Co-reporter:Ke Tian, Zhengchen Wu, Feifei Xie, Wei Hu, and Lei Li
Energy & Fuels November 16, 2017 Volume 31(Issue 11) pp:12477-12477
Publication Date(Web):October 17, 2017
DOI:10.1021/acs.energyfuels.7b02223
A series of N-doped porous carbon materials have been successfully prepared by using nitrogen-rich triarylisocyanurate-cored polymers as carbon precursor. The cross-linked networks explain the precursor with high carbonaceous residues in the following carbonization. The influence of KOH dosage and activation temperature on the specific surface area and nitrogen content of the resultant carbon materials is investigated in detail. Eventually, a maximum specific surface area of 2341 m2 g–1 and nitrogen content of 1.7 wt % are achieved in the resultant carbon materials. High CO2 capacity (30.2 wt % at 273 K/1 bar and 17.2 wt % at 298 K/1 bar) is attributed to abundant microporous structures and basic sites, superior to that of the most porous carbon materials reported in the previous literature. In addition, the carbon materials also demonstrate high H2 and CH4 uptake (2.7 wt % at 77.3 K/1.13 bar and 3.8 wt % at 273 K/1.13 bar, respectively). The characters of easy preparation and high gas uptake capacity endow this kind of carbon material with promising applications for CH4, H2, and CO2 uptake.
Co-reporter:Tianchan Luo, Hua Bai, and Lei Li
Langmuir 2017 Volume 33(Issue 1) pp:
Publication Date(Web):December 21, 2016
DOI:10.1021/acs.langmuir.6b03973
A breath figure (BF)-inspired method for preparing ordered porous films has attracted more and more attention because of its simplicity, low cost, and easy implementation. However, it remains a challenge to use this method to fabricate nanoscale porous structures without designed polymer architecture and auxiliary. Herein, we first report a facile method to fabricate BF arrays with nanopores (nanoBFAs) in reactive vapor. Depending on the chemical reaction between the formic acid (FA) droplet template and the polyvinylpyridine (PVP) segments in copolymer, we successfully create nanoBFAs by casting a PVP-containing copolymer solution in CS2 in FA vapor. The condensed FA droplets can be instantly fixed by the PVP composition, and thus the growth and the aggregation of adjacent droplets are effectively restricted. Eventually, nanoBFAs are achieved in wide range solution concentration. In addition, binary porous structures with both nano- and microscale topology can be formed by using a FA/water mixed vapor with a one-step BF process. The produced nanoBFA films exhibit excellent antireflection performance with 0.5% reflectance, which is well-preserved even after hydrophobic treatment. This modified BF technique not only facilitates the elucidation of BFA formation mechanism but also opens a new way of fabricating nanoporous structures, which may have potential applications in electronic and optical devices.
Co-reporter:Lei Ding, Hui Gao, Feifei Xie, Wenqing Li, Hua Bai, and Lei Li
Macromolecules 2017 Volume 50(Issue 3) pp:
Publication Date(Web):January 24, 2017
DOI:10.1021/acs.macromol.6b02715
Hyper-cross-linked polymers (HCPs) have aroused great interest because of their potential applications in adsorbing greenhouse gases and volatile organic compounds. However, the selection of raw materials and the postcontrol of the porosity of HCPs remain a challenge. Here, we developed new porosity-enhanced materials by chemically creating additional pores in polymer-based HCPs. The as-prepared material presents a high surface area (1201 m2 g–1), large microporous volume, and high chemical stability even in concentrated acid, thus demonstrating potential in gas capture and storage (CO2: 15.31 wt % at 273 K/1.0 bar; selectivity for CO2 against N2: 36.6; and large adsorption capacity for six organic vapors). This method of creating additional pores in polymer-based HCPs may open doors to the creation of novel porosity-enhanced materials suitable for high-performance adsorbents.
Co-reporter:Wei Wang, Yuan Yao, Tianchan Luo, Lingzhi Chen, Jiaping LinLei Li, Shaoliang Lin
ACS Applied Materials & Interfaces 2017 Volume 9(Issue 4) pp:
Publication Date(Web):January 10, 2017
DOI:10.1021/acsami.6b14024
The fabrication of desired structures is one of the most urgent topics in current research on porous polymer films. Herein, directional photomanipulation in conjunction with breath figure processing has been demonstrated for the preparation of porous polymeric films with finely tunable pore shape and size. Because of the photoinduced directional mass migration of azobenzene units upon vertical incident linearly polarized light (LPL) irradiation, round pores on honeycomb films can be reshaped into multifarious shapes including rectangle, rhombus, dumbbell, line, and so forth. In addition, slantwise LPL irradiation produces unique asymmetrical structure inside the pores oriented along the polarized direction. On the other hand, circularly polarized light (CPL) irradiation affords manipulation of the wall thickness without changing the pore shape. This versatile directional photomanipulation method can be implemented to large-area and high-throughput reshaping processes, which paves the way to a number of promising applications such as a flexible etching mask for patterning.Keywords: azobenzene; block copolymers; photomanipulation; porous films; self-assembly;
Co-reporter:Lei Li, Aijuan Zhang, Jianhui Yu, Wenqing Li, Hui Gao, Ke Tian, Hua Bai
Polymer 2017 Volume 108() pp:332-338
Publication Date(Web):13 January 2017
DOI:10.1016/j.polymer.2016.11.002
•A series of hierarchically structured porous polyureas are prepared through diisocyanate monomers and H2O.•The porous polyureas are prepared via a one-step and template-free strategy.•The nitrogen-doped porous carbon materials prepared by pyrolysis of HPUs can be used as electrode materials.A series of hierarchically structured porous polyureas are prepared through the polymerization of diisocyanate monomers and H2O via a one-step and template-free strategy. This simple archetypal reaction combines carbon dioxide foaming process and hyper-crosslinking reaction. The obtained hierarchically porous polyureas (HPUs) consist of micro- and mesopores created by hyper-crosslinking reaction, and macropores generated by carbon dioxide foaming process. The HPUs have a high surface area up to 483.3 m2/g, and large pore volume (0.76 cm3/g). Besides, the nitrogen-doped carbon materials prepared by pyrolyzing the HPUs show a high specific capacitance (209 F/g at 1.0 A/g) and good cycling stability (99.8% capacitance retention after 5000 cycles), demonstrating the advantages of the hierarchically porous structure and nitrogen-rich chemical composition of HPUs.
Co-reporter:Lei Li, Kaiwu Chen, Lichao Sun, Suyuan Xie, Shaoliang Lin
Reactive and Functional Polymers 2017 Volume 120(Volume 120) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.reactfunctpolym.2017.10.006
Co-reporter:Jianyun Ding;Aijuan Zhang;Hua Bai;Jian Li;Zhi Ma
Soft Matter (2005-Present) 2017 vol. 13(Issue 31) pp:5355-5355
Publication Date(Web):2017/08/09
DOI:10.1039/C7SM90125A
Correction for ‘Breath figure in non-aqueous vapor’ by Jianyun Ding et al., Soft Matter, 2013, 9, 506–514.
Co-reporter:Haozong Wang;Hua Bai
RSC Advances (2011-Present) 2017 vol. 7(Issue 59) pp:37380-37381
Publication Date(Web):2017/07/24
DOI:10.1039/C7RA90083J
Correction for ‘Hierarchically porous polystyrene membranes fabricated via a CO2-expanded liquid selective swelling and in situ hyper-cross-linking method’ by Haozong Wang et al., RSC Adv., 2015, 5, 68639–68645.
Co-reporter:Feifei Xie;Wei Hu;Lei Ding;Ke Tian;Zhengchen Wu
Polymer Chemistry (2010-Present) 2017 vol. 8(Issue 39) pp:6106-6111
Publication Date(Web):2017/10/10
DOI:10.1039/C7PY01240C
To circumvent the intractable disadvantages of a hyper-cross-linked strategy based on the Friedel–Crafts reaction, a new type of microporous organic polymer (MOP) has been successfully prepared using fumaronitrile and divinylbenzene via alternating radical polymerization. The obtained MOPs exhibit a maximum surface area of 805 m2 g−1 and excellent thermochemical stability. By pyrolyzing the copolymer precursor, a rich nitrogen-doped porous carbon material can be produced, which possesses a specific surface area of 1450 m2 g−1 with a CO2 uptake of 30 wt% at 273 K. The porous carbon also shows a high specific capacitance of 330 F g−1 at a current density of 1.0 A g−1 and a good cycling stability of 96.8% retention after 8000 cycles in a three electrode system. The unique synthesis strategy inspires researchers to seek novel building blocks for the scaled-up preparation of MOPs and the resulting porous carbon has promising application for gas adsorption and energy storage.
Co-reporter:Zhifeng Huang;Anan Zhou;Jifeng Wu;Yunqiang Chen;Xiaoli Lan;Hua Bai
Advanced Materials 2016 Volume 28( Issue 8) pp:1703-1708
Publication Date(Web):
DOI:10.1002/adma.201504484
Co-reporter:Wenqing Li, Aijuan Zhang, Hui Gao, Mingjie Chen, Anhua Liu, Hua Bai and Lei Li
Chemical Communications 2016 vol. 52(Issue 13) pp:2780-2783
Publication Date(Web):06 Jan 2016
DOI:10.1039/C5CC07908J
A general challenge for preparing organic microporous polymers (MOPs) is to use cheap and sustainable building blocks while retaining the advanced functions. We demonstrate a strategy to massively prepare pitch-based MOPs, which are thermally and chemically stable. A maximum BET surface area of 758 m2 g−1 and high gas storage capacity were achieved.
Co-reporter:Jianhui Yu, Jifeng Wu, Haozong Wang, Anan Zhou, Chaoqiang Huang, Hua Bai, and Lei Li
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 7) pp:4724
Publication Date(Web):February 2, 2016
DOI:10.1021/acsami.5b12180
Flexible solid-state supercapacitors attract more and more attention as the power supply for wearable electronics. To fabricate such devices, the flexible and economical current collectors are needed. In this paper, we report the stainless steel fabrics as the current collector for high-performance graphene-based supercapacitors. The stainless steel fabrics have superior properties compared with the widely used flexible current collectors. The flexible supercapacitors show large specific capacitance of 180.4 mF/cm2, and capacitance retention of 96.8% after 7500 charge–discharge cycles. Furthermore, 96.4% of the capacitance is retained after 800 repeating stretching-bending cycles. The high performance is related to the excellent conductivity, good mechanical flexibility, and high electrochemical stability of the stainless steel fabrics. The achievement of such high-performance and flexible supercapacitor can open up exciting opportunities for wearable electronics and energy storage applications.Keywords: chemically converted graphene; flexible; metallic fabric; solid-state; supercapacitor
Co-reporter:Hui Gao, Lei Ding, Wenqing Li, Guifeng Ma, Hua Bai, and Lei Li
ACS Macro Letters 2016 Volume 5(Issue 3) pp:377
Publication Date(Web):February 25, 2016
DOI:10.1021/acsmacrolett.6b00015
A novel type of hyper-cross-linked organic microporous polymer (HOMP) has been successfully prepared based on the radical copolymerization of bismaleimides and divinylbenzene. In comparison with the HOMPs prepared with cross-linking techniques, the new radical strategy circumvents some intractable problems, such as low atom economy, structure irregularity and corrosive byproducts. The obtained HOMPs have defined molecular structures due to the intrinsic alternating copolymerization properties of the two monomers. A maximum BET surface area of 841 m2 g–1 and high gas capture capacity (CO2, 11.22 wt %, 273 K/1.0 bar; H2, 0.82 wt %, 77.3 K/1.0 bar; benzene, 545 mg g–1, room temperature/0.6 bar; and cyclohexane, 1736 mg g–1, room temperature/0.6 bar) were achieved. In addition, the polymers also displayed good chemical and thermal stability, which is critical for the practical application.
Co-reporter:Lei Ding, Aijuan Zhang, Wenqing Li, Hua Bai, Lei Li
Journal of Colloid and Interface Science 2016 Volume 461() pp:179-184
Publication Date(Web):1 January 2016
DOI:10.1016/j.jcis.2015.09.031
•Breath figure is combined with hypercrosslinking to create pores in polystyrene film.•The produced films have multi-length scale porous structure.•The resulted films possess large specific surface areas.•The resulted films show excellent chemical and thermal stabilities.Multi-length scale porous polymer (MLSPP) films were fabricated using commercially available polystyrene (PS) via static breath figure (BF) process and sequent hypercrosslinking reaction. One level of ordered pores in microscale were introduced using static BF process, and the other level in nanoscale were produced by the sequent Friedel–Crafts hypercrosslinking reaction. The chemical structure of the PS MLSPP film was investigated by Fourier transformation infrared spectrometry and solid state nuclear magnetic resonance, and the morphology of the film was observed with electron microscopes. The MLSPP films showed large specific surface areas and excellent chemical and thermal stabilities, owing to the micropores and the crosslinked chemical structure produced by the Friedel–Crafts reaction. The methodology reported in this paper is a template-free, low cost and general strategy for the preparation of MLSPP films, which has potential applications in the areas of environment and energy.
Co-reporter:Jianliang Gong, Bingang Xu, Xiaoming Tao and Lei Li
Physical Chemistry Chemical Physics 2016 vol. 18(Issue 19) pp:13629-13637
Publication Date(Web):15 Apr 2016
DOI:10.1039/C6CP01538G
The intense interest surrounding asymmetrical microparticles originates from their unique anisotropic properties and promising applications. In this work, direct self-assembly of polymeric microspherical caps without the assistance of any additives has been achieved by using low-surface-tension methanol (MeOH) and high-surface-tension water as binary breath figures (BFs). With the evaporation of polystyrene (PS) solution containing low-boiling-point solvent in the binary vapors, the formed MeOH BFs could quickly diffuse into solution, while water BFs tended to remain at the solution surface. This led to the formation of a gradient nonsolvent layer at the vapor/solution interface, which induced the formation of nuclei and guided further asymmetrical growth of polymer particles. After the spontaneous removal of MeOH, water and residual solvent by evaporation, polymeric microspherical caps were left on the substrate. Through controlling the proportion of water introduced by adjusting the ratios of MeOH and water, polymeric microspherical caps with a range of controllable shapes (divided at different positions of a sphere) were successfully obtained. The formation mechanism was explained based on the difference of vapor pressure, surface tension and miscibility between the employed solvents and nonsolvents. A solvent possessing a high vapor pressure, low surface tension and good miscibility with MeOH contributed to the formation of microspherical caps. This flexible, green and straightforward technique is a nondestructive strategy, and avoids complicated work on design, preparation and removal of hard templates and additives.
Co-reporter:Haozong Wang, Jianhui Yu, Hua Bai, Lei Li
The Journal of Supercritical Fluids 2016 Volume 118() pp:89-95
Publication Date(Web):December 2016
DOI:10.1016/j.supflu.2016.07.018
PAN nanofiltration membranes were produced by scCO2 induced phase separation.The effect of experimental conditions on the membranes was studied.The membranes have unique advantages compared to commercial PAN films.Nanoporous polyacrylonitrile (PAN) membranes were prepared by a supercritical carbon dioxide induced phase separation method from a solution containing dimethyl formamide as the solvent. The influence of the experiment parameters, including temperatures, pressures and polymer concentrations, on the morphology of the nanoporous membrane were investigated in detail. The porosities of the obtained membranes were characterized by scanning electron microscopy and nitrogen adsorption technique. The PAN membranes demonstrate high pure water flux and high size selectivity, which have promising applications for the nanofiltration.
Co-reporter:Aijuan Zhang, Hui Gao, Wenqing Li, Hua Bai, Shouming Wu, Yu Zeng, Wei Cui, Xiaohong Zhou, Lei Li
Polymer 2016 Volume 101() pp:388-394
Publication Date(Web):28 September 2016
DOI:10.1016/j.polymer.2016.08.088
•A new kind of HMPs based on DDSQ was prepared through Friedel-Crafts reaction.•The produced HMPs possess a maximum BET surface area of 923 m2 g−1.•TGA curves demonstrate that the HMPs had a very high thermal stability.•The HPMs have a high gas storage capacity for CO2 and H2.A series of hybrid microporous polymers (HMPs) were prepared through Friedel-Crafts reaction with double-decker-shaped silsesquioxane as the building block. The ratio between the monomer and the crosslinker has significant influence on the surface area and porous morphology. A maximum BET surface area of 923 m2 g−1 and high gas storage capacity (CO2:10.4 wt%, 273 K/1.0 bar; H2: 0.95 wt%, 77 K/1.0 bar) were achieved. The obtained HMPs have high thermal stability due to the introduction of SiO bonds.Download high-res image (175KB)Download full-size image
Co-reporter:Aijuan Zhang, Hua Bai, and Lei Li
Chemical Reviews 2015 Volume 115(Issue 18) pp:9801
Publication Date(Web):August 18, 2015
DOI:10.1021/acs.chemrev.5b00069
Co-reporter:Jie Bai, Anan Zhou, Zhifeng Huang, Jifeng Wu, Hua Bai and Lei Li
Journal of Materials Chemistry A 2015 vol. 3(Issue 45) pp:22687-22694
Publication Date(Web):28 Sep 2015
DOI:10.1039/C5TA06204G
Graphene foams (GFs) have attracted increasing attention because they combine the unique properties of cellular materials and the excellent performance of graphene. The preparation of GFs depends mainly on the self-assembly of graphene or graphene oxide sheets, and designing and controlling the cell morphology of GFs, which determines their properties, remain a challenge. Here, we report a novel strategy for preparing GFs with a hierarchical porous structure. Our preparation method involves mechanically foaming a graphene oxide dispersion with the assistance of a surfactant, followed by lyophilization and thermal reduction. These novel GFs possess large cells created using the bubbles as templates and small pores around the edges of the cells resulting from the self-assembly of the graphene oxide sheets. Because of their unique cell structure, the GFs exhibit an ultra-low density, high porosity, good electrical conductivity, and excellent elasticity. In particular, these GFs exhibit a very large absorption capacity (600–1500 g g−1) for oils and organic solvents. Our work explores a new strategy for controlling the cell morphology and improving the performance of GFs; the results may shed new light on the relationship between the structure and properties of 3D graphene assemblies.
Co-reporter:Libin Chen, Jifeng Wu, Aijuan Zhang, Anan Zhou, Zhifeng Huang, Hua Bai and Lei Li
Journal of Materials Chemistry A 2015 vol. 3(Issue 31) pp:16033-16039
Publication Date(Web):26 Jun 2015
DOI:10.1039/C5TA03881B
Electroactive polymers constitute an important class of electrode materials for supercapacitors based on pseudocapacitance. However, it is difficult to utilize low-conductive electroactive polymers in supercapacitors, although these polymers may have large theoretical specific capacitance. In this article, we designed and prepared a novel type of electrode material, with a unique structure of low-conductive electroactive polyhydroquinone (PHQ) coated on a highly conductive three-dimensional (3D) porous graphene hydrogel (GHG). PHQ–GHG composites were prepared via a one-step reaction between graphene oxide and hydroquinone under mild conditions. Because PHQ has a large theoretical specific capacitance, and GHG possesses a 3D porous structure, large specific surface area and high electrical conductivity, the composites showed a high specific capacitance of 490 F g−1 at a current density of 24 A g−1, as well as excellent rate performance and cycling stability. These results demonstrate that PHQ–GHG composites are promising electrode materials for supercapacitors, and the method developed in this paper paves a new way for utilizing those electroactive polymers of low electrical conductivities in supercapacitors.
Co-reporter:Haozong Wang, Hua Bai and Lei Li
RSC Advances 2015 vol. 5(Issue 84) pp:68639-68645
Publication Date(Web):03 Aug 2015
DOI:10.1039/C5RA12438G
Hierarchically porous polymeric materials represent a new class of materials that have attracted both industrial and academic interest. This paper presents a novel, etching-free and versatile preparation methodology, using commercially available polystyrene and a CO2-expanded liquid selective swelling process combined with a hyper-cross-linking reaction. The morphology of the membranes was observed with electron microscopes, and the chemical structure of the membranes was investigated using Fourier transform infrared spectrometry and solid-state nuclear magnetic resonance measurements. One level of macroporous structures was produced by a CO2-expanded methanol selective swelling process, while the other level of micropores was created via the hyper-cross-linking reaction. The cross-linked membranes possessed large specific surface areas and excellent thermal stability, and have potential applications in catalysis, separation and gas storage.
Co-reporter:Tianchan Luo, Can Du, Aijuan Zhang, Laisen Wang, Hua Bai, and Lei Li
Langmuir 2015 Volume 31(Issue 49) pp:13327-13333
Publication Date(Web):November 24, 2015
DOI:10.1021/acs.langmuir.5b03886
In this article, we report the formation of nanoring structures on Fe coated substrate and their application in guiding the growth of carbon nanotube (CNT) patterns with hierarchical structures. The formation of nanorings involves the etching of polystyrene (PS) monolayer colloidal crystals (MCCs) under reactive ion etching (RIE), and the redeposition and cross-linkage of the active degradation products at the contact line between the MCCs and the substrate. After washing out the MCCs, insoluble nanorings with hexagonal order on the substrate are developed. The RIE process can control the morphology of the nanorings, as well as the distribution of the Fe element on the substrate; thus, a continuous Fe layer and separated Fe discs on the substrate are created on substrate after washing, depending on the etching time and the shield of MCCs. The surviving Fe element can work as the catalyst to initiate the in situ growth of aligned CNTs in the following chemical vapor deposition (CVD) process, while the Fe element underneath the nanorings keep its inactivity. Eventually, CNT patterns with hierarchical structures are formed. One level originates from the surviving Fe layer; the other level is templated from the nanoring structures, which cause the blank area in the CNT bundles.
Co-reporter:Aijuan Zhang, Qingkun Zhang, Hua Bai, Lei Li and Jun Li
Chemical Society Reviews 2014 vol. 43(Issue 20) pp:6938-6953
Publication Date(Web):17 Jul 2014
DOI:10.1039/C4CS00100A
Both academia and industries have put great efforts into developing non-destructive technologies for the fabrication of polymeric nanoporous materials. Such non-destructive technologies developed with supercritical CO2 (scCO2) and CO2-expanded liquids (CXLs) have been attracting more and more attention because they have been demonstrated to be green and effective media for porous polymer preparation and processing. In this tutorial review, we present several such new technologies with scCO2 and CXLs, which have the capacity to prepare polymeric nanoporous materials with unique morphologies. The fabricated nanoporous polymers have significantly improved the performance of polymeric monoliths and films, and have found wide applications as templates, antireflection coatings, low-k materials, tissue engineering scaffolds and filtration membranes. This tutorial review also introduces the associated characterization methods, including the imaging, scattering and physisorption techniques.
Co-reporter:Libin Chen, Hua Bai, Zhifeng Huang and Lei Li
Energy & Environmental Science 2014 vol. 7(Issue 5) pp:1750-1759
Publication Date(Web):24 Feb 2014
DOI:10.1039/C4EE00002A
The self-discharge (SDC) process of active electrolyte enhanced supercapacitors (AEESCs) was investigated systematically. The AEESC with hydroquinone as an active electrolyte showed higher specific capacitance but much faster SDC compared with electronic double layer supercapacitors. The electrode process of the above AEESC was studied, and the mechanism of the SDC process was investigated quantitatively. The migration of the active electrolyte between two electrodes of the device was found to be the primary reason for the fast SDC. Two strategies were designed to suppress the migration of the active electrolyte. Following these strategies, two new AEESCs were fabricated, with a Nafion® membrane as the separator and CuSO4 as the active electrolyte. The two AEESCs showed both high specific capacitances and longer SDC times, demonstrating that the problem of poor energy retention of AEESCs was successfully solved.
Co-reporter:Libin Chen, Yanru Chen, Jifeng Wu, Jianwei Wang, Hua Bai and Lei Li
Journal of Materials Chemistry A 2014 vol. 2(Issue 27) pp:10526-10531
Publication Date(Web):06 May 2014
DOI:10.1039/C4TA01319K
An electrochemical supercapacitor with a polymeric active electrolyte was designed and fabricated in this work. A water-soluble conducting polymer, sulfonated polyaniline (SPAni), was used in the supercapacitor as the active electrolyte and a semipermeable membrane was employed as the separator of the device. It was found that SPAni in the electrolyte can provide pseudocapacitance via its reversible electrochemical redox reaction. Owing to the good stability of SPAni, the supercapacitor has a long cycling life. Moreover, the migration of SPAni between the two electrodes was blocked by the semipermeable membrane separator, thus self-discharge caused by the shuttle effect of SPAni was suppressed. The research in this paper demonstrates the possibility of using a polymer as the active electrolyte in a supercapacitor and has paved a new way to achieve active electrolyte enhanced supercapacitors with high capacitance and good energy retention.
Co-reporter:Aijuan Zhang, Can Du, Hua Bai, Yange Wang, Jianwei Wang, and Lei Li
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 11) pp:8921
Publication Date(Web):May 7, 2014
DOI:10.1021/am5016952
Breath figure (BF) process is a promising technique for fabricating honeycomb polymer films. It is usually conducted in water vapor. While, in organic vapors only unique polymer can be used to prepare BF arrays as reported in our previous article (Breath Figure in Nonaqueous Vapor. Soft Matter, 2013, 506–514), although new structure features are induced in the film. In this paper, a universal modified BF processing is devised for preparing porous films in methanol vapor with conventional polymers, by adding a small amount of surface active agent into the casting solution, such as siloxane- and fluorine-containing block copolymers. The pores in the PS films prepared with this method are of cylindrical shape with large depth-diameter aspect ratio, and the diameter and depth of pores can be well controlled by the experiment conditions. Based on these results, the formation mechanism of honeycomb structure in methanol vapor is discussed.Keywords: breath figure; methanol vapor; porous films; surface tension;
Co-reporter:Can Du, Zhiyi Yao, Yunqiang Chen, Hua Bai and Lei Li
RSC Advances 2014 vol. 4(Issue 18) pp:9133-9138
Publication Date(Web):23 Jan 2014
DOI:10.1039/C3RA47950A
In this paper, a green and facile method based on substrate-enhanced electroless deposition is designed for the fabrication of three-dimensional (3D) metal nanoparticle@graphene hydrogel (MNP@GHG) composites. A galvanic cell was constructed by inducing nickel foam as the substrate of GHG, to enhance the deposition of MNPs via galvanic cell reaction. Various MNPs with redox potential higher than that of Ni, including Au, Pt, Pd and Cu, were successfully deposited onto GHG. The produced gold nanoparticles/GHG composite showed good electrocatalytic activity and was used to fabricate an amperometric sensor towards uric acid with good sensitivity.
Co-reporter:Wei Wang;Can Du;Xiaofan Wang; Xiaohua He; Jiaping Lin; Shaoliang Lin
Angewandte Chemie International Edition 2014 Volume 53( Issue 45) pp:12116-12119
Publication Date(Web):
DOI:10.1002/anie.201407230
Abstract
Porous polymeric films are of paramount importance in many areas of modern science and technology. However, processing methods typically based on direct writing, imprint, and lithography techniques have low throughput and are often limited to specific fabricated shapes. Herein, we demonstrate the directional photomanipulation of breath figure arrays (BFAs) formed by an azobenzene-containing block copolymer to address the aforementioned problems. Under the irradiation of linearly polarized light, the round pores in the BFAs were converted to rectangular, rhombic, and parallelogram-shaped pores in 30 min, due to the anisotropic mass migration based on the photo-reconfiguration of the azobenzene units. Through a secondary irradiation after rotating the sample by 90°, the transformed pores were apparently recovered. Therefore, this non-contacted, directional photomanipulation technique in conjunction with breath figure processing opens a new route to nano/microporous films with finely tuned features.
Co-reporter:Yunqiang Chen, Qingkun Zhang, Libin Chen, Hua Bai and Lei Li
Journal of Materials Chemistry A 2013 vol. 1(Issue 42) pp:13101-13110
Publication Date(Web):30 Aug 2013
DOI:10.1039/C3TA13285D
Porous composites based on basic aluminum sulfate and graphene hydrogel (BAS@GHG) were prepared via homogeneous precipitation of BAS in GHG, and used as adsorbents for fluoride removal from water. The BAS@GHG composites have a porous structure with a chemically converted graphene three dimensional network coated by a thin layer of amorphous BAS. These composites showed high adsorption capacities of up to 33.4 mg g−1 at equilibrium fluoride concentrations of 10.7 mg L−1 and temperatures of 298 K, higher than those of previously reported graphene and aluminum-based adsorbents. The adsorption kinetics and isotherm were analyzed by fitting experimental data with pseudo-first-order kinetics, the Weber–Morris model and Langmuir equations. The effects of temperature, pH value, and co-existing anions on the adsorption of fluoride were also investigated.
Co-reporter:Yunqiang Chen, Libin Chen, Hua Bai and Lei Li
Journal of Materials Chemistry A 2013 vol. 1(Issue 6) pp:1992-2001
Publication Date(Web):23 Nov 2012
DOI:10.1039/C2TA00406B
Water pollution is one of the most pervasive problems afflicting people throughout the world, while adsorption is the most widely used method to remove the contaminants from water. Here, in this paper, we report an eco-friendly graphene oxide–chitosan (GO–CS) hydrogel as a new type of adsorbent for water purification. The GO–CS hydrogels were prepared via self-assembly of GO sheets and CS chains. A three-dimensional network composed of GO sheets crosslinked by CS was found in GO–CS hydrogels. The GO–CS composite hydrogels showed high adsorption capacity towards different contaminants, including cationic and anionic dyes, as well as heavy metal ions. The mechanism of the dye adsorption was investigated with a spectral method, and an electrostatic interaction was found to be the major interaction between ionic dyes and the hydrogel. The influence of the hydrogel composition on the adsorption capacity towards different adsorbates was also studied. Finally, it was demonstrated that the GO–CS hydrogel can be used as column packing, to fabricate a column for water purification by filtration.
Co-reporter:Aijuan Zhang, Mingjie Chen, Can Du, Huizhang Guo, Hua Bai, and Lei Li
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 20) pp:10201
Publication Date(Web):September 16, 2013
DOI:10.1021/am4029203
Cleanup of oil spills is a worldwide challenge to prevent serious environmental pollution. A new kind of poly(dimethylsiloxane) (PDMS) oil absorbent with high absorption capacity and excellent reusability was prepared and used for oil/water separation. The preparation process of PDMS oil absorbents involves direct curing of a PDMS prepolymer in a p-xylene solution in the presence of commercial sugar particles, which is simple and economic. PDMS oil absorbents have interconnected pores and a swellable skeleton, combining the advantages of porous materials and gels. Absorption capacities of PDMS oil absorbents are 4–34 g/g for various oils and organic solvents, which are 3 times that reported previously. Owing to their hydrophobicity and oleophilicity, the as-obtained PDMS oil absorbents can selectively collect oils or organic solvents from water. The absorption process can be finished within tens of seconds. Furthermore, the absorbed oils or organic solvents can be recovered by compressing the oil absorbents, and after 20 absorbing/recovering cycles, PDMS oil absorbents show little loss of their absorption capacities and own weights.Keywords: oil absorbent; poly(dimethylsiloxane); porous material; reusability; swell;
Co-reporter:Can Du, Aijuan Zhang, Hua Bai, and Lei Li
ACS Macro Letters 2013 Volume 2(Issue 1) pp:27
Publication Date(Web):December 20, 2012
DOI:10.1021/mz300616z
Polymeric microsieves with uniform and tunable pores were fabricated with the breath-figure method and sequent vulcanization procedure using commercially available block copolymer polystyrene-b-polyisoprene-b-polystyrene. Uniform pore size and small film thickness endow the microsieves with high size selectivity and low operation pressure, while the cross-linked chemical structure gives them good mechanical properties and excellent chemical and thermal stability. These microsieves are able to separate particles in various media, including corrosive solvents, hot water, and organic solvents. The process reported in this communication is a simple and inexpensive method for the preparation of high-performance microsieves.
Co-reporter:Dr. Hua Bai;Can Du;Aijuan Zhang ; Lei Li
Angewandte Chemie 2013 Volume 125( Issue 47) pp:12462-12478
Publication Date(Web):
DOI:10.1002/ange.201303594
Abstract
Kondensationsmuster (breath figures; BFs) sind Anordnungen von Wassertröpfchen, die sich bilden, wenn Luftfeuchtigkeit (z. B. Atemluft) mit einer kalten Oberfläche in Kontakt kommt. Solche Muster haben in den letzten zwei Jahrzehnten vielseitige Anwendung als weiches Templat zur Herstellung von porösen Polymerfilmen gefunden. Die in den Polymerfilmen angeordneten Poren, die über ein solches Verfahren gebildet werden, werden entsprechend als Kondensationsmusterarrays bezeichnet. Mehrere unkonventionelle BF-Verfahren wurden entwickelt, um poröse Filme mit spezifischer Morphologie oder aus besonderen Ausgangsmaterialien herzustellen. Verschiedene Funktionalisierungstechniken wurden ebenfalls eingeführt, um die Eigenschaften von Polymerfilmen erheblich zu verbessern, was zu einigen neuen Anwendungen z. B. als Template, Biosensoren und Trennmembranen geführt hat. Diese Ergebnisse werden in diesem Kurzaufsatz beschrieben.
Co-reporter:Dr. Hua Bai;Can Du;Aijuan Zhang ; Lei Li
Angewandte Chemie International Edition 2013 Volume 52( Issue 47) pp:12240-12255
Publication Date(Web):
DOI:10.1002/anie.201303594
Abstract
A breath figure (BF) is the water droplet array that forms when moisture comes in contact with a cold substrate. This water droplet array has been widely utilized in the past two decades as a versatile soft template for the fabrication of polymeric porous films. Accordingly, the ordered pores on the polymer films formed with such a method are named a breath figure array (BFA).The BF templating technique is undergoing rapid development. Several unconventional BF processes have been established to prepare porous films with unique morphologies or primary materials, and various newly developed functionalization techniques have significantly improved the performance of polymeric films with BFA, leading to novel applications, including templates, biosensors, and separation membranes. These recent achievements will be described in this Minireview.
Co-reporter:Lei Li, Kaiwu Chen, Lichao Sun, Suyuan Xie, Shaoliang Lin
Reactive and Functional Polymers 2013 73(1) pp: 83-88
Publication Date(Web):January 2013
DOI:10.1016/j.reactfunctpolym.2012.08.017
Co-reporter:Jianliang Gong, Lichao Sun, Yawen Zhong, Chunyin Ma, Lei Li, Suyuan Xie and Vladimir Svrcek
Nanoscale 2012 vol. 4(Issue 1) pp:278-283
Publication Date(Web):14 Nov 2011
DOI:10.1039/C1NR11191D
Multi-level carbon nanotube (CNT) arrays with adjustable patterns were prepared by a combination of the breath figure (BF) process and chemical vapor deposition. Polystyrene-b-poly(acrylic acid)/ferrocene was dissolved in carbon disulfide and cast onto a Si substrate covered with a transmission electron microscope grid in saturated relative humidity. A two-level microporous hybrid film with a block copolymer skeleton formed on the substrate after evaporation of the organic solvent and water. One level of ordered surface features originates from the contour of the hard templates; while the other level originates from the condensation of water droplets (BF arrays). Ultraviolet irradiation effectively cross-linked the polymer matrix and endowed the hybrid film with improved thermal stability. In the subsequent pyrolysis, the incorporated ferrocene in the hybrid film was oxidized and turned the polymer skeleton into the ferrous inorganic micropatterns. Either the cross-linked hybrid film or the ferrous inorganic micropatterns could act as a template to grow the multi-level CNT patterns, e.g. isolated and honeycomb-structured CNT bundle arrays perpendicular to the substrate.
Co-reporter:Kaiwu Chen, Libin Chen, Yunqiang Chen, Hua Bai and Lei Li
Journal of Materials Chemistry A 2012 vol. 22(Issue 39) pp:20968-20976
Publication Date(Web):15 Aug 2012
DOI:10.1039/C2JM34816K
A general method for the fabrication of three-dimensional (3D) porous graphene-based composite materials is reported. This method involves two consecutive electrochemical steps. Firstly, 3D graphene (ERGO) porous material is prepared electrochemically by reducing a concentrated graphene oxide dispersion. Subsequently, the second component is electrochemically deposited onto this 3D ERGO matrix, yielding graphene-based 3D porous composite material. The prepared graphene-based composite materials have a conductive graphene network as the matrix, onto which the second component is homogeneously coated. Conducting polymers, noble metal nanoparticles and metal oxide were successfully incorporated into ERGO architectures, demonstrating the versatility of this method. Taking the ERGO–polyaniline composite as an example, the influence of deposition rate on the morphology of the composite was investigated. Finally, the application of the composite materials prepared with our method was discussed. The high surface area and low electrolyte transport resistance make these electrosynthesized composites suitable electrode materials for electrochemical devices. The ERGO–polyaniline composite electrode showed a high specific capacitance of 716 F g−1 at 0.47 A g−1, and this capacitance could be maintained at 502 F g−1 as the discharge current density was increased up to 4.2 A g−1.
Co-reporter:Yunqiang Chen, Kaiwu Chen, Hua Bai and Lei Li
Journal of Materials Chemistry A 2012 vol. 22(Issue 34) pp:17800-17804
Publication Date(Web):09 Jul 2012
DOI:10.1039/C2JM33530A
Chemically converted graphene–room temperature ionic liquid (CCG–RTIL) porous materials were prepared by electrochemical reducing graphene oxide followed by solvent exchange. The resulted CCG–RTIL materials possess 3D porous structure with textured surface, and show good stability in air. Under laser irradiation the temperature of CCG–RTIL materials increased rapidly and significantly, indicating the high photothermal conversion ability of these materials. The influence of CCG–RTIL thickness on the photothermal conversion performance was investigated. These CCG–RTIL materials were used as light absorbers to modify thermoelectric devices, forming light-driven thermoelectric generators, and significantly enhanced the performance of these devices. This work suggests that CCG–RTIL porous materials prepared by this electrochemical method are promising light absorbers for solar electric generation and other photo-thermo-electric conversion devices.
Co-reporter:Lei Li, Yawen Zhong, Jianliang Gong, Jian Li, Jin Huang, Zhi Ma
Journal of Colloid and Interface Science 2011 Volume 354(Issue 2) pp:758-764
Publication Date(Web):15 February 2011
DOI:10.1016/j.jcis.2010.11.003
Here, we present the preparation of thermally stable and solvent resistant micro-patterned polymeric films via static breath-figure process and sequent vulcanization, with a commercially available triblock polymer, polystyrene-b-polyisoprene-b-polystyrene (SIS). The vulcanized honeycomb structured SIS films became self-supported and resistant to a wide range of organic solvents and thermally stable up to 350 °C for 2 h, an increase of more than 300 K as compared to the uncross-linked films. This superior robustness could be attributed to the high degree of polyisoprene cross-linking. The versatility of the methodology was demonstrated by applying to another commercially available triblock polymer, polystyrene-b-polybutadiene-b-polystyrene (SBS). Particularly, hydroxy groups were introduced into SBS by hydroboration. The functionalized two-dimensional micro-patterns feasible for site-directed grafting were created by the hydroxyl-containing polymers. In addition, the fixed microporous structures could be replicated to fabricate textured positive PDMS stamps. This simple technique offers new prospects in the field of micro-patterns, soft lithography and templates.Graphical abstractStable and flexible honeycomb structured SIS film after 24 h vulcanization.Research highlights► Preparation of micro-patterned polymeric films via static breath figure process with triblock copolymers, polystyrene-b-polyisoprene-b-polystyrene (SIS) and hydroxyl-containing polystyrene-b-polybutadiene-b-polystyrene (SBS-OH). ► Sequent vulcanization to improve chemical and thermal stability of the micro-structured polymeric films. ► Replication of fixed microporous structures to fabricate textured positive PDMS stamps.
Co-reporter:Chun-Yin Ma, Ya-Wen Zhong, Jian Li, Cai-Kang Chen, Jian-Liang Gong, Su-Yuan Xie, Lei Li and Zhi Ma
Chemistry of Materials 2010 Volume 22(Issue 7) pp:2367
Publication Date(Web):February 16, 2010
DOI:10.1021/cm9036633
Patterning is of paramount importance in many areas of modern science and technology. As a valuable part in miniaturized devices, large-scale aligned CNTs with serial port configuration is highly desirable. Here, we reported that the synthesis of a pair of patterned carbon nanotubes with the shape of serial port by CVD starting from different breath figure templates, cross-linked polymer matrix and ferrous inorganic micropatterns. The growth mechanism of the isolated CNT bundles is attributed to the selectively interfacial aggregation of the ferrocene to the walls of the cavities, a so-called Pickering-emulsion effect, whereas the honeycomblike skeleton of the dense CNT arrays develop from the catalytically functionalized hexagonal edges. This synthesis strategy exemplifies a new possibility for making use of CNTs to fabricate functional carbons with unique geometry or specific properties in a controllable way. We expect that the methodology can be also applied onto the fabrication of patterned graphene.
Co-reporter:Lei Li, Jian Li, Yawen Zhong, Caikang Chen, Yi Ben, Jianliang Gong and Zhi Ma
Journal of Materials Chemistry A 2010 vol. 20(Issue 26) pp:5446-5453
Publication Date(Web):26 May 2010
DOI:10.1039/C0JM00405G
Here, we show a facile and versatile method preparing highly ordered ceramic microstructures on solid substrates by pyrolyzing UV cross-linked copolymer films to circumvent the expensive lithographic technique. The employed block copolymer, poly(dimethylsiloxane)-block-polystyrene (PDMS-b-PS), in this study was synthesized by controlling radical polymerization. The highly ordered microporous polymer films were formed using a static breath figure process. After 4 h UV irradiation, the PS composition was effectively cross-linked. The cross-linked microporous polymer matrix served as a structure-directing agent in the following pyrolysis process, in which the PDMS composition was converted into silica to form honeycomb structured micropatterns on the substrate. The chemical components of the ceramic microstructures were adjusted by simply mixing different functional precursors. Moreover, the ceramic microstructures on substrate could be replicated to prepare textured PDMS stamps. This simple technique offers new prospects in the fields of micropatterns, soft lithography and templates.
Co-reporter:Jian Li, Qiao-Ling Zhao, Jian-Zhuang Chen, Lei Li, Jin Huang, Zhi Ma and Ya-Wen Zhong
Polymer Chemistry 2010 vol. 1(Issue 2) pp:164-167
Publication Date(Web):11 Dec 2009
DOI:10.1039/B9PY00219G
Highly ordered microporous films containing polyolefin segment were successfully fabricated via the breath-figure (BF) method using well-defined polymethylene-b-polystyrene (PM-b-PS) diblock copolymers in CS2 under a static humid condition. The effects of molecular weight of diblock copolymers, relative humid, fabrication method and temperature on the morphology of film are investigated. The honeycomb porous films with different pore size (1.2–2.5 μm) were obtained by using PM-b-PS with different PM : PS ratio. The thick (7 μm) and thin (2 μm) films were fabricated via a different process. The film with a pothole-like structure was fabricated when using PM-b-PS with the shortest PS segment. Smaller satellite pores were found to surround the regular micropores of honeycomb films when the BF process was carried out at 28 °C.
Co-reporter:Lei Li, Yawen Zhong, Jian Li, Jianliang Gong, Yi Ben, Jin Xu, Xiaping Chen, Zhi Ma
Journal of Colloid and Interface Science 2010 Volume 342(Issue 1) pp:192-197
Publication Date(Web):1 February 2010
DOI:10.1016/j.jcis.2009.10.005
We describe a facile method to micropattern solid substrates: breath figure lithography (BFL). A honeycomb structured gold mask was prepared by sputter-coating a micro-porous polymer film with BF arrays, and then inductively coupled plasma reactive ion etching (ICP–RIE) transferred the patterns onto silicon wafer. The large etching rate selectivity between golden mask and substrate plays an important role in the effective transfer of the patterns. The versatility of the method was demonstrated by forming micropatterns on various solid substrates with adjustable sizes. Furthermore, the micropatterns on solid substrate could be replicated by PDMS stamp.Photograph of sunlight diffraction obtained from a micropatterned silicon wafer by BFL.
Co-reporter:Jian Li, Qiao-Ling Zhao, Guo-Yi Zhang, Jian-Zhuang Chen, Liang Zhong, Lei Li, Jin Huang, Zhi Ma
Solid State Sciences 2010 Volume 12(Issue 8) pp:1393-1398
Publication Date(Web):August 2010
DOI:10.1016/j.solidstatesciences.2010.05.016
A monoclinic tungsten trioxide (WO3) nanosphere film was synthesized via a sol–gel approach using an amphiphilic diblock copolymer polystyrene-b-polyacrylic acid (PS-b-PAA) as template in toluene. The morphology, surface area and crystal structure of as-synthesized WO3 were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), BET (N2) and powder X-ray diffraction (XRD). The XRD pattern of WO3 nanosphere film can be identified as a pure monoclinic WO3 phase. The WO3 precursor nanospheres had diameters ranging from 20 to 150 nm and surface area of 78.8 m2 g−1. The hydrogen gasochromic experiments revealed that such WO3 nanosphere film with high surface area had a rapid response (5 ∼ 10 s) to pure hydrogen at room temperature.
Co-reporter:Lei Li, Yawen Zhong, Chunyin Ma, Jian Li, Caikang Chen, Aijuan Zhang, Dingliang Tang, Suyuan Xie and Zhi Ma
Chemistry of Materials 2009 Volume 21(Issue 20) pp:4977
Publication Date(Web):September 30, 2009
DOI:10.1021/cm902357m
Here, we show a facile and versatile method to prepare highly ordered inorganic patterns on solid substrates by pyrolyzing UV cross-linked polymer/functional precursor hybrid films. The cross-linked polymer matrix acted as structure-directing agent in a pyrolyzing process, whereas the functional precursor was converted into the skeleton of the micropatterns. The inorganic micropatterns could be further catalytically functionalized to grow CNT and ZnO nanorod arrays by simply changing different functional precursors. This simple technique offers new prospects in the field of micropatterns, nanolithography, and template.
Co-reporter:Lei Li, Yawen Zhong, Jian Li, Caikang Chen, Aijuan Zhang, Jin Xu and Zhi Ma
Journal of Materials Chemistry A 2009 vol. 19(Issue 39) pp:7222-7227
Publication Date(Web):20 Aug 2009
DOI:10.1039/B911714H
In this article, a facile static breath-figure (BF) method to prepare highly ordered polystyrene (PS) thin films was reported. The static process was robust and tolerated more variability in casting conditions, although non-polar linear PS was not believed to be a good candidate for the BF technique. In the following UV irradiation, not only were the microporous structures well preserved, but also thermal and chemical resistance of the films was significantly improved due to the cross-linkage. Moreover, the surface wettability was changed from hydrophobicity to hydrophilicity. The cross-linked honeycomb structured PS films became resistant to a wide range of organic solvents and thermally stable up to 250 °C, an increase of more than 150 K as compared to the uncross-linked films. The simple cross-linking operation opened the door to facilely fabricate robust and low-cost microporous polymer films.
Co-reporter:Lei Li, Caikang Chen, Jian Li, Aijuan Zhang, Xinyu Liu, Bin Xu, Shubin Gao, Guanghui Jin and Zhi Ma
Journal of Materials Chemistry A 2009 vol. 19(Issue 18) pp:2789-2796
Publication Date(Web):09 Mar 2009
DOI:10.1039/B820279F
Starting from a commercially available block copolymer, polystyrene-b-polybutadiene-b-polystyrene (SBS), micro-patterned polymer films were successfully prepared by evaporating SBS/carbon disulfide solutions with different concentrations under high humidity. The influence of solution concentration on the pore size and array was investigated in detail. With the increase of solution concentration, regular pore arrays turned into random because of weakened convention. Once the concentration was more than 60 mg mL−1, a bimodal size distribution appeared. Photo-chemical cross-linking was achieved by exposing the polymer films in deep UV light (wavelength = 254 nm), monitored by attenuated total reflective Fourier transform infrared and X-ray photoelectron spectroscopy. After 1 h cross-linking, either solvent resistance or thermal stability or surface wettability of the films was significantly improved. The cross-linked honeycomb structured films became resistant to a wide range of organic solvents and thermally stable up to 350 °C, an increase of more than 250 K as compared to the un-crosslinked films. Another beneficial effect of the photo-chemical process was the formation of polar groups on the film surface, changing surface wettability from hydrophobicity to hydrophilicity, enhanced by the micro-patterned surface. The resultant films were non-cytotoxic and hence suitable as cell scaffolds. It was found that hydrophilic, micro-patterned polymer films with a uniform pore size of 3 µm facilitated cell attachment and proliferation.
Co-reporter:Lei Li, Caikang Chen, Aijuan Zhang, Xinyu Liu, Kun Cui, Jin Huang, Zhi Ma, Zhaohui Han
Journal of Colloid and Interface Science 2009 Volume 331(Issue 2) pp:446-452
Publication Date(Web):15 March 2009
DOI:10.1016/j.jcis.2008.11.053
Highly ordered honeycomb films are prepared by breath-figure method using an amphiphilic diblock copolymer of polystyrene-block-polyacrylic acid (PS-b-PAA). By simply cross-linking PS matrix via deep ultraviolet (UV) irradiation, both the solvent and thermal stability of the porous films was significantly improved while retaining the three-dimensional (3D) structures. The film surface wettability was changed from hydrophobicity to hydrophilicity by the formed polar groups during the photochemical process. After 6 h UV cross-linking, the honeycomb structures could be preserved up to 320 °C, an increase of more than 200 K as compared to the non-cross-linked films.Cross-section SEM image of PS-b-PAA film after UV exposure and thermal treatment up to 320 °C.
Co-reporter:Wenqing Li, Aijuan Zhang, Hui Gao, Mingjie Chen, Anhua Liu, Hua Bai and Lei Li
Chemical Communications 2016 - vol. 52(Issue 13) pp:NaN2783-2783
Publication Date(Web):2016/01/06
DOI:10.1039/C5CC07908J
A general challenge for preparing organic microporous polymers (MOPs) is to use cheap and sustainable building blocks while retaining the advanced functions. We demonstrate a strategy to massively prepare pitch-based MOPs, which are thermally and chemically stable. A maximum BET surface area of 758 m2 g−1 and high gas storage capacity were achieved.
Co-reporter:Libin Chen, Yanru Chen, Jifeng Wu, Jianwei Wang, Hua Bai and Lei Li
Journal of Materials Chemistry A 2014 - vol. 2(Issue 27) pp:NaN10531-10531
Publication Date(Web):2014/05/06
DOI:10.1039/C4TA01319K
An electrochemical supercapacitor with a polymeric active electrolyte was designed and fabricated in this work. A water-soluble conducting polymer, sulfonated polyaniline (SPAni), was used in the supercapacitor as the active electrolyte and a semipermeable membrane was employed as the separator of the device. It was found that SPAni in the electrolyte can provide pseudocapacitance via its reversible electrochemical redox reaction. Owing to the good stability of SPAni, the supercapacitor has a long cycling life. Moreover, the migration of SPAni between the two electrodes was blocked by the semipermeable membrane separator, thus self-discharge caused by the shuttle effect of SPAni was suppressed. The research in this paper demonstrates the possibility of using a polymer as the active electrolyte in a supercapacitor and has paved a new way to achieve active electrolyte enhanced supercapacitors with high capacitance and good energy retention.
Co-reporter:Lei Li, Caikang Chen, Jian Li, Aijuan Zhang, Xinyu Liu, Bin Xu, Shubin Gao, Guanghui Jin and Zhi Ma
Journal of Materials Chemistry A 2009 - vol. 19(Issue 18) pp:NaN2796-2796
Publication Date(Web):2009/03/09
DOI:10.1039/B820279F
Starting from a commercially available block copolymer, polystyrene-b-polybutadiene-b-polystyrene (SBS), micro-patterned polymer films were successfully prepared by evaporating SBS/carbon disulfide solutions with different concentrations under high humidity. The influence of solution concentration on the pore size and array was investigated in detail. With the increase of solution concentration, regular pore arrays turned into random because of weakened convention. Once the concentration was more than 60 mg mL−1, a bimodal size distribution appeared. Photo-chemical cross-linking was achieved by exposing the polymer films in deep UV light (wavelength = 254 nm), monitored by attenuated total reflective Fourier transform infrared and X-ray photoelectron spectroscopy. After 1 h cross-linking, either solvent resistance or thermal stability or surface wettability of the films was significantly improved. The cross-linked honeycomb structured films became resistant to a wide range of organic solvents and thermally stable up to 350 °C, an increase of more than 250 K as compared to the un-crosslinked films. Another beneficial effect of the photo-chemical process was the formation of polar groups on the film surface, changing surface wettability from hydrophobicity to hydrophilicity, enhanced by the micro-patterned surface. The resultant films were non-cytotoxic and hence suitable as cell scaffolds. It was found that hydrophilic, micro-patterned polymer films with a uniform pore size of 3 µm facilitated cell attachment and proliferation.
Co-reporter:Jianliang Gong, Bingang Xu, Xiaoming Tao and Lei Li
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 19) pp:NaN13637-13637
Publication Date(Web):2016/04/15
DOI:10.1039/C6CP01538G
The intense interest surrounding asymmetrical microparticles originates from their unique anisotropic properties and promising applications. In this work, direct self-assembly of polymeric microspherical caps without the assistance of any additives has been achieved by using low-surface-tension methanol (MeOH) and high-surface-tension water as binary breath figures (BFs). With the evaporation of polystyrene (PS) solution containing low-boiling-point solvent in the binary vapors, the formed MeOH BFs could quickly diffuse into solution, while water BFs tended to remain at the solution surface. This led to the formation of a gradient nonsolvent layer at the vapor/solution interface, which induced the formation of nuclei and guided further asymmetrical growth of polymer particles. After the spontaneous removal of MeOH, water and residual solvent by evaporation, polymeric microspherical caps were left on the substrate. Through controlling the proportion of water introduced by adjusting the ratios of MeOH and water, polymeric microspherical caps with a range of controllable shapes (divided at different positions of a sphere) were successfully obtained. The formation mechanism was explained based on the difference of vapor pressure, surface tension and miscibility between the employed solvents and nonsolvents. A solvent possessing a high vapor pressure, low surface tension and good miscibility with MeOH contributed to the formation of microspherical caps. This flexible, green and straightforward technique is a nondestructive strategy, and avoids complicated work on design, preparation and removal of hard templates and additives.
Co-reporter:Lei Li, Yawen Zhong, Jian Li, Caikang Chen, Aijuan Zhang, Jin Xu and Zhi Ma
Journal of Materials Chemistry A 2009 - vol. 19(Issue 39) pp:NaN7227-7227
Publication Date(Web):2009/08/20
DOI:10.1039/B911714H
In this article, a facile static breath-figure (BF) method to prepare highly ordered polystyrene (PS) thin films was reported. The static process was robust and tolerated more variability in casting conditions, although non-polar linear PS was not believed to be a good candidate for the BF technique. In the following UV irradiation, not only were the microporous structures well preserved, but also thermal and chemical resistance of the films was significantly improved due to the cross-linkage. Moreover, the surface wettability was changed from hydrophobicity to hydrophilicity. The cross-linked honeycomb structured PS films became resistant to a wide range of organic solvents and thermally stable up to 250 °C, an increase of more than 150 K as compared to the uncross-linked films. The simple cross-linking operation opened the door to facilely fabricate robust and low-cost microporous polymer films.
Co-reporter:Lei Li, Jian Li, Yawen Zhong, Caikang Chen, Yi Ben, Jianliang Gong and Zhi Ma
Journal of Materials Chemistry A 2010 - vol. 20(Issue 26) pp:NaN5453-5453
Publication Date(Web):2010/05/26
DOI:10.1039/C0JM00405G
Here, we show a facile and versatile method preparing highly ordered ceramic microstructures on solid substrates by pyrolyzing UV cross-linked copolymer films to circumvent the expensive lithographic technique. The employed block copolymer, poly(dimethylsiloxane)-block-polystyrene (PDMS-b-PS), in this study was synthesized by controlling radical polymerization. The highly ordered microporous polymer films were formed using a static breath figure process. After 4 h UV irradiation, the PS composition was effectively cross-linked. The cross-linked microporous polymer matrix served as a structure-directing agent in the following pyrolysis process, in which the PDMS composition was converted into silica to form honeycomb structured micropatterns on the substrate. The chemical components of the ceramic microstructures were adjusted by simply mixing different functional precursors. Moreover, the ceramic microstructures on substrate could be replicated to prepare textured PDMS stamps. This simple technique offers new prospects in the fields of micropatterns, soft lithography and templates.
Co-reporter:Yunqiang Chen, Kaiwu Chen, Hua Bai and Lei Li
Journal of Materials Chemistry A 2012 - vol. 22(Issue 34) pp:NaN17804-17804
Publication Date(Web):2012/07/09
DOI:10.1039/C2JM33530A
Chemically converted graphene–room temperature ionic liquid (CCG–RTIL) porous materials were prepared by electrochemical reducing graphene oxide followed by solvent exchange. The resulted CCG–RTIL materials possess 3D porous structure with textured surface, and show good stability in air. Under laser irradiation the temperature of CCG–RTIL materials increased rapidly and significantly, indicating the high photothermal conversion ability of these materials. The influence of CCG–RTIL thickness on the photothermal conversion performance was investigated. These CCG–RTIL materials were used as light absorbers to modify thermoelectric devices, forming light-driven thermoelectric generators, and significantly enhanced the performance of these devices. This work suggests that CCG–RTIL porous materials prepared by this electrochemical method are promising light absorbers for solar electric generation and other photo-thermo-electric conversion devices.
Co-reporter:Kaiwu Chen, Libin Chen, Yunqiang Chen, Hua Bai and Lei Li
Journal of Materials Chemistry A 2012 - vol. 22(Issue 39) pp:NaN20976-20976
Publication Date(Web):2012/08/15
DOI:10.1039/C2JM34816K
A general method for the fabrication of three-dimensional (3D) porous graphene-based composite materials is reported. This method involves two consecutive electrochemical steps. Firstly, 3D graphene (ERGO) porous material is prepared electrochemically by reducing a concentrated graphene oxide dispersion. Subsequently, the second component is electrochemically deposited onto this 3D ERGO matrix, yielding graphene-based 3D porous composite material. The prepared graphene-based composite materials have a conductive graphene network as the matrix, onto which the second component is homogeneously coated. Conducting polymers, noble metal nanoparticles and metal oxide were successfully incorporated into ERGO architectures, demonstrating the versatility of this method. Taking the ERGO–polyaniline composite as an example, the influence of deposition rate on the morphology of the composite was investigated. Finally, the application of the composite materials prepared with our method was discussed. The high surface area and low electrolyte transport resistance make these electrosynthesized composites suitable electrode materials for electrochemical devices. The ERGO–polyaniline composite electrode showed a high specific capacitance of 716 F g−1 at 0.47 A g−1, and this capacitance could be maintained at 502 F g−1 as the discharge current density was increased up to 4.2 A g−1.
Co-reporter:Yunqiang Chen, Qingkun Zhang, Libin Chen, Hua Bai and Lei Li
Journal of Materials Chemistry A 2013 - vol. 1(Issue 42) pp:NaN13110-13110
Publication Date(Web):2013/08/30
DOI:10.1039/C3TA13285D
Porous composites based on basic aluminum sulfate and graphene hydrogel (BAS@GHG) were prepared via homogeneous precipitation of BAS in GHG, and used as adsorbents for fluoride removal from water. The BAS@GHG composites have a porous structure with a chemically converted graphene three dimensional network coated by a thin layer of amorphous BAS. These composites showed high adsorption capacities of up to 33.4 mg g−1 at equilibrium fluoride concentrations of 10.7 mg L−1 and temperatures of 298 K, higher than those of previously reported graphene and aluminum-based adsorbents. The adsorption kinetics and isotherm were analyzed by fitting experimental data with pseudo-first-order kinetics, the Weber–Morris model and Langmuir equations. The effects of temperature, pH value, and co-existing anions on the adsorption of fluoride were also investigated.
Co-reporter:Yunqiang Chen, Libin Chen, Hua Bai and Lei Li
Journal of Materials Chemistry A 2013 - vol. 1(Issue 6) pp:NaN2001-2001
Publication Date(Web):2012/11/23
DOI:10.1039/C2TA00406B
Water pollution is one of the most pervasive problems afflicting people throughout the world, while adsorption is the most widely used method to remove the contaminants from water. Here, in this paper, we report an eco-friendly graphene oxide–chitosan (GO–CS) hydrogel as a new type of adsorbent for water purification. The GO–CS hydrogels were prepared via self-assembly of GO sheets and CS chains. A three-dimensional network composed of GO sheets crosslinked by CS was found in GO–CS hydrogels. The GO–CS composite hydrogels showed high adsorption capacity towards different contaminants, including cationic and anionic dyes, as well as heavy metal ions. The mechanism of the dye adsorption was investigated with a spectral method, and an electrostatic interaction was found to be the major interaction between ionic dyes and the hydrogel. The influence of the hydrogel composition on the adsorption capacity towards different adsorbates was also studied. Finally, it was demonstrated that the GO–CS hydrogel can be used as column packing, to fabricate a column for water purification by filtration.
Co-reporter:Jie Bai, Anan Zhou, Zhifeng Huang, Jifeng Wu, Hua Bai and Lei Li
Journal of Materials Chemistry A 2015 - vol. 3(Issue 45) pp:NaN22694-22694
Publication Date(Web):2015/09/28
DOI:10.1039/C5TA06204G
Graphene foams (GFs) have attracted increasing attention because they combine the unique properties of cellular materials and the excellent performance of graphene. The preparation of GFs depends mainly on the self-assembly of graphene or graphene oxide sheets, and designing and controlling the cell morphology of GFs, which determines their properties, remain a challenge. Here, we report a novel strategy for preparing GFs with a hierarchical porous structure. Our preparation method involves mechanically foaming a graphene oxide dispersion with the assistance of a surfactant, followed by lyophilization and thermal reduction. These novel GFs possess large cells created using the bubbles as templates and small pores around the edges of the cells resulting from the self-assembly of the graphene oxide sheets. Because of their unique cell structure, the GFs exhibit an ultra-low density, high porosity, good electrical conductivity, and excellent elasticity. In particular, these GFs exhibit a very large absorption capacity (600–1500 g g−1) for oils and organic solvents. Our work explores a new strategy for controlling the cell morphology and improving the performance of GFs; the results may shed new light on the relationship between the structure and properties of 3D graphene assemblies.
Co-reporter:Libin Chen, Jifeng Wu, Aijuan Zhang, Anan Zhou, Zhifeng Huang, Hua Bai and Lei Li
Journal of Materials Chemistry A 2015 - vol. 3(Issue 31) pp:NaN16039-16039
Publication Date(Web):2015/06/26
DOI:10.1039/C5TA03881B
Electroactive polymers constitute an important class of electrode materials for supercapacitors based on pseudocapacitance. However, it is difficult to utilize low-conductive electroactive polymers in supercapacitors, although these polymers may have large theoretical specific capacitance. In this article, we designed and prepared a novel type of electrode material, with a unique structure of low-conductive electroactive polyhydroquinone (PHQ) coated on a highly conductive three-dimensional (3D) porous graphene hydrogel (GHG). PHQ–GHG composites were prepared via a one-step reaction between graphene oxide and hydroquinone under mild conditions. Because PHQ has a large theoretical specific capacitance, and GHG possesses a 3D porous structure, large specific surface area and high electrical conductivity, the composites showed a high specific capacitance of 490 F g−1 at a current density of 24 A g−1, as well as excellent rate performance and cycling stability. These results demonstrate that PHQ–GHG composites are promising electrode materials for supercapacitors, and the method developed in this paper paves a new way for utilizing those electroactive polymers of low electrical conductivities in supercapacitors.
Co-reporter:Hui Gao, Lei Ding, Hua Bai, Anhua Liu, Sizhong Li and Lei Li
Journal of Materials Chemistry A 2016 - vol. 4(Issue 42) pp:NaN16498-16498
Publication Date(Web):2016/09/22
DOI:10.1039/C6TA07033G
A general challenge will be to reengineer porous materials where scale-up is prohibited by cost, retaining advanced functions but using cheaper and more sustainable building blocks. Every year the petro- and coal-chemical industry produces massive amounts of pitch, mainly composed of phenols, polycyclic aromatic hydrocarbons and heterocyclic compounds. We employed these previously ignored building blocks and prepared hyper-cross-linked polymers (HCPs) with a high surface area via a one-step Friedel–Crafts reaction. Depending on the place of origin, petroleum-pitch-based HCPs have a maximum BET surface area of 1337 m2 g−1 with good chemical stability. The inherent heteroatoms in the pitch (sulfur) and the introduced heteroatom (chlorine) endow the obtained HCPs with excellent gas adsorption capability. The uptake capacity for CO2 reaches up to 17.74 wt% (1.0 bar, 273 K) and the hydrogen storage is up to 1.83 wt% (1.13 bar, 77 K), which is much better than those of most reported microporous organic polymers. In addition, the pitch-based HCPs also show high organic vapor capture capacity at room temperature (cyclohexane: 1115 mg g−1; ethyl acetate: 685 mg g−1; methanol: 1198 mg g−1 and benzene: 890 mg g−1). The effective utilization of pitch for HCPs with high gas adsorption capability is essential for global sustainable development and environmental issues.
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