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Mantha S, Chao H, Ylitalo AS, Fitzgibbons TC, Zhou W, Ginzburg VV, Wang ZG. Surfactant in a Polyol-CO 2 Mixture: Insights from a Classical Density Functional Theory Study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:16172-16182. [PMID: 36524704 PMCID: PMC9798868 DOI: 10.1021/acs.langmuir.2c02913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 11/26/2022] [Indexed: 06/17/2023]
Abstract
Silicone-polyether (SPE) surfactants, made of a polydimethyl-siloxane (PDMS) backbone and polyether branches, are commonly used as additives in the production of polymeric foams with improved properties. A key step in the production of polymeric foams is the nucleation of gas bubbles in the polymer matrix upon supersaturation of dissolved gas. However, the role of SPE surfactants in the nucleation of gas bubbles is not well understood. In this study, we use classical density functional theory to investigate the effect of an SPE surfactant on the nucleation of CO2 bubbles in a polyol foam formulation. We find that the addition of an SPE surfactant leads to a ∼3-fold decrease in the polyol-CO2 interfacial tension at the surfactant's critical micelle concentration. Additionally, the surfactant is found to reduce the free energy barrier and affect the minimum free energy pathway (MFEP) associated with CO2 bubble nucleation. In the absence of a surfactant, a CO2-rich bubble nucleates from a homogeneous CO2-supersaturated polyol solution by following an MFEP characterized by a single nucleation barrier. Adding a surfactant results in a two-step nucleation process with reduced free energy barriers. The first barrier corresponds to the formation of a spherical aggregate with a liquid-like CO2 core. This spherical aggregate then grows into a CO2-rich bubble (spherical aggregate with a vapor-like CO2 core) of a critical size representing the second barrier. We hypothesize that the stronger affinity of CO2 for PDMS (than polyether) stabilizes the spherical aggregate with the liquid-like CO2 core, leading to a lower free energy barrier for CO2 bubble nucleation. Stabilization of such an aggregate during the early stages of the nucleation may lead to foams with more, smaller bubbles, which can improve their microstrustural features and insulating abilities.
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Affiliation(s)
- Sriteja Mantha
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
| | - Huikuan Chao
- Dow,
Inc., Midland, Michigan 48667, United States
| | - Andrew S. Ylitalo
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
| | | | - Weijun Zhou
- Dow,
Inc., Lake Jackson, Texas 77566, United States
| | - Valeriy V. Ginzburg
- Dow,
Inc., Midland, Michigan 48667, United States
- Michigan
State University, East Lansing, Michigan 48910, United States
| | - Zhen-Gang Wang
- Division
of Chemistry and Chemical Engineering, California
Institute of Technology, Pasadena, California 91125, United States
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2
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Lauricella M, Ghaani MR, Nandi PK, Meloni S, Kvamme B, English NJ. Double Life of Methanol: Experimental Studies and Nonequilibrium Molecular-Dynamics Simulation of Methanol Effects on Methane-Hydrate Nucleation. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2022; 126:6075-6081. [PMID: 35422892 PMCID: PMC8996238 DOI: 10.1021/acs.jpcc.2c00329] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 03/09/2022] [Indexed: 06/14/2023]
Abstract
We have investigated systematically and statistically methanol-concentration effects on methane-hydrate nucleation using both experiment and restrained molecular-dynamics simulation, employing simple observables to achieve an initially homogeneous methane-supersaturated solution particularly favorable for nucleation realization in reasonable simulation times. We observe the pronounced "bifurcated" character of the nucleation rate upon methanol concentration in both experiments and simulation, with promotion at low concentrations and switching to industrially familiar inhibition at higher concentrations. Higher methanol concentrations suppress hydrate growth by in-lattice methanol incorporation, resulting in the formation of "defects", increasing the energy of the nucleus. At low concentrations, on the contrary, the detrimental effect of defects is more than compensated for by the beneficial contribution of CH3 in easing methane incorporation in the cages or replacing it altogether.
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Affiliation(s)
- Marco Lauricella
- School
of Physics, University College Dublin, Belfield, Dublin 4 D04
V1W8, Ireland
- Istituto
per le Applicazioni del Calcolo, Consiglio
Nazionale delle Ricerche, 00185 Rome, Italy
| | - Mohammad Reza Ghaani
- School
of Chemical and Bioprocess Engineering, University College Dublin, Belfield, Dublin 4, Ireland
| | - Prithwish K. Nandi
- School
of Chemical and Bioprocess Engineering, University College Dublin, Belfield, Dublin 4, Ireland
| | - Simone Meloni
- School
of Physics, University College Dublin, Belfield, Dublin 4 D04
V1W8, Ireland
- Dipartimento
di Scienze Chimiche, Farmaceutiche e Agrarie (DOCPAS), University of Ferrara, 44121 Ferrara, Italy
| | - Bjorn Kvamme
- Hyzen
Energy, Laguna Hills, California 92656, United States
| | - Niall J. English
- School
of Chemical and Bioprocess Engineering, University College Dublin, Belfield, Dublin 4, Ireland
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3
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Striolo A, Phan A, Walsh MR. Molecular properties of interfaces relevant for clathrate hydrate agglomeration. Curr Opin Chem Eng 2019. [DOI: 10.1016/j.coche.2019.08.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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4
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Bertolazzo AA, Naullage PM, Peters B, Molinero V. The Clathrate-Water Interface Is Oleophilic. J Phys Chem Lett 2018; 9:3224-3231. [PMID: 29812945 DOI: 10.1021/acs.jpclett.8b01210] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The slow nucleation of clathrate hydrates is a central challenge for their use in the storage and transportation of natural gas. Molecules that strongly adsorb to the clathrate-water interface decrease the crystal-water surface tension, lowering the barrier for clathrate nucleation. Surfactants are widely used to promote the nucleation and growth of clathrate hydrates. It has been proposed that these amphiphilic molecules bind to the clathrate surface via hydrogen bonding. However, recent studies reveal that PVCap, an amphiphilic polymer, binds to clathrates through hydrophobic moieties. Here we use molecular dynamic simulations and theory to investigate the mode and strength of binding of surfactants to the clathrate-water interface and their effect on the nucleation rate. We find that the surfactants bind to the clathrate-water interface exclusively through their hydrophobic tails. The binding is strong, driven by the entropy of dehydration of the alkyl chain, as it penetrates empty cavities at the hydrate surface. The hydrophobic attraction of alkyl groups to the clathrate surface also results in strong adsorption of alkanes. We identify two regimes for the binding of surfactants as a function of their density at the hydrate surface, which we interpret to correspond to the two steps of the Langmuir adsorption isotherm observed in experiments. Our results indicate that hydrophobic attraction to the clathrate-water interface is key for the design of soluble additives that promote the nucleation of hydrates. We use the calculated adsorption coefficients to estimate the concentration of sodium dodecyl sulfate (SDS) required to reach nucleation rates for methane hydrate consistent with those measured in experiments. To our knowledge, this study is the first to quantify the effect of surfactant concentration in the nucleation rate of clathrate hydrates.
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Affiliation(s)
- Andressa A Bertolazzo
- Department of Chemistry , The University of Utah , Salt Lake City , Utah 84112-0580 , United States
- Departamento de Ciências Exatas e Educação , Universidade Federal de Santa Catarina , Blumenau , State of Santa Catarina 88040-900 , Brazil
| | - Pavithra M Naullage
- Department of Chemistry , The University of Utah , Salt Lake City , Utah 84112-0580 , United States
| | - Baron Peters
- Department of Chemical Engineering , University of California , Santa Barbara , California 93106 , United States
| | - Valeria Molinero
- Department of Chemistry , The University of Utah , Salt Lake City , Utah 84112-0580 , United States
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5
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Poon GG, Lemke T, Peter C, Molinero V, Peters B. Soluble Oligomeric Nucleants: Simulations of Chain Length, Binding Strength, and Volume Fraction Effects. J Phys Chem Lett 2017; 8:5815-5820. [PMID: 29116791 DOI: 10.1021/acs.jpclett.7b02651] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Recent theories and simulations suggest that molecular additives can bind to the surfaces of nuclei, lower the surface energy, and accelerate nucleation. Experiments have shown that oligomeric and polymeric additives can also modify nucleation rates of proteins, ice, and minerals; however, general design principles for oligomeric or polymeric promoters do not yet exist. Here we investigate oligomeric additives for which each segment of the oligomer can bind to surfaces of nuclei. We use semigrand canonical Monte Carlo simulations in a Potts lattice gas model to study the effects of oligomer chain length, volume fraction, and binding strength. We find that increasing each of those parameters lowers the nucleation barrier. At extremely low oligomer concentrations, the nucleation kinetics can be modeled as though each oligomer is a heterogeneous nucleation site in solution.
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Affiliation(s)
- Geoffrey G Poon
- Department of Chemical Engineering, University of California , Santa Barbara, California 93106, United States
| | - Tobias Lemke
- Department of Chemistry, University of Konstanz , Konstanz 78457, Germany
| | - Christine Peter
- Department of Chemistry, University of Konstanz , Konstanz 78457, Germany
| | - Valeria Molinero
- Department of Chemistry, The University of Utah , Salt Lake City, Utah 84112, United States
| | - Baron Peters
- Department of Chemical Engineering, University of California , Santa Barbara, California 93106, United States
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6
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Mochizuki K, Qiu Y, Molinero V. Promotion of Homogeneous Ice Nucleation by Soluble Molecules. J Am Chem Soc 2017; 139:17003-17006. [PMID: 29111694 DOI: 10.1021/jacs.7b09549] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Atmospheric aerosols nucleate ice in clouds, strongly impacting precipitation and climate. The prevailing consensus is that ice nucleation is promoted heterogeneously by the surface of ice nucleating particles in the aerosols. However, recent experiments indicate that water-soluble molecules, such as polysaccharides of pollen and poly(vinyl alcohol) (PVA), increase the ice freezing temperature. This poses the question of how do flexible soluble molecules promote the formation of water crystals, as they do not expose a well-defined surface to ice. Here we use molecular simulations to demonstrate that PVA promotes ice nucleation through a homogeneous mechanism: PVA increases the nucleation rate by destabilizing water in the solution. This work demonstrates a novel paradigm for understanding ice nucleation by soluble molecules and provides a new handle to design additives that promote crystallization.
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Affiliation(s)
- Kenji Mochizuki
- Department of Chemistry, The University of Utah , Salt Lake City, Utah 84112-0580, United States.,Research Institute for Interdisciplinary Science, Okayama University , Okayama 700-8530, Japan
| | - Yuqing Qiu
- Department of Chemistry, The University of Utah , Salt Lake City, Utah 84112-0580, United States
| | - Valeria Molinero
- Department of Chemistry, The University of Utah , Salt Lake City, Utah 84112-0580, United States
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7
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Abstract
We analyze the processes governing the lifetimes of transient metastable polymorphs, within the context of classical nucleation theory.
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Affiliation(s)
- Wenhao Sun
- Department of Materials Science and Engineering
- Massachusetts Institute of Technology
- Cambridge
- USA
- Materials Sciences Division
| | - Gerbrand Ceder
- Department of Materials Science and Engineering
- Massachusetts Institute of Technology
- Cambridge
- USA
- Materials Sciences Division
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8
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Poon GG, Peters B. Accelerated Nucleation Due to Trace Additives: A Fluctuating Coverage Model. J Phys Chem B 2015; 120:1679-84. [DOI: 10.1021/acs.jpcb.5b08510] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Geoffrey G. Poon
- Department of Chemical Engineering, University of California, Santa
Barbara, California 93106, United States
| | - Baron Peters
- Department of Chemical Engineering, University of California, Santa
Barbara, California 93106, United States
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9
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Zimmermann NER, Vorselaars B, Quigley D, Peters B. Nucleation of NaCl from Aqueous Solution: Critical Sizes, Ion-Attachment Kinetics, and Rates. J Am Chem Soc 2015; 137:13352-61. [DOI: 10.1021/jacs.5b08098] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
| | - Bart Vorselaars
- Department
of Physics and Centre for Scientific Computing, University of Warwick, Coventry, CV4 7AL, U.K
| | - David Quigley
- Department
of Physics and Centre for Scientific Computing, University of Warwick, Coventry, CV4 7AL, U.K
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10
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Affiliation(s)
- Baron Peters
- Department
of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
- Department
of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
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