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Chandra A, Kayal A, Das B, Chandra A. Dynamical Crossover of Interfacial Water upon Melting of a Lipid Bilayer: Influence of Different Parts of the Headgroups. J Phys Chem B 2023. [PMID: 38032152 DOI: 10.1021/acs.jpcb.3c04792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2023]
Abstract
All-atom molecular dynamics simulations of a 1,2-dimyristoyl-sn-glycero-3-phosphocholine bilayer in contact with liquid water were performed at different temperatures ranging from 285 to 320 K. We have investigated the heterogeneity and dynamical transitions in interfacial water as the lipid bilayer undergoes a melting transition. Results are obtained for water at the outer surface of the bilayer and for those buried more deeply in the lipid chains of the bilayer. It is found that lipid bilayer melting influences both the structure and dynamics of interfacial water. The number of interfacial water molecules shows a jump in the melting of the bilayer. The temperature dependence of the diffusivity and orientational relaxation of interfacial water molecules exhibits a dynamical crossover upon melting of the bilayer. The extent of dynamical crossover is found to be rather strong with significant changes in activation barriers for interfacial water around the carbonyl groups, which are deeply buried toward the lipid chains of the bilayer. The dynamical crossover gradually decreases as one moves further away from the outer surface, and it essentially vanishes for water in the region of 5-10 Å from the outer surface. It is found that the lipid melting-induced dynamical crossover of interfacial water is significant only for water that is in close proximity to the bilayer surface or deeply buried into it. The current results reveal that water molecules in different parts of the interface respond differently on melting of the bilayer. The current study also shows that the carbonyl-bound water molecules can play an important role in the phase transition of the bilayer as the temperature is raised through its melting point.
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Affiliation(s)
- Abhilash Chandra
- Department of Chemistry, Indian Institute of Technology Kanpur, Uttar Pradesh 208016, India
| | - Abhijit Kayal
- Department of Chemistry, Indian Institute of Technology Kanpur, Uttar Pradesh 208016, India
| | - Banshi Das
- Department of Chemistry, Indian Institute of Technology Kanpur, Uttar Pradesh 208016, India
| | - Amalendu Chandra
- Department of Chemistry, Indian Institute of Technology Kanpur, Uttar Pradesh 208016, India
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2
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Malik R, Chandra A. Counteracting Effects of Trimethylamine N-Oxide against Urea in Aqueous Solutions: Insights from Theoretical Two-Dimensional Infrared Spectroscopy. J Phys Chem B 2023; 127:7372-7383. [PMID: 37566900 DOI: 10.1021/acs.jpcb.3c03864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/13/2023]
Abstract
The study of small osmolytes in their aqueous solutions has gained significant attention because of their relevance to structure and thermodynamics of proteins in aqueous media. Special attention has been given to the binary and ternary aqueous solutions of urea and trimethylamine N-oxide (TMAO). Urea is a well-known protein denaturant, while TMAO protects proteins in their native states. Interestingly, TMAO counteracts urea's ability to denature proteins when present in solutions with approximately half of the concentration of urea. Vibrational spectroscopy can improve our understanding of the molecular origin of this counteracting effect because of its sensitivity to local structure and dynamics. We present results of theoretical linear vibrational and two-dimensional infrared (2DIR) spectroscopy of water in the binary and ternary aqueous solutions of TMAO and urea. The 2DIR spectra are calculated using the electronic structure/molecular dynamics approach. The non-Condon effects in spectral transitions are incorporated in the theoretical calculations of 2DIR spectra. It is found that TMAO disrupts the local structure of water, while urea leaves it essentially unaffected. The 2DIR results show that both TMAO and urea slow down the dynamics of spectral diffusion of water. The extent of slowing down is found to be particularly significant for both hydration and bulk water in the presence of TMAO which can be attributed to strong hydrogen bonds between the water and TMAO molecules. The water molecules present in the hydration layer of the solutes in the ternary solutions are found to relax at even slower rates compared to that in their binary solutions in water. The hydrogen bonds between TMAO and urea are found to be not stable. Thus, the counteracting effect of TMAO against urea is seen to take place mainly through water-mediated interactions. Such TMAO-induced effects giving rise to more structured and slower hydrogen-bonded network are successfully captured through 2DIR spectroscopic calculations.
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Affiliation(s)
- Ravi Malik
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Amalendu Chandra
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
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3
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Hendrikse RL, Amador C, Wilson MR. A many-body dissipative particle dynamics parametrisation scheme to study behaviour at air-water interfaces. SOFT MATTER 2023; 19:3590-3604. [PMID: 37161599 DOI: 10.1039/d3sm00276d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
In this article, we present a general parametrisation scheme for many-body dissipative particle dynamics (MDPD). The scheme is based on matching model components to experimental surface tensions and chemical potentials. This allows us to obtain the correct surface and mixing behaviours of complex, multicomponent systems. The methodology is tested by modelling the behaviour of nonionic polyoxyethylene alkyl ether surfactants at an air/water interface. In particular, the influence of the number of ethylene oxide units in the surfactant head group is investigated. We find good agreement with many experimentally obtained parameters, such as minimum surface area per molecule; and a decrease in the surface tension with increasing surfactant surface density. Moreover, we observe an orientational transition, from surfactants lying directly on the water surface at low surface coverage, to surfactants lying parallel or tilted with respect to the surface normal at high surface coverage. The parametrisation scheme is also extended to cover the zwitterionic surfactant lauryldimethylamine oxide (LDAO), where we provide good predictions for the surface tension at maximum surface coverage. Here, if we exceed this coverage, we are able to demonstrate the spontaneous production of micelles from the surface surfactant layer.
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Affiliation(s)
| | - Carlos Amador
- Department of Chemistry, Durham University, Durham, DH1 3LE, UK.
| | - Mark R Wilson
- Department of Chemistry, Durham University, Durham, DH1 3LE, UK.
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Dutta S, Chandra A. A Multiple Proton Transfer Mechanism for the Charging Step of the Aminoacylation Reaction at the Active Site of Aspartyl tRNA Synthetase. J Chem Inf Model 2023; 63:1819-1832. [PMID: 36893463 DOI: 10.1021/acs.jcim.2c01332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
Abstract
Aspartyl-tRNA synthetase catalyzes the attachment of aspartic acid to its cognate tRNA by the aminoacylation reaction during the initiation of the protein biosynthesis process. In the second step of the aminoacylation reaction, known as the charging step, the aspartate moiety is transferred from aspartyl-adenylate to the 3'-OH of A76 of tRNA through a proton transfer process. We have investigated different pathways for the charging step through three separate QM/MM simulations combined with the enhanced sampling method of well-sliced metadynamics and found out the most feasible pathway for the reaction at the active site of the enzyme. In the charging reaction, both the phosphate group and the ammonium group after deprotonation can potentially act as a base for proton transfer in the substrate-assisted mechanism. We have considered three possible mechanisms involving different pathways of proton transfer, and only one of them is determined to be enzymatically feasible. The free energy landscape along reaction coordinates where the phosphate group acts as the general base showed that, in the absence of water, the barrier height is 52.6 kcal/mol. The free energy barrier is reduced to 39.7 kcal/mol when the active site water molecules are also treated quantum mechanically, thus allowing a water mediated proton transfer. The charging reaction involving the ammonium group of the aspartyl adenylate is found to follow a path where first a proton from the ammonium group moves to a water in the vicinity forming a hydronium ion (H3O+) and NH2 group. The hydronium ion subsequently passes the proton to the Asp233 residue, thus minimizing the chance of back proton transfer from hydronium to the NH2 group. The neutral NH2 group subsequently takes the proton from the O3' of A76 with a free energy barrier of 10.7 kcal/mol. In the next step, the deprotonated O3' makes a nucleophilic attack to the carbonyl carbon forming a tetrahedral transition state with a free energy barrier of 24.8 kcal/mol. Thus, the present work shows that the charging step proceeds through a multiple proton transfer mechanism where the amino group formed after deprotonation acts as the base to capture a proton from O3' of A76 rather than the phosphate group. The current study also shows the important role played by Asp233 in the proton transfer process.
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Affiliation(s)
- Saheb Dutta
- Department of Chemistry, Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Amalendu Chandra
- Department of Chemistry, Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
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Bejarano JVP, Fajardo-Rojas F, Alvarez O, Burgos JC, Reyes LH, Pradilla D. Novel Biosurfactants: Rationally Designed Surface-Active Peptides and in silico Evaluation at the Decane-Water Interface. Process Biochem 2022. [DOI: 10.1016/j.procbio.2022.11.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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6
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Guo Y, Mabuchi T, Li G, Tokumasu T. Morphology Evolution and Adsorption Behavior of Ionomers from Solution to Pt/C Substrates. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c00533] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yuting Guo
- Institute of Fluid Science, Tohoku University, 2-1-1 Katahira,
Aoba-ku, Sendai 980-8577, Japan
| | - Takuya Mabuchi
- Institute of Fluid Science, Tohoku University, 2-1-1 Katahira,
Aoba-ku, Sendai 980-8577, Japan
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, 2-1-1 Katahira Aoba-ku, Sendai, Miyagi 980-8577, Japan
| | - Gaoyang Li
- Institute of Fluid Science, Tohoku University, 2-1-1 Katahira,
Aoba-ku, Sendai 980-8577, Japan
| | - Takashi Tokumasu
- Institute of Fluid Science, Tohoku University, 2-1-1 Katahira,
Aoba-ku, Sendai 980-8577, Japan
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7
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Yang XD, Chen W, Ren Y, Chu LY. Exploration of the Adsorption Kinetics of Surfactants at the Water-Oil Interface via Grand-Canonical Molecular Dynamics Simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:1277-1286. [PMID: 35015552 DOI: 10.1021/acs.langmuir.1c03205] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
It is well-known that surfactants tend to aggregate into clusters or micelles in aqueous solutions due to their special structures, and it is difficult for the surfactant molecules involved in the aggregation to move spontaneously to the oil-water interface. In this article, we developed a new grand-canonical molecular dynamics (GCMD) model to predict the saturated adsorption amount of surfactant with constant concentration of surfactant molecules in the bulk phase, which can prevent surfactants aggregating in the bulk phase and get the atomic details of the interfacial structural change with increase of the adsorption amount through a single GCMD run. The adsorption of anionic surfactant sodium dodecyl sulfate (SDS) at the heptane-water interface was studied to validate the model. The saturated adsorption amount obtained from the GCMD simulation is consistent with the experimental results. The adsorption kinetics of SDS molecules during the simulation can be divided into three stages: linear adsorption stage, transition adsorption stage, and dynamic equilibrium stage. We also carried out equilibrium molecular dynamics (EMD) simulations to compare with GCMD simulation. This GCMD model can effectively reduce the simulation time with correct prediction of the interfacial saturation adsorption. We believe the GCMD method could be especially helpful for the computational study of surfactant adsorption under complex environments or emulsion systems with the adsorption of multiple types of surfactants.
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Affiliation(s)
- Xue-Dan Yang
- School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, China
- State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, Sichuan 610065, China
- State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Wei Chen
- State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049,China
- Dalian National Laboratory for Clean Energy, Chinese Academy of Sciences, Dalian, Liaoning 116023, China
| | - Ying Ren
- State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049,China
- Innovation Academy for Green Manufacture, Chinese Academy of Sciences, Beijing 100190, China
| | - Liang-Yin Chu
- School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, China
- State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, Sichuan 610065, China
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8
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Das B, Chandra A. Ab Initio Molecular Dynamics Study of Aqueous Solutions of Magnesium and Calcium Nitrates: Hydration Shell Structure, Dynamics and Vibrational Echo Spectroscopy. J Phys Chem B 2022; 126:528-544. [PMID: 35001626 DOI: 10.1021/acs.jpcb.1c08545] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ab initio molecular dynamics simulations are performed to study the hydration shell structure, dynamics, and vibrational echo spectroscopy of aqueous Mg(NO3)2 and Ca(NO3)2 solutions. The hydration shell structure is probed through calculations of various ion-ion and ion-water radial and spatial distribution functions. On the dynamical side, calculations have been made for the hydrogen bond dynamics of hydration shells and also residence dynamics and lifetimes of water in different solvation environments. Subsequently, we looked at the dynamics of frequency fluctuations of OD modes of heavy water in different hydration environments. Specifically, the temporal decay of spectral observables of two-dimensional infrared (2DIR) spectroscopy, three pulse echo peak shift (3PEPS) measurements and also of time correlations of frequency fluctuations are calculated to investigate the dynamics of vibrational spectral diffusion of water in different hydration environments in these solutions. The OD stretch frequencies of water molecules in the vicinity of both divalent cations are found to be red-shifted and also fluctuating at a slower rate than other water molecules present in the solutions. The Mg2+ ions are found to be strongly hydrated which can be linked to their lower tendency to form contact ion-pairs and essentially no water exchange between the cationic hydration shells and bulk during the time scale of the current simulations. The stronger hydration of Mg2+ ions make their hydration shells structurally and dynamically more rigid and make the dynamics of hydrogen bonds and vibrational spectral diffusion, as revealed through spectral observables of 2DIR and 3PEPS slower than that for the Ca2+ ions. The structural and spectral dynamics of water molecules outside the cationic solvation shells in the Mg(NO3)2 solution are also found to be relatively slower than that of the Ca(NO3)2 solution and pure water which show the effects of stronger electric fields of Mg2+ ions extending beyond their first hydration shells. Also, water molecules in the hydration shells of the NO3- ions are found to relax at a slower rate in the Mg(NO3)2 solution which manifests the effect countercations have on anionic hydration shells for divalent metal nitrate solutions.
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Affiliation(s)
- Banshi Das
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Amalendu Chandra
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
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9
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Das B, Chandra A. Effects of Stearyl Alcohol Monolayer on the Structure, Dynamics and Vibrational Sum Frequency Generation Spectroscopy of Interfacial Water. Phys Chem Chem Phys 2022; 24:7374-7386. [DOI: 10.1039/d1cp04944e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The structure, dynamics and vibrational spectroscopy of water surface covered by a monolayer of stearyl alcohol (STA) are investigated by means of molecular dynamics simulations and vibrational sum frequency generation...
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10
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Peng M, Duignan TT, Nguyen CV, Nguyen AV. From Surface Tension to Molecular Distribution: Modeling Surfactant Adsorption at the Air-Water Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:2237-2255. [PMID: 33559472 DOI: 10.1021/acs.langmuir.0c03162] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Surfactants are centrally important in many scientific and engineering fields and are used for many purposes such as foaming agents and detergents. However, many challenges remain in providing a comprehensive understanding of their behavior. Here, we provide a brief historical overview of the study of surfactant adsorption at the air-water interface, followed by a discussion of some recent advances in this area from our group. The main focus is on incorporating an accurate description of the adsorption layer thickness of surfactant at the air-water interface. Surfactants have a wide distribution at the air-water interface, which can have a significant effect on important properties such as the surface excess, surface tension, and surface potential. We have developed a modified Poisson-Boltzmann (MPB) model to describe this effect, which we outline here. We also address the remaining challenges and future research directions in this area. We believe that experimental techniques, modeling, and simulation should be combined to form a holistic picture of surfactant adsorption at the air-water interface.
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Affiliation(s)
- Mengsu Peng
- School of Chemical Engineering, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Timothy T Duignan
- School of Chemical Engineering, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Cuong V Nguyen
- School of Chemical Engineering, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Anh V Nguyen
- School of Chemical Engineering, University of Queensland, Brisbane, Queensland 4072, Australia
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11
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Müller P, Bonthuis DJ, Miller R, Schneck E. Ionic Surfactants at Air/Water and Oil/Water Interfaces: A Comparison Based on Molecular Dynamics Simulations. J Phys Chem B 2021; 125:406-415. [DOI: 10.1021/acs.jpcb.0c08615] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Paulina Müller
- Physics Department, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - Douwe Jan Bonthuis
- Institute of Theoretical and Computational Physics, Technische Universität Graz, 8010 Graz, Austria
| | - Reinhard Miller
- Physics Department, Technische Universität Darmstadt, 64289 Darmstadt, Germany
| | - Emanuel Schneck
- Physics Department, Technische Universität Darmstadt, 64289 Darmstadt, Germany
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12
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Wang X, Santo KP, Neimark AV. Modeling Gas-Liquid Interfaces by Dissipative Particle Dynamics: Adsorption and Surface Tension of Cetyl Trimethyl Ammonium Bromide at the Air-Water Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:14686-14698. [PMID: 33216560 DOI: 10.1021/acs.langmuir.0c02572] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Adsorption of surfactants at gas-liquid interfaces that causes reduction in the surface tension is a classical problem in colloid and interface science with multiple practical applications in oil and gas recovery, separations, cosmetics, personal care, and biomedicine. Here, we develop an original coarse-grained model of the liquid-gas interface within the conventional dissipative particle dynamics (DPD) framework with the goal of quantitatively predicting the surface tension in the presence of surfactants. As a practical case-study example, we explore the adsorption of the cationic surfactant cetyl trimethyl ammonium bromide (CTAB) on the air-water interface. The gas phase is modeled as a DPD fluid composed of fictitious hard-core "gas" beads with exponentially decaying repulsive potentials to prevent penetration of the liquid phase components. A rigorous parametrization scheme is proposed based on matching the bulk and interfacial properties of water and octane taken as the reference compounds. Quantitative agreement between the simulated and experimental surface tension of CTAB solutions is found for a wide range of bulk surfactant concentrations (∼10-3 to ∼1 mmol/L) with the reduction of the surface tension from ∼72 mN/m (pure water) to the limiting value of ∼37.5 mN/m at the critical micelle concentration. The gas phase DPD model with the proposed parametrization scheme can be extended and applied to modeling various gas-liquid interfaces with surfactant and lipid monolayers, such as bubble suspensions, foams, froths, etc.
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Affiliation(s)
- Xinyang Wang
- Chemical and Biochemical Engineering Department, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
- School of Resources and Civil Engineering, Northeastern University, Shenyang, Liaoning 110819, China
| | - Kolattukudy P Santo
- Chemical and Biochemical Engineering Department, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Alexander V Neimark
- Chemical and Biochemical Engineering Department, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
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13
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Sadeghi MS, Moghbeli MR, Goddard WA. A coarse-grain force field based on quantum mechanics (CGq FF) for molecular dynamics simulation of poly(ethylene glycol)-block-poly(ε-caprolactone) (PEG-b-PCL) micelles. Phys Chem Chem Phys 2020; 22:24028-24040. [PMID: 33078174 DOI: 10.1039/d0cp04364h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
In order to provide the means to predict from molecular dynamics (MD) simulations the structures of copolymer-based micelles in solution, we developed coarse grain force field (CGq FF) parameters for poly(ethylene glycol) (PEG) and for poly(ε-caprolactone) (PCL). A key advance here is the use of quantum mechanics to train the parameters describing the non-bonded (NB) interactions between the CG beads. The functional forms are the same as the MARTINI CG FF so standard MD codes can be used. Our CGq FF describes well the experimentally observed properties for the polymer-air and polymer-water interfaces, indicating the accuracy of the NB interactions. The structural properties (density, radius of gyration (Rg), and end-to-end distance (h)) match both experiment and all atom (AA) simulations. We illustrate the application of this CGq FF by following the formation of a spherical micelle from 250 chains of PEG23-b-PCL9 diblock copolymer, each block with molecular weight of 1000 Daltons (10 500 beads, corresponding to 123 250 atoms), in a water box with 119 139 water beads (426 553 water molecules).
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Affiliation(s)
- Maryam S Sadeghi
- Smart Polymers and Nanocomposites Research Group, School of Chemical Engineering, Iran University of Science and Technology, Tehran 16846-13114, Iran.
| | - Mohammad Reza Moghbeli
- Smart Polymers and Nanocomposites Research Group, School of Chemical Engineering, Iran University of Science and Technology, Tehran 16846-13114, Iran.
| | - William A Goddard
- Materials and Process Simulation Center (MSC), California Institute of Technology, Pasadena, California 91125, USA.
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14
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Mustan F, Ivanova A, Tcholakova S, Denkov N. Revealing the Origin of the Specificity of Calcium and Sodium Cations Binding to Adsorption Monolayers of Two Anionic Surfactants. J Phys Chem B 2020; 124:10514-10528. [PMID: 33147954 DOI: 10.1021/acs.jpcb.0c06649] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The studied anionic surfactants linear alkyl benzene sulfonate (LAS) and sodium lauryl ether sulfate (SLES) are widely used key ingredients in many home and personal care products. These two surfactants are known to react very differently with multivalent counterions, including Ca2+. This is explained by a stronger interaction of the calcium cation with the LAS molecules, compared to SLES. The molecular origin of this difference in the interactions remains unclear. In the current study, we conduct classical atomistic molecular dynamics simulations to compare the ion interactions with the adsorption layers of these two surfactants, formed at the vacuum-water interface. Trajectories of 150 ns are generated to characterize the adsorption layer structure and the binding of Na+ and Ca2+ ions. We found that both surfactants behave similarly in the presence of Na+ ions. However, when Ca2+ is added, Na+ ions are completely displaced from the surface with adsorbed LAS molecules, while this displacement occurs only partially for SLES. The simulations show that the preference of Ca2+ to the LAS molecules is due to a strong specific attraction with the sulfonate head-group, besides the electrostatic one. This specific attraction involves significant reduction of the hydration shells of the interacting calcium cation and sulfonate group, which couple directly and form surface clusters of LAS molecules, coordinated around the adsorbed Ca2+ ions. In contrast, SLES molecules do not exhibit such specific interaction because the hydration shell around the sulfate anion is more stable, due to the extra oxygen atom in the sulfate group, thus precluding substantial dehydration and direct coupling with any of the cations studied.
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15
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Ríos-López M, Mendez-Bermúdez JG, Vázquez-Sánchez MI, Domínguez H. Surface tension calculations of the cationic (CTAB) and the zwitterionic (SB3-12) surfactants using new force field models: a computational study. Mol Phys 2019. [DOI: 10.1080/00268976.2019.1656349] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Marlene Ríos-López
- Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México, México
| | | | | | - Hector Domínguez
- Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México, México
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16
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Peng M, Nguyen AV, Wang J, Miller R. A critical review of the model fitting quality and parameter stability of equilibrium adsorption models. Adv Colloid Interface Sci 2018; 262:50-68. [PMID: 30342700 DOI: 10.1016/j.cis.2018.10.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 08/12/2018] [Accepted: 10/05/2018] [Indexed: 10/28/2022]
Abstract
We reviewed eight commonly used equilibrium adsorption models and examined their underlying assumptions, fitting qualities, and parameter stabilities. We compared several objective functions that have been applied to curve fitting analysis and a few statistics tests that have been performed to evaluate regression quality. The iteratively reweighted least squares algorithm was selected as the most suitable regression method for adsorption models in the presence of heteroscedasticity. The fraction of unexplained variance was selected to indicate the model fitting quality. Two sources of parameter instability were identified: residue instability and function instability. While the definition of the instability caused by residue is well established, we are the first to consider the instability caused by an adsorption model. The models discussed in this article can be applied to many surfactants, such as normal alcohols, polyglycol ethers, and sodium dodecyl sulfate at different salt concentrations. Our results show that both the model fitting quality and parameter instability increase with the number of parameters subject to curve fitting. For the Frumkin-type of reorientation model, the parameter instability can be as high as 25%. The high degree of instability in some complicated adsorption models may invalidate the estimated parameters. Therefore, additional measurements or simulations are required for complicated models to extract reliable model parameters.
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17
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Yadav VK. Vibrational spectral diffusion in supercritical deuterated ammonia from first principles simulations: Roles of hydrogen bonds, free ND modes and inertial rotation of ammonia molecules. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.08.089] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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18
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Yadav VK, Chandra A. Dynamics of vibrational frequency fluctuations in deuterated liquid ammonia: roles of fluctuating hydrogen bonds and free ND modes. MOLECULAR SIMULATION 2018. [DOI: 10.1080/08927022.2018.1475739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Affiliation(s)
- Vivek Kumar Yadav
- Department of Chemistry, Indian Institute of Technology Kanpur , Kanpur, India
| | - Amalendu Chandra
- Department of Chemistry, Indian Institute of Technology Kanpur , Kanpur, India
- Department of Theoretical and Computational Molecular Science, Institute of Molecular Science , Okazaki, Japan
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19
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Hydrogen bond dynamics and vibrational spectral diffusion in aqueous solution of formaldehyde: a first principles molecular dynamics study. Theor Chem Acc 2018. [DOI: 10.1007/s00214-018-2333-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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20
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Ríos-López M, Mendez-Bermúdez JG, Domínguez H. New Force Field Parameters for the Sodium Dodecyl Sulfate and Alpha Olefin Sulfonate Anionic Surfactants. J Phys Chem B 2018; 122:4558-4565. [DOI: 10.1021/acs.jpcb.8b01452] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Marlene Ríos-López
- Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México D.F. 04510, Mexico
| | - Jose Guillermo Mendez-Bermúdez
- Centro Universitario de los Valles, Universidad de Guadalajara (UdG), Carretera Guadalajara-Ameca Km 45.4, Ameca 46600, Jalisco, Mexico
| | - Hector Domínguez
- Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México D.F. 04510, Mexico
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21
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Karmakar A, Chandra A. Water under Supercritical Conditions: Hydrogen Bonds, Polarity, and Vibrational Frequency Fluctuations from Ab Initio Simulations with a Dispersion Corrected Density Functional. ACS OMEGA 2018; 3:3453-3462. [PMID: 31458597 PMCID: PMC6641502 DOI: 10.1021/acsomega.7b02036] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 03/09/2018] [Indexed: 05/27/2023]
Abstract
We have studied the effects of dispersion interactions on the dynamics of vibrational frequency fluctuations, hydrogen bonds, and free OD modes in supercritical heavy water at three different densities by means of ab initio molecular dynamics simulations. The vibrational spectral diffusion, as described by the frequency fluctuations, is studied through calculations of frequency time correlation of stretch modes of deuterated water, and its relations to the dynamics of hydrogen bonds and free OD modes are described. In addition, some of the other dynamical, structural, and electronic properties such as diffusion, rotational relaxation, radial distribution functions, hydrogen bond and coordination numbers, and dipole moments are also investigated from the perspectives of their variation with inclusion of dispersion interactions at varying density of the solvent. Although some changes in the structural properties are found on inclusion of dispersion corrections, no significant difference in the fluctuation dynamics of OD stretching frequencies and also in other dynamical quantities of supercritical water are found because of dispersion effects. The dynamics of water molecules under supercritical conditions is very fast compared to the corresponding dynamics under ambient conditions. The large thermal effects at such a high temperature seem to take over any relatively minor changes that might be introduced by weak dispersion interaction.
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22
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Sharma B, Chandra A. Nature of hydration shells of a polyoxy-anion with a large cationic centre: The case of iodate ion in water. J Comput Chem 2018; 39:1226-1235. [DOI: 10.1002/jcc.25185] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Revised: 01/18/2018] [Accepted: 01/18/2018] [Indexed: 11/09/2022]
Affiliation(s)
- Bikramjit Sharma
- Department of Chemistry; Indian Institute of Technology Kanpur; Kanpur Uttar Pradesh 208016 India
| | - Amalendu Chandra
- Department of Chemistry; Indian Institute of Technology Kanpur; Kanpur Uttar Pradesh 208016 India
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23
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Yadav S, Chandra A. Structural and Dynamical Nature of Hydration Shells of the Carbonate Ion in Water: An Ab Initio Molecular Dynamics Study. J Phys Chem B 2018; 122:1495-1504. [DOI: 10.1021/acs.jpcb.7b11636] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sushma Yadav
- Department
of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Amalendu Chandra
- Department
of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
- Department
of Theoretical and Computational Molecular Science, Institute of Molecular Science, Myodaiji, Okazaki 444-8585, Aichi, Japan
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24
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Karmakar A, Chandra A. Dynamics of vibrational spectral diffusion in water: Effects of dispersion interactions, temperature, density, system size and fictitious orbital mass. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2017.11.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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25
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Magi Meconi G, Ballard N, Asua JM, Zangi R. Shedding light on the different behavior of ionic and nonionic surfactants in emulsion polymerization: from atomistic simulations to experimental observations. Phys Chem Chem Phys 2017; 19:31692-31705. [PMID: 29165448 DOI: 10.1039/c7cp05206e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Although surfactants are known to play a vital role in polymerization reactions carried out in dispersed media, many aspects of their use are poorly understood, perhaps none more so than the vastly different action of ionic and nonionic surfactants in emulsion polymerization. In this work, we combine experimental measurements of emulsion polymerization of styrene with atomistic molecular dynamics simulations to better understand the behavior of surfactants at monomer/polymer-water interfaces. In a batch emulsion polymerization of styrene, the nonionic surfactant Disponil AFX 1080 leads to two nucleation periods, in contrast to the behavior observed for the ionic surfactant SDS. This can be explained by the absorption of the nonionic surfactant into the organic phase at the early stages of the polymerization reaction which is then released as the reaction progresses. Indeed, we find that the partition coefficient of the surfactant between the organic phase and water increases with the amount of monomer in the former, and preferential partitioning is detected to organic phases containing at least 55% styrene. Results from molecular dynamics simulations confirm that spontaneous dissolution of the non-ionic surfactant into a styrene-rich organic phase occurs above a critical concentration of the surfactant adsorbed at the interface. Above this critical concentration, a linear correlation between the amount of surfactant adsorbed at the interface and that absorbed inside the organic phase is observed. To facilitate this absorption into a completely hydrophobic medium, water molecules accompany the intruding surfactants. Similar simulations but with the ionic surfactant instead did not result in any absorption of the surfactant into a neat styrene phase, likely because of its strongly hydrophilic head group. The unusual partitioning behavior of nonionic surfactants explains a number of observable features of emulsion polymerization reactions which use nonionic surfactants and should help with future development of processes for improved control over polymerization.
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Affiliation(s)
- Giulia Magi Meconi
- POLYMAT & Departamento de Química Aplicada, Facultad de Ciencias Químicas, University of the Basque Country UPV/EHU, Avenida de Tolosa 72, 20018, Donostia-San Sebastián, Spain
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26
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Mafi A, Hu D, Chou KC. Complex Formations between Surfactants and Polyelectrolytes of the Same Charge on a Water Surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:7940-7946. [PMID: 28686450 DOI: 10.1021/acs.langmuir.7b01246] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The mechanism of complex formation between surfactants and polyelectrolytes with the same charge on the water surface was investigated using molecular dynamics simulations and phase-sensitive sum-frequency generation vibrational spectroscopy. Although complex formation between highly charged surfactants and polyelectrolytes of the same charge is generally expected to be prohibited by the electrostatic repulsive force, our study shows that it is possible to form thermodynamically stable complexes when excess ions are present in the solution. We found that anionic partially hydrolyzed polyacrylamide (HPAM) could interact with anionic sodium dodecyl sulfate (SDS) on a water surface in the presence of salts. With excess Na+ ions in the solution, the charge screening effect allows HPAM to weakly interact with SDS via hydrogen bonds. In the presence of divalent Ca2+ ions, the surfactant and the polymer are strongly coupled by forming Ca2+ ion bridges and hydrogen bonds. Our calculation shows that the presence of Ca2+ ions creates a steep binding energy of ∼30 kJ/mol near the water surface. These results were qualitatively verified using phase-sensitive sum-frequency generation vibrational spectroscopy.
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Affiliation(s)
- Amirhossein Mafi
- Department of Chemistry, University of British Columbia , Vancouver, British Columbia V6T 1Z1, Canada
- Department of Chemical and Biological Engineering, University of British Columbia , Vancouver, British Columbia V6T 1Z3, Canada
| | - Dan Hu
- Department of Chemistry, University of British Columbia , Vancouver, British Columbia V6T 1Z1, Canada
| | - Keng C Chou
- Department of Chemistry, University of British Columbia , Vancouver, British Columbia V6T 1Z1, Canada
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27
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Indelicato S, Bongiorno D, Calabrese V, Perricone U, Almerico AM, Ceraulo L, Piazzese D, Tutone M. Micelles, Rods, Liposomes, and Other Supramolecular Surfactant Aggregates: Computational Approaches. Interdiscip Sci 2017; 9:392-405. [PMID: 28478537 DOI: 10.1007/s12539-017-0234-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 03/31/2017] [Accepted: 04/24/2017] [Indexed: 12/31/2022]
Abstract
Surfactants are an interesting class of compounds characterized by the segregation of polar and apolar domains in the same molecule. This peculiarity makes possible a whole series of microscopic and macroscopic effects. Among their features, their ability to segregate particles (fluids or entire domains) and to reduce the surface/interfacial tension is the utmost important. The interest in the chemistry of surfactants never weakened; instead, waves of increasing interest have occurred every time a new field of application of these molecules has been discovered. All these special characteristics depend largely on the ability of surfactants to self-assemble and constitute supramolecular structures where their chemical properties are amplified. The possibility to obtain structural and energy information and, above all, the possibility of forecast the self-organizing mechanisms of surfactants have had a significant boost via computational chemistry. The molecular dynamics models, initially coarse-grained and subsequently (with the increasing computer power) using more accurate models, allowed, over the years, to better understand different aspects of the processes of dispersion, self-assembly, segregation of surfactant. Moreover, several other aspects have been investigated as the effect of the counterions of many ionic surfactants in defining the final supramolecular structures, the mobility of side chains, and the capacity of some surfactant to envelope entire proteins. This review constitutes a perspective/prospective view of these results. On the other hand, some comparison of in silico results with experimental information recently acquired through innovative analytical techniques such as ion mobility mass spectrometry which have been introduced.
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Affiliation(s)
- Serena Indelicato
- Dipartimento di Scienze della Terra e del Mare (DISTEM), Università degli Studi di Palermo, Palermo, Italy
| | - David Bongiorno
- Dipartimento di Scienze e Tecnologie Biologiche Chimiche e Farmaceutiche, Università degli Studi di Palermo (STEBICEF), Palermo, Italy
| | - Valentina Calabrese
- Dipartimento di Scienze e Tecnologie Biologiche Chimiche e Farmaceutiche, Università degli Studi di Palermo (STEBICEF), Palermo, Italy
| | - Ugo Perricone
- Dipartimento di Scienze e Tecnologie Biologiche Chimiche e Farmaceutiche, Università degli Studi di Palermo (STEBICEF), Palermo, Italy
| | - Anna Maria Almerico
- Dipartimento di Scienze e Tecnologie Biologiche Chimiche e Farmaceutiche, Università degli Studi di Palermo (STEBICEF), Palermo, Italy
| | - Leopoldo Ceraulo
- Dipartimento di Scienze e Tecnologie Biologiche Chimiche e Farmaceutiche, Università degli Studi di Palermo (STEBICEF), Palermo, Italy
| | - Daniela Piazzese
- Dipartimento di Scienze della Terra e del Mare (DISTEM), Università degli Studi di Palermo, Palermo, Italy
| | - Marco Tutone
- Dipartimento di Scienze e Tecnologie Biologiche Chimiche e Farmaceutiche, Università degli Studi di Palermo (STEBICEF), Palermo, Italy.
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28
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Yadav VK, Klein ML. Probing the dynamics of N-methylacetamide in methanol via ab initio molecular dynamics. Phys Chem Chem Phys 2017; 19:12868-12875. [PMID: 28470307 DOI: 10.1039/c7cp00690j] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Two-dimensional infrared (2D IR) spectroscopy of amide 1 vibrational bands provides a valuable probe of proteins as well as molecules such as N-methylacetamide (NMA), which present peptide-like H-bonding possibilities to a solvent.
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Affiliation(s)
- Vivek K. Yadav
- ICMS
- Department of Chemistry
- Temple University
- Philadelphia
- USA
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29
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The effect of spacer on the structure of surfactant at liquid/air interface: A molecular dynamics simulation study. J Mol Liq 2016. [DOI: 10.1016/j.molliq.2016.07.142] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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30
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Eftaiha AF, Wanasundara SN, Paige MF, Bowles RK. Exploring the Impact of Tail Polarity on the Phase Behavior of Single Component and Mixed Lipid Monolayers Using a MARTINI Coarse-Grained Force Field. J Phys Chem B 2016; 120:7641-51. [DOI: 10.1021/acs.jpcb.6b03970] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Ala’a F. Eftaiha
- Department
of Chemistry, The Hashemite University, P.O. Box 150459, Zarqa 13115, Jordan
- Department
of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada
| | - Surajith N. Wanasundara
- Department
of Medical Imaging, University of Saskatchewan, 103 Hospital Drive, Saskatoon, SK S7N 0W8, Canada
| | - Matthew F. Paige
- Department
of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada
| | - Richard K. Bowles
- Department
of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada
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31
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Pang J, Zhao T, Xin X, Chen Y, Tan Y, Xu G. Effect of Inorganic Salts on the Aggregation Behavior of AOT at the Air/Water Interface. J SURFACTANTS DETERG 2016. [DOI: 10.1007/s11743-016-1842-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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32
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Shen Z, Sun H. Prediction of Surface and Bulk Partition of Nonionic Surfactants Using Free Energy Calculations. J Phys Chem B 2015; 119:15623-30. [PMID: 26618714 DOI: 10.1021/acs.jpcb.5b10239] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The surface-bulk partition of nonionic surfactants was predicted by calculating chemical potential differences using two simulation boxes representing the surface and the bulk phases separately. A published coarse grained force field was modified and validated for this application. Thermodynamic integration (TI) was applied to compute excess chemical potentials. The high concentration surface was stabilized by applying an external harmonic potential, and the bulk was treated as ideal solution, which was confirmed by simulation using a lattice model at conditions near the critical micelle concentration (∼10(-5) mol/L). Based on the calculated chemical potential differences with precision of ca. 1 kJ/mol, the equilibria of surface-bulk concentration was predicted well in comparison with the experimental data.
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Affiliation(s)
| | - Huai Sun
- State Key Laboratory of Inorganic Synthesis & Preparative Chemistry, College of Chemistry, Jilin University , Changchun 130012, China
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33
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Yadav VK, Chandra A. First-Principles Simulation Study of Vibrational Spectral Diffusion and Hydrogen Bond Fluctuations in Aqueous Solution of N-Methylacetamide. J Phys Chem B 2015; 119:9858-67. [DOI: 10.1021/acs.jpcb.5b03836] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Vivek Kumar Yadav
- Department of Chemistry, Indian Institute of Technology, Kanpur, India 208016
| | - Amalendu Chandra
- Department of Chemistry, Indian Institute of Technology, Kanpur, India 208016
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34
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Chen M, Lu X, Liu X, Hou Q, Zhu Y, Zhou H. Slow dynamics of water confined in Newton black films. Phys Chem Chem Phys 2015; 17:19183-93. [PMID: 26135223 DOI: 10.1039/c5cp02908b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Slowdown of translational and reorientational dynamics of water confined in Newton black films (NBFs) is revealed by molecular dynamics simulations. As a film becomes thinner, both translational and reorientational dynamics become slower. The polarization of water molecules in the macroscopic electrostatic field across the NBF and the coordination of Na(+) ions and surfactant anionic groups around water molecules concertedly lead to slowdown of water dynamics. The polarization effect is obvious for water not coordinated by Na(+) ions, which exhibits reorientational dynamics depending on initial dipole orientations. Na(+) ions and surfactant anionic groups retard dynamics of surrounding water by decreasing the hydrogen bond exchange probability and increasing the viscosity of water. The dependences of translational and reorientational dynamics on coordination environments of water are similar. Dynamics of water in positions close to the interfaces of NBFs are mainly retarded by Na(+) ions and surfactant anionic groups, while the macroscopic polarization effect plays the main role in influencing water dynamics in positions far from the interfaces. This study sheds light on the improvement of knowledge about the water dynamics slowdown mechanism in similar environments like reverse micelles and lamellar structures.
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Affiliation(s)
- Meng Chen
- State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing, Jiangsu 210093, China.
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35
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Theoretical description of 2D-cluster formation of nonionic surfactants at the air/water interface. Colloid Polym Sci 2015. [DOI: 10.1007/s00396-015-3630-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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36
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Karmakar A, Chandra A. Water in Hydration Shell of an Iodide Ion: Structure and Dynamics of Solute-Water Hydrogen Bonds and Vibrational Spectral Diffusion from First-Principles Simulations. J Phys Chem B 2015; 119:8561-72. [DOI: 10.1021/jp510714e] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Anwesa Karmakar
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, India 208016
| | - Amalendu Chandra
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, India 208016
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37
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Zhang Y, Li D, Li Y, Zhang S, Wang M, Li Y. High electric conductivity of liquid crystals formed by ordered self-assembly of nonionic surfactant N,N-bis(2-hydroxyethyl)dodecanamide in water. SOFT MATTER 2015; 11:1762-1766. [PMID: 25605398 DOI: 10.1039/c4sm02488e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
This work reports the ordered self-assembly of nonconductive small molecules that achieved extra high conductivity, thereby stating an convenient approach for constructing a biofriendly soft material that is suitable to be used as implantable biosensors and electro-stimulated drug delivery systems. The microstructure and the conductive mechanism were investigated in detail by combining experimental methods and molecular simulation. This research demonstrated that self-assembly of amide groups with delocalized electrons into π-stacked arrays exhibited high mobilities for charge carriers. The excellent biocompatibility and processability of soft materials such as liquid crystals ensure that the system has high potential in the advance fields of biosensors and drug delivery devices.
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Affiliation(s)
- Yan Zhang
- Key Laboratory of Colloid and Interface Chemistry of State Education Ministry, Shandong University, 27 Shanda Nanlu, Jinan, Shandong 250100, P. R. China.
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38
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Tummala NR, Liu S, Argyris D, Striolo A. Interfacial water properties in the presence of surfactants. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:2084-2094. [PMID: 25631335 DOI: 10.1021/la504388r] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Water, because of its fundamental role in biology, geology, and many industrial applications and its anomalous behavior compared to that of simple fluids, continues to fascinate and attract extensive scientific interest. Building on previous studies of water in contact with different surfaces, in this study, we report results obtained from molecular dynamics simulations of water near hydrophilic and hydrophobic interfaces in the presence of nonionic and ionic amphiphilic molecules, hexaethylene glycol monododecyl ether (C12E6) and sodium dodecyl sulfate (SDS). We elucidate how these surfactants affect the packing (i.e., density profiles) and orientation of interfacial water. The results highlight the interplay of both surfactant charges and the substrate charge distribution predominantly with respect to the orientation of water molecules, up to distances longer than those expected based on simulation results on flat solid surfaces. We also quantify the dynamics of interfacial water molecules by computing the residence probability for water in contact with various substrates. We compare our results to those previously obtained for interfacial water on silica and graphite and also with experimental sum-frequency vibrational spectroscopy results at the air-water interface in the presence of surfactants. Our analysis could be useful for a better understanding of interfacial water not only near solid substrates but also near self-assembled/aggregated molecules at a variety of interfaces.
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Affiliation(s)
- Naga Rajesh Tummala
- School of Chemistry and Biochemistry, Georgia Institute of Technology , 901 Atlantic Drive, Atlanta, Georgia 30318, United States
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39
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Karmakar A, Chandra A. Effects of dispersion interaction on vibrational spectral diffusion in aqueous NaBr solutions: An ab initio molecular dynamics study. Chem Phys 2015. [DOI: 10.1016/j.chemphys.2014.11.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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40
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Kayal A, Chandra A. Exploring the structure and dynamics of nano-confined water molecules using molecular dynamics simulations. MOLECULAR SIMULATION 2015. [DOI: 10.1080/08927022.2014.998212] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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41
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Zhang L, Liu Z, Ren T, Wu P, Shen JW, Zhang W, Wang X. Understanding the structure of hydrophobic surfactants at the air/water interface from molecular level. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:13815-13822. [PMID: 25358083 DOI: 10.1021/la5030586] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Understanding the behavior of fluorocarbon surfactants at the air/water interface is crucial for many applications, such as lubricants, paints, cosmetics, and fire-fighting foams. In this study, molecular dynamics (MD) simulations were employed to investigate the microscopic properties of non-ionic fluorocarbon surfactants at the air/water interface. Several properties, including the distribution of head groups, the distribution probability of the tilt angle between hydrophobic tails with respect to the xy plane, and the order parameter of surfactants, were computed to probe the structure of hydrophobic surfactants at the air/water interface. The effects of the monomer structure on interfacial phenomena of non-ionic surfactants were investigated as well. It is observed that the structure of fluorocarbon surfactants at the air/water interface is more ordered than that of hydrocarbons, which is dominated by the van der Waals interaction between surfactants and water molecules. However, replacing one or two CF2 with one or two CH2 group does not significantly influence the interfacial structure, suggesting that hydrocarbons may be promising alternatives to perfluorinated surfactants.
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Affiliation(s)
- Li Zhang
- Department of Chemistry, Key Laboratory of Advanced Textile Materials and Manufacturing Technology of Education Ministry, Zhejiang Sci-Tech University , Xiasha Higher Education Zone, Hangzhou, Zhejiang 310018, People's Republic of China
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42
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Choudhuri JR, Chandra A. Hydrogen bonded structure, polarity, molecular motion and frequency fluctuations at liquid-vapor interface of a water-methanol mixture: An ab initio molecular dynamics study. J Chem Phys 2014; 141:134703. [DOI: 10.1063/1.4896233] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Jyoti Roy Choudhuri
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Amalendu Chandra
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
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43
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Yang C, Sun H. Surface–Bulk Partition of Surfactants Predicted by Molecular Dynamics Simulations. J Phys Chem B 2014; 118:10695-703. [DOI: 10.1021/jp506768b] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Chunwei Yang
- School of Chemistry and Chemical
Engineering and Ministry of Education Key Laboratory of Scientific
and Engineering Computing, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Huai Sun
- School of Chemistry and Chemical
Engineering and Ministry of Education Key Laboratory of Scientific
and Engineering Computing, Shanghai Jiao Tong University, Shanghai, 200240, China
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44
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Isele-Holder RE, Ismail AE. Atomistic potentials for trisiloxane, alkyl ethoxylate, and perfluoroalkane-based surfactants with TIP4P/2005 and application to simulations at the air-water interface. J Phys Chem B 2014; 118:9284-97. [PMID: 25003511 DOI: 10.1021/jp502975p] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The mechanism of superspreading, the greatly enhanced spreading of water droplets facilitated by trisiloxane surfactants, is still under debate, largely because the role and behavior of the surfactants cannot be sufficiently resolved by experiments or continuum simulations. Previous molecular dynamics studies have been performed with simple model molecules or inaccurate models, strongly limiting their explanatory power. Here we present a force field dedicated to superspreading, extending existing quantum-chemistry-based models for the surfactant and the TIP4P/2005 water model ( Abascal et al. J. Chem. Phys. , 2005 , 123 , 234505 ). We apply the model to superspreading trisiloxane surfactants and nonsuperspreading alkyl ethoxylate and perfluoroalkane surfactants at various concentrations at the air-water interface. We show that the developed model accurately predicts surface tensions, which are typically assumed important for superspreading. Significant differences between superspreading and traditional surfactants are presented and their possible relation to superspreading discussed. Although the force field has been developed for superspreading problems, it should also perform well for other simulations involving polymers or copolymers with water.
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Affiliation(s)
- Rolf E Isele-Holder
- Aachener Verfahrenstechnik: Molecular Simulations and Transformations and AICES Graduate School, RWTH Aachen University , Schinkelstraße 2, 52062 Aachen, Germany
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Shen Z, Sun H, Liu X, Liu W, Tang M. Stability of Newton black films under mechanical stretch--a molecular dynamics study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:11300-11309. [PMID: 23944752 DOI: 10.1021/la402255m] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The stability of Newton black films (NBFs) under lateral mechanical stretch was investigated by nonequilibrium molecular dynamics (NEMD) simulations using force field parameters validated by accurate prediction of surface tensions. The applied strains accelerated film ruptures, enabling efficient measurements of the critical thicknesses of the films. Two representative surfactants, sodium dodecyl sulfate (SDS) for ionic surfactant and pentaethylene glycol monododecyl ether (C12EO5H) for nonionic surfactant, were investigated and compared. The predicted critical thickness of C12EO5H-coated film is smaller than that of the SDS-coated film, which is consistent with previously reported experimental observations. Our simulation results show that while the two surfactant-coated films exhibit similar dynamic properties attributed to the Marangoni-Gibbs effect, their surface structural characteristics are quite different. Consequently the two films demonstrate distinct rupture mechanisms in which rupture starts at uncovered water domains in the SDS-coated film, but at lateral surfactant/water interfaces in the C12EO5H-coated film. Our findings provide new insights into the stabilization mechanisms of NBFs and will facilitate the design and development of new films with improved properties.
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Affiliation(s)
- Zhe Shen
- School of Chemistry and Chemical Engineering and Key Laboratory for Thin Film and Microfabrication, Ministry of Education, Shanghai Jiao Tong University , Shanghai 200240, China
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Yadav VK, Chandra A. Dynamics of supercritical methanol of varying density from first principles simulations: Hydrogen bond fluctuations, vibrational spectral diffusion, and orientational relaxation. J Chem Phys 2013; 138:224501. [DOI: 10.1063/1.4808034] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Kumar Yadav V, Chandra A. Dynamics of hydrogen bonds and vibrational spectral diffusion in liquid methanol from first principles simulations with dispersion corrected density functional. Chem Phys 2013. [DOI: 10.1016/j.chemphys.2013.01.029] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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A first principles simulation study of vibrational spectral diffusion in aqueous NaBr solutions: Dynamics of water in ion hydration shells. Chem Phys 2013. [DOI: 10.1016/j.chemphys.2012.11.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Zahariev T, Ivanova A, Velinova M, Tadjer A. Structure and aggregation proclivity of C12E3 in aqueous solution. Chem Phys 2013. [DOI: 10.1016/j.chemphys.2012.10.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Yadav VK, Karmakar A, Choudhuri JR, Chandra A. A first principles molecular dynamics study of vibrational spectral diffusion and hydrogen bond dynamics in liquid methanol. Chem Phys 2012. [DOI: 10.1016/j.chemphys.2012.09.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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