Materials Letters 188 (2017) 201–204
Contents lists available at ScienceDirect
Materials Letters
journal homepage: www.elsevier.com/locate/matlet
Hydrophobic polycarbonate monolith with mesoporous nest-like structure:
an effective oil sorbent
MARK
⁎
Bo Wang , Weiwei Chen, Lutong Zhang, Zhenzhen Li, Chuntai Liu, Jingbo Chen, Changyu Shen
College of Materials Science and Engineering, National Engineering Research Center for Advanced Polymer Processing Technology, Zhengzhou University,
Zhengzhou 450001, PR China
A R T I C L E I N F O
A BS T RAC T
Keywords:
Polymers
Phase separation
Porous materials
Oil sorbent
Polycarbonate (PC) monolith with three-dimensional interconnected mesoporous nest-like structure was first
fabricated by thermally impacted nonsolvent-induced phase separation (TINIPS) method. Owing to continuously interlaced nanofibrous skeleton, the monolith possessed a high specific surface area of 95.02 m2/g. This
novel structure also contributed to the improvement of hydrophobicity so that a high water contact angle of
143.9° was obtained. Furthermore, the as-prepared monolith could effectively adsorb various types of oils.
Based on such a unique structure as well as these outstanding properties, the PC monolith will play a big role in
the field of oil sorbents.
1. Introduction
Polymer monoliths with well-formed porous structure have
achieved great progress during the past 25 years and received
considerable attention from both academia and industry [1]. Due to
the porous structure, they possess a number of outstanding properties
such as rapid adsorption rate [2], high adsorption capacity [3] and
large porosity [4]. Therefore, many researchers focused on the application of polymer monolith as oil sorbent [3,5], with the intention to
solve the rising problem of oil pollution.
Polycarbonate (PC), a typical engineering thermoplastic in industry,
is distinguished by excellent mechanical property, dimensional stability
and thermostability. Due to its superior overall performance, porous
PC monoliths have great potential in the field of functional materials.
However, the research on PC monoliths is rarely reported up to now,
especially for their oil adsorbability. A successful fabrication of PC
monoliths with submicron-scale porous structure via nonsolventinduced phase separation (NIPS) method was achieved by Uyama
et al. and the relationship between fabrication parameter and morphology was studied [6]. Subsequently, they investigated the chemical
modification of PC monoliths [7].
Recently, we successfully fabricated PC monolith with mesoporous
nest-like structure via thermally impacted nonsolvent-induced phase
separation (TINIPS) method [8], which introduces a thermal factor
into NIPS. This preparation method is facile and low-cost because of
that it can be carried out without any template or complicated
equipment. The microstructure, hydrophobicity and oil adsorbability
⁎
of PC monolith were detailedly investigated. It is worth noticing that
the monolith exhibited high adsorption capacity for various types of
oils.
2. Experimental
2.1. Materials
PC pellets (Wonderlite PC-110 supplied by Chi Mei Corporation,
Taiwan) were used as the main raw material. Tetrahydrofuran (THF,
AR) was purchased from Tianjin Fuyu Fine Chemical Co., Ltd., China.
Deionized water was supplied by Nabaichuan Water Treatment
Equipment Co., Ltd., China. Oils (soybean oil, lubricating oil and
methylsilicone oil) and coloring agents (potassium permanganate for
water and Sudan III for oils) were used as received.
2.2. Fabrication of PC monolith
Firstly, PC pellets (7.0 g) were dissolved in THF (100 mL) at 40 °C.
After cooling down to room temperature, a certain amount of deionized
water (nonsolvent) was added into the PC solution dropwise under
strong stirring. The resultant solution was transferred into glass tubes
and kept at 4 °C for 24 h, during which phase separation took place to
form PC monolith. The residual solvent in monolith was entirely
replaced by immersion in deionized water. Finally, PC monolith was
freeze dried in vacuum at −90 °C for 48 h. (see Fig. S1 in
Supplementary Data).
Corresponding author.
E-mail address: [email protected] (B. Wang).
http://dx.doi.org/10.1016/j.matlet.2016.11.015
Received 29 December 2015; Received in revised form 10 August 2016; Accepted 5 November 2016
Available online 09 November 2016
0167-577X/ © 2016 Elsevier B.V. All rights reserved.
Materials Letters 188 (2017) 201–204
B. Wang et al.
Fig. 1. (a) Nitrogen adsorption-desorption isotherms and (b) pore width distribution of PC monolith.
Fig. 2. SEM images of PC monolith at different magnifications: (a) 5k, (b) 10k, and (c) 20k.
shown in Fig. 1a. The adsorption isotherm is classified as type IV,
indicating the existence of mesopores. The hysteresis loop is ascribed to
type H1, which suggests that cylindrical or wedge-like pores exist in the
monolith [9]. The pore width distribution (2.7–60.3 nm) is plotted in
Fig. 1b. It is clear that most of the pores are mesopores and a peak pore
width appears at 12.9 nm. The BET specific surface area of PC
monolith is 95.02 m2/g. The above results show that the PC monolith
is a mesoporous material with nanoscale pores and large specific
surface area.
The morphology of PC monolith is exhibited in Fig. 2. A novel nestlike structure composed of nanofiber network is observed. On the
whole, the porous morphology is homogeneous without any obvious
defect. The skeletons consisting of different-sized nanofibers interlace
with each other so as to form an interconnected porous structure. To
measure the size distribution of nanofibers, Image Pro Plus 6.0
software was employed and 100 nanofibers in Fig. 2c were randomly
selected to increase accuracy. The diameters of nanofibers range from
20.9 to 109.7 nm (with an average of 61.6 nm), showing a relatively
narrow size distribution. Undoubtedly, such uniform and interconnected porous structure suggests that the phase separation of PC
monolith is governed by spinodal phase separation mechanism [10]
(see Fig. S2 in Supplementary Data).
2.3. Characterization
N2 adsorption/desorption isotherms were measured with a
Micromeritics ASAP 2020 surface area and porosity analyzer at 77 K.
Specific surface area was determined by the Brunauer- Emmett-Teller
(BET) method and pore size distribution was calculated via the nonlocal density functional theory (NLDFT) method. Monolith morphology
was observed using a JEOL JSM-7500F field emission scanning
electron microscope (FE-SEM). Water contact angle measurement
was performed on a Powereach JC2000C contact angle goniometer at
room temperature. Self-cleaning behavior was examined by immersing
the monolith in water dyed with potassium permanganate for 2 min.
Oil adsorption capacity (saturation) was tested by calculating the
weight variation of monolith before and after being immersed in
50 mL of oil in a 50-mL beaker for 30 min at room temperature.
3. Results and discussion
For porous monoliths, large specific surface area and appropriate
pore size are required for practical applications. Therefore, the nitrogen
adsorption-desorption test was employed to determine both of them.
Typical nitrogen adsorption-desorption isotherms of PC monolith are
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Materials Letters 188 (2017) 201–204
B. Wang et al.
Fig. 3. (1) Water contact angle results for (2) different surfaces: (a) the surface of injection molded PC specimen, (b) the outside surface of PC monolith, and (c) the cross-section of PC
monolith; (d) Self-cleaning behavior in water.
Fig. 4. Wettability of PC monolith: (a) water, (b) soybean oil, (c) lubricating oil and (d) methylsilicone oil.
with the surface of an injection molded PC specimen used in our
previous study [12] were measured. The results are shown in Fig. 3.
The injection molded PC specimen with a contact angle of 77.2 ± 1.1° is
a typical hydrophilic material. The contact angles of monolith surface
and cross-section are 133.8 ± 2.1° and 143.9 ± 1.5°, respectively,
indicating that the PC monolith possesses excellent hydrophobicity.
Previously, Erbil et al. reported a superhydrophobic iPP coating
with bird's nest structure and proved that such porous structure
resulted in improved hydrophobicity [11]. To further determine
whether the PC monolith with similar nest-like structure had good
hydrophobicity, water contact angle measurement was carried out. For
comparison, the outside surface and cross-section of PC monolith along
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Materials Letters 188 (2017) 201–204
B. Wang et al.
Appendix A. Supporting information
In addition, the monolith also exhibits highly self-cleaning behavior in
water (see Fig. 3d).
The hydrophobicity mechanism of porous surface is relevant to two
main factors: surface roughness factor and air pocket [11]. Due to
nanofiber network structure, the PC monolith has a larger roughness
factor, resulting in enhanced hydrophobicity. As expected, the rougher
cross section has a higher water contact angle compared to the outside
surface. The air pocket formed by microscopic pore can trap air and
serve as a barrier to reduce the surface area contacted with water [13].
Thus, the mesopores in PC monolith are capable of inhibiting the
permeation of water molecules so as to increase hydrophobicity.
The wetting characteristics of monolith cross-section corresponding
to water, soybean oil, lubricating oil and methylsilicone oil are shown
in Fig. 4. The water drops on the monolith remain spherical (see
Fig. 4a) and easily roll off the cross-section, while various oils are
rapidly adsorbed (see Fig. 4b, c and d). Moreover, oil adsorption
capacity tests show that the monolith can effectively adsorb 3.96, 4.20
and 3.48 times its pristine weight of soybean oil, lubricating oil and
methylsilicone oil, respectively. These results demonstrate that the PC
monolith is an effective sorbent for various types of oils.
Supplementary data associated with this article can be found in the
online version at doi:10.1016/j.matlet.2016.11.015.
References
[1] F. Svec, Porous polymer monoliths: amazingly wide variety of techniques enabling
their preparation, J. Chromatogr. A 1217 (2010) (902-24).
[2] Y. Zhang, S. Wei, F. Liu, Y. Du, S. Liu, Y. Ji, et al., Superhydrophobic nanoporous
polymers as efficient adsorbents for organic compounds, Nano Today 4 (2009)
135–142.
[3] C. Chen, R. Li, L. Xu, D. Yan, Three-dimensional superhydrophobic porous hybrid
monoliths for effective removal of oil droplets from the surface of water, RSC Adv. 4
(2014) 17393–17400.
[4] Y. Luo, A.N. Wang, X. Gao, Miniemulsion template polymerization to prepare a
sub-micrometer porous polymeric monolith with an inter-connected structure and
very high mechanical strength, Soft Matter 8 (2012) 7547–7551.
[5] Y. Liu, G. Huang, C. Gao, L. Zhang, M. Chen, X. Xu, et al., Biodegradable polylactic
acid porous monoliths as effective oil sorbents, Compos. Sci. Technol. 118 (2015)
9–15.
[6] Y. Xin, T. Fujimoto, H. Uyama, Facile fabrication of polycarbonate monolith by
non-solvent induced phase separation method, Polymer 53 (2012) 2847–2853.
[7] Y. Xin, J. Sakamoto, A.J. van der Vlies, U. Hasegawa, H. Uyama, Phase separation
approach to a reactive polycarbonate monolith for “click” modifications, Polymer
66 (2015) 52–57.
[8] X. Sun, T. Fujimoto, H. Uyama, Fabrication of a poly (vinyl alcohol) monolith via
thermally impacted non-solvent-induced phase separation, Polym. J. 45 (2013)
1101–1106.
[9] K. Chen, W. Xu, A. Du, J. Shen, G. Wu, Z. Bao, et al., Template confined synthetic
strategy for three-dimensional free-standing hierarchical porous nanocrystalline
tantalum, Mater. Lett. 116 (2014) 31–34.
[10] E. Rezabeigi, P.M. Wood-Adams, R.A. Drew, Production of porous polylactic acid
monoliths via nonsolvent induced phase separation, Polymer 55 (2014)
6743–6753.
[11] H.Y. Erbil, A.L. Demirel, Y. Avcı, O. Mert, Transformation of a simple plastic into a
superhydrophobic surface, Science 299 (2003) 1377–1380.
[12] Y. Feng, B. Wang, F. Wang, Y. Zhao, C. Liu, J. Chen, et al., Thermal degradation
mechanism and kinetics of polycarbonate/silica nanocomposites, Polym. Degrad.
Stab. 107 (2014) 129–138.
[13] Y. Zhou, Y. Dan, L. Jiang, G. Li, The effect of crystallization on hydrolytic stability of
polycarbonate, Polym. Degrad. Stab. 98 (2013) 1465–1472.
4. Conclusion
The PC monolith with mesoporous nest-like structure was facilely
fabricated via TINIPS method. Due to interconnected porous structure
and nanofibrous skeleton, it has excellent hydrophobicity, self-cleaning
ability, and oil adsorbability. Predictably, the PC monolith will make
contributions to oil-polluted water treatment.
Acknowledgements
The authors gratefully acknowledge the financial support of this
work by National Natural Science Foundation of China (51603190,
11572290); Key Technologies R & D Program of Henan Province
(152102210245); Key Scientific Research Project of Higher
Education Institution of Henan Province (15A430046).
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