Ordered, microphase-separated, noncharged-charged diblock copolymers via the sequential ATRP of styrene and styrenic imidazolium monomers

Article abstract of DOI:10.1016/j.polymer.2014.11.009

A series of imidazolium-based noncharged-charged diblock copolymers (1) was synthesized by the direct, sequential ATRP of styrene and styrenic imidazolium bis(trifluoromethyl)sulfonamide monomers with methyl, n-butyl, and n-decyl side-chains. Small-angle X-ray scattering studies on initial examples of 1 with a total of 50 repeat units and styrene:imidazolium-styrene repeat unit ratios of 25:25, 20:30, and 15:35 showed that their ability to form ordered nanostructures (i.e., sphere and cylinder phases) in their neat states depends on both the block ratio and the length of the alkyl side-chain on the imidazolium monomer. To our knowledge, the synthesis of imidazolium-based BCPs that form ordered, phase-separated nanostructures via direct ATRP of immiscible co-monomers is unprecedented.

Full text of DOI:10.1016/j.polymer.2014.11.009

Polymer 55 (2014) 6664e6671
Contents lists available at ScienceDirect
Polymer
journal homepage: www.elsevier.com/locate/polymer
Ordered, microphase-separated, noncharged-charged diblock
copolymers via the sequential ATRP of styrene and styrenic
imidazolium monomers
,
, **
Zhangxing Shi a, Brian S. Newell b, Travis S. Bailey b *, Douglas L. Gin a
a Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA
b Department of Chemical and Biological Engineering, and Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of imidazolium-based noncharged-charged diblock copolymers (1) was synthesized by the
direct, sequential ATRP of styrene and styrenic imidazolium bis(trifluoromethyl)sulfonamide monomers
with methyl, n-butyl, and n-decyl side-chains. Small-angle X-ray scattering studies on initial examples of
1 with a total of 50 repeat units and styrene:imidazolium-styrene repeat unit ratios of 25:25, 20:30, and
15:35 showed that their ability to form ordered nanostructures (i.e., sphere and cylinder phases) in their
neat states depends on both the block ratio and the length of the alkyl side-chain on the imidazolium
monomer. To our knowledge, the synthesis of imidazolium-based BCPs that form ordered, phase-
separated nanostructures via direct ATRP of immiscible co-monomers is unprecedented.
© 2014 Elsevier Ltd. All rights reserved.
Received 16 September 2014
Received in revised form
27 October 2014
Accepted 1 November 2014
Available online 12 November 2014
Keywords:
ATRP
Ionic block copolymer
Nanostructure
1. Introduction
Although imidazolium poly(IL)s have been synthesized in a
number of polymer chain architectures [1], one motif that has
Polymerized ionic liquids (poly(IL)s) are macromolecules with
charged repeat units that are prepared from or structurally related
to ionic liquids (ILs) [1]. Since ILs are small-molecule liquid mate-
rials with a unique combination of properties (e.g., negligible vapor
pressure, ion conductivity, high solubility for certain light gases)
[2], the ability to make processible, solid-state, polymeric analogs is
highly desirable [1]. Poly(IL)s can be made by direct polymerization
of IL monomers [1] with a reactive cation or anion [2]. They can also
be formed by postpolymerization modification of uncharged
polymers containing reactive repeat units to generate the charged
moieties [1]. Imidazolium-based poly(IL)s are the most common
class of poly(IL)s because of the synthetic versatility, high CO2 gas
solubility, and ion conductivity afforded by the imidazolium units
[1,2]. These poly(IL)s have been successfully applied as new mem-
brane materials for CO2/light gas separations [3], solid-state ion
conductors [4], specialty dispersants/surfactants [5], and platforms
for new electrochemical devices [6].
received a great deal of recent research attention is phase-separated,
poly(IL)-based block copolymers (BCPs). BCPs can form phase-
separated, nanostructures ranging from simple micelles and vesi-
cles to periodic assemblies with 1D, 2D, or 3D order, making them
attractive for encapsulation/release and transport applications [7]. In
addition, alteration of BCP chemical composition and block lengths
can be used to obtain different mechanical properties and control
the phase-separated morphologies formed [7]. If one of these blocks
contains imidazolium salt units, then nanostructured BCPs can be
generated with one domain having imidazolium IL-like properties,
resulting in a material with features of BCPs and poly(IL)s.
Over the past few years, several types of imidazolium-based
BCPs containing charged and uncharged blocks have been pre-
pared using three general approaches: (1) sequential controlled/
living polymerization of an imidazolium-based monomer with an
uncharged co-monomer; (2) controlled/living polymerization of an
imidazolium monomer from the end of an uncharged polymer; or
(3) postpolymerization functionalization of an uncharged BCP
containing a reactive segment to generate imidazolium units in
situ. The first approach has included reversible addition-
fragmentation chain-transfer (RAFT) copolymerization of acry-
late-, acrylamide-, or vinyl-substituted imidazolium monomers
with conventional acrylates and acrylamides to give diblock
* Corresponding author. Tel.: þ1 970 491 4648.
** Corresponding author. Tel.: þ1 303 492 7640.
E-mail addresses: travis.bailey@colostate.edu (T.S. Bailey), gin@spot.colorado.
edu (D.L. Gin).
http://dx.doi.org/10.1016/j.polymer.2014.11.009
0032-3861/© 2014 Elsevier Ltd. All rights reserved.

Z. Shi et al. / Polymer 55 (2014) 6664e6671
6665
noncharged-charged copolymers [8e10]; and sequential ring-
opening metathesis polymerization (ROMP) of alkyl ester- and
imidazolium-containing norbornene monomers [11]. It should be
noted that shortly after this manuscript was submitted for publi-
cation, a report on the sequential atom-transfer radical polymeri-
zation (ATRP) of an imidazolium-styrene monomer and styrene
appeared on-line [12]. However, the resulting BCPs were not re-
ported to form phase-separated nanostructures and were charac-
terized only for their molecular weights [12]. The second approach
has utilized ATRP [13,14] and RAFT [15,16] of acrylate- [13,15,16] and
styrene-based [14] imidazolium monomers to form poly(IL) seg-
ments off the end(s) of uncharged telechelic [13e15] or mono-
functional [16] polymers. The third approach has involved
substitution of imidazole onto uncharged BCPs containing a reac-
tive alkyl halide block made by nitroxide-mediated polymerization
(NMP) [17e19], RAFT [20], or step-growth [21,22] polymerizations;
selective quaternization of polystyrene-b-poly(styrene-imidazole)s
formed by NMP [23]; or attachment of imidazolium groups onto
uncharged thiol-acrylate-based BCPs made by RAFT [24]. One other
related polymer modification approach is cation-exchange of
commercial alkyl-anionic BCPs with imidazolium salts to generate
BCPs with free imidazolium counterions [25]. Although many of
these materials have been demonstrated to be useful in several
applications [11c,11d,16,18,20e25], only a small subset of them has
been reported to form phase-separated, ordered nanostructures in
the solvent-free melt state [11,18,21c,22,23b,24]. The majority of
the BCPs listed above were not reported to form periodic nano-
structures [12e15,20], or they only formed micelles or non-ordered
phases [8e10,16,17,19,21a,21b,23a,25].
applications (e.g., the use of an expensive Ru-based ROMP catalyst,
residual metal contamination in the BCPs (from the catalyst) after
isolation, and elaborate monomer syntheses) [11].
Herein, we show imidazolium-based noncharged-charged
diblock copolymers (1) that form ordered, phase-separated nano-
structures in their neat melt states can be synthesized by the
sequential ATRP of styrene and several styrenic imidazolium bis(-
trifluoromethyl)sulfonamide (Tf2Ne) monomers with different-
length alkyl side-chains (2aec) (Fig. 1). Studies on nine initial ex-
amples of
1
with
a
total of 50 repeat units and
styrene:imidazolium-styrene repeat unit ratios of 25:25, 20:30, and
15:35 indicated that their ability to form ordered nanostructures
depends on both the block ratio and the length of the alkyl chain on
the imidazolium-styrene monomer. Compared to our previous
ROMP method, this controlled radical polymerization (CRP)
approach with styrenic monomers allows the use of a less expen-
sive controlled/living polymerization catalyst, minimum metal
contamination in the BCPs formed, and more facile and scalable
monomer syntheses. Although ATRP homopolymerization of
imidazolium-containing monomers is well-established [1], to our
knowledge the direct, sequential ATRP of imidazolium and hydro-
phobic monomers to generate imidazolium BCPs with ordered,
phase-separated nanostructures has not been reported [8e10,12].
As noted previously, the synthesis of poly(imidazolium-styrene)-b-
polystyrene BCPs via ATRP that was reported shortly after this
manuscript was submitted did not generate BCPs with ordered,
phase-separated nanostructures [12]. That work also utilized a
different type of ATRP (i.e., ARGET ATRP), employed a different
monomer polymerization sequence (i.e., imidazolium-styrene then
styrene), and polymerized just one imidazolium-styrene monomer
(2b) instead of a range of imidazolium monomers with different
side-chain lengths.
In 2011, our research team was one of the first to show that
imidazolium-based BCPs can form ordered nanostructures in their
neat state by using alkyl-imidazolium BCPs made from sequential
ROMP of
a norbornene-based alkyl ester monomer and a
norbornene-based imidazolium monomer [11a]. Supported mem-
branes of these materials were also found to have nanostructure-
dependent CO2 transport properties, making them potential use-
ful for gas separations [11c,d]. However, there were several limi-
tations with our initial IL-based BCP design that hampered
preparation of substantial amounts of these materials for exploring
2. Results and discussion
2.1. Materials synthesis
As a more economical and scalable alternative to ROMP, CRP was
selected because of its molecular weight (MW) and block ratio
Fig. 1. Synthesis and structures of the noncharged-charged BCPs made via sequential ATRP in this study.

6666
Z. Shi et al. / Polymer 55 (2014) 6664e6671
control, low-PDI, and ability to polymerize a broad range of acrylate
and styrene monomers (including ionic versions). Compared to the
other CRP methods (NMP, RAFT), ATRP was chosen because it uti-
lizes inexpensive and commercially available catalysts and ligands.
Also, our initial studies showed that ATRP was more promising for
the controlled polymerization of the styrenic imidazolium mono-
mers in terms of conversion and reaction time (see the
Experimental Section).
Styrenic compounds are ideal monomers for ATRP-based BCP
synthesis because of their facile synthesis and functional group
attachment. Monomers 2a and 2b were prepared by reacting 4-
vinylbenzyl chloride with the appropriate N-alkylimidazole, fol-
lowed by ion-exchange of the Cle anion with Tf2Ne according to
literature procedures [26,27a]. Compound 2c is a new monomer
and was synthesized using similar methods (see the Experimental
Section).
initiator in butyronitrile solution (see the Experimental Section and
Supplementary Data for details). Analysis of the isolated BCPs
formed by this method show very little if any residual Cu from the
polymerization catalyst (see the Supplementary Data). In our
sequential copolymerizations, controlled-length, low-PDI reactive
polystyrene blocks 3aec were first synthesized and then used as
ATRP macro-initiators to form the subsequent attached imidazo-
lium block upon addition of the appropriate amount of 2a, 2b, or 2c.
This polymerization sequence was important because of the lower
efficiency of the initiator system with the imidazolium-styrene
monomers and the inconvenient purification process of the
resulting ionic macro-initiator if the imidazolium block were
formed first.
2.2. Confirmation of controlled polymerization behavior for the
ATRP of styrenic imidazolium monomers 2aec
As shown in Fig. 1, BCPs 1aei were synthesized via ATRP of first
styrene and then monomers 2a, 2b, or 2c using CuBr/N,N,N0,N0,N00-
pentamethyldiethylenetriamine (PMDETA) as the catalyst system
and 2-(trimethylsilyl)ethyl 2-bromo-2-methyl-propanoate as the
At the start of this work, the ATRP [27], NMP [28], and RAFT
[27b] of only two styrenic imidazolium monomers (2b and a chiral
cyclohexanol-substituted imidazolium-styrene monomer [27f])
were reported in the literature. The controlled ATRP of 2a and 2c
had not been reported, and the sequential ATRP of styrene and
2aec to generate nanostructured BCPs was also unprecedented. In
order to confirm the controlled ATRP of 2a and 2c for viable BCP
synthesis with styrene, the homopolymerization kinetics of 2a and
2c were first monitored. In addition, the kinetics of the co-
polymerizations of styrene with 2aec were also studied to confirm
controlled polymerization behavior. In these initial studies,
monomer consumption and the absolute number-average MW
(Mn) values of the formed polymers were calculated by 1H NMR
integration and end-group analysis (see the Supplementary Data).
As can be seen in Fig. 2, the ATRP of 2a, the ATRP of 2c, and the
sequential ATRP of styrene followed by 2a (as a representative
copolymerization example) all show linear, first-order monomer
conversions with time and linear increases in Mn with monomer
conversion. This behavior indicates that these ATRP homo-
polymerizations and copolymerizations are well-controlled. By
varying the styrene and 2aec mole ratios in the sequential ATRP
reactions, nine BCPs (1aei) were obtained with three different
styrene:imidazolium-styrene block ratios and three different alkyl
side-chain lengths on the imidazolium-containing blocks.
2.3. Structure and molecular weight characterization of BCPs 1aei
The block composition ratios and absolute lengths of BCPs 1aei
were confirmed by 1H NMR analysis: The block lengths of the
polystyrene macro-initiators 3aec were determined by 1H NMR
end-group analysis using the trimethylsilyl (TMS) group on the
initiator as an integration reference. [29] The styrene:imidazolium-
styrene block ratios for each BCP were determined by integrating
and comparing distinct 1H NMR signals indicative of each block.
The ionic block lengths were then calculated based on the alkyl
block lengths and the block composition ratios. These results were
further confirmed by TMS end-group analysis [29] and the copo-
lymerization monomer-to-initiator ratios. Exposure of solutions of
1aei to AgNO3 did not show precipitate formation, indicating
negligible Bre in the BCPs. Consequently, the absolute Mn values for
BCPs 1aei could be calculated by simply multiplying the absolute
block lengths (as determined by 1H NMR) by the MWs of the repeat
units (see the Supplementary Data).
Unfortunately, GPC and other conventional polymer MW
determination methods (e.g., matrix-assisted laser desorption
ionization time-of-flight mass spectrometry, and light scattering)
could not be used to confirm the MW, PDI, or block structure of
1aei because of the unusual solubility and other physical
Fig. 2. Plots confirming the controlled ATRP homopolymerization of monomers 2a and
2c, and the sequential ATRP of styrene and 2a to form BCP 1d.

Z. Shi et al. / Polymer 55 (2014) 6664e6671
6667
properties of these noncharged-charged BCPs, as previously re-
ported [11a]. A modified GPC method that enables poly(IL) MW
determination was recently reported [27c]; however, we could not
modify the GPC system we used in such a fashion, and the hybrid
characteristics of noncharged-charged BCPs still presented solubi-
lity difficulties. Instead, a combination of alternative methods (i.e.,
surfactant behavior and solubility analysis, diffusion-ordered
spectroscopy (DOSY), small-angle X-ray scattering (SAXS) studies)
was used to verify the block architectures of 1aei and to differen-
tiate their behavior from that of a physical blend of polystyrene and
poly(2a)epoly(2c) homopolymers, as described previously [11a]
(see the Supplementary Data).
2.4. Characterization of the morphologies formed by BCPs 1aei
The room-temperature (25 ꢀC) morphological behavior of BCPs
1aei (following melt-phase annealing at 175 ꢀC for 30 min) from
SAXS analysis is summarized in Table 1. The SAXS profiles of these
samples at room-temperature after annealing are shown in Fig. 3.
The data confirm microphase separation for all BCP samples con-
taining methyl or n-butyl substituents on the imidazolium ring (i.e.,
1a, 1b, 1d, 1e, 1g, and 1h), regardless of the styrene:imidazolium-
styrene block ratios tested. In contrast, the BCPs with the longer
n-decyl substituent on the imidazolium block show no evidence of
microphase separation. We speculate that by increasing the non-
ionic character of the imidazolium substituent opposite the
phenyl linker, the ability of the system to separate the charged units
and create a thermodynamic advantage through microphase sep-
aration is becoming severely diminished. Differential scanning
calorimetry (DSC) measurements revealed no evidence of any
observable thermal transitions between ꢁ40 and 180 ꢀC, and thus
provided no additional insight into the microphase-separated state
of the systems beyond that provided by SAXS. That is, neither glass
transitions for the polymer blocks nor melt transitions associated
with the alkyl side-chains on the imidazolium units could be
detected in these samples. Details describing the DSC measure-
ments and representative DSC data can be found in the
Supplementary Data.
Fig. 3. SAXS profiles of BCPs 1aei at 25 ꢀC after annealing at 175 ꢀC for 30 min. The
inverted triangles indicate the expected SAXS reflection positions for spheres ordered
in a BCC lattice (1d, 1e, 1g, 1h) and hexagonally packed cylinders (1a, 1b).
Of the microphase-separated methyl and n-butyl samples, those
in which the styrene:imidazolium-styrene block ratios are fixed at
20:30 (1d, 1e) exhibit a particularly high degree of order. In fact,
both the methyl and n-butyl BCPs at this composition produce clear
diffraction peaks consistent with the symmetry of spheres on a
body-centered-cubic (SBCC) lattice, with the expected q/q* ratios of
√2 (q110), √4, √6, √8, etc. Here, q* ¼ q100 is absent due to the
reflection conditions associated with the BCC symmetry. Impor-
tantly, the q110 interplanar spacings at 25 ꢀC imply cubic unit cell
lattice constants of 16.6 and 15.5 nm for the methyl and n-butyl
substituted samples, respectively. Such large lattice constants
suggest chain stretching in these systems is significant, given the
small degrees of polymerization (DPs) used in this initial study.
Mahanthappa and coworkers saw similar evidence of chain
stretching in analogous noncharged-charged BCPs prepared by
postpolymerization modification [18]; however, their studies were
limited to compositions in which the charged imidazolium blocks
comprised only the minority component (i.e., ꢂ17 mol% of the total
number of repeat units). This was largely a constraint of the limited
DPs and MW control that they could achieve using a creative multi-
step, postpolymerization modification strategy to produce the
charged imidazolium block. In their case, they used NMP of styrene
and 4-vinylbenzyl chloride to produce modifiable polymeric pre-
cursors that were then quaternized with various N-alkylimidazoles,
followed by anion-exchange with Tf2Nꢁ [18]. In contrast, our
sequential ATRP of styrene and monomers 2aec reported here
enables these imidazolium-containing BCPs to be produced more
directly/easily and at compositions spanning the entire mole frac-
tion spectrum.
Table 1
Summary of the room-temperature morphologies formed by thermally annealed
BCPs 1aei according to SAXS analysis.
It is significant that the sphere morphology is present in BCP 1
homologs in which the charged imidazolium block comprises just
60 mol% of the repeat units in the chain. For BCPs in which the
repeat units of the two blocks are of similar volumes, such com-
positions would sit at the edge of the lamellar phase boundary. This
suggests the volume increase associated with adding the charged
imidazolium substituent to the phenyl ring in the polystyrene
backbone is substantial, and creates significant packing differences
between the ionic and nonionic blocks in the system. Mahanthappa
and coworkers actually saw lamellar morphologies forming at
BCP
n
m
R
Morphology
Observed q/q*100 values
√1, (√3), √4, √7, (√9)
1a
1b
1c
1d
1e
1f
1g
1h
1i
25 25 methyl
25 25 n-butyl
25 25 n-decyl Disordered
20 30 methyl
20 30 n-butyl
20 30 n-decyl Disordered
15 35 methyl
15 35 n-butyl
Hex (weakly ordered
Hex (weakly ordered) √1, (√3), √4, √7, (√9)
(none)
SBCC
SBCC
√2, √4, √6, √8
√2, √4, √6, √8
(none)
form scattering
form scattering
(none)
SLLP (weakly ordered)
SLLP (weakly ordered)
15 35 n-decyl Disordered

6668
Z. Shi et al. / Polymer 55 (2014) 6664e6671
imidazolium-containing repeat unit compositions as low as 8 mol%
[18]. Their results, taken together with ours, emphasize the rather
extreme asymmetry in packing introduced when one block carries
the charged imidazolium species.
supports the argument that the n-decyl substituent on the imida-
zolium ring is indeed acting to compatibilize the system. These data
also suggest that a judicious choice of alkyl substituent on the
imidazolium-styrene monomer provides a discrete method for
tuning the Flory interaction parameter for such systems. If true, one
might be able to control the ability of the system to adopt phases
like bicontinuous gyroid, which have demonstrated a clear prefer-
ence to form under more weakly segregated conditions [11b,18].
Similar to other imidazolium-based noncharged-charged BCPs
we produced in the past [11], many of the samples produced here
required an initial heating step to achieve their highest level of
order. For example, Fig. 4 shows that there is a sufficient delay in
obtaining highly ordered BCC spheres in the first heating cycle. The
gradual ordering process, evident by an evolution of the diffraction
pattern from one with broad, form factor oscillations at room
temperature, to one with multiple, easily resolved diffraction peaks
at 175 ꢀC and above. As mentioned previously, this type of behavior
in which liquid-like packing of spheres (SLLP) often exists prior to
development of the fully organized SBCC lattice is fairly common in
other BCP systems [11b,30]. As shown in Fig. 4, the highly ordered
structure established during the initial heating remains preserved
during subsequent cooling, with no evidence of any return to the
initial, less ordered state.
Based on these observations, one would expect BCPs 1a (methyl)
and 1b (n-butyl) with noncharged:charged block ratios fixed at
25:25 to exhibit phase behavior bounded by lamellae and sphere
phases. However, the broadness evident in the scattering peaks
(even after annealing at 175 ꢀC) suggests that while these samples
clearly phase-separate, they are challenged to find a well-ordered
morphology at these compositions. In Fig. 3, inverted triangular
markers above the SAXS profiles of BCPs 1a and 1b indicate the
positions of expected reflections for cylinders on a hexagonal lattice
(i.e., at q/q* ratios of √1 (q100), √3, √4, √7, √9, etc.). At this point, a
definitive assignment of the formed phase is not possible based on
scattering data alone.
The most asymmetric BCP samples (1g and 1h) with
styrene:imidazolium-styrene block ratios fixed at 15:35 are also
only weakly ordered. Based on the propensity of samples 1d and 1e
to adopt the SBCC lattice, the volume fraction of the styrene block in
1g and 1h may be significantly lower than the 0.10e0.14 range
associated with the SBCC phase. Samples in which the volume
fraction of one block approaches values less than 10% have been
found in many instances to adopt a liquid-like packing of spherical
domains (SLLP) [11b,30]. The scattering signature for these systems
is entirely consistent with that observed for 1g and 1h, with char-
acteristic shoulder adjacent to a broad primary peak associated
with form factor oscillations. Notably, these same scattering sig-
natures were also characteristic of the SBCC-forming samples (1d,
1e) prior to annealing (c.f., Fig. 4).
3. Summary
We have shown that imidazolium-based noncharged-charged
diblock copolymers (1) capable of forming ordered, phase-
separated nanostructures can be synthesized by the direct,
sequential ATRP of styrene and styrenic imidazolium bis(tri-
fluoromethyl)sulfonamide monomers containing different-length
alkyl side-chains. To our knowledge, the synthesis of
imidazolium-based BCPs of this type via direct ATRP of immiscible
co-monomers is unprecedented. SAXS studies on thermally
annealed initial examples of 1 with a total of 50 repeat units and
styrene:imidazolium-styrene repeat unit ratios of 25:25, 20:30, and
15:35 showed that their ability to form ordered nanostructures in
their neat states depends on both the block ratio and the length of
the alkyl side-chain on the imidazolium monomer. It was found
that only the BCP samples with the two shortest alkyl chains
(methyl and n-butyl) on the imidazolium monomer form ordered
nanostructures over the range of compositions tested: The methyl-
and n-butyl-imidazolium homologs with the most symmetric
noncharged:charged repeat unit ratio (25:25) exhibited scattering
signatures for weakly-ordered cylinders (hexagonal lattice), while
the methyl- and n-butyl-imidazolium BCPs with progressively
more asymmetric block ratios (20:30 and 15:35) formed spheres in
a body-centered cubic lattice or with more disordered liquid-like
packing character. In contrast, none of the BCPs containing the
longest imidazolium side-chain (n-decyl) exhibited any ordered
phase-separated structures regardless of block composition. This
result suggests that overly long alkyl chains on the ionic imidazo-
lium block can make it more miscible with the hydrophobic styrene
block and less conducive to mutual phase separation. Collectively,
these initial results with this directly polymerized IL-based BCP
system show that it may be able to target the formation of specific
phase-separated morphologies via judicious choice of
styrene:imidazolium-styrene block ratio and the nature of the
substituent(s) on the imidazolium-styrene monomer.
Inspection of each series of samples organized by fixed
styrene:imidazolium-styrene block ratio reveals that an increase in
the alkyl substituent chain length on the imidazolium ring pro-
duces a decrease in the principle domain spacing for the system.
This seemingly counter-intuitive result supports the argument that
adding nonionic character (via choice of alkyl chain length) to the
ionic block reduces the degree of segregation in the system, and
helps relieve the high degree of chain stretching required to reach a
free energy minimum. This shift towards decreased segregation
We are currently investigating if the homologs of 1 that exhibit
ordered morphologies can be fabricated into supported mem-
branes so that we can evaluate the contribution of their ordered
nanostructures in CO2/light gas separation applications. We are also
in the process of exploring a wider range of block length ratios and
the use of imidazolium-styrene monomers with other alkyl side-
Fig. 4. SAXS profiles of BCP 1d throughout the thermal annealing procedure. Peak
positions are consistent with those for spheres packed in a BCC lattice.

Z. Shi et al. / Polymer 55 (2014) 6664e6671
6669
chains in order to systematically map out the phase behavior of this
4.3. Synthesis of 1-decylimidazole
BCP system as a function of these two variables. Also of interest is
examining the effect of different associated anions in the imida-
zolium block on BCP phase behavior. It has recently been reported
that the counterion in noncharged-charged BCPs can play an
important role in controlling their morphologies [31]. One specific
objective in these structure-morphology investigations is seeing if
we can obtain a bicontinuous cubic/gyroid phase, which has so far
been elusive in imidazolium-based noncharged-charged BCPs. The
ability to directly synthesize the target BCPs via sequential ATRP of
styrene and a selected imidazolium-styrene monomer allows ready
access to the desired test materials. Future studies will also focus on
more detailed morphological analysis of the less ordered systems
using complementary visualization techniques such as electron
microscopy imaging.
This compound was synthesized using a variation of the pro-
cedure previously reported [32]. Sodium hydride (60% dispersion in
mineral oil, 1.56 g, 39.0 mmol) was suspended in dry THF (50 mL)
under Ar at 0 ꢀC. Imidazole (2.16 g, 31.7 mmol) was dissolved in dry
THF (20 mL) and added drop-wise. After 30 min, 1-bromodecane
(5.41 g, 24.5 mmol) was added. The resulting reaction mixture
was then stirred at room temperature overnight. After careful
addition of a few drops of water to quench the remaining sodium
hydride, the organic solvent was removed in vacuo, and diethyl
ether (50 mL) was added. This solution was then washed with
water (3 ꢃ 50 mL), dried over anhydrous MgSO4, filtered, concen-
trated, and then purified by flash chromatography (ethyl acetate/
hexanes ¼ 10/1 (v/v)) to give the product as a light yellow oil (yield:
4.38 g, 86%). Spectroscopic and purity data matched those reported
for this compound [32].
4. Experimental section
4.4. Synthesis of 1-(4-vinylbenzyl)-3-alkyl-imidazolium
bis(trifluoromethylsulfonyl)amide monomers (2)
4.1. Materials and general procedures
1-Bromodecane,
methylimidazole, 1-butylimidazole, 4-vinylbenzyl chloride, 2-(tri-
methylsilyl)ethanol, -bromoisobutyryl bromide, triethylamine,
sodium
hydride,
imidazole,
1-
These compounds were synthesized using a variation of the
procedures previously reported [27a,33]. The methods below detail
the synthesis of styrenic imidazolium monomer 2aec.
a
copper(I) bromide, butyronitrile, Dowex 50Wx4 ion-exchange
resin, benzoyl peroxide, N,N,N0,N0,N00-pentamethyldiethylenetri-
amine (PMDETA), and TEMPO were all purchased from the Sig-
maeAldrich Co., and used as received. Styrene was purchased from
the SigmaeAldrich Co. and purified by passage over a column of
basic alumina to remove the added radical inhibitor. Lithium bis(-
trifluoromethylsulfonyl)amide (LiTf2N) was purchased as Fluorad™
Lithium Trifluoromethane Sulfonimide from the 3M Company. All
solvents were purchased from SigmaeAldrich or Mallinckrodt, Inc.,
and purified/dehydrated via N2-pressurized activated alumina
columns, and de-gassed. The H2O used for synthesis was purified
4.4.1. Synthesis of 1-(4-vinylbenzyl)-3-methyl-imidazolium
bis(trifluoromethylsulfonyl)amide (2a)
(Note: This monomer has been reported in the literature, but the
complete synthesis and characterization data for only its chloride
derivative have been provided [33], not the Tf2Nꢁ analog 2a). 4-
Vinylbenzyl chloride (2.50 g, 16.4 mmol) and 1-methylimidazole
(1.48 g, 18.0 mmol) were stirred in acetonitrile (100 mL) at reflux
for 18 h. Upon cooling, the reaction mixture was concentrated to
form a yellow viscous oil and washed with Et2O (3 ꢃ 100 mL). The
resulting oil was then dissolved in H2O (100 mL), LiTf2N (5.17 g,
18.0 mmol) was added, and then the mixture stirred at room
temperature for 12 h. A yellow oil was then extracted from this
aqueous mixture with CH2Cl2 (3 ꢃ 50 mL). The CH2Cl2 layer was
then washed with H2O (3 ꢃ 100 mL), dried over anhydrous MgSO4,
filtered, and concentrated to give monomer 2a as a light yellow oil
and deionized, with resistivity greater than 12 MU/cm. All poly-
merizations were carried out in a dry Ar atmosphere using standard
Schlenk line techniques.
4.2. Instrumentation
(yield: 6.83 g, 87%). 1H NMR (300 MHz, CDCl3):
d8.77 (s, 1H), 7.43 (d,
1H and 13C NMR spectra were obtained using a Bruker 300
Ultrashield™ (300 MHz for 1H) spectrometer. Chemical shifts are
reported in ppm relative to residual non-deuterated solvent. HRMS
(ES) analysis was performed by the Central Analytical Facility in the
Dept. of Chemistry and Biochemistry at the University of Colorado,
Boulder. Gel permeation chromatography (GPC) was performed
using a Viscotek GPC-Max chromatography system outfitted with
three 7.5 ꢃ 340 mm Polypore™ (Polymer Laboratories) columns in
series, a Viscotek differential refractive index (RI) detector,ꢁa1nd an
Alltech column oven (mobile phase THF, 40 ꢀC, 1 mL min flow
rate). Molecular weight data obtained on this GPC system were
referenced to polystyrene molecular weight standards. NMR
diffusion-ordered spectroscopy (DOSY) experiments were per-
formed using a Varian Inova-400NMR spectrometer. Small-angle X-
ray scattering (SAXS) data were collected using a Rigaku SMax3000
J ¼ 8.2 Hz, 2H), 7.32 (d, J ¼ 8.2 Hz, 2H), 7.21 (dt, J ¼ 18.0, 1.8 Hz, 2H),
6.69 (dd, J ¼ 17.6, 10.9 Hz, 1H), 5.77 (d, J ¼ 17.6, 1H), 5.31 (d, J ¼ 10.9,
1H), 5.28 (s, 2H), 3.90 (s, 3H). 13C NMR (75 MHz, CDCl3):
d139.06,
135.92, 135.80, 131.69, 129.24, 127.30, 123.96, 122.21, 122.01, 117.76,
115.64, 53.29, 36.39. IR (neat): 3153.53, 1562.40, 1347.39, 1329.23,
1178.28, 1132.72, 1051.69, 994.24, 920.00, 830.65, 789.12, 739.18,
715.92, 635.47. HRMS (ES) calcd. for C15H15F6N3O4S2 (Mþ Tf2Ne):
479.0408; observed: 479.0424. Since imidazolium-based ionic
liquid compounds are known in the literature to have combustion
issues for C, H, and N elemental analysis [34], the 1H and 13C NMR
spectra for isolated 2a are provided in the Supplementary Data to
help confirm its purity.
4.4.2. Synthesis of 1-(4-vinylbenzyl)-3-butyl-imidazolium
bis(trifluoromethylsulfonyl)amide (2b) [27a]
High Brilliance three-pinhole SAXS system outfitted with
a
4-Vinylbenzyl chloride (2.00 g,13.1 mmol) and 1-butylimidazole
(1.79 g, 14.4 mmol) were stirred in acetonitrile (80 mL) at reflux for
18 h. Upon cooling, the reaction mixture was concentrated to form a
yellow viscous oil and washed with Et2O (3 ꢃ 80 mL). The resulting
oil was then dissolved in H2O (80 mL). LiTf2N (4.51 g, 15.7 mmol)
was added, and then the mixture stirred at room temperature for
12 h. A yellow oil was then extracted from this aqueous mixture
with CH2Cl2 (3 ꢃ 50 mL). The CH2Cl2 layer was then washed with
H2O (3 ꢃ 100 mL), dried over anhydrous MgSO4, filtered, and
MicroMax-007HFM rotating anode (Cu Ka), Confocal Max-Flux
optics, a Gabriel-type multi-wire area detector (1024 ꢃ 1024 pixel
resolution), and a Linkam thermal stage. Differential scanning
calorimetry (DSC) measurements were performed using a Mettler
Toledo DSC823e and a Julabo FT100 Intracooler. Energy-dispersive
X-ray spectroscopy (EDS) was performed using a JEOL JSM-6480
scanning electron microscope with an elemental detection lower
limit of carbon.

6670
Z. Shi et al. / Polymer 55 (2014) 6664e6671
concentrated to give monomer 2b as a light yellow oil (yield: 5.81 g,
85%). Spectroscopic and purity data matched those reported for this
compound [27a].
4.6.1. Example: synthesis of polystyrene macro-initiator 3a
Styrene (2.50 g, 24.0 mmol) and PMDETA (22.3 mg,
0.129 mmol) were added to a flame-dried Schlenk flask and
degassed by three freeze-pump-thaw cycles. The flask was then
allowed to warm to room temperature, back-filled with argon, and
CuBr (18.4 mg, 0.128 mmol) was added. The resulting mixture was
stirred at room temperature for 30 min and TMS-EBMP (229 mg,
0.857 mmol) was added. The flask was then place in an oil bath at
90 ꢀC for 22 h. The content of the flask was purified as described in
general procedures to give 3a as a white solid (yield: 2.25 g, 82%).
DP ¼ 25; PDI ¼ 1.12; Mn ¼ 2871 g/mol (calculated using 1H NMR
polymer end-group analysis. See the Supplementary Data for de-
tails on how the DP and absolute Mn were determined using 1H
NMR analysis).
4.4.3. Synthesis of 1-(4-vinylbenzyl)-3-decyl-imidazolium
bis(trifluoromethylsulfonyl)amide (2c)
4-Vinylbenzyl chloride (1.00 g, 6.55 mmol) and 1-
decylimidazole (1.50 g, 7.20 mmol) were stirred in acetonitrile
(40 mL) at reflux for 18 h. Upon cooling, the reaction mixture was
concentrated to form a yellow viscous oil and washed with Et2O
(3 ꢃ 40 mL). The resulting oil was then dissolved in H2O (40 mL).
LiTf2N (2.26 g, 7.87 mmol) was added, and then the resulting
mixture stirred at room temperature for 12 h. A yellow oil was then
extracted from this aqueous mixture with CH2Cl2 (3 ꢃ 50 mL). The
CH2Cl2 layer was then washed with H2O (3 ꢃ 100 mL), dried over
anhydrous MgSO4, filtered, and concentrated to give monomer 2c
as a light yellow oil (yield: 3.49 g, 88%). 1H NMR (300 MHz, CDCl3):
4.7. Synthesis of BCPs 1aei via ATRP of imidazolium-styrene
monomers 2aec from polystyrene macro-initiators 3aec
d
8.88 (s, 1H), 7.44 (d, J ¼ 8.2 Hz, 2H), 7.33 (d, J ¼ 8.2 Hz, 2H), 7.24 (dt,
J ¼ 12.0, 2.0 Hz, 2H), 6.69 (dd, J ¼ 17.6, 10.9 Hz, 1H), 5.78 (d, J ¼ 17.6,
1H), 5.31 (d, J ¼ 10.8, 1H), 5.31 (s, 2H), 4.16 (t, J ¼ 7.4 Hz, 2H),
In a typical procedure, the appropriate amount of the desired
imidazolium monomer 2, PMDETA, and butyronitrile were added
to a flame-dried Schlenk flask and degassed by three freeze-pump-
thaw cycles. After the flask was allowed to warm to room tem-
perature and back-filled with Ar, the appropriate amount of CuBr
was then added. The resulting mixture was then stirred at room
temperature for 30 min, and then the appropriate amount of the
desired polystyrene macro-initiator 3 was added. The flask was
then placed in a 90 ꢀC oil bath. Upon complete consumption of
monomer 2 (as verified by 1H NMR analysis), the contents of the
flask were cooled to room temperature, diluted with acetone,
stirred with Dowex 50Wx4 ion-exchange resin for 15 min, and then
filtered through a short plug of basic alumina. The resulting solu-
tion was then concentrated in vacuo, diluted with acetone, and
added to a MeOH/H2O (3/1 (v/v)) mixture. The resulting precipitate
was then dissolved in acetone, re-precipitated by adding into
hexanes, and isolated by filtration. This dissolution/precipitation
procedure was repeated one more time to give the desired BCP 1 as
a white solid (see Table S2 in the Supplementary Data). Contact of a
solution of the final BCPs with AgNO3 showed no AgBr precipitate
formation, indicating negligible Bre anion in the polymers. 1H NMR
analysis of the BCPs 1aei confirmed the absence of any residual
unreacted monomer. The synthesis of 1a is shown below as a
representative example. The synthesis details for BCPs 1bei are
provided in the Supplementary Data. The block compositions and
Mn values of 1aei were calculated based on the 1H NMR analysis
(see the Supplementary Data).
1.93e1.76 (m, 2H), 1.39e1.17 (m, 14H), 0.87 (t, J ¼ 7.0 Hz, 3H). 13
C
NMR (75 MHz, CDCl3):
d139.19, 135.83, 135.58, 131.69, 129.29,
127.41, 122.45, 122.24, 122.08, 117.82, 115.76, 53.46, 50.49, 31.95,
30.18, 29.51, 29.40, 29.34, 28.96, 26.24, 22.77, 14.21. IR (neat):
3146.88, 2927.24, 2856.85, 1560.77, 1456.43, 1348.21, 1182.03,
1133.87, 1053.89, 990.02, 914.86, 830.80, 788.70, 739.55, 653.29.
HRMS (ES) calcd. for
C
24H33F6N3O4S2 (Mþ Tf2Ne): 605.1817;
observed: 605.2435. Since imidazolium-based ionic liquid com-
pounds are known in the literature to have combustion issues for C,
H, and N elemental analysis [34], the 1H and 13C NMR spectra for
isolated 2c are provided in the Supplementary Data to help confirm
its purity.
4.5. Synthesis of 2-(trimethylsilyl)ethyl 2-bromo-2-
methylpropanoate (TMS-EBMP)
This compound was synthesized using the previously reported
procedure [27c]. Spectroscopic and purity data matched those re-
ported for this compound [27c].
4.6. Synthesis of polystyrene macro-initiators 3aec via ATRP of
styrene
These compounds were synthesized using a variation of the
procedures previously reported [35]. In a typical procedure, the
desired amount of purified styrene and PMDETA were added to a
flame-dried Schlenk flask and degassed by three freeze-pump-
thaw cycles. After the flask was then allowed to warm to room
temperature and back-filled with Ar, the desired amount of CuBr
was added. The resulting mixture was then stirred at room tem-
perature for 30 min, and TMS-EBMP was added. The flask was then
placed in a 90 ꢀC oil bath for 22 h. The contents of the flask were
cooled to room temperature, dissolved in acetone, stirred with
Dowex 50Wx4 ion-exchange resin for 30 min, and filtered through
a short plug of basic alumina. The resulting solution was then
concentrated in vacuo, diluted with Et2O, precipitated by adding
into MeOH, and the precipitate recovered by filtration. This disso-
lution/precipitation procedure was repeated two more times to
give the desired polystyrene macro-initiator 3 as a white solid
(Table 1). 1H NMR analysis of 3aec confirmed the absence of
unreacted styrene monomer. The synthesis of 3a is shown below as
a representative example. The synthesis details for 3b and 3c are
provided in the Supplementary Data. The DP and Mn values of 3aec
were calculated based on the 1H NMR end-group analysis (see the
Supplementary Data).
4.7.1. Example: synthesis of BCP 1a
Imidazolium monomer 2a (418 mg, 0.871 mmol), PMDETA
(24.0 mg, 0.139 mmol), and butyronitrile (1 mL) were added to a
flame-dried Schlenk flask and degassed by three freeze-pump-
thaw cycles. After the flask was allowed to warm to room tem-
perature and back-filled with Ar, CuBr (20.0 mg, 0.139 mmol) was
added. The resulting mixture was stirred at room temperature for
30 min, and macro-initiator 3a (100 mg, 0.0348 mmol) was added.
The flask was then placed in a 90 ꢀC oil bath and stirred. Upon
complete consumption of monomer 2a (as verified by 1H NMR
analysis), the resulting reaction mixture was purified as described
in the general procedure above to give BCP 1a as a white solid
(yield: 0.303 g, 58%). Block repeat unit molar ratio ¼ 1:1 (styr-
ene:imidazolium-styrene); block length composition ¼ 25-b-25
(styrene-b-imidazolium-styrene); Mn ¼ 14,856 g/mol (calculated
based on 1H NMR analysis. See the Supplementary Data for details
on how the copolymer block composition, block lengths, and Mn
were determined).

Z. Shi et al. / Polymer 55 (2014) 6664e6671
6671
(c) Vygodskii Y, Shaplov A, Lozinskaya E, Lyssenko K, Golovanov D,
Malyshkina I, et al. Macromol Chem Phys 2008;209:40.
[5] (a) Marcilla R, Curri ML, Cozzoli PD, Mart0ınez MT, Loinaz I, Grande H, et al.
Small 2006;2:507;
4.8. General procedure for verification of the controlled
polymerization character of the ATRP of styrenic imidazolium
monomers 2aec
(b) Fukushima T, Kosaka A, Yamamoto Y, Aimiya T, Notazawa S, Takigawa T,
et al. Small 2006;2:554.
[6] (a) Ho HA, Leclerc M. J Am Chem Soc 2003;125:4412;
(b) Ricks-Laskoski HL, Snow AW. J Am Chem Soc 2006;128:12402.
[7] For a recent review on morphologies of BCPs, see: Mai Y, Eisenberg A Chem
Soc Rev 2012;41:5969.
The appropriate amount of the desired styrenic imidazolium
monomer 2, PMDETA, and butyronitrile were added to a flame-
dried Schlenk flask and degassed by three freeze-pump-thaw cy-
cles. After the flask was allowed to warm to room temperature and
back-filled with Ar, the appropriate amount of CuBr was added. The
resulting mixture was stirred at room temperature for 30 min, and
then the appropriate amount of TMS-EBMP or the desired poly-
styrene macro-initiator 3 was added. The flask was then placed in a
90 ꢀC oil bath and stirred. At selected timed intervals, samples of
the reaction mixture were taken, and the polymers were precipi-
tated in MeOH/H2O (3/1 v/v) for NMR analysis (see the
Supplementary Data for details).
[8] Vijayakrishna K, Jewrajka SK, Ruiz A, Marcilla R, Pomposo JA, Mecerreyes D,
et al. Macromolecules 2008;41:6299.
[9] Mori H, Yahagi M, Endo T. Macromolecules 2009;42:8082.
€
[10] Karjalainen E, Chenna N, Laurinmaki P, Butcher SJ, Tenhu H. Polym Chem
2013;4:1014.
[11] (a) Wiesenauer EF, Edwards JP, Scalfani VF, Bailey TS, Gin DL. Macromolecules
2011;44:5075;
(b) Scalfani VF, Wiesenauer EF, Ekblad JR, Edwards JP, Gin DL, Bailey TS.
Macromolecules 2012;45:4262;
(c) Nguyen PT, Wiesenauer EF, Gin DL, Noble RD. J Membr Sci 2013;430:312;
(d) Wiesenauer EF, Nguyen PT, Newell BS, Bailey TS, Noble RD, Gin DL. Soft
Matter 2013;9:7923.
[12] He H, Luebke D, Nulwala H, Matyjaszewski K. Macromolecules 2014;47:6601.
http://dx.doi.org/10.1021/ma501487u. Publication Date (Web): September
17, 2014.).
4.9. Small-angle X-ray scattering (SAXS)
[13] Texter J, Vasantha VA, Crombez R, Maniglia R, Slater L, Mourey T. Macromol
Rapid Commun 2012;33:69.
[14] Agudelo NA, Elsen AM, He H, Lopez BL, Matyjaszewski K. J Polym Sci A: Polym
Chem 2014. http://dx.doi.org/10.1002/pola.27300 [Published on-line].
[15] Chanthad C, Masser KA, Xu K, Runt J, Wang Q. J Mater Chem 2012;22:341.
[16] Li J, Liang J, Wu W, Zhang S, Zhang K, Zhou H. New J Chem 2014;38:2508.
[17] (a) Stancik CM, Lavoie AR, Schutz J, Achurra PA, Lindner P, Gast AP, et al.
Langmuir 2004;20:596;
(b) Stancik CM, Lavoie AR, Achurra PA, Waymouth RM, Gast AP. Langmuir
2004;20:8975.
[18] Weber RL, Ye Y, Schmitt AL, Banik SM, Elabd YA, Mahanthappa MK. Macro-
molecules 2011;44:5727.
Small-angle X-ray scattering (SAXS) data were collected using a
sample-to-detector distance of 2.19 m. Copolymer samples were
sandwiched between Kapton windows (0.05 mm thick ꢃ 10 mm
diameter). Before collection of temperature-dependent SAXS data,
the sample stage temperature was allowed to equilibrate for 5 min
under vacuum, unless otherwise stated. Data were collected under
vacuum (~100 mtorr) with exposure times of 1200 s for all samples.
SAXS data were azimuthally integrated from the 2D detector pat-
terns and plotted as logarithmic intensity vs. the scattering wave
ꢀ
[19] Green MD, Choi J-H, Winey KI, Long TE. Macromolecules 2012;45:4749.
[20] Gu Y, Timothy P, Lodge TP. Macromolecules 2011;44:1732.
[21] (a) Rao AHN, Thankamony RL, Kim H-J, Namb S, Kim T-H. Polymer 2013;54:
111;
vector, q, defined as q ¼ (4
p/l) sin(2qB/2), where 2qB is the angle
between the incident and scattered waves.
(b) Rao AHN, Kim H-J, Namb S, Kim T-H. Polymer 2013;54:6918;
(c) Rao AHN, Kim H-J, Namb S, Kim T-H. Int J Hydrog Energy 2014;39:5919.
[22] Han GL, Xu PY, Zhou K, Zhang QG, Zhu AM, Liu QL. J Membr Sci 2014;464:72.
[23] (a) Green MD, Wan D, Hemp ST, Choi J-H, Winey KI, Heflin JR, et al. Polymer
2012;53:3677;
(b) Jangu C, Wang J-HH, Wang D, Sharick S, Heflin JR, Winey KI, et al. Mac-
romol Chem Phys 2014;215:1319.
[24] Adzima BJ, Venna SR, Klara SS, He H, Zhong M, Luebke DR, et al. J Mater Chem
A 2014;2:7967.
[25] Gao R, Wang D, Heflin JR, Long TE. J Mater Chem 2012;22:13473.
[26] Bara JE, Lessmann S, Gabriel CJ, Hatakeyama ES, Noble RD, Gin DL. Ind Eng
Chem Res 2007;46:5397.
[27] (a) Tang J, Tang H, Sun W, Radosz M, Shen Y. J Polym Sci A: Polym Chem
2005;43:5477;
Acknowledgments
Financial support for the work performed at CU Boulder was
provided by the Department of Energy ARPA-e program (grant: DE-
AR0000098) and matching funds from Total, S.A. (France). Financial
support for the work performed at CSU was provided by the Na-
tional Science Foundation (grant: CBET-1160026) and the ACS Pe-
troleum Research Fund (grant: 52018-ND7). SAXS studies were
performed at CSU using a regional instrument supported by the
National Science Foundation MRI Program (grant: DMR-0821799).
(b) He X, Yang W, Pei X. Macromolecules 2008;41:4615;
(c) He H, Zhong M, Adzima B, Luebke D, Nulwala H, Matyjaszewski K. J Am
Chem Soc 2013;135:4227;
Appendix A. Supplementary data
(d) Oh JY, Chi WS, Lee JH, Kim JH, Kang SW. Ind Eng Chem Res 2013;52:9607;
(e) Chi WS, Hong SU, Jung B, Kang SW, Kang YS, Kim JH. J Membr Sci
2013;443:54;
(f) Karjalainen E, Izquierdo DF, Marti-Centelles V, Luis SV, Tenhu H, Garcia-
Verdugo E. Polym Chem 2014;5:1437;
(g) Hu H, Yuan W, Zhao H, Baker GL. J Polym Sci A: Polym Chem 2014;52:121;
(h) He H, Averick S, Roth E, Luebke D, Nulwala H, Matyjaszewski K. Polymer
2014;55:3330;
(i) He H, Zhong M, Luebke D, Nulwala H, Matyjaszewski K. J Polym Sci A:
Polym Chem 2014;52:2175.
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.polymer.2014.11.009.
References
[1] For recent reviews on poly(IL)s, see: (a) Green O, Grubjesic S, Lee S,
Firestone MA. J Macromol Sci C Polym Rev 2009;49:339;
(b) Yuan J, Mecerreyes D, Antonietti M. Prog Polym Sci 2013;38:1009;
(c) Lu J, Yan F, Texter J. Prog Polym Sci 2009;34:431;
(d) Anderson E, Long T. Polymer 2010;51:2447;
(e) Jaeger W, Bohrisch J, Laschewsky A. Prog Polym Sci 2010;35:511.
[2] For a recent review on IL and IL monomer design, see: Green MD, Long TE
J Macromol Sci C Polym Rev 2009;49:291.
[3] (a) Ding S, Tang H, Radosz M, Shen Y. J Polym Sci A: Polym Chem 2004;42:
5794;
(b) Bara JE, Lessmann S, Gabriel CJ, Hatakeyama ES, Noble RD, Gin DL. Ind Eng
Chem Res 2007;46:5397.
[4] (a) Ohno H, Ito K. Chem Lett 1998;27:751;
[28] Long S, Wan F, Yang W, Guo H, He X, Ren J, et al. J Appl Polym Sci 2013:2687.
€
[29] Pach M, Zehm D, Lange M, Dambowsky I, Weiss J, Laschewsky A. J Am Chem
Soc 2010;132:8757.
[30] (a) Guo C, Bailey TS. Soft Matter 2010;6:4807;
(b) Scalfani VF, Bailey TS. Macromolecules 2011;44:6557.
[31] Sing CE, Zwanikken JW, Olvera de la Cruz M. Nat Mater 2014;13:694.
[32] Zhao H, Foss Jr FW, Breslow R. J Am Chem Soc 2013;130:12590.
[33] Zhao D, Fei Z, Ang WH, Dyson PJ. Small 2006;2:879.
[34] Schenkel MR, Zhao R, Robertson LA, Wiesenauer BR, Clark NA, Gin DL. Liq
Cryst 2013;40:1067. and references therein.
[35] Xia J, Matyjaszewski K. Macromolecules 2011;30:7697.
(b) Ohno H, Yoshizawa M, Ogihara W. Electrochim Acta 2004;50:255;