri-
ries of polyvinyl acetate (PVAc), polybutyl acrylate (PBA), and
polystyrene (PSt) latexes have been successfully synthesized, each block copolymers of ethylene oxide and ethyl acrylate, by atom
one throughout by the emulsion copolymerization in the presence transfer radical polymerization, was reported by Dai et al.[
10]
.
of a PUS. This polymeric surfactant exhibited excellent surface
The surface tension of these polymeric surfactants in aqueous
solutions was about 44 mN/m. However, the results that those
groups obtained were not optimistic. In the past decade, ex-
tensive studies in academic and industrial laboratories have fo-
cused on the development of functional surfactants, especially
surfactants containing unsaturated bonds. Such polymeric sur-
factants can be used as emulsifiers in emulsion polymerization
and can copolymerize with latex, thus imparting to the latex ex-
activity, and the surface tension decreased with an increase in the
concentration of the polyurethane surfactant.
Keywords diethylene glycol monoallyl ether, polyurethane, surface
tension, surfactant
INTRODUCTION
cellent stability against high electrolyte concentrations, freeze-
Polymeric surfactants, which contain both hydrophobic seg-
ments and hydrophilic segments, have attracted great inter-
est in recent years because of their unique solution proper-
ties as a result of their amphiphilic molecular structure. They
are among the most versatile products and have found poten-
thaw cycling, and high shear rates. Liu et al. [
11,12]
synthesized
an amphiphilic poly(ethylene oxide) (PEO) macromonomer
ω-methoxypoly(ethylene oxide)40undecyl α-methacrylate] and
[
subsequently used it as a polymerizable surfactant in the syn-
thesis of monodisperse polystyrene microlatexes by emulsion
polymerization. Wang et al.[ studied the emulsion polymer-
ization of styrene with the homopolymer of sodium dodecyl allyl
sulfosuccinate as a polymeric surfactant. In recent years, much
[
1,2]
tial applications in emulsion polymerization , oil enhanced
13]
[
3]
[4]
recovery , biomedical materials , Langmuir-Blodgett (LB)
films [ , biomimetism , and so on.
5]
[6]
Compared with low-molecular-weight surfactants, poly-
meric surfactants usually have low surface activity because of
attention has also been paid to the development of hydropho-
bically associating polymers, [
14,15]
which are of great interest
[
7]
their high molecular weight. Ogino et al. once pointed out that
polymeric surfactants with high molecular weights generally are
unable to reduce the surface tension to approximately 50 mN/m.
for their unique rheological behaviors. However, one major dif-
ficulty in the synthesis of hydrophobically modified polymers
originates from the insolubility of the hydrophobic comonomer
in water. Polymerizable polymeric surfactants are helpful for
solving this difficulty.
Thus, it is desirable to synthesize polymeric surfactants that
have high surface activity and contain polymerizable func-
tional groups. Because polycondensation and polyaddition re-
actions are generally much easier and cheaper for the prepara-
tion of block copolymers of low molecular weights (e.g., from
To improve the surface activity of polymeric surfactants, some
intensive research has been carried out. Baines et al.[8] synthe-
sized a series of diblock copolymers of 2-(dimethylamino) ethyl
methacrylate and methyl methacrylate and found that the surface
tension of one sample was about 45 mN/m at a concentration of
[
9]
0
.15 wt%. Vamvakaki et al. showed that lightly quaternized
1
000 to 50,000), we synthesized a novel polyurethane surfac-
Received 4 March 2013; accepted 23 March 2013.
Address correspondence to Hamid Javaherian Naghash, Depart-
ment of Chemistry, Shahreza Branch, Islamic Azad University, P.O.
Box 311-86145, Shahreza, Isfahan, I. R. Iran. E-mail: Javaherian@
iaush.ac.ir
tant that contained functional polymerizable double bonds. The
polyurethane surfactant that we discuss in this article can reduce
the surface tension to as low as 37.6 mN/m. The sample that
we synthesized, had low critical micelle concentration (cmc).
927

928
H. J. NAGHASH ET AL.
As discussed previously, this functional polyurethane surfactant
may find potential application in emulsion polymerization and,
as the hydrophobic part, in the synthesis of hydrophobically
associating water-soluble polymers.
TABLE 1
Recipe for the synthesis of PUD
Ingredients
Charge (g)
PPG(M.W.: 1000)
HMDI
DGME
80.00
13.44
11.68
1.50
EXPERIMENTAL
Materials and Equipment
TEA
The monomers, St (Aldrich), BA (Aldrich) and VAc (Fisher D.D.W
Scientific Co) were freed from the inhibitor by shaking with 10%
aqueous NaOH, washing with water, and drying over Na2SO4.
Then, they were distilled under reduced pressure before use
80.00
a purity of 99.2% (Agilent 7890A gas chromatography). The
◦
and stored at −20 C to avoid thermal polymerization. The ini-
1
structure of the compound was confirmed by FT-IR, H NMR
and C NMR. The reaction process is outlined in Scheme 1.
tiator, KPS, hexamethylene diisocyanate (HMDI), diethylene
glycol, allyl chloride, and tetrahydrofuran (THF) were supplied
13
by Merck, Hohenbrunn, Germany, and were used as received. Preparation of the Polyurethane Surfactant
Polypropylene glycol 1000 (PPG-1000, Korea Polyol Ltd., Ko-
rea) was dried and degassed at 65 C, under vacuum. Dibutyltin reactor with mechanical stirrer, thermometer, condenser, and
A 250 mL, round bottomed, 4-necked-flask, separable glass
◦
dilaurate (DBTDL, Aldrich, Gillingham, UK) was analytical nitrogen purge was used. Basic recipe for the synthesis of the
grade and used directly without further purification. Water used non-ionic polyurethane surfactant is listed in Table 1. Polyaddi-
in this experiment was twice distilled and then deionized.
2
tion reaction was carried out in a N atmosphere in a constant-
Fourier-transform infrared (FT-IR) spectroscopy analysis temperature water bath. DGME and HMDI were first charged
◦
was performed with a Nicolet Impact 400D Model spec- into the reactor and heated to 80 C under stirring to obtained
trophotometer (Nicolet Impact, Madison, USA) using KBr pel- NCO end caped polyurethane (NCO-PU), and then dibutyltin
lets. The spectra were obtained over the wave-number range dilaurate was dropped into the reactor, while keeping the tem-
−
1
−1
◦
4
000–400 cm at a resolution of 2 cm using an MCT detec- perature at 80 C. The reaction proceeded over approximately
tor with co-addition of 64 scans. NMR Spectra were recorded 2 h, PPG was subsequently charged, and reaction proceeded for
1
31
on a Bruker AV600 NMR Spectrometer ( H, 600 MHz, C, another 3 h at the same temperature. This PU was then neutral-
50 MHz). Chemical shifts were reported in ppm and referenced ized by the addition of TEA at 25 C, followed by dispersion at
to residual solvent resonances ( H, C) or an internal standard. high speed (1200 rpm) with distilled water, which was added
Scanning electron micrographs were taken on a JEOL-JXA 840 drop-wise to produce a waterborne PU dispersion. The reaction
A SEM (JEOL, Boston, USA). The specimens were prepared for process is outlined in Scheme 2.
SEM by freeze-fracturing in liquid nitrogen and the application
of a gold coating of approximately 300 A with an Edwards S
50 B sputter coater. A gel permeation chromatograph (Model
00, Analytical Scientific Instruments, USA) with a refractive
◦
1
1
13
◦
Semi-Continuous Emulsion Polymerization Using
Polyurethane Surfactant
1
5
Semi-continuous emulsion copolymerization of vinyl acetate
index detector (RI2000, Schambeck, Germany), and two Jordi (VAc), butyl acrylate (BA) or styrene (St) with polyurethane
gel divinyl benzene mixed bed (Jordi FLP, USA) columns were surfactant were carried out using a 500 mL four-necked round-
used to measure the molecular weight, relative to the polystyrene bottom flask equipped with a reflux condenser, a stainless-steel
◦
standards at 30 C. The carrier solvent was tetrahydrofuran at a stirrer, a sampling device, and one feed stream. The feed stream
flow rate of 1 ml/min. The surface tension was measured us- was a solution of VAc, BA or St each one through emulsion
ing German du Nouy surface tension equipment. The measured copolymerization. Before emulsion copolymerization start-up,
◦
temperature was established at (25 ± 0.1) C.
the reaction vessel was first charged with the desired amounts of
water, polyurethane surfactant, NaHCO3, and initiator solution
(2.8 × 10 molL ), respectively. During polymerization, the
−3
−1
Synthesis of Diethylene Glycol Monoallyl Ether (DGME)
(
4.0 g, 0.1 mol of) NaOH and the solvent (dioxane) were reaction mixture was stirred at a rate of 100 rpm, and the tem-
introduced into a 100 mL three-necked round bottomed flask. perature was maintained at 65 C. After 5 min, 10 w% of total
Then (7.6 g, 0.1 mol of) allyl chloride and (21.2 g, 0.2 mol amount of the monomer was added to the flask in a period of
of) diethylene glycol were added drop-wise with rapid stirring 20 min. Then, the temperature was kept at 80 C until the end of
at 50–55 C. After the completion of the addition, stirring was polymerization (4 h). The polymerization was performed with
◦
◦
◦
◦
continued for 6 h at 50–55 C. The crude product was dried feeding rate of 1.0 mL/min under N2 atmosphere, to investigate
with magnesium sulfate. The solid material was filtered off. The the effect of surfactant concentration on monomer conversion.
solvent was distilled off and the residue was purified by column A typical recipe for the preparation of a product is given in
chromatography to give the compound in a yield of 82.5% and Table 2. In order to determine the conversion percentage during

POLYURETHANE SURFACTANT
929
FIG. 1. FT-IR spectra of (A) allyl chloride, (B) diethylene glycol, (C) DGME.
the polymerization process, it was necessary to withdraw sam- Water Absorption
ples at various intervals from the reaction vessel. These samples
are relatively small so that the overall composition in the reactor W ) were immersed in water for 24 h at 25 C. After the residual
Dried films (30 mm × 30 mm; original weight designated as
◦
0
is not seriously affected; once a sample is removed and put in water was wiped from the films using filter paper, the weight
[
17]
a watch glass, polymerization is terminated by the addition of (W ) was measured immediately
.
1
7
ppm hydroquinone. Then, two drops of ethanol were added to
It was calculated as follows: water absorption, R (%) =
the sample as a coagulant, and the contents of the watch glass ((W − W )/ W ) × 100
1
0
0
were evaporated at room temperature and then dried to a con-
stant weight in a vacuum oven. The conversion percentage was RESULTS AND DISCUSSION
determined gravimetrically. The purification and precipitation
[
16]
Spectral Analysis of Diethylene Glycol Monoallyl
Ether (DGME)
of the polymer were done using a reported method
.
Figure 1 shows the typical FT–IR spectra of (A) allyl chlo-
ride, (B) diethylene glycol, and (C) DGME. In the Figure 1(A)
Film Formation
Films were prepared with a dry thickness of about 0.5 mm.
−1
,
there are absorption peaks at 2949 and 1292 cm , which are
After casting the emulsion onto glass plates (20 cm × 20 cm), the
ascribed to the vibration of CH2 and C-Cl. Figure 1(B) indicates
films were allowed to dry for one week at ambient temperature
−1
strong absorption peak at 3380 cm , which is ascribed to the
vibration of –OH. According to Figure 1(C), there is strong ab-
◦
(
25 C).
−
1
sorption peak at 3404 cm , which is ascribed to the vibration
−1
of –OH. The absorption peaks at 1712 and 1457 cm were
attributed to C O and C C stretch vibration, respectively.
TABLE 2
Recipe for the semi-continuous emulsion polymerization of
VAc, BA or St
1
The H-NMR of DGME was shown in Figure 2, it can be seen
that all the relevant peaks of molecule could be found in this
Figure. The peaks at 3.6 ppm result from the groups of –CH2 in
the chain of (-OCH2CH2)2, in the molecule of DGME. Also, one
peak has been observed at 4 ppm, which is belonging to –OH,
and two signals of the CH2 CH–bond have been obtained at
Ingredients
Charge (g)
PUS
0.20
100.00
0.60
0.20
0.04
Demineralized water
HEC
NaCl
NaHCO3
Initiator: KPS
VAc
BA
St
5.2 ppm. A small peak at 5.9 ppm results from the group of
CH–CH2.
Figure 3 indicates the 13C-NMR spectrum of DGME. The
0.03
signals at 60–70 ppm were attributed to the (OCH2CH2)
groups. Also, carbon of –CH2 group was seen at 73 ppm. Two
peaks have been observed at 117 and 134 ppm, which are be-
longing to CH2 CH-.
51.60
51.60
51.60

930
H. J. NAGHASH ET AL.
FIG. 2. 1H-NMR spectrum of DGME.
FIG. 4. FT-IR spectra of (A) DGME, (B) NCO-PU, and (C) PUS.
Figure 6 indicates the 13C NMR spectrum of NCO-PU. The
number of carbons in the NCO-PU is compatible with the num-
ber of spectra.
Spectral Analysis of Polyurethane Surfactant (PUS)
Figure 4 illustrates the FT–IR spectra of (A) DGME, (B)
NCO-PU, and (C) PUS, respectively. It can be seen from Fig-
ure 4(A) that there are strong absorption peaks at 3404 and
1
The H-NMR of PUS was shown in Figure 7, it can be seen
that all the relevant peaks of PU could be found in this Figure.
Two peaks have been observed at 5.2 ppm, which are belonging
to (CH2 CH-). The peak at 5.9 ppm results from the group of
−1
2
–
1
926 cm , which are ascribed to the vibration of –OH, and
CH2 groups, respectively. The absorption peaks at 1712 and
−1
647 cm were attributed to C O and C C stretch vibration.
–CHCH2, and the peaks at 3.4–3.6 ppm results from the group
According to Figure 4(B) there are strong absorption peaks at
of –OCH2CH2 in the molecule of PUS. Also a small peak has
been observed at 4.9 ppm, which is belonging to -NH group.
−1
3
314, 2931, 2268, and 1683 cm , which are ascribed to the
13
vibration of –NH, –CH2, N C O, and C C groups. As shown
Figure 8 indicates the C-NMR spectra of PUS. The number
of carbons in the PUS is compatible with the number of spectra.
−1
in Figure 4(C), a new sharp peak appeared at 3322 cm , which
was attributed to N–H absorption. Also, the absorption peak
−1
at 1550 cm was attributed to N–H bond vibration and C–N Effect of the PUS Concentration on the Surface Tension
symmetry stretch vibration.
According to Figure 9, the surface tension decreases with an
The H-NMR of NCO-PU was shown in Figure 5, it can be increase in the concentration of the polyurethane surfactant in
seen that all the relevant peaks of molecule could be found in an aqueous solution. This trend resembles what appears in con-
this Figure. The peaks at 1.2–1.5 ppm results from the groups of ventional low-molecular-weight surfactant, but it is noteworthy
1
–
CH2 in the chain of –NH–(CH2)– in the molecule of NCO–PU. that, after the critical micelle concentration (CMC) was reached,
Also one peak has been observed at 4.8 ppm, which is belonging the surface tension could still be reduced slightly, and there is
to –NH and two signals of the CH2 CH–bond have been ob- no inflection point in the curve as known for typical surfactants.
tained at 5.2 ppm, respectively. A small peak at 5.8 ppm results As for low molecular-weight surfactants, the surface tension
from the group of CH–CH2.
FIG. 3. 13C NMR spectrum of DGME.
FIG. 5. 1H-NMR spectrum of NCO-PU.

POLYURETHANE SURFACTANT
931
FIG. 6. 13C NMR spectrum of NCO-PU.
FIG. 8. 13C NMR spectrum of PUS.
usually remains constant after the CMC is reached. Thus, this
phenomenon is interesting. To the contrary, Ismail [18] once
synthesized a series of water-soluble polyurethane surfactants
by the addition polymerization of TDI to poly (ethylene gly-
col) and/or castor oil and ethylene glycol. He found that the
curve of the surface tension versus the molar concentration was
just like that of classical low-molecular-weight surfactants. In
other words, the surface tension was stable after the CMC was
reached. The same results also occurred in the work of Shi
oriented on the surface with their hydrophilic parts dissolved
in the aqueous solution. Consequently, the surface tension was
reduced.
UV spectroscopy has been widely used to determine the
CMC and investigate the aggregate behaviors of surfac-
[22–24]
tants
. The results of UV spectra in the various concen-
trations show a redshift occurred, after some sample reached
a certain concentration, and increasing the concentration made
the redshift greater. This indicated that an interaction between
the macromolecular chains had to exist, and after the CMC,
the polyurethane surfactant could accumulate to form micelle
aggregates between molecules. The CMC data given by the
UV solution were approximately in agreement with what we
obtained with a surface tensiometer.
et al.[ and Riess et al. . The reason, that the surface ten-
sion could still be reduced slightly after the CMC was reached
in our work, may be that the arrangements of polyurethane
surfactants on the surface were not as tight as those of tra-
ditional low-molecular-weight surfactants. As the concentra-
tion of the polyurethane surfactant increased, the chains of the
macromolecules could be condensed further. This increased the
arrangement density of the hydrophobic part on the surface and
resulted in the decrease of the surface tension. The curve of
the surface tension versus the concentration obtained by Adler
et al.[ is similar to what we obtained. Figure 9 shows that the
sample had good surface activity and very low CMC values,
which could reduce the surface tension to as low as 35 mN/m.
The ability to reduce the surface tension increased with an in-
crease in the hydrophobic segment. That is, while the ratio of the
hydrophobic segment increased, more hydrophobic chains were
19]
[20]
Effect of Salt on the Surface Tension
It is widely accepted that the addition of electrolytes has an
[25–27]
effect on the surface tension
. As revealed by Figure 10, the
addition of salt led to a slight decrease in the surface tension of
PUS. This was due to the fact that the addition of salt increased
the ionic strength of the aqueous solution. The hydrophilic parts
of the polyurethane surfactants consisted of polyoxyethylene,
21]
FIG. 9. Surface tension against molar concentration of PU-based copolymeric
surfactant.
FIG. 7. 1H-NMR spectrum of PUS.

932
H. J. NAGHASH ET AL.
Effect of the Rest Time on the Surface Tension
It has been found that time is needed for polyurethane sur-
factants to reach a constant surface tension, and that the time
needed to obtain a constant value of the surface tension varies
as the concentration of the polyurethane surfactant changes[
.
29]
According to the experimental results, we think that it must take
some time for macromolecules of polyurethane surfactants to
migrate to the surface. As for polymeric surfactants, they usually
have a high molecular weight, and there exist interaction and
entanglement between the long macromolecular chains, when
they dissolve in water. The rest time allows them to adjust their
conformation sufficiently and results in a better arrangement on
the surface. The time needed to achieve a constant value of the
surface tension for surfactants at a higher concentration level is
FIG. 10. Surface tension against molar concentration of PU-based copoly-
meric surfactants at different NaCl concentration aqueous solution.
+
whose oxygen atom could interact with H2O or H3O by a hy- less than that at a lower concentration level.
drogen bond and, consequently, was a little positive[ . When
28]
Effect of PUS Concentration on Reaction Rate
the polyurethane surfactants were dissolved in water, the hy-
drophilic parts pointed to the water, whereas the hydrophobic
parts aggregated on the surface (away from the water). As the
salt was added, the repulsion between oriented hydrophobic
heads and hydrophilic heads could be reduced. This resulted
in a closer packaging of the surfactants on the surface and,
therefore, reduced the surface tension. The effect of salt on the
surface tension reduction, varied in terms of the concentration
of the polyurethane surfactants. Figure 10 indicates that the ef-
fect of salt on the surface tension was more prominent at a
lower concentration level. This may be attributed to the fact
that macromolecular chains of the polyurethane surfactants at
a lower concentration level, which could be condensed further
when salt was added, were not arrayed as tightly as those at a
higher concentration level.
Although emulsion copolymerization of VAc, BA and St
has been well established [
30,31]
, their copolymerization in pres-
ence of PUS has not been reported. Therefore, the role of this
surfactant is not perfectly clear. It is possible that during the
copolymerization process, this polymeric surfactant will make
part of the copolymer chain. However, the extent of its incorpo-
ration in the polymer chain was not measured. Figure 11 shows
the effect of PUS on the reaction rate versus time for BA, St
and VAc, respectively, where the initial initiator and PUS con-
−
3
−1
centration were fixed at I0 = 2.8 × 10 molL . It can be
observed that the rate of reaction increased in the order VAc
>
St > BA. This result shows that the PUS is a better surfactant
for VAc emulsion copolymerization in comparison with BA and
St. According to the experimental results, we think that St is a
hydrophobic monomer, due to benzene ring and consequently
it’s resonance effect with the electrons of double bond. So a
disinclined reaction will be obtained between St and PUS. Also
there is a long hydrophobic chain in the BA monomer and this
is a cause for a low reaction rate of PBA.
Effect of the Temperature on the Surface Tension
The obtained result demonstrates the variation of the sur-
◦
face tension of PUS in aqueous solutions at 14, 20, and 25 C.
The surface tension decreased with an increase in the temper-
ature. This was due to the fact that more heat was absorbed as
the temperature increased, and the heat allowed enough energy
for the molecules of the polyurethane surfactants to surmount
the attractive forces of the interior, and subsequently migrate to
the surface. The enrichment of the polyurethane surfactants on
the surface led to the decrease in the surface tension accordingly.
Here we also can explain this phenomenon in terms of the Gibbs
adsorption equation:
On the other hand, the obtained results demonstrated that the
reaction rate increased by increasing PUS concentrations.
dγ
da
a
ꢀ
= −
×
[1]
RT
where Г is the surface excess concentration, γ is the surface ten-
sion, α is the solution activity, R is the gas constant, and T is the
absolute temperature. The Gibbs adsorption equation indicates
that the adsorption amount will increase with an increase in the
temperature. Thus, it gives an excellent explanation for what we
have discussed.
FIG. 11. The effect of PUS with constant concentration on monomer conver-
sion vs. time for PBA (ꢁ), PSt (ꢀ) and PVAc (•) at T = 80 a˚ C, I0 = 2.80 ×
−
3
−1
10 molL .

POLYURETHANE SURFACTANT
933
Morphologies of Latex Particles of PVAc, PBA, and PSt
The particle morphologies of the PVAc, PBA, and PSt has
been illustrated in Figure 13(A–C). Comparing all the micro-
graphs, we can conclude that the morphology of the copoly-
mer particles is all spherical and it is almost homogeneous in
the particles. Double bond containing PUS is often used for
copolymerization with acrylic monomers[
36,37]
. It is commonly
held that they can easily copolymerize with those monomers,
because there exists a CH2 C (CH3) COO– group with a simi-
lar structure. However, most copolymerization is carried out in
an organic solvent. In our study, the free-radical copolymeriza-
tion of PUS with other monomers was conducted in an aqueous
system.
FIG. 12. Molecular weight measurements of (A) PSt, (B) PVAc and (C) PBA
films.
Molecular Weights of PVAc, PBA, and PSt
The molecular weight is considered to be one of the
most important parameters of polyurethane. The mechanical
CONCLUSIONS
property is significantly affected by the molecular weight of
polyurethane[
32,33]
By the polycondensation of HMDI with PPO and DGME,
we synthesized a novel of diblock non-ionic polyurethane sur-
factant that contained reactive double bond. This polymeric sur-
factant had good surface activity. The surface tension of this
polyurethane surfactant in aqueous solution changed as the con-
centration changed. An increase in the temperature was favor-
able for the enhancement of the surface activity, and the ad-
dition of salt led to the reduction of the surface tension. In
this experiment, we also found that time was needed for the
polyurethane surfactant to reach a constant value of the surface
tension. This polymeric surfactant has potential application in
emulsion polymerization as promising alternative to conven-
tional low-molecular-weight surfactant. At the same time, it can
incorporate with hydrophilic chains as the hydrophobic part in
the synthesis of hydrophobically associating water-soluble poly-
mers. Further studies in this direction are currently in progress.
. The polyurethane molecular weight depends
[
34,35]
on the polyol, chain extender, and diisocyanate content
.
Figure 12(A–C) shows the molecular weight of PSt, PVAc, and
PBA, respectively. According to this Figure it can be observed
that the molecular weight increases in the order PSt > PVAc >
PBA. The PSt exhibited the highest molecular weight among all
of the samples, and the PVAc samples exhibited lower molecular
weight than the others.
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