A novel semi-fluorinated graft copolymer containing perfluorocyclobutyl aryl ether-based backbone

Article abstract of DOI:10.1016/j.jfluchem.2011.08.002

The synthesis of a series of novel semi-fluorinated graft copolymers bearing perfluorocyclobutyl (PFCB) aryl ether-based backbone and polystyrene side chains is described. This work initially focused on the synthesis of a trifluorovinyl ether (TFVE) monomer containing a bromine atom, which could be employed as an initiating site for atom transfer radical polymerization (ATRP). Thermal cyclopolymerization of this TFVE monomer provided a macromolecular initiator followed by subsequent initiating ATRP of styrene to afford the desired PFCB aryl ether-based graft copolymers.

Full text of DOI:10.1016/j.jfluchem.2011.08.002

Journal of Fluorine Chemistry 133 (2012) 184–189
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
A novel semi-fluorinated graft copolymer containing perfluorocyclobutyl aryl
ether-based backbone
*
Sen Zhang, Hao Liu, Yan Deng, Xiaoyu Huang
Key Laboratory of Organofluorine Chemistry and Laboratory of Polymer Materials, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai
200032, PR China
A R T I C L E I N F O
A B S T R A C T
Article history:
The synthesis of a series of novel semi-fluorinated graft copolymers bearing perfluorocyclobutyl (PFCB)
aryl ether-based backbone and polystyrene side chains is described. This work initially focused on the
synthesis of a trifluorovinyl ether (TFVE) monomer containing a bromine atom, which could be
employed as an initiating site for atom transfer radical polymerization (ATRP). Thermal cyclopolymer-
ization of this TFVE monomer provided a macromolecular initiator followed by subsequent initiating
ATRP of styrene to afford the desired PFCB aryl ether-based graft copolymers.
Received 29 June 2011
Received in revised form 2 August 2011
Accepted 3 August 2011
Available online 11 August 2011
Keywords:
ß 2011 Elsevier B.V. All rights reserved.
Perfluorocyclobutyl (PFCB)
Graft copolymer
ATRP
Fluoropolymer
1. Introduction
possibility of PFCB aryl ether homopolymers. Meanwhile, the
relatively high polymerization temperature (>150 8C) makes it
The incorporation of fluorine into polymers for advanced
materials continues to be attractive in recent decades because of
the unique properties of fluorinated polymers [1]. In particular,
partially fluorinated polymers exhibit dramatic and tailorable
changing in property with controlled incorporation of fluorine.
Perfluorocyclobutyl (PFCB) aryl ether polymers are a class of
amorphous partially fluorinated polymers which not only provide
the conventional properties of fluoropolymer such as high thermal
and thermal oxidative stability, chemical resistance, but also
possess many other advantages including optical transparency and
improved processability; thus, they can be applied in optics,
aerospace coatings, and battery electrolyte [2–5].
difficult for the copolymerization of commonly used monomers
(styrene, acrylate, etc.) with TFVE monomers. Thus, the
application of PFCB aryl ether polymers has been obviously
confined.
For enlarging its application range, it is significant to combine
the high performance of PFCB aryl ether polymer with other
commercial polymers. Recently, a few examples of modified PFCB
aryl ether-based block copolymers have been reported [9–12].
Graft copolymers with a stable covalent-bonded linkage between
the backbone and side chains may be also a good choice. Graft
copolymers offer the unique possibility of tailoring materials
properties through their numerous structural variables that can be
modified such as composition and density of the grafts [13–15].
Properties such as morphology, order–disorder transitions, phase
behavior and compatibility with other polymers can be greatly
changed by post-modification of the backbone of fluoropolymers.
Depending on the nature of the copolymer, graft polymers may
possess specific properties while retaining the desirable properties
of the parent fluoropolymers.
The synthesis of graft fluoropolymers, however, can still pose a
significant challenge. Generally, three strategies including graft-
ing-through, grafting-onto, and grafting-from were used for the
synthesis of graft copolymers [16]. The grafting-onto technique is
the grafting of side chains onto the backbone by a coupling
reaction. Ligon et al. directly grafted fluoroalkyl side chains onto
PFCB aryl ether polymers with Umemoto’s FITS reagents [12]. The
fluoroalkylated PFCB polymers (20% functionalized) showed
PFCB aryl ether polymers are generally prepared by thermal
[2
p + 2p] cycloaddition polymerization of trifluorovinyl ether
(TFVE) monomers above 150 8C in bulk or in solution without
any initiator or catalyst as shown in Scheme 1. TFVE monomers
are stable and may be synthesized from a variety of commer-
cially available phenols. Alternatively,
a variety of TFVE
monomers have been synthesized via the intermediate strategy
[6–8]. This methodology has worked well for incorporating
functionality into the monomers. However, this technology is
currently still restricted by the cost and availability. Direct
polymerization of functional TFVE monomers only offers limited
* Corresponding author. Tel.: +86 21 54925310; fax: +86 21 64166128.
E-mail address: xyhuang@mail.sioc.ac.cn (X. Huang).
0022-1139/$ – see front matter ß 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2011.08.002

S. Zhang et al. / Journal of Fluorine Chemistry 133 (2012) 184–189
185
Scheme 1. Thermal cyclopolymerization of trifluorovinyl aryl ether monomer.
Scheme 2. Synthesis of PFCB aryl ether-based graft copolymer 3.
increases in both hydrophobicity and oleophobicity. This strategy
provides relatively simple method of synthesizing graft
In this paper, we utilized the intermediate strategy to prepare a
TFVE monomer 1 with a secondary bromine atom as ATRP
initiating group as shown in Scheme 2. Thermal cyclopolymeriza-
tion of monomer 1 gave a PFCB aryl ether homopolymer 2
possessing pendant ATRP initiating groups in every repeating unit,
i.e., PFCB macroinitiator 2 was formed. ATRP of styrene initiated by
macroinitiator 2 through the grafting-from strategy afforded a
novel semi-fluorinated graft copolymer 3 containing a PFCB aryl
ether polymeric backbone and polystyrene side chains. All
compounds in this paper were characterized by FT-IR, 1H NMR,
13C NMR, 19F NMR, MS, and GPC in detail.
a
fluoropolymers; however, this functionalization reaction was
undergoing normally in an uncontrolled way, with an insufficient
grafting efficiency, resulting in limited grafting density. Recently,
atom transfer radical polymerization (ATRP) has been successfully
used to prepare the graft copolymers based on the grafting-from
method, i.e., side chains are grafted from the backbone via ATRP
initiated by the pendant initiating groups on the backbone
polymers [17,18]. Specifically, the living characteristic of ATRP
enables it to control both the molecular weights and molecular
weight distributions of side chains. Mayes et al. succeeded in
performing the direct graft copolymerization of methacrylates via
ATRP using secondary fluorine on PVDF backbone as initiating sites
[19]. Zhang and Russell grafted polystyrene and poly(tert-butyl
acrylate) from poly(vinylidene fluoride-co-chlorotrifluoroethy-
lene) via ATRP [20]. Their synthetic approaches offer a convenient
way to modify fluoropolymers.
2. Results and discussion
2.1. Design and synthesis of monomer 1
In ATRP, alkyl bromide with radical stabilizing substituent
(such as carbonyl group) on the a-carbon has been widely used as

186
S. Zhang et al. / Journal of Fluorine Chemistry 133 (2012) 184–189
Scheme 3. Synthesis of TFVE monomer 1.
initiators. Preparation of graft copolymer through the grafting-
from strategy requires the polymeric backbone comprising
monomer units with pendant ATRP initiating groups. 2-Bromo-
propionate group is a kind of commonly used ATRP initiating group
and it is easily introduced into molecules by esterification. And it
was reported that this type of ATRP initiating group is stable at a
high temperature (200 8C) [10]. Thus, a new TFVE monomer 1
containing a 2-bromopropionate group was designed and the
intermediate strategy was utilized to synthesize TFVE monomer 1
(Scheme 3). Trifluorovinyloxybenzene was first prepared by
fluoroalkylation of phenol with BrCF2CF2Br followed by subse-
quent elimination of BrF with zinc. Next, a secondary bromine
atom (–COCHBrCH3) was introduced into the 4-position of
trifluorovinyl aryl ether by Friedel-Crafts reaction with 2-
bromopropionyl chloride and the key intermediate 4 was obtained
in good yield. The 1H NMR spectrum of 4 is shown in Fig. 1A. The
peaks at 7.18 and 8.07 ppm were attributed to 4 protons of
benzene ring, and the signals at 1.89 (–COCH(CH3)Br) and 5.24 (–
COCH(CH3)Br) ppm belonged to the protons of 2-bromopropionate
group, respectively. The sharp peak at 1834 cmꢀ1 (–OCF55CF2) in
FT-IR spectrum and the signals at ꢀ119.0, ꢀ125.6 and ꢀ135.0 ppm
in 19F NMR spectrum gave a clue of the existence of trifluorovinyl
group.
3,5-Dihydroxybenzyl alcohol is a versatile building block for
organic synthesis, having two different hydroxyl groups in it. One
is phenol hydroxyl and the other is benzyl hydroxyl. The phenol
hydroxyl is more reactive and would make nucleophilic attack on
the secondary bromine and the benzyl hydroxyl would keep
inertness. Thus, compound 5 was prepared in the presence of
Fig. 1. 1H NMR spectra of 4 (A) and 5 (B).

S. Zhang et al. / Journal of Fluorine Chemistry 133 (2012) 184–189
187
Table 1
Synthesis of graft copolymer 3 initiated by macroinitiator 2.a
b
b
Sample
Temperature (8C)
Time (h)
Mn (g/mol)
Mw/Mn
3a
3b
3c
3d
110
110
110
110
4
5
6
7
58,100
56,800
62,500
77,000
2.31
2.39
3.14
2.45
a
Initiated by macroinitiator 2 (Mn = 8600 g/mol, Mw/Mn = 2.10) in diphenyl ether,
[St]:[Br group]:[CuBr]:[PMDETA] = 100:1:1:2.
b
Measured by GPC in THF at 35 8C.
and ꢀ135.0 ppm in 19F NMR spectrum (Fig. 2C) illustrated the
remaining of trifluorovinyl groups. From the above results, it can
be concluded that we have successfully synthesized TFVE
monomer 1 containing an ATRP initiating group.
2.2. Preparation of macroinitiator 2
PFCB macroinitiator 2 was prepared by thermal cyclopolymer-
ization of TFVE monomer 1 (Scheme 2). The homopolymerization
was carried out in diphenyl ether at 180 8C. 1H NMR and 19F NMR
were employed to examine the chemical structure of macro-
initiator 2. We still found the peaks of –COCH(CH3)Br group at 4.31
and 1.70 ppm and the protons of benzene rings at 8.09, 7.15, 6.43,
and 6.35 ppm as shown in Fig. 3, which are similar with that of
monomer 1. Br atom kept inert during the thermal cyclo-
polymerization according to previous report [10]. The existence
of PFCB linkage was also affirmed by the typical multiplets ranging
from ꢀ128 to ꢀ134 ppm in 19F NMR spectrum. In addition, TFVE
end group signals were found at ꢀ119.0, ꢀ125.6 and ꢀ135.0 ppm.
All these evidence showed that a PFCB aryl ether-based macro-
initiator bearing ATRP initiating groups in every repeating unit was
successfully synthesized.
Fig. 2. FT-IR (A), 1H NMR (B) and 19F NMR (C) spectra of TFVE monomer 1.
Cs2CO3 by nucleophilic substitution reaction and it was easily
separated by silica chromatography as a light yellow oil. Fig. 1B
shows 1H NMR spectrum of 5 and new peaks at 6.46, 6.33 (C6H6)
and 4.53 (–CH2–OH) ppm were found in comparison with that of 4
(Fig. 1A). This result indicated that two phenol hydroxyls were
both transformed into ether linkage while benzyl hydroxyl was
remained under the current reaction condition. The sharp peak at
1834 cmꢀ1 (–OCF55CF2) in FT-IR spectrum and the signals at
ꢀ119.0, ꢀ125.6 and ꢀ135.0 ppm in 19F NMR spectrum after the
nucleophilic reaction demonstrated that shows the vinyl group
was not affected during the reaction.
Finally, compound 5 was esterified with 2-bromopropionyl
chloride in dichloromethane to afford the desired monomer 1,
which was characterized by FT-IR, 1H NMR, and 19F NMR. Typical
signals of the carbonyl group appeared at 1743 and 1698 cmꢀ1 in
FT-IR spectrum (Fig. 2A). As shown in Fig. 2B, two new peaks at
4.32 and 1.76 ppm corresponded to the newly introduced –
COCH(CH3)Br group. Furthermore, the peak at 1834 cmꢀ1 (–
OCF55CF2) in FT-IR spectrum and the signals at ꢀ119.0, ꢀ125.6
2.3. Synthesis of graft copolymer 3
The graft copolymer 3 was prepared by the grafting-from
strategy via ATRP of styrene using homopolymer 2 as macro-
initiator (Mn = 8600, Mw/Mn = 2.10) and CuBr/N,N,N0,N0,N00-penta-
methyldiethylenetriamine (PMDETA) as catalytic system. The
polymerization was performed in diphenyl ether at 110 8C and
the results are listed in Table 1. All products’ molecular weights are
much higher than that of the macroinitiator, indicating the
occurrence of the polymerization of styrene. Moreover, the
molecular weights of graft copolymers increased with the
ascending of polymerization time, which accorded with the living
nature of ATRP.
The copolymer 3c (Mn = 62,500) was also hydrolyzed with KOH
to cleave polystyrene side chains according to previous report [21].
GPC measurement was run for the cleaved PS side chains and the
result indicated that Mn,GPC of the cleaved polystyrene side chains
was 4200. The narrow molecular weight distribution (Mw/
Mn = 1.26) of the cleaved polystyrene side chains obtained from
GPC is the evidence that polystyrene side chains were well-
defined.
The graft copolymers were characterized by FT-IR, 1H NMR, and
19F NMR. A sharp band at 962 cmꢀ1 attributed to perfluorocyclo-
butyl unit was found in FT-IR spectrum and two sharp peaks at 698
and 757 cmꢀ1 confirmed the existence of mono-substituted
benzene ring of polystyrene segment. Fig. 4A presents 1H NMR
spectrum of the graft copolymer in CDCl3. The peaks at 8.10 and
6.40 ppm were attributed to the protons of benzene ring of PFCB
aryl ether-based backbone, and the typical signals of polystyrene
side chains were found to appear at 1.43 (–CH2–), 1.79 (–CH–), and
6.53, 6.93 ppm (benzene ring). 19F NMR of graft copolymer 3 was
Fig. 3. 1H NMR spectrum of macroinitiator 2.

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S. Zhang et al. / Journal of Fluorine Chemistry 133 (2012) 184–189
4.2. Measurements
1H and 13C NMR spectra were obtained with a Varian
Mercury 300 spectrometer (300 MHz). 19F NMR spectroscopy
measurements were collected on a Bruker AM-300 spectrometer
(282 MHz). All NMR spectra were collected in CDCl3, TMS (1H
NMR) and CDCl3 (
13C NMR) were used as internal standards and
CF3CO2H was used as external standard for 19F NMR. FT-IR
spectra were recorded on a Nicolet AVATAR-360 FT-IR spectro-
photometer with a resolution of 4 cmꢀ1. EI-MS was measured by
an Agilent 5937N system. HRMS were recorded on a Waters
Micromass GCT instrument. Relative molecular weights and
molecular weight distributions (Mw/Mn) were measured by a
Waters gel permeation chromatography (GPC) system equipped
with a Waters 1515 Isocratic HPLC pump, a Waters 2414
refractive index (RI) detector and a set of Waters Styragel
columns (HR3 (500–30,000), HR4 (5000–600,000) and HR5
(50,000–4,000,000), 7.8 mm ꢁ 300 mm, particle size:
5 mm).
GPC measurements were carried out at 35 8C using THF as
eluent with a flow rate of 1.0 mL/min. The system was calibrated
with linear polystyrene standards.
Fig. 4. 1H NMR (A) and 19F NMR (B) spectra of graft copolymer 1.
4.3. Synthesis of compound 4
similar to that of macroinitiator 2 (Fig. 4B), which illustrated that
PFCB-based polymeric backbone was stable under ATRP condition.
Solubility test for copolymer 3 was performed in four kinds of
solvents with low boiling point, tetrahydrofuran, chloroform,
dichloromethane, and acetone. The graft copolymer 3 shows
excellent solubility in the above solvents, which was similar to the
result of corresponding ABA triblock copolymer containing 2
polystyrene segments [10].
The compound 4 was synthesized according to Scheme 3 by
three steps using phenol as starting material [10]. Synthesis of
(1,2,2-trifluorovinyloxy)benzene was similar to those reported
procedures in previous literature [23].
To a 250 mL dried three-neck round-bottom flask fitted with a
condenser and a thermometer, (1,2,2-trifluorovinyloxy)benzene
(11.7971 g, 68 mmol) and CH2Cl2 (100 mL) were added under N2
followed by adding 2-bromopropionyl chloride (7 mL, 69 mmol)
and aluminum chloride (AlCl3) (9.94 g, 74 mmol). The solution
was heated to 30 8C for 8 h, then the flask was cooled to 0 8C, and
granular ice was added to terminate the reaction. 1 M HCl (80 mL)
was added to the solution and the organic layer was washed by
brine (3ꢁ 50 mL) followed by drying over MgSO4. A straw yellow
3. Conclusion
A new TFVE monomer 1 with ATRP initiating group was
synthesized via intermediate strategy. The thermal cyclopolymer-
ization of monomer 1 provided a PFCB aryl ether polymer with
pendent ATRP initiating groups, i.e., macroinitiator 2. ATRP of
styrene initiated by macroinitiator 2 formed the graft copolymer 3,
which contained PFCB polymer backbone and polystyrene side
chains. The resulting graft copolymer 3 shows good solubility in
common used solvents.
solid, 2-bromo-1-(p-trifluorovinyloxy)phenylpropan-1-one
(17.5765 g, 83.6%), was obtained by flash column chromatogra-
phy. 1H NMR (300 MHz, CDCl3):
(ppm): 1.89 (d, J = 6.3 Hz, 3H),
5.24 (q, J = 6.6 Hz, 1H), 7.18 (d, J = 8.7 Hz, 2H), 8.07 (d, J = 9.0 Hz,
2H). 19F NMR (282 MHz, CDCl3):
(ppm): ꢀ119.0 (dd, 1F), ꢀ125.6
(cmꢀ1): 3023, 2983, 2923,
4
d
d
(dd, 1F), ꢀ135.0 (dd, 1F). FT-IR (KBr):
n
1834 (OCF55CF2), 1689, 1601, 1505, 847.
4. Experimental
4.4. Synthesis of compound 5
4.1. Materials
To a 250 mL dried three-neck round-bottom flask fitted with
a condenser, 3,5-dihydroxybenzyl alcohol (6.44 g, 46 mmol),
K2CO3 (19.06 g, 138 mmol), Cs2CO3 (0.456 g, 1.38 mmol) and
acetone (150 mL) were added under N2 followed by adding
compound 4 (28.44 g, 92 mol). The solution was heated to 60 8C
for 10 h, then the flask was cooled to room temperature. One
hundred milliliters of water and 50 mL of diethyl ether were
added into the solution, and the organic layer was washed by
brine (3ꢁ 50 mL) followed by drying over MgSO4. A light yellow
oil (19.19 g, 70%) was obtained by flash column chromatogra-
Styrene (St, Aldrich, 99%) was washed with 5% aqueous NaOH
solution to remove inhibitor and then with water, dried with
MgSO4, and distilled twice over CaH2 under reduced pressure
before use. Copper(I) bromide (CuBr, Aldrich, 98%) was purified
by stirring overnight over CH3CO2H at room temperature,
followed by washing the solid with ethanol, diethyl ether, and
acetone prior to drying at 40 8C in vacuum for 1 day. Granular
zinc was activated by washing in 0.1 M HCl followed by drying at
140 8C in vacuo for 10 h. 1,2-Dibromotetrafluoroethane was
prepared by condensing equimolar amounts of Br2 and tetra-
fluoroethylene at ꢀ195 8C followed by warming up to 22 8C [22].
All solvents were purified by standard methods prior to use.
Phenol (Aldrich, 99%), N,N,N0,N0,N00-pentamethyldiethylenetria-
mine (Acros, 98%), and 2-bromopropionyl chloride (Acros, 98%)
were used as received. All other chemicals and reagents were
purchased from Alfa Aesar or Sigma Aldrich and used as received
unless otherwise stated.
phy. 1H NMR (300 MHz, CDCl3):
d (ppm): 1.66 (d, J = 6.6 Hz, 6H),
4.53 (s, 2H), 5.33 (q, J = 6.6 Hz, 2H), 6.33 (s, 1H), 6.46 (s, 2H), 7.15
(d, J = 8.1 Hz, 4H), 8.10 (d, J = 8.1 Hz, 4H). 19F NMR (282 MHz,
CDCl3):
1F). 13C NMR (75 MHz, CDCl3):
106.4, 115.7, 130.6, 131.5, 134.3, 144.1, 146.8, 149.6, 158.6,
197.2. FT-IR (KBr):
(cmꢀ1): 3503, 2988, 2936, 1834, 1697,
d
(ppm): ꢀ119.0 (dd, 1F), ꢀ125.6 (dd, 1F), ꢀ135.0 (dd,
d
(ppm) 18.54, 64.79, 101.6,
n
1600, 1503, 1457, 1317, 1275, 1207, 1167, 1144, 964, 845. EI-MS
m/z: 596. HRMS: C29H22F6O7, Calcd. 596.1270, Found 596.1271.

S. Zhang et al. / Journal of Fluorine Chemistry 133 (2012) 184–189
189
4.5. Synthesis of TFVE monomer 1
concentrated and precipitated in methanol. The crude product
was purified by three times of dissolution and precipitation,
followed by drying under vacuum to obtain 0.51 g of graft
copolymer 3c. GPC: Mn = 62,500, Mw/Mn = 3.14. 1H NMR
In a 50 mL dried three-neck round-bottom flask, 5 (1.0715 g,
1.80 mmol) and triethylamine (0.5 mL, 3.6 mmol) were dissolved
in 25 mL of dichloromethane and the mixture was stirred at 0–5 8C.
2-Bromopropionyl chloride (0.18 mL, 1.80 mmol) was added and
the mixture was stirred for another 1 h. Finally, the mixture was
stirred at room temperature for 1 h. The precipitated triethylam-
monium chloride was filtered and the filtrate was washed twice
with water. The solution was dried over MgSO4 followed by the
concentration to remove solvent. The desired product 1 of yellow
oil was obtained by flash column chromatography. 1H NMR
(300 MHz, CDCl3):
d
(ppm): 1.43, 1.79, 6.35, 6.53, 6.93, 8.09. 19F
(ppm): ꢀ119.0 (dd), ꢀ125.6 (dd), ꢀ128.2
(cmꢀ1
NMR (282 MHz, CDCl3):
d
to ꢀ133.5 (m, cyclobutyl-F6), ꢀ135.0 (dd). FT-IR (KBr):
n
)
2924, 1735, 1695, 1600, 1495, 1453, 962, 846, 757, 698.
4.8. Cleavage of polystyrene side chains
The graft copolymer 3c (0.10 g, Mn = 62,500, Mw/Mn = 3.14) was
dissolved in 5 mL of THF. Next, 3 mL of KOH solution (1 M in
ethanol) was added and the mixture was refluxed for 2 days. The
solution was concentrated and precipitated into acetonitrile to
obtain the cleaved polystyrene side chains since the backbone is
(300 MHz, CDCl3):
d (ppm): 1.66 (d, J = 6.6 Hz, 6H), 1.76 (d,
J = 7.2 Hz, 3H), 4.32 (q, J = 7.2 Hz, 1H), 5.00 (q, J = 6.6 Hz, 2H), 5.33
(s, 2H), 6.35 (s, 1H), 6.43 (s, 2H), 7.15 (d, J = 8.4 Hz, 4H), 8.09 (d,
J = 8.4 Hz, 4H). 19F NMR (282 MHz, CDCl3):
d
(ppm): ꢀ119.0 (dd,
1F), ꢀ125.6 (dd, 1F), ꢀ135.0 (dd, 1F). 13C NMR (75 MHz, CDCl3):
d
soluble in acetonitrile. GPC: Mn = 4,200, Mw/Mn = 1.26. FT-IR: n
(ppm) 18.5, 21.3, 39.8, 66.8, 102.5, 107.3, 130.6, 131.2, 134.7,
(cmꢀ1): 3025, 2983, 2923, 1601, 1493, 1452, 757, 698.
138.0, 143.1, 146.4, 150.5, 158.6, 169.7, 196.8. FT-IR (KBr):
n
(cmꢀ1): 3074, 2988, 2937, 1834, 1743, 1698, 1599, 1503, 1458,
Acknowledgements
1317, 1275, 1207, 1168, 1144, 964, 845. EI-MS m/z: 730. HRMS:
C32H25BrF6O8, Calcd. 730.0637, Found 730.0641.
The author thanks the financial support from Natural Science
Foundation of China (20674094 and 21074145) and Ministry of
Science and Technology of ‘‘National High Technology Research
and Development Program’’ (2006AA03Z541).
4.6. Preparation of PFCB aryl ether-based macroinitiator 2
To a predried 25 mL Schlenk flask sealed with a rubber septum,
trifluorovinyl ether monomer 1 (0.77 g, 1.05 mmol) and diphenyl
ether (6 mL) were added under N2 and followed by three cycles of
freezing–pumping–thawing. The flask was placed in an oil bath at
180 8C for polymerization. The reaction lasted for another 12 h and
was quenched by immersing the flask in liquid N2. Dichloro-
methane (20 mL) was added to dilute the solution, and the solution
was added to 300 mL of methanol to precipitate the solid product.
The crude product was purified by three times of dissolution and
precipitation, followed by drying under vacuum to obtain 0.54 g of
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4.7. Synthesis of graft copolymer 3
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A typical procedure of synthesis of graft copolymer 3 is listed as
follows: ATRP macroinitiator 2 (0.2 g, Mn = 8600 g/mol) and CuBr
(19 mg, 0.12 mmol) were added to a 25 mL Schlenk flask (flame-
dried under vacuum just before use) sealed with a rubber septum
under N2. After three cycles of evacuating and backfilling with N2,
styrene (1.3 mL, 12.0 mmol), PMDETA (0.05 mL, 0.24 mmol), and
diphenyl ether (2 mL) were introduced via a gastight syringe
followed by three cycles of freezing–pumping–thawing. The
mixture was stirred at room temperature for 10 min so that the
mixture became homogeneous. The flask was placed in an oil bath
at 110 8C for polymerization. The polymerization was quenched by
immersing the flask in liquid N2 after 6 h. THF was added to dilute
the solution, and the solution was filtered through a short Al2O3
column to remove the catalyst. The resulting solution was