Thermal property of an aggregation-induced emission fluorophore that forms metal-ligand complexes with Zn(ClO4)2 of salicylaldehyde azine-functionalized polybenzoxazine

Article abstract of DOI:10.1039/c5ra09409g

In this report, we designed a new and simple salicylaldehyde azine-functionalized benzoxazine (azine-BZ) monomer via Mannich condensation reaction of aniline and paraformaldehyde with 1,2-bis(2,4-dihydroxybenzylidene)hydrazine in 1,4-dioxane. Compared wit

Full text of DOI:10.1039/c5ra09409g

View Article Online
View Journal
RSC Advances
This article can be cited before page numbers have been issued, to do this please use: M. G. Mohamed,
R. Lin, J. Tu, F. Lu, J. Hong, K. Jeong, C. Wang and S. Kuo, RSC Adv., 2015, DOI: 10.1039/C5RA09409G.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. This Accepted Manuscript will be replaced by the edited,
formatted and paginated article as soon as this is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/advances

Page 1 of 11
ARTICLE TYPE
CREATED USING THE RSC ARTICLE TEMPLRATSE (CVERA. d3.1v)a- SnEcEeWsWW.RSC.ORG/ELECTRONICFILES FOR DETAILS
View Article Online
DOI: 10.1039/C5RA09409G
www.rsc.org/xxxxxx | XXXXXXXX
Thermal Property and AggregationꢀInduced Emission Fluorophore That Forms Metal–Ligand
Complexes with Zn(ClO4)2 of Salicylaldehyde Azine–Functionalized Polybenzoxazine
Mohamed Gamal Mohamed,a RueyꢀChorng Lin,a JiaꢀHuei Tu,a FangꢀHsien Lu,a JinꢀLong
5
Hong,a KwangꢀUn Jeong,c ChihꢀFeng Wang,d and ShiaoꢀWei Kuoa,b,
*
Received (in XXX, XXX) Xth XXXXXXXXX 200X, Accepted Xth XXXXXXXXX 200X
First published on the web Xth XXXXXXXXX 200X
DOI: 10.1039/b000000x
In this report, we designed a new and simple salicylaldehyde azine–functionalized benzoxazine (AzineꢀBZ) monomer via Mannich
10 condensation reaction of aniline and paraformaldehyde with 1,2ꢀbis(2,4ꢀdihydroxybenzylidene)hydrazine in 1,4ꢀdioxane. Compared with
3ꢀphenylꢀ3,4ꢀdihydroꢀ2Hꢀbenzooxazine monomer (263 °C), the maximum exothermic peak of AzineꢀBZ was shifted to a lower
temperature (213 °C) based on differential scanning calorimetry (DSC) analyses because of the basicity of the phenolic group (OH) in
the ortho position and the azine groups. Blending AzineꢀBZ with different weight ratios of zinc perchlorate [Zn(ClO4)2] to form
benzoxazine/zinc ion complexes not only afflicted the thermal properties based on thermogravimetric analysis (TGA) due to physical
15 crosslinking through metal–ligand interactions, but also expedite ringꢀopening polymerization, decreasing the curing temperature from
213 to 184 °C (at 10 wt% Zn2+). Based on the fluorescence results, the AzineꢀBZ and AZineꢀBZ/Zn(ClO4)2 complexes were nonꢀ
emissive in THF solution. Their fluorescence increased gradually upon on the addition of water contents as poor solvent. Interestingly,
both the pure AzineꢀBZ and blending wotj Zn(ClO4)2 still emitted light after thermal curing at 150 °C, as determined through
photoluminescence measurements, indicating that the azine group could act as a probe of the curing behavior of the benzoxazine
20 monomer, as well as a fluorescent chemosensor for Zn2+ and, possibly, other transition metal ions through a metal–ligand charge transfer
mechanism.
Introduction
Benzoxazine monomer is a molecule where it contains on
25 an oxazine ring (a heterocyclic sixꢀmembered ring with oxygen
and nitrogen atoms) is connected to a benzene ring. The last
60 (e.g., propargyl, nitrile, alkyl, carboxyl, hydroxyalkyl) have
been synthesized.17ꢀ20 Two types of BZꢀbased composites have
been developed: fiberꢀreinforced PBZ composites and
inorganic particle–reinforced PBZ composites (e.g., silica,
TiO2, magnetic nanoparticles).21
few decades, polybenzoxazine (PBZs) is
a
class of
thermosetting resins which have been attracted widely due to
their specific potential applications as phenolic resins
30 materials.1ꢀ3 Polybenzoxazines (PBZs) produces from the
thermal curing of oxazine ring in benzoxazine monomer
without any catalyst, affording to highly dense crossꢀlinked
network materials with strongly intra and intermolecular
hydrogen bonding between phenolic groups and tertiary amine
35 in Mannich linkage after ringꢀopening polymerization.4 Many
literatures reported that the potential applications of
polybenzoxazines in industrial field, due to their unique
characteristics such as, flame resistance, low surface energies,
high thermal and mechanical stabilities, and low water
40 adsorption.5,6
BZs are versatile thermoset resins synthesized through
Mannich condensation between an aromatic phenol, a primary
amine, and formaldehyde.7ꢀ12 Nowadays, these phenolic resins
can be used as thermoset to prepare polymer nanocomposites
45 due to their unique excellent thermal properties.13ꢀ16 The
polybenozoxazine chemistry offers flexibility of many
molecular designs, thereby facilitating the preparation of
different PBZ nanocomposites. To control the properties of
PBZs, several derivatives functionalized with reactive groups
65
Most fluorescing materials weaken the emissive
properties, when they aggregated in a poor solvent or in the
solid state. This phenomenon, known as aggregationꢀcaused
quenching (ACQ),22,23 greatly decreased the applicability of
such materials as organic lightꢀemitting materials or fluorescent
70 chemosensors.24ꢀ26 At the beginning of this century, Tang et al.
reported that many materials can be emitted light when
dispersed in a poor solvent or fabricated into film in nanoꢀ
aggregate state, these interesting phenomenon, namely as
aggregationꢀinduced emission (AIE) or aggregationꢀinduced
75 enhanced emission (AIEE).27ꢀ28 AIE fluorescent materials
become very strongly emissive in aggregate or solid state, but
become very strongly emitters when aggregated as powders or
nanoꢀaggregates. There are many mechanisms behind AIE
include restricted intramolecular rotation (RIR),29,30 twisting
80 intramolecular charge transfer (TICT)31 and planarity and
rotation ability.32 Tang et al. also reported that a series of
salicylaldehyde azine derivatives exhibited AIE characteristics
in good solvents, but displayed very weak emissions while
being strongly luminescent in poor solvents.33 Several
85 fluorescent chemosensors reported have been designed based
on the mechanisms of photoinduced electron transfer (PET)34,
fluorescence resonance intramolecular charge transfer
(FRICT)35, and metal–ligand charge transfer (MLCT)36,
respectively. Tain et al. reported that Schiff base–modified
90 triphenylaminobenzimidazole and pyridinecarboxaldehyde
derivatives displaying AIEE characteristics acted as
chemosensors for Cu(II) and Zn(II) ions.37
50 aDepartment of Materials and Optoelectronic Science,
Centerfor Functional Polymers and Supramolecular Materials,
National Sun YatꢀSen University, Kaohsiung, Taiwan
Eꢀmail: kuosw@faculty.nsysu.edu.tw
bDepartment of Medicinal and Applied Chemistry, Kaohsiung
55 Medical University, Kaohsiung, Taiwan.
cDepartment of PolymerꢀNano Science and Technology,
Chonbuk National University, Jeonju, Korea
As a result, in this article we synthesized a new BZ
monomer containing a salicylaldehyde azine unit (AzineꢀBZ)
dDepartment of Materials Science and Engineering, IꢀShou
University, Kaohsiung, Taiwan
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 | 1

RSC Advances
Page 2 of 11
View Article Online
CREATED USING THE RSC ARTICLE TEMPLATE (VER. 3.0) - SEE WWW.RSC.ORG/ELECTRONICFILES FOR DETAILS
DOI: 10.1039/C5RA09409G
www.rsc.org/xxxxxx | XXXXXXXX
ARTICLE TYPE
Scheme 1: Synthesis and chemical structures of (a) 2,4ꢀdihydroxybenzaldehyde, (b) CN4OH, (c) AzineꢀBZ, (d, e) poly(AzineꢀBZ), and
(f) the poly(AzineꢀBZ)/Zn(ClO4)2 complex.
5
through facile and simple Mannich condensation reaction of
1,2ꢀbis(2,4ꢀdihydroxybenzylidene)hydrazine (CN4OH),
paraformaldehyde, and aniline in the presence 1,4ꢀdioxane as
good solvent (Scheme 1). We also studied the thermal curing
polymerization, thermal stabilities, the absorption and emission
stirring overnight at room temperature, the precipitate was
filtered off and washed three times with EtOH. The yellow
powder was recrystallized from a small amount of THF,
40 affording yellow crystals (8.50 g, 86%); FTIR (KBr, cm–1):
3200–3400 (OH stretching). 1H NMR (500 MHz, DMSOꢀd6, δ,
ppm): 11.94 (s, 1H, OHa), 10.10 (s, 1H, OHb), 8.75 (d, 2H, Hc),
7.36 (t, 2H, Hd), 7.04 (d, 1H, He), 6.96 (t, 1H, Hf). 13C NMR
(125 MHz, DMSOꢀd6, δ, ppm): 162.9, 162.6, 161.5, 133.6,
45 110.8, 110.8, 108.8, 103.1. High resolution FTꢀMS (m/z) for
MH+ (C14H12N2O4): 273.09: calc.: 272.08 (Figure S2).
10 behavior, specific metalꢀligand interaction when AzineꢀBZ
blended with various weight ratios of zinc perchlorate
[Zn(ClO4)2], before and after thermal curing via chelation
complexes by using differential scanning calorimetry (DSC),
Fourier
transform
infrared
analysis
(FTIR)
(TGA),
spectroscopy,
UVꢀVis and
15 thermogravimetric
photoluminescence (PL) spectroscopy. In addition, we used
transmission electron microscopy (TEM) and dynamic light
scattering (DLS) to characterize the selfꢀassembled nanoꢀ
aggregates morphology which formed from the AzineꢀBZ
20 monomer in THF/water solvent pairs.
Synthesis of AzineꢀBZ39
50 mL of 1,4ꢀdioxane/ethanol, paraformaldehyde (0.882 g, 29.4
50 mmol), 1,2ꢀbis(2,4ꢀdihydroxybenzylidene)hydrazine CN4OH
(2.00 g, 7.35 mmol), and aniline (1.37 g, 14.7 mmol) were
mixed in a 150ꢀmL twoꢀneck roundꢀbottom flask under a N2
atmosphere with a reflux condenser. The reaction solution was
heated under reflux for 18 h at 90–110 °C. After that, cooling
55 the reaction mixture to room temperature, the solvent was
evaporated under reduced pressure to give a yellow solid,
which was purified through column chromatography (SiO2;
EtOAc) to give a yellow solid (3.21 g, 87%). FTIR (KBr, cm–
1): 3300–3200 (OH stretching), 931 and 1488 (vibrations of
60 trisubstituted benzene ring). 1H NMR (500 MHz, CDCl3, δ,
ppm): 11.93 (s, 1H, Ha), 8.71 (s, 1H, Hb), 4.70 (s, 2H, ArꢀCH2ꢀ
N), 5.33 (s, 2H, OꢀCH2ꢀN), 6.92–8.43 (m, CH aromatic). 13C
NMR (125 MHz, CDCl3, δ, ppm): 45.93 (CCH2N), 80.04
(OCH2N). High resolution FTꢀMS (m/z) for MH+
65 (C14H12N2O4): 507.20: calc.: 506.20 (Figure S3).
Experimental Section
Materials
Paraformaldehyde (96%), aniline, 2,4ꢀDihydroxybenzaldehyde
25 were used as received from Acros. Ethyl acetate (EA),
hydrazine monohydrate (98%), chloroform, dichloromethane,
ethanol, tetrahydrofuran (THF), and 1,4ꢀdioxane were used as
received from Scharlau. Zinc perchlorate hexahydrate
[Zn(ClO4)2·6H2O] was purchased from Aldrich and dried
30 overnight in a vacuum oven at 70 °C to remove water.
Bis(2,4ꢀdihydroxybenzylidene)hydrazine (CN4OH)33,38
Under a N2 atmosphere in a 150ꢀmL twoꢀneck roundꢀbottom
flask equipped with a stirrer bar, hydrazine monohydrate (0.900
35 g, 18.1 mmol), 2,4ꢀdihydroxybenzaldehyde (5.00 g, 36.2
mmol) were dissolved in absolute EtOH (100 mL) After
2
| Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]

Page 3 of 11
ARTICLE TYPE
CREATED USING THE RSC ARTICLE TEMPLRATSE (CVERA. d3.1v)a- SnEcEeWsWW.RSC.ORG/ELECTRONICFILES FOR DETAILS
View Article Online
DOI: 10.1039/C5RA09409G
www.rsc.org/xxxxxx | XXXXXXXX
collected at a spectral resolution of 4 cm–1. Differential
35 scanning calorimeter (DSC) measurements were conducted
with TA Qꢀ20 with operated under a N2 as purge gas (50
mL/min) at heating rate of 20 oC/min. The sample (ca. 3ꢀ5 mg)
was placed in a sealed aluminum sample pan. Dynamic curing
scans were recorded from 30 to 350 °C at a heating rate of 20
40 °C min–1. The thermal stabilities of the samples were measured
using a TA Qꢀ50 thermogravimetric analyzer operated under a
N2 as purge gas (60 mL/min) at heating rate of 20 oC/min from
30 to 800 °C under UV–Vis spectra were recorded using a
Shimadzu mini 1240 spectrophotometer; the concentration of
45 AzineꢀBZ in THF was 10–4 M. Photoluminescence spectra was
collected at room temperature using a monochromatized Xe
light source. Particle sizes of the aggregates in solution were
measured by DLS using a Brookhaven 90 plus spectrometer
equipped with a temperature controller. Argon into laser
50 operating at 658 nm was used as the light source. TEM images
were recorded using a JEOLꢀ2100 transmission electron
microscope operated at an accelerating voltage of 200 kV. The
molecular weights of CN4OH and AzineꢀBZ were recorded
using a Bruker Solarix high resolution Fourier Transform Mass
55 spectroscopy system FTꢀMS (Bruker, Bremen, Germany).
b
H2O
d-DMSO
a
c
c
a
b
e,f
e
f
d
d
g
f
a
g
c
c
Aromatic
1,4-dioxane
H2O
a
f
14
12
10
8
6
4
2
0
Chemical shift (ppm)
Figure 1: 1H NMR spectra of (a) CN4OH and (b) AzineꢀBZ
a
f
e
DMSO-d6
a
d
c
b
b
e
f
d
c
a
Results and Discussion
Synthesis and Characterization of CN4OH and AzineꢀBZ
Scheme 1 displays our synthesis of the salicyaldehyde azine–
60 functionalized BZ monomer (AzineꢀBZ). First, we employed a
Schiff base condensation of 2,4ꢀdihydroxybenzaldehyde with
hydrazine monohydrate in EtOH to obtain CN4OH; we then
prepared AzineꢀBZ with high purity more than 95% in through
CDCl3
c
a
d
b
Aromatic
a
Mannich
condensation
reaction
of
CN4OH,
f
o
e
a
f
65 paraformaldehyde, and aniline in 1,4ꢀdioxane at 80ꢀ90 C. We
carefully confirmed the chemical structures of CN4OH and
AzineꢀBZ via 1H NMR, 13C NMR, and FTIR spectroscopy.
Figure 1 illustrated the 1H NMR spectra of CN4OH and Azineꢀ
BZ. The spectrum of CN4OH [Figure 1(a)] features signals at
70 10.10 and 11.94 ppm, representing the OH groups of the
phenolic units, as well as signals in the range 6.33–7.40 ppm
for the aromatic protons and at 8.69 ppm for the N=CH groups.
The spectrum of the AIE unit (azine)–based BZ monomer
[Figure 1(b)] lacked the peak at 10.10 ppm for the OHb proton
75 of CN4OH, but featured peaks at 6.36–7.26 ppm for the
aromatic protons and resonances at 4.70 (ArCH2N) and 5.33
(OCH2N) ppm at a 1:1 ratio; no signal was present near 4.0
ppm, corresponding to an NCH2Ph unit, as a result of ring
opening of the BZ moiety; no other major peaks were evident
80 in the 1H NMR spectrum, indicating that AzineꢀBZ had
successfully formed. Figure 2 presents the 13C NMR spectra of
CN4OH and AzineꢀBZ. The spectrum of CN4OH [Figure 2(a)]
features signals for the carbon nuclei in the aromatic rings and
double bonds in the range 103.77–163.27 ppm. The spectrum
85 of AzineꢀBZ [Figure 2(b)] displays characteristic resonances
for the ArCH2N and OCH2N units of the oxazine ring at 45.93
and 80.05 ppm, respectively. Figure S1 presents the FTIR
spectra of CN4OH and AzineꢀBZ, recorded at room
temperature. The spectrum of CN4OH [Figure S1(a)] features
90 three sharp peaks at 3217, 3481, and 3522 cm–1 for the intra
and intermolecular hydrogenꢀbonded and free OH groups, and
sharp signals for the aromatic rings at 831, 1599, 1619, and
3033 cm–1. The spectrum of AzineꢀBZ [Figure S1(b)] features
characteristic absorption bands at 1366 (tetrasubstituted
95 benzene ring), 1225 (asymmetric COC stretching), 1042
(symmetric COC stretching), and 931 (stretching vibrations of
oxazine ring) cm–1.
b
c
d
e
180
160
140
120
100
80
60
40
20
0
Chemical Shift (ppm)
5
Figure 2: 13C NMR spectra of (a) CN4OH and (b) AzineꢀBZ
Poly(AzineꢀBZ)/Zinc Complexes
Zn(ClO4)2 (1, 2, 3, 4, 5, or 10 wt%) was dissolved in 5 mL of
10 THF 1 h. Then, Zn(ClO4)2 solutions were added dropwise to
AzineꢀBz solutions. After that, the AzineꢀBz/Zn(ClO4)2
complexes solutions were stirred for 2 days, the removal of
solvent under reduced pressure. Each blended mixture was
poured into a stainlessꢀ mold and polymerized in a stepwise
15 manner, with heating at 110, 150, 180, 210, and 240 °C for 2 h
at each temperature. The color of each cured sample was dark
red.
Nanoaggregates of AzineꢀBZ and AzineꢀBZ/Zinc
20 Complexes
Stock solutions of AzineꢀBZ and AzineꢀBZ/Zinc were prepared
in THF at 100ꢀmL volumetric flask with concentrations of 1 ×
10ꢀ4 M. Then, water (poor solvent) was added dropwise under
vigorous stirring to prepare different volume ratios (0–90%)
25 was reached. PL spectra of the suspension of nanoꢀaggregates
were recorded immediately.
Characterization
Nuclear magnetic resonance (1H and 13C NMR) spectra were
30 recorded on an INOVA 500 by using DMSOꢀd6 and CDCl3 as
solvents. Fourier transform infrared (FTIR) spectra of the KBr
disks of CN4OH and AzineꢀBZ were measured by a Bruker
Tensor 27 FTIR spectrophotometer and thirtyꢀtwo scans were
3

RSC Advances
Page 4 of 11
View Article Online
CREATED USING THE RSC ARTICLE TEMPLATE (VER. 3.0) - SEE WWW.RSC.ORG/ELECTRONICFILES FOR DETAILS
DOI: 10.1039/C5RA09409G
www.rsc.org/xxxxxx | XXXXXXXX
ARTICLE TYPE
400
Azine-BZ (10-4 M)
THF/H2O
CN4-OH (10-4 M)
THF/H2O
(A)
(B)
3500
100/0
80/20
60/40
50/50
40/60
30/70
100/0
70/30
40/60
20/80
10/90
350
300
250
200
150
100
50
3000
20/80
10/90
2500
(C)
2000
1500
1000
500
0
0
400
500
600
700
400
500
600
700
Wavelength (nm)
Figure 3: (A, B) PL spectral changes of (A) CN4OH and (B) AzineꢀBZ (1.0 × 10–4 mol L–1) and (C) PL intensity of AzineꢀBZ in
THF/water mixtures at various water fractions.
High resolution FTꢀMS displayed the exactly molecular
weights of CN4OH and AzineꢀBZ, respectively (supporting
information Figure S2 and S3). Combined these spectral data
are consistent with the successful synthesis of a new AzineꢀBZ
15 monomer.
Optical Properties and AIE of CN4OH and AzineꢀBZ
The UV–Vis absorption spectrum of AzineꢀBZ monomer in
THF (1 × 10–4 M) features (Figure S4) an absorption peak at
20 370 nm that we attribute to the π–π* transition of the
salicylaldehyde azine unit. Most reported salicylaldehyde azine
are fluorescent AIE materials and it can emit different light in
their aggregated states, presumably because of RIR and
excited state intramolecular proton transfer [ESIPT].33,38 We
25 investigated the AIE phenomena of CN4OH and AzineꢀBZ in
THF/H2O mixtures at water contents in the range 0–90%.
CN4OH and AzineꢀBZ are both soluble in common organic
solvents (THF, DMSO, DMF), but insoluble in water and
hexane. As expected, solutions of CN4OH and AzineꢀBZ in
30 THF are virtually nonꢀluminescent, as determined from their
fluorescence spectra [Figures 3(A) and 3(B)]. The fluorescence
intensities increased gradually, however, when the water
content was greater than 80% for CN4OH and 90% for Azineꢀ
BZ [Figure 3(C)], with the emissions of CN4OH and AzineꢀBZ
35 turning on and displaying green fluorescence. These emissions
from CN4OH and AzineꢀBZ were presumably induced through
aggregate formation, suggesting that both CN4OH and Azineꢀ
BZ exhibit AIE. In addition, we found that AzineꢀBZ could
5
Figure 4: (a) Particle size distributions of AzineꢀBZ in
form nanoparticles in solution; we used transmission electron
40 microscopy (TEM) and dynamic light scattering (DLS) to
THF/water mixtures at water fractions of 50, 80, and 90%. (b,
c) TEM images of AzineꢀBZ at a concentration of 1.0 × 10–4
mol L–1 in THF/water mixtures at ratios of (b) 20:80 and (c)
10 10:90 (v/v)
4
| Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]

Page 5 of 11
ARTICLE TYPE
CREATED USING THE RSC ARTICLE TEMPLRATSE (CVERA. d3.1v)a- SnEcEeWsWW.RSC.ORG/ELECTRONICFILES FOR DETAILS
View Article Online
DOI: 10.1039/C5RA09409G
www.rsc.org/xxxxxx | XXXXXXXX
213 oC
262 J/g
1223 cm-1
923 cm-1
(B)
(A)
(a) Uncuring
(b) 110 oC
(a) Uncuring
215 oC
199 J/g
(b) 110 oC
(c) 150 oC
(d) 180 oC
233 oC
128 J/g
(c) 150 oC
(d) 180 oC
(e) 210 oC
(f) 240 oC
(e) 210 oC
(f) 210 oC
4000
3000
2000
1000
100
150
200
250
300
Wavenumber (cm-1)
Temperature (oC)
Figure 5: (A) DSC profile and (B) FTIR spectra of AzineꢀBZ monomer recorded after thermal treatments
100
images were smaller than those measured using DLS, because
evaporation was necessary to prepare the samples for TEM,
unavoidably leading to collapse and shrinkage of the particles.
We suspect that CN4OH and AzineꢀBZ emitted intensely in
20 their aggregated states because the large amount of water leads
to form spherical nanoꢀaggregated structures thereby restricted
intramolecular rotation of the phenyl rings rotors of CN4OH
and AzineꢀBZ.
80
60
40
20
0
Azine-BZ
110 oC
150 oC
180 oC
210 oC
240 oC
25 Thermal Curing and AIE of AzineꢀBZ
Differential scanning calorimetry (DSC) is a convenient and
simple method to understand and investigate the study the
thermal curing and ringꢀopening polymerization of the Azineꢀ
BZ monomer. The DSC thermograms of the pure AzineꢀBZ
30 monomer, recorded at a heating rate of 20 °C min–1 from 20 to
350 oC, reveal [Figure 5(A)] an exothermic peak with the
curing temperature at 213 °C and a reaction heat of 262 J g–1.
Based on DSC profile the polymerization exotherm maximum
temperature for AzineꢀBZ (213 °C) was lower than that (263
35 °C) for conventional 3ꢀphenylꢀ3,4ꢀdihydroꢀ2Hꢀbenzooxazine
(Paꢀtype)1, presumably because the basic azine group in the
backbone structure catalyzed the ringꢀopening polymerization.
100
200
300
400
500
600
700
Temperature (oC)
5
Figure 6: Thermogravimetric analyses of AzineꢀBZ monomer,
recorded after thermal polymerization at 110, 150, 180, 210
and 240 oC
investigate the growth of these nanoꢀaggregates at high water
o
Clearly, after thermal treatment at 180 and 240 C for 2 h at
10 contents 90% (Figure 4). The TEM images in Figures 4(b) and
4(c) reveal nanoꢀaggregates having sizes of approximately
100–200 nm, consistent with the DLS data. The particle sizes
decreased upon increasing the water content, reaching
approximately 215 nm when the water content was 90 wt%
15 [Figure 4(a)]. The particle sizes determined from the TEM
each temperature of AzineꢀBZ, the maximum exothermic peak
40 completely disappeared which indicating the completion of
ringꢀopening polymerization of AzineꢀBZ. We also studied the
thermal polymerization of AzineꢀBZ at elevated temperatures
in Figure 5(B). As shown in Figure 5(B) displays that the
5

RSC Advances
Page 6 of 11
View Article Online
CREATED USING THE RSC ARTICLE TEMPLATE (VER. 3.0) - SEE WWW.RSC.ORG/ELECTRONICFILES FOR DETAILS
DOI: 10.1039/C5RA09409G
www.rsc.org/xxxxxx | XXXXXXXX
ARTICLE TYPE
226 oC
20000
17500
15000
12500
10000
7500
AIE-BZ
25 o
C
C
C
C
40 o
60 o
80 o
(a) Pure AzineꢀBZ
110 o
120 o
130 o
140 o
150 o
160 o
180 o
210 o
240 o
C
C
C
C
C
C
C
C
C
(b) 1wt% Zn
(c) 2wt% Zn
(d) 3 wt% Zn
5000
(e) 4 wt% Zn
(f) 5 wt% Zn
2500
184 oC
(g) 10 wt% Zn
0
500
600
700
80
120
160
200
240
280
Wavelength (nm)
Temperature (oC)
Figure 7: PL spectra of AzineꢀBZ monomer in the bulk state,
recorded after each curing stage
35 Figure 9: DSC thermograms of AzineꢀBZ in the presence of
various weight ratios of Zn(ClO4)
25000
(a)
(b)
DSC Curve of Azine-BZ
PL Internsity
intramolecular hydrogen bonding involving the azine groups
[Scheme 1(d)]. Figure 7 presents the PL spectra of pure Azineꢀ
40 BZ recorded after thermal curing at various temperatures. The
maximum intensity emission of the uncured AzineꢀBZ was
higher than those after curing. Interestingly, AzineꢀBZ still
20000
15000
10000
5000
0
1
emitted light after curing at 150 °C. The H NMR spectrum of
AzineꢀBZ after thermal curing at 150 °C indicated that ringꢀ
45 opening polymerization had not occurred: the two peaks at 4.70
and 5.33 ppm representing the oxazine ring were still present
[Figure S5(b)]. The emission was quenched after curing at 180,
210, and 240 °C. As a result, the emission from the azine could
also be used as a probe of the extent of curing of the BZ
50 monomer. Figure 8 summarizes the PL intensity of pure Azineꢀ
BZ after each curing and DSC thermal scan. The emission
intensity was quenched after curing at 180 °C [Figure 8(b)],
consistent with the initial thermal curing based on DSC
analysis [Figure 8(a)]. In addition, the characteristic absorption
55 bands at 923 cm–1 disappeared completely after curing at 180
°C [Figure 5(B)]. To the best of our knowledge, this report
provides the first example of emission behavior being used to
monitor curing behavior in a manner consistent with DSC and
FTIR spectroscopic data.
100
150
200
250
Temperature (oC)
5
Figure 8: (a) DSC scan and (b) PL intensity of pure AzineꢀBZ
monomer after each thermal curing stag
intensities of the characteristic absorption bands of
10 antisymmetric COC and outꢀofꢀplane of benzene mode with
attached to benzene ring gradually disappeared after thermal
curing at 180 oC, corresponding to ringꢀopening of benzoxazine
monomer and formation of Poly(AzineꢀBZ). In addition, a new
absorption signal appearing at 3433 cm–1, was corresponding to
15 the released OH group, consistent with the DSC analyses.
Thermal stability of AzineꢀBZ has been investigated by
thermogravimetric analysis as shown in Figure 6 after various
thermal treatments. Our TGA analysis revealed (Figure 6) that
the initial thermal decomposition temperature (Td5) was
20 strongly dependent on the curing exothermic peak in the DSC
analysis [Figure 5(A)]. For example, the initial thermal
decomposition temperatures were near 215 and 233 °C when
the curing temperatures were 110 and 150 °C, respectively;
these values are close to the curing exothermic peaks in the
25 DSC analyses in Figure 5(A). In addition, the value of Td5 and
the char yield both increased upon increasing the curing
temperature. When the curing temperature was 240 °C, the
value of Td5 increased significantly to 340 °C and the char yield
was approximately 55 wt%. This char yield is higher than that
30 of conventional 3ꢀphenylꢀ3,4ꢀdihydroꢀ2Hꢀbenzooxazine (ca. 48
wt%) at 700 °C, indicating a more highly crossꢀlinked structure
arising from the presence of the azine groups, as well as from
60
AIE Phenomena and Thermal Polymerization of Azineꢀ
BZ/Zn(ClO4)2 Complexes
The thermal uncuring behavior of AzineꢀBZ/Zn(ClO4)2
complexes was investigated using DSC and FTIR, respectively.
65 Figure 9 reveals that the thermal curing peaks shifted to lower
temperature upon increasing the Zn(ClO4)2 content, decreasing
from 213 °C initially to 184 °C in the presence of 10 wt%
Zn(ClO4)2, suggesting that the Zn2+ ions enhanced the ring
opening process.39ꢀ41 FTIR analyses was carried out to
70 investigate the specific interaction (metalꢀligand interaction) of
AzineꢀBZ after blended with various Zn(ClO4)2 contents at
ambient temperature and the spectra displayed in Figure 10.
Analysis of these spectra suggests that the shifts observed in
the absorption peaks of the polymer structures were caused by
75 specific ion–dipole interactions. Concentrating on the azine
band at 1632 cm–1, we assign the new band at 1664 cm–1 that
appeared at 5 or 10 wt% Zn(ClO4)2 to the azine groups
coordinating as πꢀbonding ligands to zinc cations (inset to
Figure 10). Therefore, the higher energy of this new absorption
80 was the result of formation of such a metalꢀligand complex.
6
| Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]

Page 7 of 11
ARTICLE TYPE
CREATED USING THE RSC ARTICLE TEMPLRATSE (CVERA. d3.1v)a- SnEcEeWsWW.RSC.ORG/ELECTRONICFILES FOR DETAILS
View Article Online
DOI: 10.1039/C5RA09409G
www.rsc.org/xxxxxx | XXXXXXXX
1632 cm-1
1664 cm-1
(g) 10 wt% Zn
(f) 5 wt% Zn
(e) 4 wt% Zn
(d) 3 wt% Zn
(c) 2 wt% Zn
(b) 1 wt% Zn
(a) Pure
Azine-BZ
1700
1680
1660
1640
1620
1600
1580
1560
Wavenumber (cm-1)
Figure 10: FTIR spectra of AzineꢀBZ in the presence of various amounts of Zn(ClO4)2, recorded at ambient temperature
(B)
1223 cm-1
923 cm-1
(A) Azine-BZ/Zn(ClO4)2 ( 5 wt%)
(a) Uncuring
(a) Uncuring
(b) 110 oC
(c) 150 oC
(b) 110 oC
(c) 150 oC
(d) 180 oC
(d) 180 oC
(e) 210 oC
(e) 210 oC
(f) 240 oC
4000
280
3000
2000
1000
120
160
200
240
Wavenumber (cm-1)
Temperature (oC)
5
Figure 11: (A) DSC thermograms and (B) FTIR spectra of AzineꢀBZ monomer in the presence of 5 wt% Zn(ClO4)2, recorded after each
curing stage
7

RSC Advances
Page 8 of 11
View Article Online
CREATED USING THE RSC ARTICLE TEMPLATE (VER. 3.0) - SEE WWW.RSC.ORG/ELECTRONICFILES FOR DETAILS
DOI: 10.1039/C5RA09409G
www.rsc.org/xxxxxx | XXXXXXXX
ARTICLE TYPE
Scheme 2: (Left) Possible model of a poly(AzineꢀBZ)/Zn(ClO4)2 complex. (Right) Possible modes of metal–ligand complexes between
Zn(ClO4)2 and poly(AzineꢀBZ).
900
Azine BZ
1 wt% Zn
2 wt% Zn
3 wt% Zn
4 wt% Zn
5 wt% Zn
10 wt% Zn
30000
25000
20000
15000
10000
5000
0
(A)
800
600
400
200
0
(B)
800
700
600
500
400
300
200
100
0
AzineꢀBZ/Zn
ꢀ4
3 wt%, 10 M
)
(ClO )
4 2
(
THF:H
O
2
100:0
80:20
60:40
50:50
40:60
30:70
20:80
10:90
0
20
40
60
80
Water Fraction (%)
450
500
550
600
650
700
400
450
500
550
600
650
700
750
800
Wavelength (nm)
Wavelength (nm)
5
Figure 12: PL spectra of AzineꢀBZ blended with a various
weight ratios of Zn(ClO4)2 in the bulk state, recorded at room
temperature.
Figure 13: (A) PL spectral changes and (B) PL intensities of
AzineꢀBZ blended with 3 wt% Zn(ClO4)2 (1.0 × 10–4 mol L–1)
in THF/water mixtures at various water fractions.
30
phenolic and phenoxy structure.42 We suspect that the Zn2+ ions
coordinated effectively to the O and/or N atoms during ring
opening of the BZ units; Scheme 2 presents some possible
structures.
10 In addition, the thermal polymerization of AzineꢀBZ/5 wt%
Zn(ClO4)2 complex was studied by DSC measurement. As
revealed in Figure 11(A), the enthalpy of the curing exotherm
decreased gradually upon increasing the temperature of the
curing process, reaching zero at a curing temperature of 180
15 °C. Figure 11(B) presents corresponding FTIR spectra recorded
after thermal curing of the 5 wt% Zn(ClO4)2 blend at various
temperatures. The characteristic absorption bands of the
ozaxine units at 1223 and 931 cm–1 disappeared after thermal
curing at temperatures from 180 to 240 °C. Much literature
20 reported there are many catalysts (e.g. Li+, Fe+3...) can act as
effective promotors and accelerating for ringꢀopening
polymerization of benzoxazine. The mechanism of ringꢀ
opening polymerization of benzoxazines using catalyst is
divided into three steps; coordinationꢀring opening,
25 electrophilic attack and finally rearrangement affording to
35 As mentioned above, the salicylaldehyde azine derivatives
exhibit AIE features and emit light in their aggregated state
because of restricted rotation of their N–N single bonds; in
addition, salicylaldehyde azines bearing ortho OH groups on
their phenyl rings can undergo intramolecular hydrogen
40 bonding, which could lead to excited state intramolecular
proton transfer (ESIPT). 33,43 AzineꢀBZ exhibits weak emission
in solution because of intramolecular hydrogen bonding
between the phenolic OH group and the N atom of the imino
group that undergoes ESIPT phenomena. We were also
45 interested in examining the AIEꢀactive behavior of AzineꢀBZ
when blended with Zn(ClO4)2. Figure 12 presents the PL
spectra of AzineꢀBZ in the presence of various amounts of
Zn(ClO4)2 in the bulk state. Interestingly, the PL intensities
8
| Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]

Page 9 of 11
ARTICLE TYPE
CREATED USING THE RSC ARTICLE TEMPLRATSE (CVERA. d3.1v)a- SnEcEeWsWW.RSC.ORG/ELECTRONICFILES FOR DETAILS
View Article Online
DOI: 10.1039/C5RA09409G
www.rsc.org/xxxxxx | XXXXXXXX
25000
20000
15000
10000
5000
0
Figure 15 presents the thermal stability of AzineꢀBZ
blended with various contents of Zn(ClO4)2 after thermal
35 curing at 210 °C under N2 at heating rate 20 oC/min, as
investigated using TGA. As expected, the thermal
decomposition temperature and char yield both increased upon
increasing the Zn(ClO4)2 content. we found that the
decomposition temperature value (Td5) and char yield for the
40 AzineꢀBZ/5 wt% Zn2+ complex was higher (350 °C, 61 wt%)
than that for pure AzineꢀBZ (312 °C, 48 wt%), because the
Zn2+ ions increased the degree of crosslinking (inset to Figure
15), in addition to the crosslinking through intraꢀ and
intermolecular hydrogen bonding, after ring opening.
AzineꢀBZ
AzineꢀBZ/
3 wt% Zn(ClO4)2
o
110
150
180
210
C
C
C
C
o
o
o
o
240 C
45
Conclusions
450
500
550
600
650
700
A new Azineꢀbased BZ monomer has been designed and that
exhibits aggregation induced emission (AIE) behavior. DSC
50 analysis revealed that the exothermic peak for the ring opening
polymerization of AzineꢀBZ shifted to lower temperature,
compare to that for a standard BZ, because the basicity of the
phenolic unit facilitated the ring opening process. Furthermore,
the azine unit in the BZ monomer has high affinity for Zn2+
55 ions, not only promoting ring opening polymerization at a
lower curing temperature (from 213 °C in the absence of the
Zn2+ ions to 184 °C in their presence). Based on
thermogravametric results, the improving of thermal stability of
AzineꢀBZ/Zn(ClO4)2 complexes, due to the presence of strong
60 polymerꢀmetal complexes. AzineꢀBZ coordinated with
[Zn(ClO4)2] through metal–ligand interactions, increasing the
fluorescence emission intensity relative to that of the pure
AzineꢀBZ monomer as a result of MLCT. The PL properties of
the azine units and the metal–ligand complexes mode suggest
65 that such monomers might be act as probes for realizing the
thermal curing behavior of BZ rings; as fluorescent
chemosensors for Zn2+ and other transition metal ions, even at
high curing temperatures (e.g., 150 °C); and as components
within polymer/inorganic hybrid materials.
Wavelength (nm)
Figure 14: PL spectra of AzineꢀBZ blended with 3 wt%
Zn(ClO4)2 in the bulk state, recorded at room temperature after
each thermal curing stage
5
100
Azine-BZ
1 wt% Zn
2 wt% Zn
3 wt% Zn
4 wt% Zn
5 wt% Zn
80
60
40
20
0
100
200
300
400
500
600
700
70
Temperature (oC)
Acknowledgment
Figure 15: TGA analyses of AzineꢀBZ blended with various
amounts of Zn(ClO4)2, recorded after thermal curing at 210 °C
This study was supported financially by the Ministry of
Science and Technology, Taiwan, Republic of China, under
contracts MOST103ꢀ2221ꢀEꢀ110ꢀ079ꢀMY3 and MOST102ꢀ
75 2221ꢀEꢀ110ꢀ008ꢀMY3. We thank Mr. HsienꢀTsan Lin of the
Regional Instruments Center at National Sun YatꢀSen
University for help with the TEM experiments.
10 when the contents of zinc ions were 1, 2, 3, and 4 wt% were
higher than that of pure AzineꢀBZ, due to the Zn2+ ion having
closedꢀshell dꢀorbitals; thus, the energy transfer process could
not occur, leading to enhance metal–ligand charge transfer
(MLCT),36,37 as depicted in Scheme 2. In contrast, the PL
15 intensity decreased when content of Zn2+ ions was 5 or 10 wt%,
presumably because the Zn2+ ions coordinated to the azine
units as displayed in Figure 10, changing the mechanism of the
MLCT. To further study the optical properties of the
aggregated AzineꢀBZ/3 wt% Zn2+ ion complex, we examined
20 the fluorescence in THF in the presence of a poor solvent
(water). As revealed in Figure 13, AzineꢀBZ in the presence of
3 wt% Zn2+ ions in pure THF displayed a nonꢀemissive PL
intensity, with the PL intensity increasing upon addition of
water up to a fraction of 90%—characteristic AIE behavior.
25 Figure 14 presents PL spectra of the AzineꢀBZ/3 wt%
Zn(ClO4)2 complex after thermal curing at various
temperatures. The PL intensity of this complex was higher than
that of pure AzineꢀBZ prior to curing, consistent with MLCT.
Upon increasing the curing temperature, the PL intensity
30 decreased gradually until quenching completely at curing
temperatures from 180 to 240 °C, similar to the behavior of the
pure AzineꢀBZ monomer.
Electronic Supplementary Information (ESI) Available:
80 FTIR, UV, MS, and 1H NMR spectra of pure AzineꢀBZ.
References
(1) H. Ishida, “Handbook of Polybenzoxazine”, ed. Ishida, H.
and Agag, T., Elsevier, Amsterdam 2011, ch. 1, p. 1.
85 (2) N. Ghosh. B. Kiskan and Y. Yagci , Prog. Polym. Sci.,
2007, 32:1344ꢀ1391.
(3) Y. Yagci Y, B. Kiskan and N.N .Ghosh, J. Polym. Sci. Part
A: Polym. Chem., 2009, 47, 5565ꢀ5576.
(4) (a) T. Takeichi and T. Agag, High Perform. Polym., 2006,
90
18, 777ꢀ797. (b) Y. X. Wang and H. Ishida, Polymer,
1999, 40, 4563ꢀ4570. (c) M. Zhang, Z. Tan, S. Hu, J. Qiu
and C. Liu, RSC. Adv., 2104,
(5) (a) H. Ishida and Y. H. Lee, Polym. Polym. Compos.,
2011, , 121ꢀ134. (b) H. D. Kim and H. Ishida, J. Phys.
4, 44234ꢀ44243.
9
95
Chem. A., 2002, 106, 3271ꢀ3280. (c) H. D. Kim and H.
Ishida, Macromol. Symp., 2003, 195, 123ꢀ140. (d) S. W.
Kuo, Y. C. Wu, C. F. Wang and K. U. Jeong, J. Phys.
9

RSC Advances
Page 10 of 11
View Article Online
CREATED USING THE RSC ARTICLE TEMPLATE (VER. 3.0) - SEE WWW.RSC.ORG/ELECTRONICFILES FOR DETAILS
DOI: 10.1039/C5RA09409G
www.rsc.org/xxxxxx | XXXXXXXX
ARTICLE TYPE
Chem. C., 2009, 13, 20666ꢀ20673. (e) C. F. Wang, S. F.
Chiou, F. H. Ko, J. K. Chen, C. T. Chou, C. F. Huang, S.
W. Kuo and F. C. Chang, Langmuir., 2007, 23, 5868ꢀ5871.
(f) W. H. Hu, K. W. Huang, and S. W. Kuo, Polym. Chem.,
Li, F. Y. Z. Shen and L. M. Hanif, Chem. Commun., 2007,
231ꢀ233.
(30) Z. P. Yu, Y. Y. Duan, L. H. Cheng, Z. L. Han, Z. Zheng, H.
P. Zhou, J. Y. Wu and Y. P. Tian, J. Mater. Chem., 2012,
22, 16927ꢀ16932.
(31) Y. Qian, M. M. Cai, X. H. Zhou, Z. Q. Gao, X. P. Wang,
Y. Z. Zhao, X. H. Yan, W. Wei, L. H. Xie and W. Huang,
J. Phys. Chem. C, 2012, 116, 12187ꢀ12195.
(32) Z. Q. Xie, B. Yang, G. Cheng, L. L. Liu, F. He, F. Z. Shen,
Y. G. Ma and S. Y. Liu, Chem. Mater., 2005, 17, 1287ꢀ
1289.
5
2012,
3
, 1546ꢀ1554.
70
75
80
(6) (a) Q. Li, and X. Zhong, Langmuir, 2007, 27, 8365ꢀ8369.
(b) H. Oie, A. Sudo and T. Endo, J. Polym. Sci., Part A:
Polym. Chem., 2011, 49, 3174ꢀ3183. (c) A. Sudo, R.
Kudo, H. Nakuyama, K. Airma and T. Endo,
Macromolecules, 2008, 41, 9030ꢀ9034. (d) S. W. Kuo and
F. C. Chang, Prog. Polym. Sci., 2011, 36, 1649ꢀ1696. (e)
M. G. Mohamed, K. C. Hsu, and S. W. Kuo, Polym.
10
(33) W. Tang, Y. Xiang and A. Tong, J. Org. Chem., 2009, 74
,
Chem., 2015,
Y. Gu, RSC Adv., 2015,
6
, 2423ꢀ2433. (f) C. Li, Q. Ran, R. Zhu, and
, 22593ꢀ22600.
2163ꢀ2166.
5
(34) S. L. Liu, D. Li, Z. Zhang, G. K. S. Prakash, P. S. Conti,
Z. B. Li, Chem. Commun., 2014, 50, 7371.
(35) L. L. Long, W. Y. Lin, B. B. Chen, W. S. Gao, L. Yuan,
Chem. Commun., 2011, 47, 893.
15 (7) C. K. Chozhan, M. Alagar and P. Gnanasundarm, Acta
Mater., 2009, 28, 338ꢀ794.
(8) M. G. Mohamed, H. K. Shih, and S. W. Kuo, RSC Adv.,
2015,
5
, 12763ꢀ12772.
(36) B. K. An, S. K. Kwon, S. D. Jung, S. Y. Park, J. Am.
Chem. Soc., 2002, 124, 14410ꢀ14415.
85 (37) W. Tang, Y. Xiang and A. Tong, J. Org. Chem., 2009, 74,
(9) H. Ishida and H. Y. Low, Macromolecules, 1997, 30
1099ꢀ1106.
,
20
25
30
(10) T. Agag and T. Takeichi, Polymer, 2000, 41, 7083ꢀ7090.
2163ꢀ2166.
(11) P. Phirivawirut, R. Magaraphan and H. Ishida, Mater. Res.
Innova., 2001, , 187ꢀ198.
(38) G. Liu, M. Yang, L. Wang, J. Zheng, H. Zhou, J. Wu and
Y. Tian, J. Mater. Chem. C., 2014, , 2684ꢀ2691.
(39) M. G. Mohamed, W. C. Su, Y. C. Lin, C. F. Wang, J. K.
Chen, K. U. Jeong and S. W. Kuo, RSC Adv., 2014,
50373ꢀ50385.
(40) Y. H. Low and H. Ishida, Polym. Degrad. Stab., 2006, 91
4
2
(12) M. R. Vengatesan, S. Devaraiu , K. Dinkaran and M.
Alagar, J. Mater. Chem., 2012, 22, 7559ꢀ7559.
(13) C. F. Wang, Y. C. Su, S.W. Kuo, C.F. Huang, Y. C. Sheen
and F. C. Chang, Angew. Chem. Int. Ed., 2006, 45, 2248ꢀ
2251.
90
4
,
,
805ꢀ815.
(14) T. Agag, R. C. Arza, F. H. J. Maurer and H. Ishida,
Macromolecules, 2010, 43, 2748ꢀ2758.
(41) O. T. Lekesiz and J. Hacaloglu, Polymer, 2014, 55, 3533ꢀ
3542.
95
(15) A. Chernykh, T. Agag and H. Ishida, Polymer, 2009, 50
,
(42) C. Liu, D. Shen, M. R. Sebastian, J. Marquet and R.
Schonfold, Macromolecules, 2011, 44, 4616ꢀ4622.
(43) T. S. Hsiao, S. L. Deng, K. Y. Shih and J. L. Hong, J.
3153ꢀ3157.
(16) H. M. Qi, G. Y. Pan and Q. Y. Zhuang, Polym. Eng. Sci.,
2010, 50, 1751ꢀ1757.
Mater. Chem. C, 2014, 2, 4828ꢀ4834.
35 (17) Z. Brunovska, and H. Ishida, J. Appl. Polym. Sci., 1999,
73, 2937ꢀ2949.
100
(18) T. Takeichi, K. Nakamura, T. Agag and H. Muto, Des.
Monomers Polym., 2004, 7, 727ꢀ740.
(19) R. Kudoh, A. Sudo and T. Endo, Macromolecules, 2010,
43, 1185ꢀ1187.
40
(20) Y. C. Ye, Y. J. Huang, F. C. Chang, Z. G. Xue and X. L.
Xie, Polym. Chem., 2014,
(21) (a) J. Liu, C. Scott, S. Winroth, J. Maia, and H. Ishida,
RSC Adv., 2015, , 16785ꢀ16791. (b) K. Sethuraman, and
M. Alagar, RSC Adv., 215, 9607ꢀ9617. (c) R.
Sasikumar, M. Ariraman, M. and M. Alagar, RSC Adv.,
2014, , 19127ꢀ19136.
5, 2863ꢀ2871.
5
45
5,
4
(22) S. W. Thomass, G. D. Joly and T. M. Swager, Chem. Rev.,
2007, 107, 1339ꢀ1386.
50 (23) C. T. Chen, Chem. Mater., 2004, 16, 4389ꢀ4400.
(24) R. T. K. Kwok, J. L. Geong, J. W. Y. Lam, E. G. Zhao, G.
Wang, R. Y. Zhan, B. Liu and B. Z. Tang, J. Mater. Chem.
B., 2014, 2, 4134.
(25) Y. Q. Dong, J. W. Y. Lam, A. J. Qin, Z. Li, J. Z. Sun, H. Y.
Sung, I. D. Williams and B. Z. Tang, Chem. Commun.,
2007, 40ꢀ42.
55
(26) H. Saigusa and E. C. Lim, J. Phys. Chem., 1995, 99
,
15738ꢀ15747.
(27) J. Luo, Z. Xie, J. W. Y. Lam, L. Cheng, H. Chen, C. Qiu,
H. S. Kwok, X. Zhan, Y. Liu, D. Zhu and B. Z. Tang,
Chem. Commun., 2001, 1740ꢀ1741.
60
(28) J. Chen, C. C. W. Law, J. W. Y. Lam, Y. Dong, S. M. F.
Lo, I. D. Williams, D. Zhu and B. Z. Tang, Chem. Mater.,
2003, 15, 1535ꢀ1546.
65 (29) Y. P. Li, F. Li, H. Y. Zhang, Z. Q. Xie, W. J. Xie, H. Xu, B.
10 | Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]

Page 11 of 11
ARTICLE TYPE
CREATED USING THE RSC ARTICLE TEMPLRATSE (CVERA. d3.1v)a- SnEcEeWsWW.RSC.ORG/ELECTRONICFILES FOR DETAILS
View Article Online
DOI: 10.1039/C5RA09409G
www.rsc.org/xxxxxx | XXXXXXXX
Graphical abstract
A
new salicylaldehyde azine–functionalized benzoxazine
5
(AzineꢀBZ) monomer formed benzoxazine/zinc ion complexes
that not only improved the thermal properties but also
facilitated ringꢀopening polymerization.
11