Surfactant Assembly within Pickering Emulsion Droplets for Fabrication of Interior-Structured Mesoporous Carbon Microspheres

Article abstract of DOI:10.1002/anie.201805022

Large-sized carbon spheres with controllable interior architecture are highly desired, but there is no method to synthesize these materials. Here, we develop a novel method to synthesize interior-structured mesoporous carbon microspheres (MCMs), based on the surfactant assembly within water droplet-confined spaces. Our approach is shown to access a library of unprecedented MCMs such as hollow MCMs, multi-chambered MCMs, bijel-structured MCMs, multi-cored MCMs, “solid” MCMs, and honeycombed MCMs. These novel structures, unattainable for the conventional bulk synthesis even at the same conditions, suggest an intriguing effect arising from the droplet-confined spaces. This synthesis method and the hitherto unfound impact of the droplet-confined spaces on the microstructural evolution open up new horizons in exploring novel materials for innovative applications.

Full text of DOI:10.1002/anie.201805022

A Journal of the Gesellschaft Deutscher Chemiker
Angewandte
Chemie
International Edition
www.angewandte.org
Accepted Article
Title: Surfactant Assembly within Pickering Emulsion Droplets
for Fabrication of Interior-Structured Mesoporous Carbon
Microspheres
Authors: Dawei Liu, Nan Xue, Lijuan Wei, Ye Zhang, Zhangfeng Qin,
Xuekuan Li, Bernard P. Binks, and Hengquan Yang
This manuscript has been accepted after peer review and appears as an
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of the final Version of Record (VoR). This work is currently citable by
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To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.201805022
Angew. Chem. 10.1002/ange.201805022
Link to VoR: http://dx.doi.org/10.1002/anie.201805022
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10.1002/anie.201805022
Angewandte Chemie International Edition
COMMUNICATION
Surfactant Assembly within Pickering Emulsion Droplets for
Fabrication of Interior-Structured Mesoporous Carbon
Microspheres
Dawei Liu, Nan Xue, Lijuan Wei, Ye Zhang, Zhangfeng Qin, Xuekuan Li, Bernard P. Binks, and
Hengquan Yang*
Abstract: Large-sized carbon spheres with controllable interior
architecture are highly desired, but there is no method to synthesize
these materials. Here, we develop a novel method to synthesize
interior-structured mesoporous carbon microspheres (MCMs), based
on the surfactant assembly within water droplet-confined spaces.
Our approach is shown to access a library of unprecedented MCMs
such as hollow MCMs, multi-chambered MCMs, bijel-structured
MCMs, multi-cored MCMs, “solid” MCMs, and honeycombed MCMs.
These novel structures, unattainable for the conventional bulk
synthesis even at the same conditions, suggest an intriguing effect
arising from the droplet-confined spaces. This synthesis method and
the hitherto unfound impact of the droplet-confined spaces on the
microstructural evolution open up new horizons in exploring novel
materials for innovative applications.
carbon nanospheres because it is non-trivial to realize delicate
control of their interior structure. Although spraying,[8] emulsion,[9]
aerosol-assisted self-assembly[5a] and dripping[10] methods have
been explored to prepare carbon materials, these approaches
are usually limited to producing spherical particles of sizes
ranging from sub-micron to a few microns.[8,9a] Moreover, the
resultant carbon microspheres fail to possess complex interior
structures because of the inability of these methods in
diversifying the assembly at a micron scale.
Herein, we report a novel approach to attain this goal. This
approach mainly involves independent formation of crust and
interior architectures. Water droplets in nanoparticle-stabilized
emulsions (Pickering emulsions) are used as spherical
templates to grow outer crusts because they are of much higher
stability than conventional surfactant-stabilized droplets.[11] The
surfactant-directed assembly inside the Pickering water droplets
is capitalized to create internal structures. Since nanoparticle
emulsifier and surfactants differ significantly in nature, our
strategy makes it possible to optionally tailor the interior
structure of MCMs through changing synthesis conditions, while
not affecting the outer crust. To the best of our knowledge, for
the first time, surfactant assembly inside Pickering droplets is
proposed to synthesize materials although Pickering droplets
were previously reported to be used as spherical templates to
fabricate polymer microspheres.[12] Our method is shown to
access a library of unprecedented micron-sized carbon spheres
with novel interior structures including hollow MCMs, multi-
chambered MCMs, bijel-structured MCMs, multi-cored MCMs,
“solid” MCMs, and honeycombed MCMs.
Carbon spheres are one of the most important materials for
catalysis, separation, and energy storage.[1] Driven by their
appealing applications, various carbon spheres with hollow,[2]
yolk–shell,[3] and multi-shell[4] architectures have been
successfully fabricated. However, these achievements are
largely limited to nanometer-sized carbon microspheres. In fact,
for many practical applications, micron-sized spheres are highly
desirable because of easy processing and separation compared
to nanospheres.[5] More desirable is those mesoporous carbon
microspheres that possess
a
hierarchical or multi-
compartmentalized interior structure because such a structure
can significantly benefit mass transport-relevant processes[6] and
enable spatio-temporal control of a chemical process occurring
in their interior.[7]
The synthesis process started with preparation of a water-in-
oil Pickering emulsion by homogenizing a mixture of toluene and
water in the presence of phenolic resol (oligomer), NaOH, silica
particles (Pickering emulsifier) and the amphiphilic triblock
polymer Pluronic F127. Subsequently, polymerization at
oil/water interfaces and within water droplets took place at 80–
110 oC, forming polymer microspheres. After carbonization at
600 oC MCMs were obtained. The morphology and internal
structure of the obtained samples were characterized by
scanning electron microscopy (SEM). For example, the sample
synthesized at 0.4 mol L–1 NaOH (100 oC, 30 wt% phenol)
consists of discrete, regular spheres of 60–80 μm in size and
their surfaces are relatively smooth (Figures 1A,B). From their
cross-sections, one can see there are numerous uniform small
spheres of ca. 5 μm inside the hollow microsphere (Figures
1C,D). The crust thickness of hollow microspheres is 2–3 μm
(Figure S1). This material is accordingly denoted as multi-cored
MCMs. Transmission electron microscopy (TEM) images
(Figures 1E,F) show large domain regularity with a well-ordered
However, fabrication of interior-structured mesoporous carbon
microspheres (MCMs) is extremely challenging in comparison to
[*]
D. Liu, Dr. Y. Zhang, Prof. Z. Qin, Prof. X. Li
State Key Laboratory of Coal Conversion, Institute of Coal
Chemistry, Chinese Academy of Sciences
Taiyuan 030001, China
D. Liu, N. Xue, L. Wei, Prof. H. Yang
School of Chemistry and Chemical Engineering, Shanxi
University
Taiyuan 030006, China
E-mail: hqyang@sxu.edu.cn
D. Liu
University of Chinese Academy of Sciences
Beijing 100049, China
Prof. B. P. Binks
School of Mathematics and Physical Sciences, University of Hull
Hull HU6 7RX, United Kingdom
Supporting information and the ORCID identification number(s)
for the author(s) of this article can be found under
http://dx.doi.org/10.1002/anie.xxxxxxxxx
̅
body-centered cubic (Im3m) mesostructure. Their N2 sorption
isotherm shows a typical type-IV curve and two hysteresis loops
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10.1002/anie.201805022
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mol L–1 led to “solid” microspheres (Figures 2A, S4C and S5).
Their ordered mesoporous structures are also confirmed by N2
sorption analysis (Figure S4D), XRD measurement (Figure S4E)
and TEM observation (Figure S4F).
A)
B)
C)
D)
In parallel, we found that when the polymerization temperature
was decreased from 100 down to 80 and 90 C or increased up
100 μm
10 μm
10 μm
5 μm
o
I)
to 110 oC (0.4 mol L–1 NaOH, 30 wt% phenol), the interior
structure and external surface underwent a considerable change.
For the MCMs synthesized at 80 oC, there are many
homogeneously distributed micrometer-sized holes on their
external surface (Figure S6A). Interestingly, their interior exhibits
a coarsened bijel (bicontinuous) structure,[15] in which many
gullies are three-dimensionally interconnected (Figures 2B and
S6A). When the polymerization temperature was increased to 90
oC, the holes on the external surface nearly disappeared and the
bijel interior structure was more pronounced (Figures 2B and
S6B). When the polymerization temperature was raised to 110
oC, a honeycombed structure was observed within microspheres
(Figures 2B and S6C). N2 sorption analysis confirmed their
mesoporous structures (Figure S7).
E)
F)
50
40
30
20
10
0
3)
D=112 μm
200
5
5
5
14
200 μm
35 45
5-1
<85
85-95
150
100
50
-105
5-11 5-12 5-1
10 11 12
>
95
200 μm
Size (m1)3
50
40
30
20
10
0
D=200 μm
2)
20 nm
20 nm
5
5
5
5
5
5
265
145
<
>
240
1)
145-1
16
2
05-2
2
2
2
4
65-1S188i5z-2e0 (2m5-2)45-26
110
H)
220 G)
50
40
30
20
10
0
D=59 μm
200
180
160
140
200
211
0
40
80
>
<
40-50 50-60 60-70
Size (m7)0-80
100 μm
0.0
0.2
0.4
0.6
0.8
1.0
1
2
3
4
Relative Pressure (P/Po
)
2θ (degree)
Emulsification conditions
Figure 1. A–H) Characterization of multi-cored MCMs. A) Low magnification
SEM image. B) SEM image for a single microsphere. C) SEM image showing
the interior structure of microsphere cut deliberately. D) High magnification
SEM image showing its interior structure. E) TEM image viewed from [110]
direction. F) TEM image viewed from [100] direction. G) N2 adsorption-
desorption isotherm. H) Small-angle XRD pattern. I) SEM images and tuning
of MCMs size through varying emulsification conditions: (1) 25,000 rpm, 2.5 wt%
silica emulsifier; (2) 8,000 rpm, 2.5 wt% silica emulsifier; (3) 8,000 rpm, 1.5 wt%
silica emulsifier.
Another interesting observation is that the dosage of carbon
precursor also induced changes in the interior structure. When a
o
limited amount of phenol (7.5 wt%, 0.4 mol L–1 NaOH, 100 C,
molar ratio of phenol to formaldehyde was fixed at 1:2 for all
cases) was used, crumpled hollow MCMs with crust thickness of
about 1 μm were obtained (Figures 2B and S8B). It is worth
mentioning that this crust still possesses a mesoporous structure,
which is confirmed by XRD (Figure S9A), N2 sorption analysis
(Figure S9B) and TEM observation (Figure S10). Increasing the
(Figure 1G). The former hysteresis loop belongs to an H1-type
and the latter features an H3-type. They correspond to
mesopores and the void spaces arising from stacking of inner
carbon nanospheres, respectively. The specific surface area,
pore volume and pore size of MCMs were determined
respectively to be 580 m2 g–1, 0.36 cm3
g–1 and 7 nm (Figure S2). The pore size
Multi-chambered
Multi-cored
MCMs
“Solid”
MCMs
“Solid”
MCMs
A)
MCMs
is much larger than those of typical
mesoporous carbon materials,[13] due to
the swelling effects caused by toluene.
The small-angle X-ray diffraction (XRD)
pattern exhibits an intense diffraction
peak at 2θ = 0.6o together with two
weak diffraction peaks at 0.9o and 1.2o
(Figure 1H). These peaks can be
Base: 0.2 mol L−1
0.4 mol L−1
0.6 mol L−1
0.8 mol L−1
indexed as (110), (200) and (211)
Coarsened bijel-structured
Bijel-structured
MCMs
Multi-cored
MCMs
Honeycombed
MCMs
B)
MCMs
̅
reflections of body-centered cubic Im3m
symmetry,[14] which is in agreement with
the TEM results. Notably, after removal
of the initially added silica emulsifier
from the surfaces of MCMs using HF,
their morphology, interior structure and
ordered mesopores were well preserved,
and the surface area and pore volume
gained a slight increase (Figure S3).
80 oC
90 oC
100 oC
110 oC
Temperature
Interestingly, we found that the interior
structure of MCMs strongly depended
on the base concentration applied
although the spherical morphology was
not altered. When decreasing the NaOH
concentration from 0.4 to 0.2 mol L–1,
plenty of macropores of 1.5–3.0 μm
appear. The macropores are distributed
homogeneously throughout the interior
of the microspheres (Figures 2A and
S4A; referred as to multi-chambered
Multi-chambered
MCMs
Hollow MCMs
MCMs).
Increasing
the
NaOH
Figure 2. SEM images showing the interior structural evolution of MCMs as a function of A) base
concentration, and B) temperature and amount of phenol. Scale bar = 10 μm.
concentration up to 0.6 and then to 0.8
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phenol amount to 15 wt% led to multi-chambered MCMs
(Figures 2B and S8A). When the phenol amount reached 30
wt%, multi-cored MCMs were produced (earlier).
reaches a certain threshold value, homogeneous nucleation and
growth within the droplet-confined spaces begins to occur
(Figure 3B). It is should be noted that amphiphilic F127 can
stabilize small oil drops within the water droplets, forming an oil-
in-water-in-oil (O/W/O) multiple emulsion. This is validated by
optical microscopy observation (Figure S16A). Due to the high
Laplace pressure,[17b] these oil drops are stable only at relatively
low temperatures or low base concentrations. The presence of
toluene drops inside water droplets leads to a multi-chambered
structure because the polymerization of nanomicelle composites
takes place outside the inner toluene drops. Under certain
conditions, induced by the polymerization, the enclosed liquid
mixture including toluene, water, nanomicelle composites and
Besides the interior structure, the size of MCMs can be tuned
through variation of the size of the water droplets. It is well
known that higher particle concentration and higher stirring
speed lead to smaller Pickering emulsion droplets.[16] Following
this principle, the average diameter of resultant MCMs can be
tuned from 59 μm to 200 μm (Figure 1I), highlighting the
additional flexibility of our synthesis protocol. It is worth
emphasizing that each type of MCM has good structural
homogeneity, which is confirmed by multiple SEM images for
each sample (Figures S11 and S12). It is not surprising when
one considers that each individual droplet provides a very similar
microenvironment for the structural evolution, ensuring the high
uniformity.
Given such a diversity of the interior structures, we are aware
of the uniqueness of the underlying mechanism for the structural
evolution. The phenolic resol oligomers co-assemble with F127
through hydrogen bonding interactions, forming nanomicelle
composites within the water droplets.[14] These composites
migrate towards the oil/water interface, deposit there and further
grow into mesoporous structures around the inner surfaces of
water droplets (Figure 3A). This is because the liquid-liquid
interface can induce heterogeneous nucleation, which requires a
lower energy in comparison to homogeneous nucleation.[17a] The
preferential growth of the shell is supported by a control
experiment, in which a limited amount of phenol (7.5 wt%) leads
to a crust alone (Figure 2B). As such, the surface of each droplet
acts as geometric template for growing a spherical crust. This is
confirmed by another control experiment, in which the absence
of droplets led to irregular morphology (Figures S13 and S14).
Besides directing the ordered mesoporous structure, the
presence of F127 helps to form smooth surfaces, which is
supported by the F127-free experiment (Figure S15). When the
concentration of nanomicelle composites within water droplets
F127
undergoes
microphase
change
via
spinodal
decomposition,[18a] yielding a bijel (bicontinuous) phase. The
polymerization facilitates the instant solidification and arrest of a
local metastable phase of the viscous liquids, yielding bijel-
structured MCMs. Because the solidification rate is relatively
o
o
slow at 80 C, a coarsened bijel structure is captured. At 90 C
its rate increases, leading to finer bijel structure. As
a
polymerization proceeds, the inner toluene is hunted out,
generating holes on the surface of MCMs, as evidenced by the
SEM images in Figure S6A. Upon increasing the temperature or
increasing the concentration of base, inner toluene drops cannot
form at the beginning (Figure S16B) and the confined space
becomes
a completely aqueous environment. High base
concentration and high temperature promote formation of more
nuclei, which subsequently grow into nanospheres within the
hollow MCMs (multi-cored MCMs). When increasing the NaOH
concentration up to 0.6 mol L–1, oligomers bear more
charges.[18b] As a result, all the oligomers are distributed within
water droplets. More precursors available for polymerization
lead to a monolith structure within the confined spaces (“solid”
MCMs), which is supported by the mass measurement of the
resultant polymer microspheres (Table S1). When the
temperature reaches 110 oC, gaseous water is generated and
small bubbles form inside the water droplets.
These small bubbles can be stabilized by
Polymerization at the oil/water interface:
A)
amphiphilic F127 molecules or nanomicelle
composites by adsorption at their surface.
This case leads to a honeycombed interior
structure (honeycombed MCMs). These
microstructures form during polymerization,
which is confirmed by their SEM images
captured for the polymers (Figures S17 and
S18).
Hydrogen-bonding Interaction
CH3
HO CH2CH2
O
CH2CH2
O
CH2CHO CH2CH2
O
H
n
n
m
H
O
H
H
O
O
O-
H2
C
H2
C
H2
C
CH2OH
HOH2
C
n
Hollow MCMs
Surfactant-directed assembly within a droplet-confined space:
B)
In the presence of gas
Such a unique mechanism is related to the
droplet-confined spaces. This is supported
by comparison with synthesis in bulk
systems (Figures S13 and S14). Using bulk
systems (the synthesis conditions are exactly
the same conditions as those in emulsion
systems), the honeycombed, coarsened bijel,
pronounced bijel, and multi-cored structures
were not obtained, but instead irregular
particles without complex microstructures
were generated. Such an impact is
In the presence of toluene inside the droplet
In the absence of toluene inside the droplet
bubbles inside the droplet
Multi-chambered
MCMs
Bijel-structured
MCMs
Multi-cored
MCMs
“Solid”
MCMs
Honeycombed
MCMs
understandable
when
considering
microphase changes. In the confined spaces
created by the droplets and subsequent solid
crusts where the efflux and influx are
restricted, the microphase change of the
viscous liquids proceeds relatively slowly.
Water
Toluene
Resol
F127
Aggregation
Bubble
Nanomicelle composite
Figure 3. Schematic illustration of the formation mechanism of various interior-structured MCMs. A)
Interfacial polymerization of phenolic resol in the presence of F127. B) Evolution of the interior
structures.
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(multi-cored) catalyst gave above 93% conversions. From the
seventh to the tenth cycle, 87–96% conversions were still
obtained through prolonging the reaction time (Figure S20D).
The results of a hot filtration experiment show that the catalytic
activity of the filtrate is very low and ca. 0.1 ppm Ru was
detected in the filtrate (Figure S23). The recyclability of the
Ru/MCMs was superior to that of a benchmarking catalyst Ru-
supported commercial active carbon (Figures S24 and S25A).
The Ru NPs size of the spent Ru/MCMs catalyst was
determined to be ca. 2.2 nm (only slight increase in size, Figure
S21D), which is much smaller than that of the benchmarking
catalyst (5 nm, Figure S25B). This could be ascribed to the
mesoporous structure that prevents the aggregation of Ru NPs.
Furthermore, MCMs can be incorporated with catalytically
active sites even involving multi-components. After confirming
that our protocol enables the synthesis of nitrogen (N)-
functionalized MCMs (Figures S26–S28 and Table S6), we
simultaneously introduced both N and Co elements into MCMs
via a one-pot synthesis, expecting that Co nanoparticles (NPs)
interact with N-rich carbon surfaces.[20a] The N, Co co-decorated
catalyst was prepared via simple modification of the above
synthesis protocol by adding Co(OAc)2·4H2O and melamine at
the beginning (Figure S29). Nitroarene hydrogenation was used
to evaluate these catalysts. Over the optimized catalyst
A)
B)
In confined spaces
16
14
12
10
8
110
200
211
Assembly
6
4
2
20 nm
50 nm
0
1
2
3
5
2θ (degree) 4
F127
Resol
SiO2
In the bulk system
8
7
6
5
4
3
2
1
0
110
Toluene
Nanomicelle
composite
20 nm
50 nm
1
2
3
5
2θ (degree)4
Im m
Figure 4. Comparisons of mesopore ordering of carbon materials synthesized
in the confined system and in the bulk system, and mechanism for ordering
enhancement. A) Small-angle XRD patterns and TEM images of carbon
materials synthesized (0.4 mol L–1 NaOH, 100 oC, 30 wt% phenol) in droplet-
confined spaces and in the bulk system. B) Formation of Im3m mesostructure
within the droplet-confined space.
̅
This scenario benefits solidification and arresting of the
structures of local metastable phases.[18a]
More impressively, the droplet-confined spaces also impact
the mesopore ordering. As Figure 4A shows, even under exactly
the same conditions, the small-angle XRD pattern of MCMs
exhibits an apparent increase in the intensity of the (110)
diffraction peak when compared to the material synthesized in
the bulk system. Remarkably, the former clearly exhibits (200)
and (211) diffraction peaks, while the latter does not. Such a
periodicity enhancement is further confirmed by TEM
observation (Figure 4A). Moreover, MCMs synthesized at other
temperatures and base concentrations also exhibit significant
enhancement in mesopore periodicity as compared to the
materials synthesized in bulk (Figures S4E, S13 and S19).
These findings point to the fact that a long-range mesopore
ordering enhancement originates from the droplet-confined
spaces. In the bulk system, the driving force for self-assembly is
mainly dictated by weak interactions between nanomicelle
composites, while in the droplet systems the confinement-
induced entropy loss may help to improve the periodicity and
promote the close packing of nanomicelle composites (Figure
4B), which was observed in silica–surfactant assemblies in the
cylinder-confined system.[18c]
To verify the merits of these interior-structured MCMs, we
examined their catalytic performance with the hydrogenation of
levulinic acid to γ-valerolactone.[19] Ru nanoparticles (NPs, 2.0
nm; Figures S20A,B and S21A–C) were introduced into their
mesopores through an impregnation method (Table S2), leading
to catalysts for this reaction. It was found that the hydrogenation
rate significantly depends on their interior structure although the
selectivity was 100% in all cases (Figure S20C). After 80 min the
conversion order is: Ru/MCMs (multi-cored, 99%) > Ru/MCMs
(bijel-structured, 93%) > Ru/MCMs (multi-chambered, 85%) >
Ru/MCMs (“solid”, 78%). These differences should be attributed
to the difference in diffusional transport within microspheres
since both the experiment of varying stirring rate and the Weisz–
Prater criterion (see notes in Figure S22) revealed that this
reaction was limited by diffusion. To the best of our knowledge,
this is the first attempt to improve the diffusivity of micron-sized
carbon sphere-based catalysts through finely tuning their interior
structures. Another attractive feature of these catalysts is easy
separation from the reaction system through simple filtration,
and does not require high-speed centrifugation. From the
second to the sixth reaction cycle, the recovered Ru/MCMs
o
Co/NMCMs-900 (900 means carbonization at 900 C) with a 2.5
wt% Co loading, nitrobenzene was fully converted to aniline with
> 99% selectivity within 3 h (Tables S3–S5). This catalyst
worked well for other nitroarenes containing methyl, vinyl,
methoxyl, amino, chloro- and bromo-substituents (Figure S30).
99% conversions and above 94% selectivity were obtained
within 4–6 h. Its activity and selectivity are comparable to the
reported catalysts prepared with expensive Co complex
precursors or special supports such as carbon nanotubes.[20]
The turn over number (TON) for ten reaction cycles reaches 982,
which is even higher than most Co-based catalysts (Figures S31,
S32 and Table S7).[20] The high activity and stability can be
explained by the possibility that our synthesis protocol allows N
and C precursors and Co salts to be mixed in water droplets at a
molecular level, thus enhancing their strong interactions.
In summary, a method based on surfactant assembly within
Pickering emulsion droplet has been successfully developed for
the fabrication of uniform mesoporous carbon micrometer-sized
spheres with complex interior structures. This approach allows
the interior architecture to be easily tailored through adjustment
of synthesis parameters, leading to a library of unprecedented
interior-structured
mesoporous
carbon
microspheres.
Impressively, Pickering emulsion droplets were found to not only
play an important role in the evolution of the complex interior
structure but also significantly enhance the periodicity of
mesoporous structures, suggesting a novel confinement effect.
The interior-structured microspheres exhibited significantly
enhanced diffusivity and ability to be separated, highlighting their
superiority in technical applications. Moreover, this approach
proves adaptable to fabrication of N-Co co-decorated MCMs
catalysts via a one-pot synthesis, which exhibited excellent
activity, selectivity and recyclability in the selective
hydrogenation of nitroarenes. The results presented here open
up new horizons in carbon materials as well as other inorganic
materials research as they not only supply a novel avenue to
fabrication of micron-sized spheres with complex interior
structures but also shed light on insights into the profound
impact of the droplet-confined space on the evolution of the
microstructure.
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Acknowledgements
[11] M. Zhang, L. Wei, H. Chen, Z. Du, B. P. Binks, H. Yang, J. Am. Chem.
Soc. 2016, 138, 10173−10183.
[12] a) Y. Yang, Z. Wei, C. Wang, Z. Tong, ACS Appl. Mater. Interfaces
2013, 5, 2495-2502; b) M. Li, R. L. Harbron, J. V. Weaver, B. P. Binks,
S. Mann, Nat. Chem. 2013, 5, 529-536.
This work is supported by the Natural Science Foundation of
China (21733009, 21573136 and U1510105), the Program for
New Century Excellent Talents in University (NECT-12-1030),
and the Program for Youth Sanjin Scholar.
[13] T. Y. Ma, L. Liu, Z. Y. Yuan, Chem. Soc. Rev. 2013, 42, 3977−4003.
[14] Y. Meng, D. Gu, F. Zhang, Y. Shi, H. Yang, Z. Li, C. Yu, B. Tu, D. Zhao,
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[15] C. Huang, J. Forth, W. Wang, K. Hong, G. S. Smith, B. A. Helms, T. P.
Russell, Nat. Nanotechnol. 2017, 12, 1060−1063.
Keywords: Pickering emulsions • surfactant assembly • carbon
microspheres • mesoporous materials • confinement effects
[16] M. Zhang, R. Ettelaie, T. Yan, S. Zhang, F. Cheng, B. P. Binks, H. Yang,
J. Am. Chem. Soc. 2017, 139, 17387−17396.
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10.1002/anie.201805022
Angewandte Chemie International Edition
COMMUNICATION
COMMUNICATION
Dawei Liu, Nan Xue, Lijuan Wei, Ye
Zhang, Zhangfeng Qin, Xuekuan Li,
Bernard P. Binks, and Hengquan
Yang*
Confinement
Surfactant assembly within Pickering
droplet-confined spaces makes
difference in the fabrication of
inorganic microspheres. It is
demonstrated that library of
mesoporous carbon microspheres
(MCMs) including hollow MCMs,
multi-cored MCMs, multi-chambered
is
powerful:
a
a
Surfactant Assembly within
Pickering Emulsion Droplets for
Fabrication of Interior-Structured
Mesoporous Carbon Microspheres
MCMs,
bijel-structured
MCMs,
honeycombed MCMs and “solid”
MCMs come into the world.
This article is protected by copyright. All rights reserved.