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Brush-shaped RAFT polymer micelles as nanocarriers for a ruthenium (II) complex photodynamic anticancer drug
European Polymer Journal 119 (2019) 477–486
Contents lists available at ScienceDirect
European Polymer Journal
journal homepage: www.elsevier.com/locate/europolj
Study on the synergistic anticorrosion property of a fully bio-based
polybenzoxazine copolymer resin
⁎
Yitong Zhanga, Xiaoyun Liua, , Guozhu Zhanb, Qixin Zhuanga, Ruhong Zhanga, Jun Qiana,
T
⁎
a
The Key Laboratory of Advanced Polymer Materials of Shanghai, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai
200237, China
b
The 806th Institute of the Eighth Academy of CASC, Huzhou 313000, China
A R T I C LE I N FO
A B S T R A C T
Keywords:
Renewable
Polybenzoxazine
Anticorrosion
Dielectric constants
In this paper a novel bio-based benzoxazine, dehydroabietylamine benzoxazine monomer (D-Bz), was synthesized and a series of copolymers were prepared by using D-Bz and two other bio-based benzoxazines 6-allyl-8methoxy-3-octadecyl-3, 4-dihydro-2H-benzoxazine (S-Bz) and 6-allyl-3 –(furan-2-ylmethl)-8-methoxy-3, 4-dihydro-2H-benzoxazine (F-Bz). The structure, morphology and curing process are characterized by 1H nuclear
magnetic resonance spectroscopy (1H NMR), mass spectrometry (MS), fourier transform infrared spectroscopy
(FTIR), scanning electron microscope (SEM), differential scanning calorimetry (DSC) and thermogravimetric
analysis (TGA). Electrochemical techniques such as open circuit voltage time (OCPT), Tafel and electrochemical
impedance spectra (EIS) were used to study their electrochemical corrosion properties. Results show that among
these copolymer, when the ratio of S-Bz: D-Bz: F-Bz is 1:6:3, the copolymer has good synergistic effects, showing
a lower dielectric constant (2.47 at 1000 Hz), higher crosslink density (5.29*E−4 mol/ml), lower corrosion
current (0.030 µA/cm2) and the best electrochemical corrosion efficiency (99.73%).
1. Introduction
energy and dielectric properties [17–28]. PBz has been studied as an
anti-corrosion coating [16,29–34], shown to inhibit the corrosion of
coated steel samples due to the formation of a stable network that diminished the permeability of corrosion agents to the metallic substrate
[35–39]. Lin et al. mixed blends possessing a maleimide-containing
benzoxazine compound (MI-Bz) and an amine-capped aniline trimer
(ACAT) [30]. Lin’s study found that a covalent bond was established
between the ACAT and MI-Bz compounds which had a synergistic effect
on their respective anticorrosion properties. Caldona et al. adopted
rubber-modified PBz as an anti-corrosion coating for low carbon steel
[31]. Electrochemical measurements recorded after immersion in
chloride solution showed that the rubber-modified PBz was able to
protect the carbon steel from corrosion attack due to its slow surface
energy properties and water resistance ability (contact angle:
CA = 101°). The electrochemical corrosion protection efficiency is
about 92%. Most studies on the corrosion protection of PBz coated
metals look at the homopolymer or composite; however, the preparation of composite materials also requires consideration of the compatibility and dispersion of the applied filler particles [31]. Therefore, it is
necessary to study the synergistic effects of different PBz coatings on
corrosion resistance.
Nowadays, inspired by environmental protection policies, the use of
Corrosion is the destruction and deterioration of materials caused
by the reaction of materials with their environment; it is the main factor
causing the failure of metal materials. Corrosion has adverse impacts on
the chemical, shipping, manufacturing and architectural industries
[1,2]. One of most widely used methods to mitigate corrosion is
polymer coatings which provide a physical barrier against corrosion
[3–5]. These physical barriers prevent oxygen, water and corrosive ions
from coming into contact with the metal substrate in order to protect
from corrosion [6,7].
At present, there are many kinds of polymers used in anti-corrosion
coatings, among which epoxy resin [8,9], polyaniline [10,11], phenolic
resin [12] and the like have been studied. Of these polymers, phenolic
resins are widely used as binders and coatings due to their high mechanical strength, excellent thermal stability and chemical resistance
[13,14].
A new type of thermosetting phenolic resin, benzoxazine resin, have
highly exceptional properties, such as excellent chemical resistance,
thermal stability, high char yield, very long shelf life [15,16]. In addition, Polybenzoxazine resin (PBz) has shown other excellent properties, such as low water absorption, near-zero shrinkage, low surface free
⁎
Corresponding authors.
E-mail addresses: liuxiaoyun@ecust.edu.cn (X. Liu), qianjun@ecust.edu.cn (J. Qian).
https://doi.org/10.1016/j.eurpolymj.2019.07.020
Received 5 March 2019; Received in revised form 4 July 2019; Accepted 15 July 2019
Available online 15 July 2019
0014-3057/ © 2019 Elsevier Ltd. All rights reserved.
European Polymer Journal 119 (2019) 477–486
Y. Zhang, et al.
purchased from Sigma-Aldrich. Chemicals and solvents were used asreceived without further purification. The Q235 carbon steel
(10 mm × 10 mm × 0.2 mm) electrodes were rinsed by ultrasonication
in anhydrous acetone and anhydrous ethanol for cleaning the surface
contaminants. After that, the Q235 were polished using 400, 800 and
1500-grit sand papers.
renewable resources as chemical raw materials has become an important topic for researchers in various fields. Bio-based materials have
the advantages of being ‘green’, environmental friendliness, and resource-saving. Renewables are gradually becoming a leading industry
that guides scientific and technological innovation and economic development [37–39]. Our research group has previously reported two
novel bio-based benzoxazines, obtained from rosin (Dehydroabietylamine), which have high corrosion resistance and an electrochemical corrosion protection efficiency of 83% [40]. The materials
also have a stable open circuit voltage time in corrosion resistance and
low dielectric constants.
There are several formulas used to explain the relationships between the dielectric constant, capacitance, water absorption and
coating failure parameters. The parallel plate model formula (1) [41]
describe show, when an electrolyte solution with a large dielectric
constant penetrates into the coating, the dielectric constant K of the
coating will increase and, when the coating area (A) and thickness (d)
are constant, the corresponding capacitance (C) of the coating will also
increase. According to formula (2) [42], it can be known that the
foaming rate or porosity parameter F of the coating will increase. This
parameter corresponds to the microscopic foaming and micropore
production of the coating, which reduces the corrosion resistance of the
coating. As for the water absorption rate of the coating, we can refer to
the formula (3) [42]: when the water absorption of the coating (Xv%) is
low, the coating capacitance only changes a little with time. That is to
say, C(0) and C(t) are approximately equal.
C = Kε0
A
d
2.2. Synthesis of monomers
2.2.1. Synthesis of D-Bz
D-Bz was prepared by the fowling procedure: under condensed reflux conditions, eugenol (30 mmol, 4.92 g), dehydroabietylamine
(30 mmol, 9.50 g) and paraformaldehyde (60 mmol, 1.8 g) were placed
in a 500 mL round-bottomed flask (Scheme 1). Then 200 mL of dioxane
was added as the solvent. The mixture was stirred at 70 °C until it was
completely dissolved, and then the mixture was heated to 85 °C and
maintained at this temperature for 12 h. After cooling to room temperature, the crude product was concentrated under reduced pressure
to remove dioxane, and the residual solid washed several times with
95 °C 1% aqueous NaHCO3 to remove unreacted eugenol. The product
was purified by recrystallizing in ethanol to remove dehydroabietylamine and by products. The resulting powdery brown solid
was dried at 65 °C in a vacuum oven. The yield was 77%, and the
melting point was 97 °C. FTIR (KBr, cm−1) is shown in Fig. S1: 2930
(CeH), 2865 (CeH), 1233 (CeOeC), 1158 (CeNeC), 1092 (CeOeC),
938 (CeH). 1H NMR (400 MHz, CDCl3, δ, ppm) is shown in Fig. S2:
7.2–6.2 (AreH), 3.8 (eOCH3), 5.9, 5.0 and 3.2 (eCH2eCH]CH), 4.8
(OeCH2eN), 3.7 (AreCH2eN). Mass spectrometry (MS) (m/z) is 473.2
as shown in Fig. S3. (The theoretical molecular weight of D-Bz is 473 g/
mol).
(1)
C = C 0F
(2)
XV % = 100 × log[C (t )/ C (0)]/log(80)
(3)
2.2.2. Synthesis of S-Bz
S-Bz (6-allyl-8-methoxy-3-octadecyl-3, 4-dihydro-2H-benzoxazin)
was prepared based on already reported method [43,44]. The reaction
process is shown in Scheme 1. The yield was 87%, and the melting point
was 50 °C. FT-IR (KBr, cm−1) is shown in Fig. S1: 2930 (CeH), 2865
(CeH), 1230 and 1092 (CeOeC), 1154 (CeNeC), 944 (CeH). 1H NMR
(400 MHz, CDCl3, δ, ppm) is shown in Fig. S4: 3.8 (eOCH3), 3.2, 5.9
and 5.0 (eCH2eCH]CH), 4.8 (OeCH2eN), 3.9 (AreCH2eN).
C0: coating capacitance per unit area; Xv%: the water absorption of the
coating; C(0): Coating starting capacitance; C(t): Coating capacitance at
time t.
Some researchers also reported that the higher cross-link density of
the coating could increase electrochemical corrosion [16,43,44]. P.
Thirukumaran synthesized bio-based benzoxazines 6-allyl-8-methoxy3-octadecyl-3, 4-dihydro-2H-benzoxazin (S-Bz) and 6-allyl-3 –(furan-2ylmethl)-8-methoxy-3, 4-dihydro-2H-benzoxazine (F-Bz) [44]. It was
found that the corresponding polymer PS-Bz has good flexibility and
that PF-Bz has good crosslink density, although their corrosion resistance was not reported.
Naturally, we are motivated to study the anti-corrosion of bio-based
benzoxazine coating with low dielectric constant, low water absorption
and high cross-link density organic resins in order to improve upon
corrosion protection. In this work, we expanded our previous research
and synthesized a new bio-based benzoxazine resin (Scheme 1), D-Bz
(Dehydroabietylamine benzoxazine monomer). Since the PD-Bz (Dehydroabietylamine polybenzoxazine) has a low dielectric constant and
more stable electrochemical corrosion resistance, we studied the copolymer of D-Bz with S-Bz and F-Bz in order to achieve higher electrochemical corrosion protection efficiency. The thermal curing process, thermal stability, crosslink density, contact angle, water
absorption, dielectric properties and electrochemical corrosion resistance of the coating was investigated.
2.2.3. Synthesis of F-Bz
F-Bz (6-allyl-3 –(furan-2-ylmethl)-8-methoxy-3, 4-dihydro-2H-benzoxazine) was prepared based on already reported method [43,44]. The
reaction process is shown in Scheme 1. The yield was 93%, and the
melting point was 75 °C. FT-IR (KBr, cm−1) is shown in Fig. S1: 2930
(CeH), 2865 (CeH), 1589, 1003 and 733 (vibrations of the furan ring),
1233 and 1095 (CeOeC), 1146 (CeNeC), 1092 (CeOeC), 943 (CeH).
1
H NMR (400 MHz, CDCl3, δ, ppm) is shown in Fig. S5: 6.63–6.45
(AreH), 3.8 (eOCH3), 5.9, 5.0 and 3.2 (eCH2eCH]CH), 7.3, 6.8–6.2
(Hydrogen proton on furan ring), 4.8(OeCH2eN), 4.0 (AreCH2eN).
2.3. Preparation of corresponding polybenzoxazines and copolymers
The three benzoxazine monomers, S-Bz, D-Bz, and F-Bz, were mixed
according to a certain molar ratio (Table 1), dissolved in tetrahydrofuran (THF) and the solution poured into ceramic models. Then,
the ceramic models were placed into a vacuum drying oven at 80 °C for
24 h to remove the solvent. After that, they were cured in a tube furnace
and the steps were as follows: 100 °C (1 h), 150 °C (1 h), 180 °C (2 h),
200 °C (2 h), and 230 °C (1 h). Thereafter, samples were cooled to room
temperature and the resulting polymers were named PSDF-Bz (Table 1).
2. Experimental
2.1. Materials
Dehydroabietylamine (90%), furfurylamine (99%), octadecylamine
(99%), sodium chloride (99.5%), sodium bicarbonate (AR grade), sodium hydroxide (AR grade), eugenol (99%), paraformaldehyde (AR
grade), dioxane (AR grade), tetrahydrofuran (AR grade), acetic acid
(AR grade), ethanol (AR grade) and anhydrous acetone (AR grade) were
2.4. Characterization
FTIR spectra were measured with a Bruker Vector 22 FTIR analyzer.
All samples were finely ground with KBr powder and pressed into a thin
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European Polymer Journal 119 (2019) 477–486
Y. Zhang, et al.
Scheme 1. Structure of bio-based benzoxazine monomers (D-Bz, S-Bz, F-Bz).
Table 1
The name of the cured resin and its monomer ratio.
Table
2. DSC data of SDF-Bzs.
Monomer
S-Bz
D-Bz
F-Bz
Corresponding polymer
Name
Tm (°C)
Tonset (°C)
Tmax (°C)
Processiing windows (°C)
SDF-Bz(10/0/0)
SDF-Bz(0/10/0)
SDF-Bz(0/0/10)
SDF-Bz(4/6/0)
SDF-Bz(3/6/1)
SDF-Bz(2/6/2)
SDF-Bz(1/6/3)
SDF-Bz(0/6/4)
10
0
0
4
3
2
1
0
0
10
0
6
6
6
6
6
0
0
10
0
1
2
3
4
PSDF-Bz(10/0/0)
PSDF-Bz(0/10/0)
PSDF-Bz(0/0/10)
PSDF-Bz(4/6/0)
PSDF-Bz(3/6/1)
PSDF-Bz(2/6/2)
PSDF-Bz(1/6/3)
PSDF-Bz(0/6/4)
SDF-Bz(10/0/0)
SDF-Bz(0/10/0)
SDF-Bz(0/0/10)
SDF-Bz(4/6/0)
SDF-Bz(3/6/1)
SDF-Bz(3/6/2)
SDF-Bz(1/6/3)
SDF-Bz(0/6/4)
50
97
75
54/97
53/74/97
53/74/97
53/74/97
74/97
193
198
169
194
187
182
183
177
221
226
210
223
219
215
213
212
143
101
94
97
90
85
86
80
disk. 1H NMR spectra were recorded with 1H NMR spectrometer
(Bruker, 400 MHz) using CDCl3 as the solvent and TMS as the internal
standard. DSC was carried out on an Instruments DSC Model 2920. Both
samples were heated at a rate of 10 °C/min under nitrogen flow of
50 mL/min, and an indium standard was used for calibration. The glass
transition temperature (Tg) of polybenzoxazine was studied by DSC.
TGA was carried out on a TA Instrument Model 2050 with a heating
rate of 10 °C/min under nitrogen flow of 40 mL/min. The dielectric
properties of polybenzoxazines were analyzed with a Concept 40
Broadband dielectric analyzer at 25 °C. The crosslinking density of
corresponding polybenzoxazines was analyzed with IIC XLDS-15 analyzer at room temperature. Tafel, electrochemical impedance spectroscopy (EIS) and OPCT curves and Tafel plots were studied with an
Electrochemical Workstation CHI 760E. Q235 low-carbon steels
(1 cm × 1 cm × 0.2 cm) were washed with acetone twice before being
used. All samples were immersed in 3.5% sodium chloride saline for
7 days before electrochemical tests. The morphology of the coated and
uncoated steels were observed by SEM.
are assigned to the melting points of S-Bz, D-Bz and F-Bz, respectively.
The exothermic peaks demonstrate the ring-opening polymerization of
oxazine rings. The onset ring-opening temperatures of S-Bz and D-Bz
are 193 °C and 198 °C, while the value for F-Bz is 169 °C due to the
electrophilic substitution reaction of furan ring [47].
Fig. S6b displays the curing process of the copolymer. The relevant
data are summarized in Table 2. As the content of F-Bz increases in the
copolymer SDF-Bz, the curing exothermic peak gradually shifts to a
lower temperature.
3.2. Thermal properties of PSDF-Bz
Figs. S7 and S8 display the thermal properties of PSDF-Bz, and
Table 3 summarizes the data. The Tg of PSDF-Bz(0/0/10) has the
highest temperature of 148 °C due to the furan ring in PSDF-Bz(0/0/10)
which increases crosslink density [46]. In addition, hydrogen bonds
formed by oxygen atoms in the furan ring also increase the Tg [48].
PSDF-Bz(10/0/0) contains a long alkyl chain and the molecule is relatively soft, which makes the Tg of PSDF-Bz(10/0/0) lower. As the
content of F-Bz increases in the copolymer, the Tg tends to increase. The
Tg of copolymers were also calculated by the FOX formula, as shown in
formula (4) and it was found that the TgFOX were close to the experimental dates [49]. Moreover, only one Tg is found in all copolymers,
which indirectly reflects the good compatibility of the three resins in
the copolymer.
3. Results and discussion
3.1. Curing behavior of SDF-Bz
The polymerization behavior of the SDF-Bz resins was studied by
DSC (Fig. S6). The bulky amine moiety does not degrade during the
cure [45,46] and the relevant parameters of the monomer curing process are shown in Table 2. The endothermic peaks at 50, 97 and 75 °C
1
w
W
= 1 + ...+ n
Tg
Tg1
Tgn
479
(4)
European Polymer Journal 119 (2019) 477–486
Y. Zhang, et al.
Table 3
Thermal properties and crosslink density of PSDF-Bzs.
Sample
T5 (°C)
T10 (°C)
CY (%)
LOI values
Tg (°C)
TgFOX (°C)
Crosslink density (*E−4 mol/ml)
PSDF-Bz (10/0/0)
PSDF-Bz (0/10/0)
PSDF-Bz (0/0/10)
PSDF-Bz (4/6/0)
PSDF-Bz (3/6/1)
PSDF-Bz (2/6/2)
PSDF-Bz (1/6/3)
PSDF-Bz (0/6/4)
316
341
375
320
327
348
357
368
346
378
405
358
363
382
388
394
24
38
54
32.4
35
36
38
41
27.1
32.7
39.1
30.46
31.5
31.9
32.7
33.9
101
135
148
118
123
130
133
137
–
–
–
120
125
130
135
139
3.617
4.762
5.585
4.88
5.038
5.165
5.289
5.433
W1…Wn are the mass percentage of each type of monomers, Tg1…Tgn
are the glass transition temperature of each type of monomer homopolymers (the unit is K).
The TGA curves of PSDF-Bzs show that the onset weight-loss of the
polymers and copolymers are beyond 300 °C (Fig. S8); it is associated
with the degradation at the Mannich bridge. The temperatures of 5%
weight-loss (T5) of all copolymers are higher than 300 °C, which means
they all have good thermal stability.
The Limit Oxygen Index (LOI) value of the coating is also an important indicator of its flame retardancy [50]. LOI values were calculated from the TGA data using the Van Krevelan and Hofytzerequations
[50]. The formula (5) is as follows:
measurements were performed on bare carbon steel and various coated
samples before exposure in a corrosive medium. As shown in Fig. 2,
with the absence of a protective coating, Q235 steel could be readily
attacked by corrosive species due to its hydrophilic surface
(CA = 87.5°) and primordial battery system. The PSDF-Bz(10/0/0)
coating shows a higher CA of 109.33°, caused by the hydrogen bonds
and long aliphatic groups in the PSDF-Bz, which results in the low SFE
energy of PSDF-Bz [30,53]. The crosslink network of PSDF-Bz can also
diminish the permeability of water to the metallic substrate [54,55].
It has also been shown that, as the content of F-Bz increases, the CA
values decrease since the PF-Bz has more hydroxyl groups which enable
the membrane surface to bond with more water molecules [16]. Whilst
not as good for anti-corrosion, hydroxyl groups also contribute to the
interfacial adhesion between Q235 and resins, which can prevent the
permeation of water [56,57].
(5)
LOI = 17.5 + 0.4CY
Table 3 summarizes the LOI of homopolymers and copolymers. CY
is Carbon Yield. It can be seen that the LOI value increases with the
increase in F-Bz content. The LOI value of all copolymer resins exceeds
30. It is known that most bio-based benzoxazine resins have poor
thermal properties. This result indicates that the PSDF-Bz(0/0/10) may
have greater applications than ordinary bio-based benzoxazine.
3.5. Water absorption behavior
The water absorption behavior of the PSDF-Bz coatings were studied
in 3.5% NaCl aqueous solution for 20 days. The results are shown in
Fig. 3. On the 10th day, the water absorption of all the samples reached
a saturated state; the saturated water absorption rates were less than
2%. In addition, the water absorptions of most copolymer coatings were
lower than of a homopolymer. Further, it was found that the water
absorbability of the resin slightly changed with the composition of the
copolymer. This result reflects the synergistic effect of resins in the
copolymer [58]. An increase in the furan ring concentration improves
the crosslink density of the coating [59], which could reduce the free
space. Besides this effect, the nature of the material also affects the
water absorption of the material and the long alkyl chain imparts a low
surface energy to the PBz coatings, making it difficult for water molecules to contact the surface of the material. It was found that copolymer
PSDF-Bz(3/6/1) shows the lowest water absorption rate of only 0.988%
after 20 days. Copolymer PSDF-Bz(1/6/3) and PSDF-Bz(2/6/2) also
have low water absorption.
3.3. Dielectric properties of polymer and copolymer coatings
Fig. 1 shows the dielectric constant and dielectric loss of PSDF-Bzs.
It has been found that the dielectric constants of all copolymers are
lower than 2.9 when the frequency is greater than 103 Hz, moreover,
they have low dielectric loss. They are much lower than that of other
PBzs, where the dielectric constant is usually in the range of 2.5–4
[51,52]. It is expected that this excellent dielectric property means the
copolymers may have high molar volumes and may have a good effect
on the corrosion resistance of the copolymer, according to formula (1)
[41].
3.4. Static water contact angle (CA)
In
order
to
investigate
the
surface
hydrophobicity,
CA
Fig. 1. Dielectric property of PSDF-Bzs (a) Dielectric Constant (b) Dielectric Loss.
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Y. Zhang, et al.
Fig. 2. Static water contact angles of Q235 and PBz coatings.
evaluated to study the corrosion resistance of PSDF-Bz coatings. The
open circuit voltages (Eocp), recorded for both coated and uncoated
Q235 steel, were plotted as a function of immersion time. Compared
with Q235 carbon steel without the PSDF-Bz coating, the Eocp value of
coated Q235 carbon steel increased from −1.019 V to −0.7014 V after
100 min of immersion time. It can be seen from Fig. 4 that, among the
three homopolybenzoxazine coatings, the Eocp of PSDF-Bz (0/10/0) is
highest after 3500 s immersion and shows only comparatively small
changes over time, suggesting that the PSDF-Bz (0/10/0) has excellent
corrosion resistance [60,61]. Since Eocp is related to CA and water absorption, despite the initial Eocp of PSDF-Bz (0/0/10) being high, immersion in a 3.5% NaCl aqueous solution for 6000 s reduces Eocp to
−0.7581 V (due to its high water absorption and poor hydrophobicity).
The corresponding microscopic interpretation is that water molecules
can easily enter the metal surface through pores in the coating/substrate, resulting in a decline in Eocp data for later testing. Although
PSDF-Bz(10/0/0) has good hydrophobicity (CA = 109.33°) and low
water absorption (1.319%), its Eocp is still lower than the other two
samples. The reason for this phenomenon may be that the long alkyl
chain imparts a lower surface free energy to the material, reducing its
affinity to the metal matrix; therefore, the adhesion between the metal
and the coating of the material is not strong.
Fig. 3. Water absorption curves of PSDF-Bz at 25 °C.
3.6. Open circuit potential time (OCPT) characterization
The corrosion resistant properties were observed in 3.5 wt% NaCl
aqueous solutions for coated and uncoated Q235 steel using an electrochemical work station. The OCPT, Tafel curve and EIS spectra were
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Y. Zhang, et al.
Fig. 4. The OCPT values of coated and uncoated Q235 steels.
As shown in Fig. 4b, copolymer coated Q235 steel has more positive
Eocp values compared to uncoated Q235 steel or homopolymer-coated
Q235 steel, even after 6000 s exposure to 3.5% NaCl aqueous solution.
The Eocp of PSDF-Bz (0/6/4) with higher water absorption and lower
hydrophobicity decreased rapidly with time. Samples with lower water
absorption, such as PSDF-Bz (1/6/3) and PSDF-Bz (2/6/2), show a
larger Eocp, while PSDF-Bz (3/6/1) and PSDF-Bz (4/6/0), which have
better hydrophobicity and low water absorption rates, have a more
negative Eocp. A possible reason for this effect is that the dielectric
coefficient results in an increase in tantalum capacitance and a more
negative Eocp while forming the electrolytic cell. The PSDF-Bz(1/6/3)
coated carbon steel shows high initial and lowest Eocp (−0.4713 V to
−0.4661 V) values, which means it may have higher corrosion resistance.
E (%) is the metal protection efficiency. Icorr and Icorr (c ) are the corrosion current values in the absence and presence of the coatings, respectively. The corrosion rate and protection efficiency could be calculated from Ecorr and Icorr for quantitative evaluation of the
anticorrosion performance (Table 4). In the case of bare low carbon
steel, the Ecorr is −0.573 V, which is improved to −0.497 V (PSDF-Bz
(10/0/0)), −0.371 V (PSDF-Bz (0/10/0)) and −0.325 V (PSDF-Bz (0/
0/10)) when coated with the cured homopolymer of benzoxazine.
Moreover, the current of anodic polarization curve of the PSDF-Bz
samples showed a significant decrease, which means that the anodic
dissolution process of the metals were delayed due to the benzoxazine
coatings.
It can be seen that the PSDF-Bz(3/6/1), PSDF-Bz(2/6/2) and PSDFBz(1/6/3) have the highest corrosion protection efficiency. The corresponding corrosion resistance E% values are 98.87%, 99.23% and
99.74%, respectively. These data are higher than for homopolymers
(PSDF-Bz(10/0/0), PSDF-Bz(0/10/0) and PSDF-Bz (0/0/10)) due to the
synergistic effect. This result reflects the synergistic effect of the three
components. PSDF-Bz (3/6/1), PSDF-Bz (2/6/2) and PSDF-Bz (1/6/3)
coatings also have low water absorption and excellent dielectric properties resulting in a small portion of water molecules entering the
polymer network, which hindered the closed circuit of the metal substrate and the power supply electrode [16,67,68]. Besides low water
absorption, PSDF-Bz (1/6/3) has a lower dielectric constant, that is to
say, the number of microcapacitors per unit volume of the coating is
lower and the resulting interface polarization is weaker. Logically, the
PSDF-Bz (1/6/3) coating has the lowest electrochemical corrosion rate
3.7. Tafel characterization
The Tafel plots obtained by immersing the samples in 3.5% NaCl
aqueous solution are shown in Fig. 5 and Table 4. All electrochemical
tests are averages of 10 samples except extreme data. Corrosion potential (Ecorr) and corrosion current (Icorr) were obtained using the extrapolation method [62,63]. Amore negative Ecorr and larger Icorr
usually correspond to a faster corrosion rate while a more positive Ecorr
and smaller Icorr mean a slower corrosion process [64]. The protection
efficiencies (E%) are calculated using formula (6) [65,66]:
E (%) = [(Icorr − Icorr (c ))/ Icorr ]*100
(6)
Fig. 5. The Tafel curves of coated and uncoated Q235 steels.
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Fig. 6. (a) Nyquist plots of coated and uncoated Q235 steels; (b) Bode plots of coated and uncoated Q235 steels.
Table 4
Result of electrochemical corrosion measurement in 3.5% NaCl solution.
Sample
Ecorr (V)
Icorr (µA/cm2)
Corrosion rate (mm/year)
Protection efficiency E (%)
Bare metal
PSDF-Bz (10/0/0)
PSDF-Bz (0/10/0)
PSDF-Bz (0/0/10)
PSDF-Bz (4/6/0)
PSDF-Bz (3/6/1)
PSDF-Bz (2/6/2)
PSDF-Bz (1/6/3)
PSDF-Bz (0/6/4)
−0.573
−0.497
−0.371
−0.325
−0.291
−0.275
−0.189
−0.170
−0.278
11.600
6.472
1.899
1.304
0.807
0.131
0.089
0.030
0.275
5.298 * 10−2
2.956 * 10−2
8.733 * 10−3
5.954 * 10−3
3.689 * 10−3
5.984 * 10−5
4.097 * 10−5
1.402 * 10−5
1.255 * 10−4
–
44.21
83.63
88.96
93.04
98.87
99.23
99.74
97.63
Fig. 7. SEM images of (a) Bare steel (b) PSDF-Bz(0/10/0) (c) PSDF-Bz(3/6/1) (d) PSDF-Bz(1/6/3) (e) PSDF-Bz(0/6/4) before immersion and after 7 days immersion
(f), (g), (h), (i), (j).
increases, resulting in an increase in C (t ). The penetration of the
electrolyte solution into the coating will reach saturation after a certain
period of time, after which the coating capacitance (Cc) will no longer
increase significantly due to changes in the dielectric constant of the
coating [42]; however, as the electrolyte solution penetrates to the
interface of the coating/substrate and forms a corrosion-reactive microbattery in the interfacial zone, the measured impedance spectrum
will have two time constants. The time that the impedance spectrum
appears two time constants, while the surface of the coating do not yet
formed macroscopic pores, is called the mid-soaking period.
The evaluation of the performance of the coating by the EIS measurement in the middle of the immersion is extremely important because the results of the impedance measurements are extremely sensitive to a change in information on coating/substrate interface structure.
Furthermore, the Nyquist plots of uncoated mild steel Q235 were fitted
using an equivalent circuit of R(CR), as presented in Fig. 8a, and then
coated mild steel Q235 in the mid-soaking period of the immersion
and the highest corrosion resistance efficiency (E% = 99.74%).
3.8. Electrochemical impedance spectra characterization
Generally, electrochemical impedance spectra (EIS) and SEM
images (Fig. 7) of the morphology before and after corrosion are used to
further evaluate and compare the barrier and the anticorrosion ability
of composite coatings in a corrosive medium such as 3.5% NaCl solution [55,69]. The EIS results were fitted by Z view software based on
different equivalent circuit models to quantitatively assess the performance of these coatings.
The relationship between the dielectric constant, water absorption
and EIS results can be analyzed according to formula (3). During the
process of corrosion of a polymer-coated metal, we refer to the time
when the water does not reach the coating/substrate interface. As
shown in formula (3), at this stage, water molecules continuously enter
the coating, and the water absorption of the polymer coating ( XV %)
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Y. Zhang, et al.
Fig. 8. The proposed circuit model for (a) uncoated Q235 steel and (b) coated Q235 steels.
Table 5
Anticorrosion properties of Q235 and PSDF-Bz coatings.
Sample
Rs (Ω cm2)
Cc * 10−5 (F cm−2)
Rc (Ω cm2)
Cdl * 10−4 (F cm−2)
Rct (Ω cm2)
Q235
PSDF-Bz(10/0/0)
PSDF-Bz(0/10/0)
PSDF-Bz(0/0/10)
PSDF-Bz(4/6/0)
PSDF-Bz(3/6/1)
PSDF-Bz(2/6/2)
PSDF-Bz(1/6/3)
PSDF-Bz(0/6/4)
10.56
23.4
61.5
35.8
11.5
62.7
27.21
32.58
33.12
–
1.44
7.951
4.035
3.91
7.01
4.55
4.464
8.064
–
52.74
556.9
261.9
249
1431
4042
5315
3280
31.40
1.270
4.125
4.45
1.03
1.61
1.061
1.330
2.11
90.52
126.3
5251
9411
1118
13,000
13,570
13,800
11,330
were fitted using an equivalent circuit of R(CR)(CR), as presented in
Fig. 8b. In the second model, the electrolyte solution penetrates into the
coating/substrate interface through the microspores on the surface of
the coating and the foaming of the interface region is local, corresponding to the microspores.
Considering the equivalent circuit model proposed for PSDF-Bz
coatings, Rc (coating resistance) and Cc (coating capacitance) are related to electrolyte/coating interface; Rct and Cdl are also related to the
charge transfer reactions at the electrolyte/substrate interface [70]. The
corresponding parameters derived from the two models are summarized in Table 5. All electrochemical tests are averages of 10 samples
except extreme data.
As shown by Nyquist polt (Fig. 6), The PSDF-Bz(1/6/3) coated steel
sample shows the maximum diameter of the semicircle; the value of Rc
is found to be 5.315 Ω cm2. The value of Rct is the transfer resistance
between the electrolyte and the substrate. In general, the magnitude of
the Rct value reflects the difficulty of charge transfer in the metal matrix. The larger the value of Rct, the better the corrosion resistance of
the coating has. As shown in Table 5, the Rc value of the copolymerized
benzoxazine resin is 1–2 orders of magnitude higher than the coating
resistance of the homopolybenzoxazine resin. A similar phenomenon is
found in the Rct.
This phenomenon is attributed to the synergistic effect of each
component of the copolymer resin. The long alkyl chain in PSDF-Bz(10/
0/0) imparts excellent hydrophobicity to the coating and PSDF-Bz(0/
10/0) improves steady corrosion resistance. Furthermore, the low dielectric constant inherent with PSDF-Bz(0/0/10) and the high crosslink
density of the furan ring promotes cross-linking. From Table 4 and
Fig. 8, it can be seen that, with a decrease in the dielectric constant of
the copolymer, the interfacial polarization will decrease during electrochemical corrosion. Therefore, PSDF-Bz (1/6/3) displays the best
synergistic effects with a low dielectric constant, low water absorption,
high coating capacitance and coating resistance, which all result in the
best anticorrosion properties among the PSDF-Bz copolymers.
4. Conclusions
In this study, a novel low dielectric and fully bio-based benzoxazine
D-Bz was synthesized and copolymerized with S-Bz and F-Bz. It was
found that, when the ratio of S-Bz:D-Bz:F-Bz was 1:6:3, the copolymer
shows good synergistic effects. It is found that PSDF-Bz(1/6/3) has both
a low curing temperature (183 °C) and a high residual carbon ratio
(38%). Dielectric characterization, CA and water absorption tests show
that PSDF-Bz(1/6/3) has excellent dielectric stability (2.47 at 1000 Hz),
and low hydrophilicity (CA 97.5°) and water absorption (0.98%). In
conclusion, PSDF-Bz(1/6/3)’s electrochemical corrosion resistance tests
show excellent performance values, with corrosion protection efficiency
up to 99.73%.
Acknowledgements
This work was financially supported by the National Natural Science
Foundation of China (51573045, 51773060), the International
Collaboration Research Program of Science and Technology
Commission of Shanghai (16520722000), Shanghai Natural Science
Foundation
(16ZR1407700),
Shanghai
Rising-Star
Program
(17QB1401200), and Shanghai Aerospace Science and Technology
Innovation Fund (SAST2017-115).
Appendix A. Supplementary material
Supplementary data to this article can be found online at https://
doi.org/10.1016/j.eurpolymj.2019.07.020.
References
[1] A. Mohammadi, M. Barikani, A.H. Doctorsafaei, A.P. Isfahani, E. Shams, B. Ghalei,
Aqueous dispersion of polyurethane nanocomposites based on calix [4] arenes
modified graphene oxide nanosheets: Preparation, characterization, and anti-
484
European Polymer Journal 119 (2019) 477–486
Y. Zhang, et al.
amine-capped aniline trimer, Polym. Chem. 5 (14) (2014) 4235–4244.
[31] E.B. Caldona, A.C. Leon, B. Pajarito, B.B. Pajarito, R.C. Advincula, Novel anti-corrosion coatings from rubber-modified polybenzoxazine-based polyaniline composites, Appl. Surf. Sci. 422 (2017).
[32] M. Raicopol, B. Bălănucă, K. Sliozberg, B. Schluter, Vegetable oil-based polybenzoxazine derivatives coatings on Zn–Mg–Al alloy coated steel, Corros. Sci. 100
(2015) 386–395.
[33] S. Li, C.X. Zhao, Y. Wang, L. Hui, Y.T. Li, Synthesis and electrochemical properties
of electroactive aniline-dimer-based benzoxazines for advanced corrosion-resistant
coatings, J. Mater. Sci. 53 (10) (2018) 7344–7356.
[34] M. Poorteman, A. Renaud, J. Escobar, L. Dumas, P. Dubois, Thermal curing of paraphenylenediamine benzoxazine for barriercoating applications on 1050 aluminum
alloys, Prog. Org. Coat. 97 (2016) 99–109.
[35] A. Renaud, L. Bonnaud, L. Dumas, T. Zhang, P. Dubois, M.G. Olivier, A benzoxazine/substituted borazine composite coating: a new resin for improving the corrosion resistance of the pristine benzoxazine coating applied on aluminum, Eur.
Polym. J. 109 (2018) 460–472.
[36] J. Escobar, M. Poorteman, L. Dumas, L. Bonnaud, P. Dubois, Thermal curing study
of bisphenol a benzoxazine for barrier coatingapplications on 1050 aluminum alloy,
Prog. Org. Coat. 79 (2015) 53–61.
[37] M.L. Salum, D. Iguchi, C.R. Arza, L. Han, H. Ishida, Making benzoxazines greener:
design, synthesis, and polymerization of a bio-based benzoxazine fulfilling two
principles of green chemistry, ACS Sustain. Chem. Eng. J. 6 (2018) 13096–13106.
[38] D.W. Zhao, C. Chen, Q. Zhang, W.S. Chen, S.X. Liu, Q.W. Wang, High performance,
flexible, solid-state supercapacitors based on a renewable and biodegradable mesoporous cellulose membrane, Adv. Energy Mater. 7 (18) (2017) 1700739.
[39] F. Chen, Y.J. Zhu, Z.C. Xiong, T.W. Sun, Y.Q. Shen, Highly flexible superhydrophobic and fire-resistant layered inorganic paper, ACS Appl. Mater. Inter 8
(50) (2016) 34715–34724.
[40] X.Y. Liu, R.H. Zhang, T.Q. Li, P.F. Zhu, Q.X. Zhuang, Novel fully bio-based benzoxazines from rosin: synthesis and properties, ACS Sustain. Chem. Eng. J. 5 (11)
(2017).
[41] E. Cruz-Valeriano, D.E. Guzmán-Caballero, T. Escamilla-Díaz, A. Gutierrez-Peralta,
M. Davila, A. Torres-Ochoa, Dielectric constant measurement using atomic force
microscopy of dielectric films: a system theory approach, Appl. Phys. A. 124 (10)
(2018) 667.
[42] J. Zhang, C.N. Cao, Evaluation of organic coatings by electrochemical impedance
spectroscopy, Corros. Protec. 3 (1998) 99–104.
[43] P. Thirukumaran, R. Sathiyamoorthi, P. Shakila, A.S. Parveen, M. Sarojadevi, New
benzoxazines from renewable resources for green composite applications, Polym.
Compos. 37 (2) (2016) 573–582.
[44] R. Thirukumaran, P. Sathiyamoorthi, A.S. Shakila, M. Parveen, Synthesis and copolymerization of fully biobased benzoxazines from renewable resources, ACS
Sustain. Chem. Eng. 2 (12) (2014).
[45] F. Kasapoglu, I. Cianga, Y. Yagci, T. Takeichi, Photoinitiated cationic polymerization of monofunctional benzoxazine, J. Polym. Sci. Pol. Chem. 41 (2003)
3320–3328.
[46] H. Ishida, S. Ohba, Synthesis and characterization of maleimide and norbornene
functionalized benzoxazines, Polymer 46 (15) (2005) 5588–5595.
[47] N.K. Sini, J. Bijwe, I.K. Varma, Renewable benzoxazine monomer from vanillin:
synthesis, characterization, and studies on curing behavior, J. Polym. Sci. Pol.
Chem. 52 (1) (2014) 7–11.
[48] X.B. Shen, L.J. Cao, Y. Liu, J.Y. Dai, X.Q. Liu, S.Y. Du, How does the hydrogen
bonding interaction influence the properties of polybenzoxazine? An experimental
study combined with computer simulation, Macros. 51 (2018) 4782–4799.
[49] M. Barde, K. Avery, C.W. Edmunds, N. Labbe, M.L. Auad, Cross-Linked acrylic
polymers from the aqueous phase of biomass pyrolysis oil and acrylated epoxidized
soybean oil, ACS Sustain. Chem. Eng. 7 (2019) 2216–2224.
[50] J.Y. Dai, N. Teng, X.B. Shen, Y. Liu, L.J. Cao, J. Zhu, X.Q. Liu, Synthesis of biobased
benzoxazines suitable for vacuum-assisted resin transfer molding process via introduction of soft silicon segment, Ind. Eng. Chem. 57 (2018) 3091–3102.
[51] J. Leonhardt, P. Hugo, Comparison of thermokinetic data obtained by isothermal,
isoperibolic, adiabatic and temperature programmed measurements, J. Therm.
Anal. Calorim. 49 (3) (1997) 1535–1551.
[52] P. Prabunathan, P. Thennarasu, J.K. Song, M. Alagar, Achieving low dielectric,
surface free energy and UV shielding green nanocomposites via reinforcing biosilica aerogel with polybenzoxazine, New J. Chem. 41 (13) (2017).
[53] Y.F. Chen, B.T. Wang, F.L. Li, C.J. Teng, Micro-structure, mechanical properties and
dielectric properties of bisphenol a allyl compound-bismaleimide modified by
super-critical silica and polyethersulfone composite, J. Electron. Mater. 46 (7)
(2017) 4656–4661.
[54] T. Kao, J. Chen, C. Cheng, C.I. Sue, F.C. Chang, Low-surface-free-energy polybenzoxazine/polyacrylonitrile fibers for biononfouling membrane, Polymer 54 (1)
(2013) 258–268.
[55] E. Caldona, A.C. De, B.B. Pajarito, R.C. Advincula, Novel anti-corrosion coatings
from rubber-modified polybenzoxazine-based polyaniline composites, Appl. Surf.
Sci. 422 (2017).
[56] G.S. Lai, W.J. Lau, P.S. Goh, A.F. Ismail, Y.H. Tan, C.Y. Chong, R. Krause-Rehberg,
S. Awad, Tailor-made thin film nanocomposite membrane incorporated with graphene oxide using novel interfacial polymerization technique for enhanced water
separation, Chem. Eng. J. 344 (2018).
[57] Y.Q. Zhan, J.M. Zhang, X.Y. Wan, Z.H. Long, S.J. He, Y. He, Epoxy composites
coating with Fe3O4, decorated graphene oxide: Modified bio-inspired surface
chemistry, synergistic effect and improved anti-corrosion performance, Appl. Surf.
Sci. 436 (2018) 756–767.
[58] Z. Wang, Q.C. Ran, R.Q. Zhu, Y. Gu, Curing behaviors and thermal properties of
corrosion properties, Chem. Eng. J. 349 (2018) 466–480.
[2] A. Seongpil, W.L. Min, L.Y. Alexander, S.Y. Sam, A review on corrosion-protective
extrinsic self-healing: comparison of microcapsule-based systems and those based
on core-shell vascular networks, Chem. Eng. J. 344 (2018) 206–220.
[3] G.S. Morteza, S. Mohammadreza, R. Bahram, Fabricating an epoxy composite
coating with enhanced corrosion resistance through impregnation of functionalized
graphene oxide-co-montmorillonite nanoplateletp, Corros. Sci. 129 (2017) 38–53.
[4] Y.Y. Qian, Y.X. Li, S. Jungwirth, N. Seely, Y. Fang, X.M. Shi, The application of anticorrosion coating for preserving the value of equipment asset in chloride-laden
environments: a review, Int. J. Electrochem. Sci. 10 (2015) 10756–10780.
[5] F. Khelife, S. Ershov, M. Druart, Y. Habibi, D. Chicot, A multilayer coating with
optimized properties for corrosion protection of Al, J. Mater. Chem. 3 (2015)
15977.
[6] A. Renaud, M. Poorteman, J. Escobar, L. Dumas, Y. Paint, P. Dubois, M.G. Olivier, A
new corrosion protection approach for aeronautical applications combining a
Phenol-paraPhenyleneDiAmine benzoxazine resin applied on sulfo-tartaric anodized aluminum, Prog. Org. Coat 112 (2017) 278–287.
[7] B. Nikravesh, B. Ramezanzadeh, A.A. Sarabi, S.M. Kasiriha, Evaluation of the corrosion resistance of an epoxy-polyamide coating containing different ratios of micaceous iron oxide/Al pigments, Corros. Sci. 53 (4) (2011) 1592–1603.
[8] S.S. Jia, X.H. Lu, S. Luo, Y. Qing, N. Yan, Y.Q. Wu, Efficiently texturing hierarchical
epoxy layer for smart superhydrophobic surfaces with excellent durability and exceptional stability exposed to fire, Chem. Eng. J. 348 (2018) 212–223.
[9] Z.J. Thompson, M.A. Hillmyer, J. Liu, H.J. Sue, M. Dettloff, F.S. Bates, Block copolymer toughened epoxy: role of cross-link density, Macros 42 (7) (2009)
2333–2335.
[10] B. Ramezanzadeh, G. Bahlakeh, M. Ramezanzadeh, Polyaniline-cerium oxide (PAniCeO2) coated graphene oxide for enhancement of epoxy coating corrosion protection performance on mild steel, Corros. Sci. 137 (2018) 111–126.
[11] B. Grgur, M. Gvozdenović, V. Mišković-Stanković, Corrosion behavior and thermal
stability of electrodeposited PANI/epoxy coating system on mild steel in sodium
chloride solution, Prog. Org. Coat. 56 (2) (2006) 214–219.
[12] C.L. Zhou, J.P. Lin, X. Lu, Z. Xin, Enhanced corrosion resistance of polybenzoxazine
coatings by epoxy incorporation, RSC Adv. 6 (34) (2016) 28428–28434.
[13] P. Campaner, D. D'Amico, L. Longo, C. Stifani, A. Tarzia, Cardanol-based novolac
resins as curing agents of epoxy resins, J. Appl. Polym. Sci. 114 (6) (2010)
3585–3591.
[14] S.W. Choi, S. Ohba, Z. Brunovska, K. Hemvichian, H. Ishida, Synthesis, characterization and thermal degradation of functional benzoxazine monomers and polymers
containing phenylphosphine oxide, Polym. Degrad. Stabil. 91 (5) (2006)
1166–1178.
[15] F.W. Holly, A.C. Cope, Condensation products of aldehydes and ketones with oaminobenzyl alcohol and o-hydroxybenzylamine, J. Am. Chem. Soc. 66 (11) (1944)
1875–1879.
[16] G.A. Phalak, D.M. Patil, S.T. Mhaske, Synthesis and characterization of thermally
curable Guaiacol based poly (benzoxazine –urethane) coating for corrosion protection on mild steel, Eur. Polym. J. 88 (2016).
[17] H. Ishida, D.J. Allen, Physical and mechanical characterization of near-zero
shrinkage polybenzoxazines, J. Polym. Sci. Pol. Phys. 34 (6) (2015) 1019–1030.
[18] A.Q. Dayo, B.C. Gao, J. Wang, W.B. Liu, M. Derradji, A.H. Shah, A.A. Babar, Natural
hemp fiber reinforced polybenzoxazine composites: curing behavior, mechanical
and thermal properties, Compos. Sci. Technol. 144 (2017).
[19] H.G. Dong, X. Zhong, X. Lu, Y. Lv, Effect of N-substituents on the surface characteristics and hydrogen bonding network of polybenzoxazines, Polymer 52 (4)
(2011) 1092–1101.
[20] A.H. Telli, J. Hacaloglu, Effects of aromatic diboronic acid on thermal charateristics
of polybenzoxazines based on phenol and aniline, Eur. Polym. J. 108 (2018)
182–190.
[21] L. Jin, T. Agag, H. Ishida, Bis(benzoxazine-maleimide)s as a novel class of high
performance resin: synthesis and properties, Eur. Polym. J 46 (2) (2010) 354–363.
[22] S. Saiev, L. Bonnaud, P. Dubois, D. Beljonne, R. Lazzaroni, Modeling the formation
and thermomechanical properties of polybenzoxazine thermosets, Polym. Chem. 8
(2017) 5988.
[23] K. Zhang, Q. Zhuang, X. Liu, G. Yang, R. Cai, Z. Han, A new benzoxazine containing
benzoxazole-functionalized polyhedral oligomeric silsesquioxane and the corresponding polybenzoxazine nanocomposites, Macros 46 (7) (2013) 2696–2704.
[24] K. Zhang, Z. Shang, C.J. Evans, L. Han, H. Ishida, S. Yang, Benzoxazine atropisomers: intrinsic atropisomerization mechanism and conversion to high performance thermosets, Macros 51 (19) (2017) 7574–7585.
[25] S. Saiev, L. Bonnaud, L. Dumas, T. Zhang, P. Dubois, D. Beljonne, Do carbon nanotubes improve the thermomechanical properties of benzoxazine thermosets? ACS
Appl. Mater. Interfaces 10 (2018) 26669–26677.
[26] A. Trejo-Machin, P. Verge, L. Puchot, R. Quintana, Phloretic acid as an alternative
to the phenolation of aliphatic hydroxyls for the elaboration of polybenzoxazine,
Green. Chem 19 (2017) 5065.
[27] L. Puchot, P. Verge, S. Peralta, Y. Habibi, C. Vancaeyzeele, Elaboration of bioepoxy/benzoxazine interpenetrating polymer networks: a composition-to-morphology mapping, Polym. Chem. 9 (2018) 472.
[28] R.V. Lloyd, R. Jessica, H. Ishada, L. Diego, Development of fully biobased highperformance bis-benzoxazine under environmentally friendly conditions, ACS
Sustain. Chem. Eng. 6 (2018) 5485–5494.
[29] C. Aydogan, B. Kiskan, S. Hacioglu, L. Toppare, Y. Yagci, Electrochemical manipulation of adhesion strength of polybenzoxazines on metal surfaces: from strong
adhesion to dismantling, Rsc. Adv. 4 (52) (2014) 27545–27551.
[30] S.C. Lin, C.S. Wu, J. Yeh, Y.L. Liu, Reaction mechanism and synergistic anticorrosion property of reactive blends of maleimide-containing benzoxazine and
485
European Polymer Journal 119 (2019) 477–486
Y. Zhang, et al.
Res. 13 (1) (2016) 63–72.
[65] H. Wei, D.W. Ding, S. Wei, Z.H. Guo, Anticorrosive conductive polyurethane multiwalled carbon nanotube nanocomposites, J. Mater. Chem. 1 (36) (2013)
10805–10813.
[66] S.A. Haddadi, S.A.A. Ramazani, M. Mahdavian, P. Taheri, J.M.C. Mol, Fabrication
and characterization of graphene-based carbon hollow spheres for encapsulation of
organic corrosion inhibitors, Chem. Eng. J. 352 (2018) 909–922.
[67] D. Prasai, J.C. Tuberquia, R.R. Harl, K. Jennings, Graphene: corrosion-inhibiting
coating, ACS Nano 6 (2) (2012) 1102–1108.
[68] D.M. Patil, G.A. Phalak, S.T. Mhaske, Enhancement of anti-corrosive performances
of cardanol based amine functional benzoxazine resin by copolymerizing with
epoxy resins, Prog. Org. Coat. 105 (2017) 18–28.
[69] Y.W. Ye, Z.Y. Liu, W. Liu, D.W. Zhang, H.C. Zhao, L.P. Wang, X.G. Li,
Superhydrophobic oligoaniline-containing electroactive silica coating as pre-process coating for corrosion protection of carbon steel, Chem. Eng. J. 348 (2018)
940–951.
[70] M.T. Mo, W.J. Zhao, Z.F. Chen, E.Y. Liu, Q.J. Xue, Corrosion inhibition of functional
graphene reinforced polyurethane nanocomposite coatings with regular texture,
RSC Adv. 6 (10) (2016) 7780–7790.
benzoxazine and N, N′-(2, 2, 4-trimethylhexane-1, 6-diyl) dimaleimide blend, J.
Appl. Polym. Sci. 129 (3) (2013) 1124–1130.
[59] Y. Liu, Z. Yue, J. Gao, Synthesis, characterization, and thermally activated polymerization behavior of bisphenol-S/aniline based benzoxazine, Polymer 51 (16)
(2010) 3722–3729.
[60] J.Y. Dai, N. Teng, X.B. Shen, Y. Liu, L.J. Cao, X.Q. Liu, Synthesis of bio-based
benzoxazines suitable for vacuum assisted resin transfer molding (RTM) process via
introduction of soft silicon segment, Ind. Eng. Chem. Res. 57 (8) (2018).
[61] M.H. Wang, Q.H. Li, X.G. Li, Y.C. Liu, L.Z. Fan, Effect of oxygen-containing functional groups in epoxy/reduced graphene oxide composite coatings on corrosion
protection and antimicrobial properties, Appl. Surf. Sci. 448 (2018) 351–361.
[62] H. Vakili, B. Ramezanzadeh, R. Amini, R. Amini, The corrosion performance and
adhesion properties of the epoxy coating applied on the steel substrates treated by
cerium-based conversion coatings, Corros. Sci. 94 (2015) 466–475.
[63] K.C. Chang, W.F. Ji, M.C. Lai, Y.R. Hsiao, C.H. Hsu, T.L. Chuang, Correction: synergistic effects of hydrophobicity and gas barrier properties on the anticorrosion
property of PMMA nanocomposite coatings embedded with graphene nanosheets,
Polym. Chem. 5 (23) (2014) 6865-6865.
[64] C.L. Zhou, X. Lu, Z. Xin, Y.F. Zhang, Intercalated polybenzoxazine/organoclay
composites with enhanced performance in corrosion resistance, J. Coat. Technol.
486