Shiling Yuan

Shandong University, Chi-nan-shih, Shandong Sheng, China

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Publications (46)66.74 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The aggregation behaviors of two trisiloxane-tailed surface active ionic liquids in water have been investigated by coarse-grained (CG) molecular dynamics simulation on the basis of MARTINI force field. The new CG model is developed from the optimized molecule computed by using density functional theory. Direct comparison of angles and bonds obtained from all-atom (AA) simulations with those calculated from the CG model has been conducted to validate the latter model. Excellent agreement between AA and CG demonstrates that the potential of the new CG model can represent the complex system well. The long time CG simulation has been performed to understand the formation process of micelles when dissolving ionic liquids in water. Vesicles were observed at the final stage of the simulation and their partially truncated views and density profiles were obtained to describe the structure in detail.
    Journal of Dispersion Science and Technology 11/2014; 35(11). · 0.60 Impact Factor
  • Fengfeng Gao, Hui Yan, Qiwei Wang, Shiling Yuan
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    ABSTRACT: In enhanced oil recovery (EOR), the micro-oil droplet heavily affected the stability of foam and prevented foam flooding. In this paper, the oil bridge-stretching mechanism of foam rupture was described through molecular dynamics with the aim of providing supplements to the experiments at the molecular level. Two important phenomena for foam rupture have been pointed out by the simulation. One is about the pseudoemulsion film, representing the stability of the oil-water-air three phase interface. The bound water connecting the headgroups of the surfactant through strong H-bonding interactions played a vital role in the stability of the pseudoemulsion film. These water molecules could hinder the disappearance of the water phase in the pseudoemulsion film. The additional energy barrier, which was influenced by the surfactant concentration, also played a vital role in preventing the destruction process. The other factor is about the oil bridge, which appeared after the destruction of the pseudoemulsion film. The external horizontal force stretched the bridge resulting in the destruction of the bridge. The process was decided by the properties of the oil molecules. In the simulation, the stretching force was divided into three stages including the initial increasing force, the middle equilibrium force and the final decreasing force. Especially the second equilibrium force, which stretched the middle of the oil bridge so that it became thin, was vital to the foam rupture. The concentration and properties of the oil molecules were the crucial factors for foam rupture. The simulated results offer important supplements to experiments.
    Physical Chemistry Chemical Physics 07/2014; · 3.83 Impact Factor
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    ABSTRACT: The adsorption of the anionic surfactant, sodium dodecylsulfate (SDS) in poly(ethylene oxide) (PEO) brush was studied by molecular dynamics simulations. Our simulations revealed that surfactant can adsorb in polymer brush as micellar aggregates and the polymer would reside at the hydrocarbon-water interface of SDS micelles. This association between surfactant and polymer was mainly driven by the hydrophobic interaction between the polymer and surfactant tails. In the simulation, with the increasing of surfactant concentration, a plateau value representing saturated adsorption was observed. The height of polymer brush was mainly affected by the adsorbed surfactant at low grafting density of polymer; however, it was primarily controlled by the grafting density at high grafting density. Our conclusions at the molecular level were in close agreement with experiment about the adsorption of surfactant in polymer brushes.
    Journal of Molecular Modeling 06/2014; 20(6):2267. · 1.98 Impact Factor
  • Peili Zhang, Zhen Xu, Qian Liu, Shiling Yuan
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    ABSTRACT: In this paper, the detachment mechanism of alkane molecules from one hybrid hydrophobic and hydrophilic solid surface was studied by molecular dynamics simulation. First, some alkyl chains were linked through C-O bonds with silica surface to get one half-hydrophobic one, and the other half-hydrophilic area was still same as silica surface, thus one modified hybrid hydrophobic and hydrophilic silica surface was constructed. Second, some alkane molecules were adsorbed on the hybrid surface to get one whole hydrophobic oil layer, and the detachment mechanism of alkane molecules on the surface was discussed in aqueous solution using molecular dynamics. The simulated results showed that the key to the detachment of alkane molecules is the formation of water channel in oil layer between water phase and solid surface. In the detachment process, water molecules can penetrate oil layer to the silica surface through the strong H-bonding interaction among water molecules in water channel, and soon these molecules can form a gel layer along the silica surface by fast diffusion under the H-bonding interaction and electrostatic interaction between water molecules and silica surface. At last, the half-hydrophilic area on hybrid surface becomes hydrophilic again after the oil layer's detachment, and alkane molecules aggregate on the modified surface linked the alkyl chains. For the hybrid surface, some of alkane molecules insert into the interstice among the alkyl chains, and thus the oil drop cannot be dispatched thoroughly from the surface linked alkyl chains in aqueous solution. Our results showed that the detachment mechanism of oil from hybrid surface is different, compared with the whole pure hydrophilic surface.
    The Journal of Chemical Physics 04/2014; 140(16):164702. · 3.12 Impact Factor
  • BaoShuo Li, ShiLing Yuan
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    ABSTRACT: The TiMgAlCu mixed oxides, based on hydrotalcite-like compounds, was developed as novel SOx removal catalysts for FCC (fluid catalytic cracking) process. The mixed oxides were prepared by modified co-precipitation method and estimated for SOx removal under conditions similar to those of FCC units. XRD, TG/DTA and N2 adsorption analysis were performed to investigate the physicochemical and textural properties of the samples. The analysis results indicated that all the samples exhibit good dispersion of metal oxides in the matrix. The SOx adsorption–reduction tests showed that the novel TiMgAlCu catalysts with 15%Ti and 1% Cu had a good performance on SOx removal. Moreover, the particle size had obvious effect on the adsorption activity of sulfur remove catalysts and the best fit particle size is from 100 to 300 μm.
    Ceramics International. 01/2014; 40(8):11559–11566.
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    ABSTRACT: MD simulations snapshots of the adsorption structure of oppositely charged polyelectrolyte and ionic surfactant complexes at the interface.
    Colloids and Surfaces A Physicochemical and Engineering Aspects 01/2014; 454:104–112. · 2.11 Impact Factor
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    ABSTRACT: Molecular dynamics simulations and quantum mechanics calculation were employed to study the deposition behavior of organic luminescent molecules rubrene onto bare dioxide silicon substrate and self-assembled monolayers (SAM) patterned substrate. A mixed system was constructed to investigate the edge-induced area-selective growth. Our simulation results suggest that the functionalized SAM decoration on the substrate surface exerts significant effect on the growth behavior and crystallinity of rubrene molecules. In the mixed system, the rubrene molecules diffused and preferetially deposited along the step-edge of SAM and formed a typical π-conjugated structure by standing up-right.
    Chemical Physics Letters 05/2013; 571:38–43. · 2.15 Impact Factor
  • Fengfeng Gao, Hui Yan, Shiling Yuan
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    ABSTRACT: In this paper, the solubilisation process of pyrene molecule, as the fluorescence probe molecule, in cetyltrimethylammonium bromide (CTAB) surfactant micelle solution is studied by molecular dynamics (MD) method. When one pyrene molecule is in the micellar solution, it can be adsorbed into the micelle spontaneously and vertically. The probe molecule mainly locates in the interior cavity or the palisade layer of the micelle. When two pyrene molecules exist in the micellar solution, they transfer from the interior to the palisade layer. Although strong π–π interactions exist between the pyrene molecules, the pyrenes separate to each other in the palisade layer in two-third simulated time.
    Molecular Simulation 01/2013; 39(13). · 1.06 Impact Factor
  • RSC Advances 01/2013; 1. · 2.56 Impact Factor
  • Hua Wang, Heng Zhang, Chengbu Liu, Shiling Yuan
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    ABSTRACT: Coarse-grained molecular dynamics simulations have been performed to study the self-assembly of polymer, polyacrylamide (PAM) and surfactant, sodium dodecylsulfate (SDS) in aqueous solution. Our simulations revealed that PAM curled into clusters in the absence of SDS, while it was stretched if SDS was added. For the SDS-PAM complexes, the aggregate formation process can be divided into three stages: firstly, PAM quickly absorbs some SDS monomers until the radius of gyration (Rg) of polymer reaches a minimum; then, PAM stretches and the Rg of PAM increases due to more and more adsorbed SDS; ultimately, the commonly accepted "necklace" structure is formed with PAM located at the interface of the hydrophobic and hydrophilic regions of the SDS micelle. The main driving force for the association was hydrophobic interactions between the polymer backbone and the surfactant hydrophobic tails. As the concentration of SDS increased, the Rg of PAM increased up to a maximum, indicating the polymer was saturated with surfactant.
    Journal of Colloid and Interface Science 07/2012; 386(1):205-11. · 3.17 Impact Factor
  • Qian Liu, Shiling Yuan, Hui Yan, Xian Zhao
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    ABSTRACT: The mechanism of oil detachment from solid surfaces in aqueous surfactant solutions is studied by molecular dynamics simulations. At the initial simulation, the hydrophilic silica surface changes into a hydrophobic one due to the adsorption of the alkane molecules. Two-dimensional ordered arrangement of alkane molecules on the first layer is the key to the oil detachment from the silica surface. Upon addition of cetyltrimethylammonium bromide (CTAB) solution, the alkane molecules on the solid surface can be detached from a hydrophilic silica surface. Ultimately, the silica surface becomes hydrophilic, and the oil molecules are solubilized in the surfactant micelles. During the process of oil detachment, it is demonstrated that the formation of a water channel in the oil phase between the surfactant solution and the silica surface is vital for the oil detachment. Meanwhile, water molecules can penetrate the oil-water interface by diffusion and form the gel layer at the water-silica interface under the hydrogen-bonding and electrostatic interaction, in the close vicinity of the contact line. Both of these will accelerate the removal of the oil molecules from the silica surface under the surfactant solution. According to the energy and configurations with time evolution, one three-stage model of oil detachment from the silica surface is developed at the molecular level. The simulation results agree with the experimental phenomenon.
    The Journal of Physical Chemistry B 03/2012; 116(9):2867-75. · 3.61 Impact Factor
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    ABSTRACT: Maize leaves and sheaths are cheap agricultural byproducts that contain an abundance of amorphous hydrated silica (named phytoliths). However, there have been no attempts at utilizing the phytoliths to synthesize silica nanotubes. In this paper, we describe the morphologies and microstructures of phytoliths in leaves and sheaths of maize, and synthesize hollow silica nanotubes using the phytoliths in cetyltrimethyl ammonium bromide (CTAB) /sodium dodecyl benzene sulfonate (SDBS) surfactant system. TEM and SEM images show that the phytoliths exist in cross and dumbbell shapes in maize. The silica nanotubes obtained from the naturally deposited phytoliths exhibit special blue photoluminescence. This optical characteristic indicates that the agro-based waste materials may have potential applications in the fields of light localization and other integrated optical devices.
    Industrial & Engineering Chemistry Research. 10/2011; 50(22).
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    ABSTRACT: The phase behavior of a kind of star-like block polyether in aqueous solution is studied by MesoDyn simulation method in the absence and presence of shear. With the polyether concentration increasing, different mesoscale structures are found in the absence and presence of shear. (1) In the absence of shear, there are four different structures formed with the increasing polyether concentration. The first is micellar phase, including sphere-like micelle and wormlike micelle, the second is bicontinuous phase, the third is lamellar phase, and the fourth is reversed micellar phase, including reversed worm-like micelle and reversed hexagonal micelle. (2) In the presence of shear, there are three morphologies formed in all studied concentrations; they are hexagonal phase, lamellar phase and reverse hexagonal phase, which align in the flow direction. The detailed structures and forming mechanisms of different aggregates are given by analyzing simulation results.
    Soft Matter 09/2011; 7(19):9035-9042. · 3.91 Impact Factor
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    ABSTRACT: Hierarchical In(2)O(3) rod-like microbundles were fabricated via the Pluronic F127-(EO(106)PO(70)EO(106)-) assisted hydrothermal reaction followed by calcining the In(OH)(3) precursors. The results revealed that the In(2)O(3) microarchitectures were constructed with well-aligned one-dimensional (1D) single-crystalline nanorods with highly uniform morphologies and particular exposed facets. Structural analysis suggested that the In(2)O(3) nanorods were enclosed by {110} and {001} facets. The triblock copolymer acted as a structure-directing agent and played a key role in the formation of In(OH)(3) microbundles. The formation of the precursors In(OH)(3) microbundles was studied through contrastive experiments and computational simulation, which can be contributed to the soft-template-directed self-assembly mechanism. The gas sensing properties of the as-prepared In(2)O(3) microbundles were investigated. Compared to the samples prepared in the absence of F127, the In(2)O(3) microbundles exhibited a superior sensing performance toward 2-chloroethanol vapor, which can be explained by hierarchically ordered structures and exposed crystal surfaces.
    Journal of Colloid and Interface Science 02/2011; 354(1):89-93. · 3.17 Impact Factor
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    ABSTRACT: A series of MD simulations were conducted towards the selective deposition of organic luminescent molecules 3(5)-(9-anthryl) pyrazole (ANP) and perylene onto different densely packed organosilane self-assembled monolayers (SAMs). Our simulations indicated that the packing density of alkyl chains on SAM may directly control the site-selective deposition of organic molecules. Additionally we propose a possible mechanism for this phenomenon, which can also explain the experimental findings of the selective deposition of organic molecules onto template structures, made of l-α-dipalmitoyl-phosphatidylcholine (DPPC) in alternating liquid expanded (LE) and liquid condensed (LC) states.
    Chemical Physics Letters 01/2011; 507:138-143. · 2.15 Impact Factor
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    ABSTRACT: Self-assembly of ABA triblock copolymer confined in concentric-spherical nanopores was studied using MesoDyn simulation. Our calculation shows that in this confined geometry a zoo of exotic structures can be formed. These structures include perforated vesicle like carbon fullerene, strip pattern and hybrid structure. Moreover, the dependence of the chain conformation on the volume fraction, the interactions between blocks and the diameter of the spherical pore are also investigated. The results of these simulations can be used to predict the amphiphilic triblock copolymer morphologies confined in concentric-spherical nanopores and should be helpful in designing polymeric nanomaterials in future.
    Colloids and Surfaces A-physicochemical and Engineering Aspects - COLLOID SURFACE A. 01/2011; 384(1):212-218.
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    ABSTRACT: Molecular dynamics simulations have been performed to investigate the effect of inorganic salts on the structural and dynamic properties of alkyl benzene sulfonate monolayer formed at the air/water interface. The alkyl benzene sulfonates are two surfactant isomers in the family of sodium hexadecane benzene sulfonates defined by 1C16 and 5C16, indicating a benzene sulfonate group attached to the first and fifth carbon atom in hexadecane backbone. It has been observed that both benzene ring groups and headgroups (-SO(3)(-)) are hydrated due to their polar nature. Water molecules can form stable hydrogen bonds with headgroups of surfactants, and the counterions (Na(+), Mg(2+), or Ca(2+)) are distributed close to the air/water interface. The stronger electrostatic repulsion drives the 1C16 monolayer arranged in disorder in comparison with 5C16, and the presence of inorganic salts may screen electrostatic repulsions between headgroups and decrease the thickness of the interfacial water layer, which follows the series Ca(2+) > Mg(2+) > Na(+). The order of inorganic salt tolerance of two surfactants is 5C16 > 1C16. The counterions may penetrate into the hydration shell of the surfactant headgroups and restrict the mobility of the water molecules situated in this area.
    The Journal of Physical Chemistry B 03/2010; 114(15):5025-33. · 3.61 Impact Factor
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    ABSTRACT: In this paper, amorphous hydrated silica in Gramineae plant, named as phytoliths, was extracted and investigated from wheat straw. Porous nano-structured silica was prepared from agricultural waste materials through combustion and acid leaching. The results show that: i) the phytoliths in epidermal cells of wheat straw are round with a diameter of 14–22μm, while those in trachea are oblong with a length of 18–40μm and a width of 12–18μm. These different phytoliths are all core–shell structures with the silica shell and the organism core of the plant cells; ii) The distribution of particle size, surface area, pore diameter and pore volume of nano-structured silica samples decreases with the increase of calcining temperature, and at a higher temperature, some agglomerates are formed. The results of this work are useful for scientists pursuing new synthetic route for valuable and widely applicable nanoscale silica materials, also helping to solve disposal and pollution problems.
    Journal of Non-Crystalline Solids 01/2010; 356(50):2781-2785. · 1.72 Impact Factor
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    ABSTRACT: Since cyclodextrins (CDs) were discovered to be an excellent reagent to disperse carbon nanotubes (CNTs), they were used for the construction of CD/CNT based electrodes. Therefore, it is crucial to investigate the interactions between CDs and CNTs for their applications. Herein, β-cyclodextrin (β-CD) and their four derivatives, 2-O-(2-hydroxypropyl)-β-cyclodextrin (2-HP-β-CD), 6-O-(2-hydroxypropyl)-β-cyclodextrin (6-HP-β-CD), 2-O-(2-hydroxybutyl)-β-cyclodextrin (2-HB-β-CD) and 6-O-(2-hydroxybutyl)-β-cyclodextrin (6-HB-β-CD), were employed to investigate the interactions with single-walled carbon nanotubes (SWNTs) both in anhydrous and aqueous conditions by molecular dynamics simulation. The results showed that the interactions between SWNTs and CDs were strongly influenced by the structures of CDs such as substituted group and position. The attractive interactions between SWNTs and CDs monotonically increased with the radius of SWNT. Van der Waals attraction was the dominating force for CDs wrapped onto the surface of the nanotube ropes. Therefore, the results could provide a fundament for the choice of CDs in their further applications.
    Computational Materials Science - COMPUT MATER SCI. 01/2010; 50(2):283-290.
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    ABSTRACT: The dispersion effect of carbon nanotubes (CNTs) in aqueous solutions by a silicon surfactant (ethoxy modified trisiloxane, named Ag-64) was investigated in detail using experimental method and molecular dynamics simulation. The Si–O–Si chain of silicon surfactant was flexible due to long Si–C bond and it could easily wrap onto the surface of CNTs through hydrophobic and other intermolecular interactions. The hydrophilic part of PEO provided the CNTs dispersed in the aqueous solution and prevented CNTs from aggregating in water through steric stabilization. It was found that Ag-64 could disperse CNTs with different diameters and it was an effective dispersing agent. The results of molecular dynamics simulation indicated that Ag-64 molecules could wrap onto the surface of CNTs leading to steric stabilization so that it could well disperse CNTs, and Van der Waals attraction was the dominating force of Ag-64 adsorbing onto CNTs. Our study may provide experimental and theoretical basis for using silicon surfactants to disperse CNTs, which can open the avenue of new applications for silicon surfactants.
    Colloids and Surfaces A-physicochemical and Engineering Aspects - COLLOID SURFACE A. 01/2009; 350(1):101-108.