Co-reporter:Yongsan Li, Yingwei Zhang, Feng Shi, Lei Tao, Yen Wei, Xing Wang
Colloids and Surfaces B: Biointerfaces 2017 Volume 149() pp:168-173
Publication Date(Web):1 January 2017
DOI:10.1016/j.colsurfb.2016.10.021
•Modulus regulated 3D-Cell proliferation is studied in a self-healing hydrogel.•This self-healing hydrogel is growth-factor-free, modulus tunable and injectable.•3D cell proliferation before and after injection is presented.•The proliferating rates of the encapsulated cells are quantified.•This hydrogel offer potentially higher therapeutic efficiency for cell-therapy.Cell therapy has attracted wide attention among researchers in biomaterial and medical areas. As a carrier, hydrogels that could keep high viability of the embedded cells have been developed. However, few researches were conducted on 3D cell proliferation, a key factor for cell therapy, especially after injection. In this study, we demonstrated for the first time the proliferation regulation of the 3D-embedded L929 cells in a modulus-tunable and injectable self-healing hydrogel before and after injection without adding specific growth factor. The cells showed a stiffness-dependent proliferation to grow faster in higher stiffness hydrogels. The proliferating rates of the encapsulated cells before and after injection were quantified, and the shearing force as a possible negative influence factor was discussed, suggesting the both internal property of the hydrogel and injection process are critical for further practical applications. Due to the high operability and good biocompatibility, this injectable self-healing hydrogel can be a promising carrier for cell therapy.Proliferation of the 3D-embedded cells was studied using a modulus-tunable self-healing hydrogel carrier, especially after injection.
Co-reporter:Guannan Ju;Fengli Guo;Qian Zhang;Alexer J. C. Kuehne;Shuxun Cui;Mengjiao Cheng
Advanced Materials 2017 Volume 29(Issue 37) pp:
Publication Date(Web):2017/10/01
DOI:10.1002/adma.201702444
Macroscopic supramolecular assembly (MSA) represents a new advancement in supramolecular chemistry involving building blocks with sizes beyond tens of micrometers associating through noncovalent interactions. MSA is established as a unique method to fabricate supramolecularly assembled materials by shortening the length scale between bulk materials and building blocks. However, improving the precise alignment during assembly to form orderly assembled structures remains a challenge. Although the pretreatment of building blocks can ameliorate order to a certain degree, defects or mismatching still exists, which limits the practical applications of MSA. Therefore, an iterative poststrategy is proposed, where self-correction based on dynamic assembly/disassembly is applied to achieve precise, massive, and parallel assembly. The self-correction process consists of two key steps: the identification of poorly ordered structures and the selective correction of these structures. This study develops a diffusion-kinetics-dependent disassembly to well identify the poorly aligned structures and correct these structures through iterations of disassembly/reassembly in a programmed fashion. Finally, a massive and parallel assembly of 100 precise dimers over eight iteration cycles is achieved, thus providing a powerful solution to the problem of processing insensitivity to errors in self-assembly-related methods.
Co-reporter:Mengjiao Cheng;Yingwei Zhang;Song Wang
Nanoscale (2009-Present) 2017 vol. 9(Issue 44) pp:17220-17223
Publication Date(Web):2017/11/16
DOI:10.1039/C7NR07059D
Macroscopic supramolecular assembly (MSA) is a newly established methodology to construct supramolecular materials directly from large building blocks. Demonstrations of MSA for various functions are urgently needed to advance MSA from fundamental studies to practical uses. Here we propose the fabrication of DNA microarrays by combining MSA and magnetic-assisted localization.
Co-reporter:Yue Wang;Wenjun You;Yifan Song;Xiangxin Li;Dengli Qiu;Mengjiao Cheng
Journal of Materials Chemistry B 2017 vol. 5(Issue 2) pp:375-381
Publication Date(Web):2017/01/04
DOI:10.1039/C6TB01780K
Due to the noncovalent interactions between the layers of polyelectrolyte films, the layer-by-layer assembled multilayered films always face the challenge of low film stiffness and chemical stability under extreme conditions. To handle this issue, we incorporated 4,4′-diazostilbene-2,2′-disulfonic acid disodium salt (DAS) as a crosslinker and subsequently photocrosslinked the layers of a poly(allylamine hydrochloride)/catalase multilayered film. The results showed that DAS could stabilize the prepared film in a manner similar to the traditional cross-linker glutaraldehyde. The multilayered film showed good biocompatibility with a positive effect on cell proliferation. Therefore, by using the commercially available DAS crosslinker, we provide a synthesis-free and biocompatible method to stabilize polyelectrolyte multilayers for broad and significant applications in biological fields, e.g., varying crosslinking density to adjust the mechanical strength of biomaterials, stabilizing susceptible biofilms, or introducing functional groups onto cell membranes.
Co-reporter:Lina Zhang;Mengmeng Song;Meng Xiao
Advanced Functional Materials 2016 Volume 26( Issue 6) pp:851-856
Publication Date(Web):
DOI:10.1002/adfm.201504305
Harvesting energy from environment has attracted increasing attention for its potential applications in fabricating minigenerator. However, most studies in the fabrication of mini- or nanogenerators are based on the concept of piezoelectricity or triboelectrification while few of the reports paid attention to the classical theory of Faraday's law. Herein, a pH responsive smart surface is combined with the reaction between CaCO3 and HCl to develop a new minigenerator, which can convert mechanical energy generated from the chemical reaction into electrical energy through cutting magnetic lines with moving conductive lines. The conductive lines are connected with a smart device consisting of a pH-responsive cube, a hydrophobic cube, and a quartz cell window; the device can perform diving-surfacing cycled motions with an intelligent initiation through the adjustment of the solution. The device can surface through gathering CO2 bubbles from the reaction between CaCO3 and HCl and dive by releasing the bubbles on the water/air interface. Moreover, the results demonstrate that the inert CO2 was nonhazardous to the smart surfaces, which is meaningful for durable electricity generation.
Co-reporter:Meng Xiao, Lei Wang, Fanqin Ji, and Feng Shi
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 18) pp:11403
Publication Date(Web):April 20, 2016
DOI:10.1021/acsami.6b00550
Energy conversion from a mechanical form to electricity is one of the most important research advancements to come from the horizontal locomotion of small objects. Until now, the Marangoni effect has been the only propulsion method to produce the horizontal locomotion to induce an electromotive force, which is limited to a short duration because of the specific property of surfactants. To solve this issue, in this article we utilized the decomposition of hydrogen peroxide to provide the propulsion for a sustainable energy conversion from a mechanical form to electricity. We fabricated a mini-generator consisting of three parts: a superhydrophobic rotator with three jaws, three motors to produce a jet of oxygen bubbles to propel the rotation of the rotator, and three magnets integrated into the upper surface of the rotator to produce the magnet flux. Once the mini-generator was placed on the solution surface, the motor catalyzed the decomposition of hydrogen peroxide. This generated a large amount of oxygen bubbles that caused the generator and integrated magnets to rotate at the air/water interface. Thus, the magnets passed under the coil area and induced a change in the magnet flux, thus generating electromotive forces. We also investigated experimental factors, that is, the concentration of hydrogen peroxide and the turns of the solenoid coil, and found that the mini-generator gave the highest output in a hydrogen peroxide solution with a concentration of 10 wt % and under a coil with 9000 turns. Through combining the stable superhydrophobicity and catalyst, we realized electricity generation for a long duration, which could last for 26 000 s after adding H2O2 only once. We believe this work provides a simple process for the development of horizontal motion and provides a new path for energy reutilization.Keywords: bubble propulsion; energy conversion; horizontal locomotion; mini-generator; smart device
Co-reporter:Raheel Akram, Mengjiao Cheng, Fengli Guo, Saleem Iqbal, and Feng Shi
Langmuir 2016 Volume 32(Issue 15) pp:3617-3622
Publication Date(Web):March 30, 2016
DOI:10.1021/acs.langmuir.6b00115
The mismatching phenomena are ubiquitous in complex and advanced self-assembly, such as hierarchical assembly, macroscopic supramolecular assembly, and so on. Recently, for macroscopic supramolecular assembly, the strategy of maximizing the interactive surface area was used and supposed to handle this problem; however, now there is little understanding of whether interactive surface area is the dominant factor to guide the assembly patterns. Herein by taking millimeter cylinder building blocks with different diameter/height (d/h) ratios as model systems, we have investigated the interactive-surface-area-dependent assembling behaviors in macroscopic supramolecular assembly. The results showed that the increasing d/h ratio of cylinders contributed to selectivity of face-to-face assembled pattern over face-to-side or side-to-side geometries, thus having improved the ordering degree of the assembled structures; however, the mismatching phenomena could not be totally avoided due to high colliding chances in kinetics and the thermally favorable stability of these structures. We further confirmed the above hypothesis by in situ measurements of interactive forces of building blocks with different assembled patterns. This work of macroscopic supramolecular assembly provides an in situ visible platform, which is significant to clarify the influences of interactive surface area on the assembly behaviors.
Co-reporter:Xinglong Luan, Tao Huang, Yan Zhou, Qi An, Yue Wang, Yaling Wu, Xiangming Li, Haitao Li, Feng Shi, and Yihe Zhang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 49) pp:
Publication Date(Web):September 26, 2016
DOI:10.1021/acsami.6b10453
Interfacial properties including permeation, catalytic efficiency, Raman signal enhancement capabilities, and cell spreading efficiencies are important features that determine material functionality and applications. Here, we propose a facile method to adjust the above-mentioned properties by controlling the cross-linking degrees of multilayer using a photoactive molecule. After treating the cross-linked films in basic solutions, films with different cross-linking degrees presented varying residue thicknesses and film morphologies. As a result, these different films possessed distinct molecular loading and release characteristics. In addition, gold nanoparticles (AuNPs) of different morphological traits were generated by redox reactions coupled with diffusion within these films. The AuNP–polyelectrolyte obtained from the polyelectrolyte films of the medium cross-linking degrees displayed the highest catalytic efficiency and signal enhancement capabilities. Furthermore, cells responded to the variation of film cross-linking degrees, and on the films with the highest cross-linking degree, cells adhered with the highest speed. We expect this report to provide a general interfacial material engineering strategy for material designs.Keywords: catalytic efficiency; cell spreading; interfacial permeation; layer-by-layer; photochemical cross-linking; signal enhancement capability;
Co-reporter:Lingling Yu;Mengjiao Cheng;Mengmeng Song;Dequn Zhang;Meng Xiao
Advanced Functional Materials 2015 Volume 25( Issue 36) pp:5786-5793
Publication Date(Web):
DOI:10.1002/adfm.201502447
Smart motions of objects from the submicrometer to millimeter scale through chemical control with stimulus-responsive way are significant to achieve various applications. However, the intelligence of the current devices with chemical responding system remains to be improved; especially, achieving a round-way motion is still a challenge. Therefore, two types of actuators are simultaneously integrated into single smart device at the opposite ends to achieve cooperated functions in an orderly manner. One actuator is the pH-responsive power supply of hydrogen bubbles produced from the reaction between magnesium and HCl. The smart device undergoes on–off–on locomotion through control over the solution pH values by using the pH-responsive actuator of magnesium–HCl system. The other actuator is the hydrogen peroxide-responsive system of oxygen bubbles generated through the decomposition of hydrogen peroxide catalyzed by platinum aggregates. When introducing hydrogen peroxide solution into the system, the generated oxygen bubbles at the opposite end of the device to push the device backward for round-way motions. For the first time, two different types of actuators are simultaneously integrated into single smart device without disturbing each other, which realize pH-responsive round-way motions of the smart device and improve the system intelligence for further applications.
Co-reporter:Mengjiao Cheng;Yue Wang;Lingling Yu;Haijia Su;Weidong Han;Zaifu Lin;Jianshu Li;Haojie Hao;Chuan Tong;Xiaolei Li
Advanced Functional Materials 2015 Volume 25( Issue 44) pp:6851-6857
Publication Date(Web):
DOI:10.1002/adfm.201503366
3D ordered structures beyond microscale with targeted modification are catching increasing attention due to its application as tissue scaffolds. Especially scaffolds with necessary growth factors at designated locations are meaningful for induced cell differentiation and tissue formation. However, few fabrication methods can address the challenge of introducing bioactive species to the interior targeted places during the preparation process. Herein, for the first time macroscopic supramolecular assembly is applied to obtain such 3D ordered structures and established a proof-of-concept idea of complex scaffold with targeted modification. Taking strip-like polydimethylsilicon building block as a model system, microscaled multilayered structures have been fabricated with parallel aligned building blocks in each layer. The morphology can be adjusted in a flexible way by tuning the number of layer, the space between two adjacent building blocks, and the position and orientation of each PDMS. The as-prepared 3D structures are demonstrated biocompatible and potential as scaffolds for 3D cell culture. Moreover, bioactive species can be in situ incorporated into designated locations within the 3D structure precisely. In this way, a novel strategy is provided to address the current challenges in fabricating complex 3D tissue scaffolds with localized protein for future induced cell differentiation.
Co-reporter:Yue Wang, Qi An, Yong Zhou, Yue Niu, Raheel Akram, Yihe Zhang and Feng Shi
Journal of Materials Chemistry A 2015 vol. 3(Issue 4) pp:562-569
Publication Date(Web):14 Nov 2014
DOI:10.1039/C4TB01688B
The layer-by-layer (LbL) technique has been intensively investigated as a straightforward method for the incorporation of drug molecules or other bioactive species, enabling retarded release in drug delivery devices, in bioactive interfaces, in tissue engineering, and in regenerative medicine. The preparation of crosslinked LbL multilayers with embedded drug reservoirs for delayed release remains a challenging task, however. In the present study we have developed a method for the simultaneous utilisation of covalent interlayer linkages and drug reservoirs that can hold model drug molecules. A strategy of post-infiltration of photoactive bifunctional small molecules followed by UV irradiation has been employed for crosslinking the LbL multilayers, incorporating poly(amido amine) (PAMAM) molecules, which serve as a drug reservoir. The covalent linkage significantly alters the release profile of the model drug from the multilayers, with retarded release of hydrophobic molecules from a solvent, and enabling the loaded multilayers to withstand rinsing with 75% ethanol, the most commonly used sterilization procedure.
Co-reporter:Qi An, Yihe Zhang, Kaikai Lv, Xinglong Luan, Qian Zhang and Feng Shi
Nanoscale 2015 vol. 7(Issue 10) pp:4553-4558
Publication Date(Web):05 Feb 2015
DOI:10.1039/C5NR00026B
In this paper, we present a facile method for the fabrication of a functionally integrated device, which has the multi-functions of the oil-containment boom, oil-sorption material, and water/oil-separating film, through a single immersion step in an ethanol solution of stearic acid. During the simple immersion process, the two dominant factors of superhydrophobicity, surface roughness and low-surface-energy coatings, could be accomplished simultaneously. The as-prepared functionally integrated device with superhydrophobicity/superoleophilicity displayed a lower density than that of water, such that it could float on water and act as an oil-containment boom; an efficient oil-absorbing property, which was attributed to the capillary effect caused by micrometer-sized pore structures and could be used as oil-sorption materials; a high oil/water separating efficiency which was suitable for water/oil-separating film. In this way, the functions of oil collection, absorption, and water/oil separation are integrated into a single device, and these functions could work independently, reducing the cost in terms of energy consumption and being versatile for a wide range of applications.
Co-reporter:Chao Jiang, Caijun Luo, Xiaolin Liu, Lei Shao, Youqing Dong, Yingwei Zhang, and Feng Shi
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 20) pp:10920
Publication Date(Web):May 8, 2015
DOI:10.1021/acsami.5b02179
The layer-by-layer (LbL) assembled multilayer has been widely used as good barrier film or capsule due to the advantages of its flexible tailoring of film permeability and compactness. Although many specific systems have been proposed for film design, developing a versatile strategy to control film compactness remains a challenge. We introduced the simple mechanical energy of a high gravity field to the LbL assembly process to tailor the multilayer permeability through adjusting film compactness. By taking poly(diallyldimethylammonium chloride) (PDDA) and poly{1–4[4-(3-carboxy-4-hydroxyphenylazo)benzenesulfonamido]-1,2-ethanediyl sodium salt} (PAzo) as a model system, we investigated the LbL assembly process under a high gravity field. The results showed that the high gravity field introduced effectively accelerated the multilayer deposition process by 20-fold compared with conventional dipping assembly; the adsorption rate was positively dependent on the rotating speed of the high gravity equipment and the concentration of the building block solutions. More interestingly, the film compactness of the PDDA/PAzo multilayer prepared under the high gravity field increased remarkably with the growing rotational speed of the high gravity equipment, as demonstrated through comparisons of surface morphology, cyclic voltammetry curves, and photoisomerization kinetics of PDDA/PAzo multilayers fabricated through the conventional dipping method and through LbL assembly under a high gravity field, respectively. In this way, we have introduced a simple and versatile external form of mechanical energy into the LbL assembling process to improve film compactness, which should be useful for further applications in controlled ion permeability, anticorrosion, and drug loading.Keywords: acceleration of diffusion process; high gravity field; improvement of film compactness; layer-by-layer assembly; photoisomerization of Azo group; reduction of ion permeability;
Co-reporter:Mengjiao Cheng, Chao Jiang, Caijun Luo, Yajun Zhang, and Feng Shi
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 33) pp:18824
Publication Date(Web):August 10, 2015
DOI:10.1021/acsami.5b05555
The zigzag film growth behavior in the layer-by-layer (LbL) assembly method is a ubiquitous phenomenon for which the growth mechanism was rarely investigated, especially for small molecules. To interpret the zigzag increasing manner, we hypothesized that the desorption kinetics of small molecules was dominant for the film growth behavior and demonstrated this hypotheis by introducing the high-gravity technique into the LbL assembly of a typical polyelectrolyte/small molecule system of polyethylenimine (PEI) and meso-tetra(4-carboxyphenyl)porphine (Por). The results showed that the high-gravity technique remarkably accelerated the desorption process of Por; the high-gravity LbL assembly provides a good platform to reveal the desorption kinetics of Por, which is tedious to study in conventional situation. We found that as much as 50 min is required for Por molecules to reach desorption equilibrium from the substrate to the bulk PEI solution for the conventional dipping method; however, the process could be accelerated and require only 100 s if a high-gravity field is used. Nonequilibrated desorption at 10 min for normal dipping and at 30 s for high-gravity-field-assisted assembly both exhibited a zigzag film growth, but after reaching desorption equilibrium at 100 s under a high-gravity field, film growth began to cycle between assembly and complete disassembly instead of LbL assembly. For the first time we have proven that the high-gravity technique can also accelerate the desorption process and demonstrated the desorption-dependent mechanism of small molecules for zigzag film growth behaviors.Keywords: desorption; high gravity; layer-by-layer assembly; small molecule; zigzag increasing
Co-reporter:Mengjiao Cheng, Songsong Zhang, Hongyu Dong, Shihui Han, Hao Wei, and Feng Shi
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 7) pp:4275
Publication Date(Web):February 3, 2015
DOI:10.1021/am5085012
The durability of superhydrophobic surface is a major problem to restrict industrial application of superhydrophobic materials from laboratory research, which can be attributed to a more general issue of mechanical stability for superhydrophobic coatings. Therefore, in order to handle this issue, we have fabricated a mechanically stable drag-reducing coating composed of elastic polydimethylsiloxane (PDMS) and hydrophobic copper particles on model ships, which can resist mechanical abrasion and has displayed a durable drag-reducing effect. In comparison with normal Au superhydrophobic coatings, the as-prepared PDMS/copper coatings showed durable drag reduction performance with a similar drag-reducing rate before (26%) and after (24%) mechanical abrasion. The mechanism for the enhanced mechanical stability and maintained drag reduction of the superhydrophobic surfaces was investigated through characterizations of surface morphology, surface wettability, and water adhesive force evaluation before and after abrasion. This is the first demonstration to realize the application of durable drag reduction by improving the mechanical stability of superhydrophobic coatings. We do believe that superhydrophobic surfaces with good resistance to mechanical abrasion or scratching may draw wide attention and gain significant applications with durable drag-reducing properties.Keywords: durable drag reduction; mechanical stability; superhydrophobic materials; water adhesive force
Co-reporter:Xiaolin Liu, Kun Zhao, Chao Jiang, Yue Wang, Lei Shao, Yajun Zhang and Feng Shi
Soft Matter 2015 vol. 11(Issue 28) pp:5748-5753
Publication Date(Web):18 Jun 2015
DOI:10.1039/C5SM01055A
Loading functional small molecules into nano-thin films is fundamental to various research fields such as membrane separation, molecular imprinting, interfacial reaction, drug delivery etc. Currently, a general demand for enhancing the loading rate without affecting the film structures exists in most infiltration phenomena. To handle this issue, we have introduced a process intensification method of a high gravity technique, which is a versatile energy form of mechanical field well-established in industry, into the investigations on diffusion/infiltration at the molecular level. By taking a polyelectrolyte multilayer as a model thin film and a photo-reactive molecule, 4,4′-diazostilbene-2,2′-disulfonic acid disodium salt (DAS), as a model small functional molecule, we have demonstrated remarkably accelerated adsorption/infiltration of DAS into a poly(allylamine hydrochloride) (PAH)/poly(acrylic acid) (PAA) multilayer by as high as 20-fold; meanwhile, both the film property of the multilayer and photoresponsive-crosslinking function of DAS were not disturbed. Furthermore, the infiltration of DAS and the surface morphology of the multilayer could be tuned based on their high dependence on the intensity of the high gravity field regarding different rotating speeds. The mechanism of the accelerated adsorption/infiltration under the high gravity field was interpreted by the increased turbulence of the diffusing layer with the thinned laminar boundary layer and the stepwise delivery of the local concentration gradient from the solution to the interior of the multilayer. The introduction of mechanical field provides a simple and versatile strategy to address the paradox of the contradictory loading amount and loading rate, and thus to promote applications of various membrane processes.
Co-reporter:Meng Xiao;Yiming Xian ;Dr. Feng Shi
Angewandte Chemie International Edition 2015 Volume 54( Issue 31) pp:8952-8956
Publication Date(Web):
DOI:10.1002/anie.201502349
Abstract
Macroscopic supramolecular assembly bridges fundamental research on molecular recognition and the potential applications as bulk supramolecular materials. However, challenges remain to realize stable precise assembly, which is significant for further functions. To handle this issue, the Marangoni effect is applied to achieve spontaneous locomotion of macroscopic building blocks to reach interactive distance, thus contributing to formation of ordered structures. By increasing the density of the building blocks, the driving force for assembly transforms from a hydrophobic–hydrophobic interaction to hydrophilic–hydrophilic interaction, which is favorable for introducing hydrophilic coatings with supramolecular interactive groups on matched surfaces, consequently realizing the fabrication of stable precise macroscopic supramolecular assemblies.
Co-reporter:Meng Xiao;Yiming Xian ;Dr. Feng Shi
Angewandte Chemie 2015 Volume 127( Issue 31) pp:9080-9084
Publication Date(Web):
DOI:10.1002/ange.201502349
Abstract
Macroscopic supramolecular assembly bridges fundamental research on molecular recognition and the potential applications as bulk supramolecular materials. However, challenges remain to realize stable precise assembly, which is significant for further functions. To handle this issue, the Marangoni effect is applied to achieve spontaneous locomotion of macroscopic building blocks to reach interactive distance, thus contributing to formation of ordered structures. By increasing the density of the building blocks, the driving force for assembly transforms from a hydrophobic–hydrophobic interaction to hydrophilic–hydrophilic interaction, which is favorable for introducing hydrophilic coatings with supramolecular interactive groups on matched surfaces, consequently realizing the fabrication of stable precise macroscopic supramolecular assemblies.
Co-reporter:Mengmeng Song;Mengjiao Cheng;Guannan Ju;Yajun Zhang
Advanced Materials 2014 Volume 26( Issue 41) pp:7059-7063
Publication Date(Web):
DOI:10.1002/adma.201402237
Co-reporter:Mengjiao Cheng;Qian Liu;Guannan Ju;Yajun Zhang;Lei Jiang
Advanced Materials 2014 Volume 26( Issue 2) pp:306-310
Publication Date(Web):
DOI:10.1002/adma.201302187
Co-reporter:Mengjiao Cheng;Jianshu Li;Zaifu Lin;Chao Jiang;Meng Xiao;Liqun Zhang;Wantai Yang;Toshio Nishi
Advanced Materials 2014 Volume 26( Issue 19) pp:3009-3013
Publication Date(Web):
DOI:10.1002/adma.201305177
Co-reporter:Meng Xiao, Chao Jiang and Feng Shi
NPG Asia Materials 2014 6(9) pp:e128
Publication Date(Web):2014-09-01
DOI:10.1038/am.2014.76
Combining a stimuli-responsive material and the Marangoni effect, a microactuator containing a ultraviolet (UV)-light-responsive photoresist and surfactant is fabricated. The locomotion of a functionally cooperating device loaded with the microactuator can be initiated by irradiation with 365 nm UV light, ceased by the removal of the UV light and restarted by re-exposure to the UV light. Moreover, the device exhibits good direction control via selective irradiation of photoresponsive microactuators at designated locations. This work is the first example using the chemical Marangoni effect to produce photoresponsive ON-OFF-ON motion of a macroscopic object on water surfaces with little impact on the experimental environment and opens up new opportunities for the design of novel advanced functional materials with controlled properties.
Co-reporter:Guannan Ju, Mengjiao Cheng and Feng Shi
NPG Asia Materials 2014 6(7) pp:e111
Publication Date(Web):2014-07-01
DOI:10.1038/am.2014.44
To handle the serious issue of increasing oil spill accidents, many strategies have been proposed to either clean spilt oil or separate water/oil mixture. Especially, superhydrophilic/underwater superoleophobic smart materials have recently shown advantages in overcoming problems of oil blocking and water barriers during conventional oil/water-separating process of oil-rich mixtures with superhydrophobic/superoleophilic materials. However, to the best of our knowledge, no prior reports have detailed smart materials with the wetting properties of superhydrophobic/superoleophilic that can be applied in continuous in situ separations of oil/water/oil ternary mixtures, which are common in practical oil spill cases. Herein, we describe the fabrication and efficacy of a pH-responsive smart device for continuous in situ separations of such oil/water/oil ternary mixtures without the need for ex situ treatments. In air, the superhydrophobic/superoleophilic surface of the device allowed dichloromethane to permeate through while preventing water from passing. The superhydrophilicity/underwater superoleophobicity of the device surface following alkaline treatments prevented the passage of hexane while allowing water to penetrate the device.
Co-reporter:Chao Jiang, Xiaolin Liu, Caijun Luo, Yajun Zhang, Lei Shao and Feng Shi
Journal of Materials Chemistry A 2014 vol. 2(Issue 34) pp:14048-14053
Publication Date(Web):24 Jun 2014
DOI:10.1039/C4TA02437K
The high gravity technique is a strongly intensified process used for rapid mass and heat transfer, which has rarely been applied for the construction of layer-by-layer (LbL) self-assembled films. Herein, we used a poly(acrylic acid) (PAA)/poly(allylamine hydrochloride)–porphine complex (PAH–Por) multilayer to investigate the assembly behaviors between exponential and linear growth, and introduced strong shear stress using a high gravity field to reduce the accumulated surface roughness in exponentially growing films. The results demonstrated that strong shear stress in a high gravity field could transform film growth from exponential to linear. This phenomenon is thought to be the result of reducing surface roughness through shear forces, which was supported by stepwise characterization of ultraviolet-visible spectra and atomic force microscopy. Moreover, the intensified LbL deposition to achieve a transformation from exponential to linear growth could be applied to other systems, including PAH–PAA complex/poly(sodium-p-styrenesulfonate) (PSS) and PAH/PSS multilayers.
Co-reporter:Mengjiao Cheng, Qian Liu, Yiming Xian, and Feng Shi
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 10) pp:7572
Publication Date(Web):April 9, 2014
DOI:10.1021/am500910y
Macroscopic supramolecular assembly is a promising bottom-up method to construct ordered three-dimensional structures in a programmable way because of its flexible tailoring features. To handle the challenges of precisely aligning the building blocks, we proposed the combination of magnetic field-assisted localization for the locomotion of building blocks and host/guest supramolecular recognition for their immobilization. By applying this strategy, we have realized the stepwise construction of microscale glass fibers into an ordered complex pattern. Furthermore, through the introduction of a competitive guest molecule to disassemble the assembled structure, we demonstrated that the interaction between the fibers and the substrate was supramolecular rather than nonselective stickiness. Multivalent theory was used to interpret the mechanism for the interaction process.Keywords: macroscopic supramolecular assembly; magnetic field-assisted localization; multivalency; ordered three-dimensional structure;
Co-reporter:Xiaolin Liu, Caijun Luo, Chao Jiang, Lei Shao, Yingwei Zhang and Feng Shi
RSC Advances 2014 vol. 4(Issue 103) pp:59528-59534
Publication Date(Web):04 Nov 2014
DOI:10.1039/C4RA11048J
Rapid construction of layer-by-layer (LbL) self-assembled multilayers on non-planar substrates is challenging because most conventional LbL processes are time consuming, which restricts further applications of LbL in industry and its commercialization. Therefore, herein we introduced the high gravity (HG) technique, which is a well-established industrial chemical engineering process for intensification of mass transfer, into the LbL assembly process to realize rapid film deposition on porous nickel foam. By using a model system of electrostatically driven PDDA/AuNPs multilayers, the adsorption kinetics, LbL procedure and film morphology have been examined under both conventional dipping conditions and a HG field. The results show that the time to reach saturated adsorption of building blocks with the HG field has been shortened remarkably by up to 16 times while the film quality remains identical. In this way, the fabrication of LbL multilayers can be highly accelerated in the presence of a HG field without disturbing the film quality on non-planar substrates. Moreover, the mechanism for the rapid construction of LbL multilayers using the HG technique is interpreted using the boundary layer theory that the highly turbulent flow in the HG field enhanced the mass transfer rate for the rapid adsorption of building blocks onto substrates.
Co-reporter:Qi An, Yong Zhou, Yajun Zhang, Yihe Zhang and Feng Shi
RSC Advances 2014 vol. 4(Issue 11) pp:5683-5688
Publication Date(Web):19 Nov 2013
DOI:10.1039/C3RA45646C
We report a facile method for the fabrication of robust polyelectrolyte multilayers including strong polyanions. Covalently cross-linked PAH/PSS [PAH: poly(allylamine hydrochloride); PSS: poly(sodium-p-styrene sulfonate)] multilayered films are fabricated using a traditional layer-by-layer technique, followed by post-infiltration of a bifunctional photoactive molecule 4,4′-diazido-2,2′-stilbenedisulfonic acid disodium (DAS) and subsequent photochemical cross-linking. The stability of the cross-linked multilayers was enhanced significantly. Over 90% of the cross-linked multilayers were preserved in a basic solution or good solvent of the polyelectrolyte, forming a clear comparison with the un-crosslinked multilayers, which almost completely decomposed under the circumstances mentioned above.
Co-reporter:Mengjiao Cheng, Guannan Ju, Chao Jiang, Yajun Zhang and Feng Shi
Journal of Materials Chemistry A 2013 vol. 1(Issue 43) pp:13411-13416
Publication Date(Web):11 Sep 2013
DOI:10.1039/C3TA12607B
To handle serious underwater oil spills, we have designed a functionally integrated device which can continuously clean up spilled oil underwater or on the water's surface in a directional manner, guided by a magnetic field, collecting the oil into the interior of the device and recycling it. The collecting efficiency is higher than 90%.
Co-reporter:Hongyu Dong, Mengjiao Cheng, Yajun Zhang, Hao Wei and Feng Shi
Journal of Materials Chemistry A 2013 vol. 1(Issue 19) pp:5886-5891
Publication Date(Web):05 Mar 2013
DOI:10.1039/C3TA10225D
We have fabricated a self-cleaning coating on a model ship with a large and curved surface by electroless deposition of gold aggregates, and the superhydrophobic model ship exhibited a remarkable drag reduction of 38.5% at a velocity of 0.46 m s−1. The as-prepared coating exhibits excellent superhydrophobic properties, with a contact angle as high as 159.7°. To rule out the influence of wetting area differences between superhydrophobic coated materials and normal materials, we modified the large curved surface of a model ship with the self-cleaning coating and investigated its drag reducing properties at high speed. The results showed that the superhydrophobic coating took effect in reducing drag; the mechanism of the drag reduction is discussed based on the plastron effect and Newton's law of viscosity.
Co-reporter:Yong Zhou, Mengjiao Cheng, Xiaoqun Zhu, Yajun Zhang, Qi An and Feng Shi
Journal of Materials Chemistry A 2013 vol. 1(Issue 37) pp:11329-11334
Publication Date(Web):23 Jul 2013
DOI:10.1039/C3TA12699D
In this paper, we have developed a facile and general strategy to enhance the stability of multilayers incorporating nanoparticles and the weak polyelectrolyte poly(allylamine hydrochloride) (PAH). Using Fe3O4 nanoparticles (Fe3O4 NPs) and Au nanoparticles (Au NPs) as separate model systems, after multilayers of nanoparticles and PAH were constructed employing the layer-by-layer (LbL) technique, 4,4′-diazostilbene-2,2′-disulphonic acid disodium salt (DAS) was post-infiltrated into the multilayers and subsequent photochemical cross-linking was completed under UV irradiation. The stability of multilayers with Fe3O4 NPs and Au NPs were both improved significantly, and less than 15% of the nanoparticles were lost from the multilayers after an intensive agitation. The UV-visible spectroscopy and atomic force microscopy measurements supported the improvement of the stability of the multilayers.
Co-reporter:Yong Zhou, Mengjiao Cheng, Xiaoqun Zhu, Yajun Zhang, Qi An, and Feng Shi
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 17) pp:8308
Publication Date(Web):August 7, 2013
DOI:10.1021/am4023626
In this paper, we have demonstrated a facile strategy to prepare molecularly imprinted layer-by-layer nanostructured films. This strategy has circumvented the requirement of using photocross-linkable polymers, which suffered from tedious synthetic processes in the construction of surface molecular imprinting in layer-by-layer (SMI-LbL) devices. The described SMI-LbL device was constructed by employing the traditional construction procedures of LbL systems, followed by the postinfiltration of bifunctional photosensitive cross-linking agent 4,4′-diazostilbene-2,2′-disulfonic acid disodium salt into the prepared multilayers, and subsequent photocross-linking. A robust SMI-LbL device with high fatigue-resistance was achieved. The preparation conditions have been optimized to achieve repeated unloading and rebinding of the targeting molecule with high fidelity. The combination of templating and cross-linking is the core factor to achieve high fidelity and high efficiency of the SMI-LbL device.Keywords: diazostilbene; layer-by-layer; photo-cross-linking; self-assembly; supramolecular; surface molecular imprinting;
Co-reporter:Xiaoqun Zhu, Xiuwei Fan, Guannan Ju, Mengjiao Cheng, Qi An, Jun Nie and Feng Shi
Chemical Communications 2013 vol. 49(Issue 73) pp:8093-8095
Publication Date(Web):16 Jul 2013
DOI:10.1039/C3CC44580A
We develop a facile method to immobilize cucurbituril on silicon substrates through photochemical reaction with azido groups. Combining photolithography and the competitive molecular recognition between CB[7] and acridine orange base or 1-adamantanecarboxylic acid, a patterned surface with reversible fluorescence emission can be obtained.
Co-reporter:Mengjiao Cheng, Chao Jiang, Zhiyi Ding, Yajun Zhang, Yu Fu and Feng Shi
Physical Chemistry Chemical Physics 2013 vol. 15(Issue 36) pp:15172-15176
Publication Date(Web):16 Jul 2013
DOI:10.1039/C3CP52217B
The patterning of layer-by-layer (LbL) polyelectrolyte multilayers with metal ions is important for the facile fabrication of circuits or selective catalysis. The strategy includes two issues: the incorporation of metal ions and their controlled assembly–disassembly, which require a good understanding of the assembly mechanism. Therefore, we explored the LbL assembly between a polycation, poly-(diallyldimethylammonium chloride) (PDDA) and an inorganic single charged molecule, [AuCl4]−, which could assemble at pH = 3.7 and disassemble at lower pH values. Moreover, we have demonstrated that the driving force in the assembly is a ligand-to-metal charge transfer interaction. Combining the controlled assembly–disassembly of PDDA–[AuCl4]− multilayers and photolithography, we obtained a surface pattern of PDDA–[AuCl4]− multilayers.
Co-reporter:Chao Jiang, Mengjiao Cheng, Haitao Liu, Lei Shao, Xiaofei Zeng, Yajun Zhang, and Feng Shi
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 37) pp:13393-13400
Publication Date(Web):2017-2-22
DOI:10.1021/ie401769h
We have fabricated a transparent composite film with UV and near-infrared (near-IR) double-blocking properties using polyethyleneimine (PEI), indium tin oxide (ITO), and zinc oxide (ZnO) through layer-by-layer (LbL) assembly under an ultrasonic field. By applying ultrasonic-assisted LbL assembly, the aggregation of nanoparticles has been excluded, resulting in a flatter and more transparent (visible range) film than that obtained under conventional LbL assembly. Moreover, the effects of the ultrasonic field are discussed in terms of the fact that the transformation between the states of PEI/ITO films assembled with or without ultrasonic field was reversible. To enhance the UV-blocking properties in the most damaging region (290–350 nm), we incorporated ZnO nanoparticles, which can block UV rays below 350 nm, and the obtained hybrid multilayer displayed a high transparency of over 85% (visible range) and good UV-/near-IR double-blocking effects that shielded nearly 80% of the UV rays under 350 nm and 80% of the IR radiation above 1600 nm.
Co-reporter:Nannan Sun, Jianming Chen, Chao Jiang, Yajun Zhang, and Feng Shi
Industrial & Engineering Chemistry Research 2012 Volume 51(Issue 2) pp:788-794
Publication Date(Web):December 5, 2011
DOI:10.1021/ie201996t
We have developed an enhanced wet-chemical method to prepare patterned silicon templates with controlled depths at microscale by combining photolithography with electroless metal etching. The silicon masks are obtained in the following procedures: patterned silicon wafers selectively etch through galvanic reactions and result in patterned surfaces with silicon nanoarrays in exposed areas during photolithography; the as-etched silicon wafers are corroded in a mixture etching solution to remove silicon nanoarrays, leading to patterned silicon templates.
Co-reporter:Xiaoqun Zhu, Bowen Wang, Feng Shi, and Jun Nie
Langmuir 2012 Volume 28(Issue 40) pp:14461-14469
Publication Date(Web):September 13, 2012
DOI:10.1021/la303244p
We develop a facile method for preparing copper nanoparticles and patterned surfaces with copper stripes by ultraviolet (UV) irradiation of a mixture solution containing a photoinitiator and a copper–amine coordination compound. The copper–amine compound is formed by adding diethanol amine to an ethanol solution of copper chloride. Under UV irradiation, free radicals are generated by photoinitiator decomposition. Meanwhile, the copper–amine coordination compound is rapidly reduced to copper particles because the formation of the copper–amine coordination compound prevents the production of insoluble cuprous chloride. Poly(vinylpyrrolidone) is used as a capping agent to prevent the aggregation of the as-prepared copper nanoparticles. The capping agent increases the dispersion of copper nanoparticles in the ethanol solution and affects their size and morphology. Increasing the concentration of the copper–amine coordination compound to 0.1 M directly forms a patterned surface with copper stripes on the transparent substrate. This patterned surface is formed through the combination of the heterogeneous nucleation of copper nanoparticles and photolithography. We also investigate the mechanism of photoreduction by UV–vis spectroscopy and gas chromatography–mass spectrometry.
Co-reporter:Lanxin Ma, Mengjiao Cheng, Guijin Jia, Youqing Wang, Qi An, Xiaofei Zeng, Zhigang Shen, Yajun Zhang, and Feng Shi
Langmuir 2012 Volume 28(Issue 25) pp:9849-9856
Publication Date(Web):May 28, 2012
DOI:10.1021/la301553w
In the present article, we have developed a facile and rapid method to fabricate a polyelectrolyte multilayer under high gravity field and investigated the difference of mass transfer in the diffusing process between LbL self-assembled technique under high gravity field (HG-LbL) and dipping assembly. Herein, we have employed polyethyleneimine and zinc oxide nanoparticles, which is a well-known UV blocking material with typical absorption properties in the range of 300–400 nm, as building blocks and applied hydrogen bonding as the driving force to construct the multilayer under HG-LbL and dipping assembly. The results show that, compared with dipping assembly, HG-LbL can highly improve the utilization and adsorption efficiency of building blocks by hastening the diffusing process, and meanwhile the resulting multilayer films still achieve comparable quality as those prepared from dipping assembly.
Co-reporter:Xiaosa Zhang, Chao Jiang, Mengjiao Cheng, Yong Zhou, Xiaoqun Zhu, Jun Nie, Yajun Zhang, Qi An, and Feng Shi
Langmuir 2012 Volume 28(Issue 18) pp:7096-7100
Publication Date(Web):April 19, 2012
DOI:10.1021/la300611g
In this letter, we have developed a facile method to enhance the stability of polyelectrolyte multilayers. We fabricate conventional polyelectrolyte multilayers of PAH/PAA through electrostatic layer-by-layer (LbL) assembly and then postinfiltrate photosensitive cross-linking agent 4,4′-diazostilbene-2,2′-disulfonic acid disodium salt into the LbL films. After cross-linking by UV irradiation, the stability of the photo-cross-linked multilayer is highly improved as evidenced by the lack of dissolution under ultrasonication in saturated SDS aqueous solutions for 10 min. Moreover, by taking advantage of the different stability of the LbL film before and after UV irradiation, a patterned surface can be achieved.
Co-reporter:Mengjiao Cheng, Haitao Gao, Yajun Zhang, Wolfgang Tremel, Jian-Feng Chen, Feng Shi, and Wolfgang Knoll
Langmuir 2011 Volume 27(Issue 11) pp:6559-6564
Publication Date(Web):May 4, 2011
DOI:10.1021/la201399w
The formation of ordered complex structures is one of the most challenging fields in the research of biomimic materials because those structures are promising with respect to improving the physical and mechanical properties of man-made materials. In this letter, we have developed a novel approach to fabricating complex structures on the mesoscale by combining magnetic-field-induced locomotion and supramolecular-interaction-assisted immobilization. We have employed a magnetic field to locomote the glass fiber, which was modified by the layer-by-layer self-assembly of magnetic nanoparticles, to desired positions and have exploited the supramolecular interaction to immobilize glass fiber onto the appointed position. By magnetically induced micromanipulation, we can drive another fiber across the former one and finally obtain a crossing structure, which can lead to more complex structures on the mesocale. Moreover, we have constructed a mesoscale structure, termed “CHEM”, to demonstrate further the application of this method.
Co-reporter:Mengjiao Cheng, Yongfeng Gao, Xianpeng Guo, Zhaoyuan Shi, Jian-feng Chen, and Feng Shi
Langmuir 2011 Volume 27(Issue 12) pp:7371-7375
Publication Date(Web):May 17, 2011
DOI:10.1021/la201168j
In this Letter, we have fabricated a multifunctional device for highly efficient and inexpensive oil spill cleanup by combining electroless metal deposition with self-assembled monolayers, which has integrated the functions of oil containment booms, oil-sorption materials, oil skimmers, and water–oil separating devices. This functionally integrated device has a lower density than that of water, which leads to a potential application as oil containment booms; it can take up oil that is 3.5 times its own weight, which shows excellent oil-sorption properties, with the water–oil separating yield of the as-prepared device being up to 92%. The device has the advantages of high efficiency, capacity of antiwave, and reproducibility, which is suitable for many types of organic solvents or oils, even for emulsion of petroleum and water, and thus is a proof-of-principle idea to be applied in marine spilt oil cleanup and other water–oil separating systems.
Co-reporter:Yongfeng Gao;Mengjiao Cheng;Baoling Wang;Zeguo Feng
Advanced Materials 2010 Volume 22( Issue 45) pp:5125-5128
Publication Date(Web):
DOI:10.1002/adma.201001577
Co-reporter:Xiaoqun Zhu, Xiuwei Fan, Guannan Ju, Mengjiao Cheng, Qi An, Jun Nie and Feng Shi
Chemical Communications 2013 - vol. 49(Issue 73) pp:NaN8095-8095
Publication Date(Web):2013/07/16
DOI:10.1039/C3CC44580A
We develop a facile method to immobilize cucurbituril on silicon substrates through photochemical reaction with azido groups. Combining photolithography and the competitive molecular recognition between CB[7] and acridine orange base or 1-adamantanecarboxylic acid, a patterned surface with reversible fluorescence emission can be obtained.
Co-reporter:Yong Zhou, Mengjiao Cheng, Xiaoqun Zhu, Yajun Zhang, Qi An and Feng Shi
Journal of Materials Chemistry A 2013 - vol. 1(Issue 37) pp:NaN11334-11334
Publication Date(Web):2013/07/23
DOI:10.1039/C3TA12699D
In this paper, we have developed a facile and general strategy to enhance the stability of multilayers incorporating nanoparticles and the weak polyelectrolyte poly(allylamine hydrochloride) (PAH). Using Fe3O4 nanoparticles (Fe3O4 NPs) and Au nanoparticles (Au NPs) as separate model systems, after multilayers of nanoparticles and PAH were constructed employing the layer-by-layer (LbL) technique, 4,4′-diazostilbene-2,2′-disulphonic acid disodium salt (DAS) was post-infiltrated into the multilayers and subsequent photochemical cross-linking was completed under UV irradiation. The stability of multilayers with Fe3O4 NPs and Au NPs were both improved significantly, and less than 15% of the nanoparticles were lost from the multilayers after an intensive agitation. The UV-visible spectroscopy and atomic force microscopy measurements supported the improvement of the stability of the multilayers.
Co-reporter:Yue Wang, Qi An, Yong Zhou, Yue Niu, Raheel Akram, Yihe Zhang and Feng Shi
Journal of Materials Chemistry A 2015 - vol. 3(Issue 4) pp:NaN569-569
Publication Date(Web):2014/11/14
DOI:10.1039/C4TB01688B
The layer-by-layer (LbL) technique has been intensively investigated as a straightforward method for the incorporation of drug molecules or other bioactive species, enabling retarded release in drug delivery devices, in bioactive interfaces, in tissue engineering, and in regenerative medicine. The preparation of crosslinked LbL multilayers with embedded drug reservoirs for delayed release remains a challenging task, however. In the present study we have developed a method for the simultaneous utilisation of covalent interlayer linkages and drug reservoirs that can hold model drug molecules. A strategy of post-infiltration of photoactive bifunctional small molecules followed by UV irradiation has been employed for crosslinking the LbL multilayers, incorporating poly(amido amine) (PAMAM) molecules, which serve as a drug reservoir. The covalent linkage significantly alters the release profile of the model drug from the multilayers, with retarded release of hydrophobic molecules from a solvent, and enabling the loaded multilayers to withstand rinsing with 75% ethanol, the most commonly used sterilization procedure.
Co-reporter:Mengjiao Cheng, Chao Jiang, Zhiyi Ding, Yajun Zhang, Yu Fu and Feng Shi
Physical Chemistry Chemical Physics 2013 - vol. 15(Issue 36) pp:NaN15176-15176
Publication Date(Web):2013/07/16
DOI:10.1039/C3CP52217B
The patterning of layer-by-layer (LbL) polyelectrolyte multilayers with metal ions is important for the facile fabrication of circuits or selective catalysis. The strategy includes two issues: the incorporation of metal ions and their controlled assembly–disassembly, which require a good understanding of the assembly mechanism. Therefore, we explored the LbL assembly between a polycation, poly-(diallyldimethylammonium chloride) (PDDA) and an inorganic single charged molecule, [AuCl4]−, which could assemble at pH = 3.7 and disassemble at lower pH values. Moreover, we have demonstrated that the driving force in the assembly is a ligand-to-metal charge transfer interaction. Combining the controlled assembly–disassembly of PDDA–[AuCl4]− multilayers and photolithography, we obtained a surface pattern of PDDA–[AuCl4]− multilayers.
Co-reporter:Mengjiao Cheng, Guannan Ju, Chao Jiang, Yajun Zhang and Feng Shi
Journal of Materials Chemistry A 2013 - vol. 1(Issue 43) pp:NaN13416-13416
Publication Date(Web):2013/09/11
DOI:10.1039/C3TA12607B
To handle serious underwater oil spills, we have designed a functionally integrated device which can continuously clean up spilled oil underwater or on the water's surface in a directional manner, guided by a magnetic field, collecting the oil into the interior of the device and recycling it. The collecting efficiency is higher than 90%.
Co-reporter:Hongyu Dong, Mengjiao Cheng, Yajun Zhang, Hao Wei and Feng Shi
Journal of Materials Chemistry A 2013 - vol. 1(Issue 19) pp:NaN5891-5891
Publication Date(Web):2013/03/05
DOI:10.1039/C3TA10225D
We have fabricated a self-cleaning coating on a model ship with a large and curved surface by electroless deposition of gold aggregates, and the superhydrophobic model ship exhibited a remarkable drag reduction of 38.5% at a velocity of 0.46 m s−1. The as-prepared coating exhibits excellent superhydrophobic properties, with a contact angle as high as 159.7°. To rule out the influence of wetting area differences between superhydrophobic coated materials and normal materials, we modified the large curved surface of a model ship with the self-cleaning coating and investigated its drag reducing properties at high speed. The results showed that the superhydrophobic coating took effect in reducing drag; the mechanism of the drag reduction is discussed based on the plastron effect and Newton's law of viscosity.
Co-reporter:Chao Jiang, Xiaolin Liu, Caijun Luo, Yajun Zhang, Lei Shao and Feng Shi
Journal of Materials Chemistry A 2014 - vol. 2(Issue 34) pp:NaN14053-14053
Publication Date(Web):2014/06/24
DOI:10.1039/C4TA02437K
The high gravity technique is a strongly intensified process used for rapid mass and heat transfer, which has rarely been applied for the construction of layer-by-layer (LbL) self-assembled films. Herein, we used a poly(acrylic acid) (PAA)/poly(allylamine hydrochloride)–porphine complex (PAH–Por) multilayer to investigate the assembly behaviors between exponential and linear growth, and introduced strong shear stress using a high gravity field to reduce the accumulated surface roughness in exponentially growing films. The results demonstrated that strong shear stress in a high gravity field could transform film growth from exponential to linear. This phenomenon is thought to be the result of reducing surface roughness through shear forces, which was supported by stepwise characterization of ultraviolet-visible spectra and atomic force microscopy. Moreover, the intensified LbL deposition to achieve a transformation from exponential to linear growth could be applied to other systems, including PAH–PAA complex/poly(sodium-p-styrenesulfonate) (PSS) and PAH/PSS multilayers.
Co-reporter:Yue Wang, Wenjun You, Yifan Song, Xiangxin Li, Dengli Qiu, Mengjiao Cheng and Feng Shi
Journal of Materials Chemistry A 2017 - vol. 5(Issue 2) pp:NaN381-381
Publication Date(Web):2016/11/22
DOI:10.1039/C6TB01780K
Due to the noncovalent interactions between the layers of polyelectrolyte films, the layer-by-layer assembled multilayered films always face the challenge of low film stiffness and chemical stability under extreme conditions. To handle this issue, we incorporated 4,4′-diazostilbene-2,2′-disulfonic acid disodium salt (DAS) as a crosslinker and subsequently photocrosslinked the layers of a poly(allylamine hydrochloride)/catalase multilayered film. The results showed that DAS could stabilize the prepared film in a manner similar to the traditional cross-linker glutaraldehyde. The multilayered film showed good biocompatibility with a positive effect on cell proliferation. Therefore, by using the commercially available DAS crosslinker, we provide a synthesis-free and biocompatible method to stabilize polyelectrolyte multilayers for broad and significant applications in biological fields, e.g., varying crosslinking density to adjust the mechanical strength of biomaterials, stabilizing susceptible biofilms, or introducing functional groups onto cell membranes.
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