Confined Polar Mixtures within Cylindrical Nanocavities

Using molecular dynamics experiments, we have extended our previous analysis of equimolar mixtures of water and acetonitrile confined between silica walls [J. Phys. Chem. B 2009, 113, 12744] to examine similar solutions trapped within carbon nanotubes and cylindrical silica pores. Two different carb...

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Autores principales:	Rodriguez, J., Elola, M.D., Laria, D.
Formato:	JOUR
Materias:	Acetonitrile Carbon nanotubes Hydrophobicity Mixtures Molecular dynamics Organic solvents Oxygen Silica Tubes (components) Aprotic solvents Carbon tube Characteristic time Concentration fluctuation Confined liquids Cylindrical cavities Different solvents Dispersive forces Equimolar mixtures Hydrophobic cavities Inner cavities Nano-cavities OH group Oxygen site Pore wall Silanol groups Silica pores Silica substrate Similar solution Solvent species Time correlation functions Trimethylsilyl groups Tube walls Nanopores
Acceso en línea:	http://hdl.handle.net/20.500.12110/paper_15206106_v114_n23_p7900_Rodriguez
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	todo:paper_15206106_v114_n23_p7900_Rodriguez
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spelling	todo:paper_15206106_v114_n23_p7900_Rodriguez2023-10-03T16:20:21Z Confined Polar Mixtures within Cylindrical Nanocavities Rodriguez, J. Elola, M.D. Laria, D. Acetonitrile Carbon nanotubes Hydrophobicity Mixtures Molecular dynamics Organic solvents Oxygen Silica Tubes (components) Aprotic solvents Carbon tube Characteristic time Concentration fluctuation Confined liquids Cylindrical cavities Different solvents Dispersive forces Equimolar mixtures Hydrophobic cavities Inner cavities Nano-cavities OH group Oxygen site Pore wall Silanol groups Silica pores Silica substrate Similar solution Solvent species Time correlation functions Trimethylsilyl groups Tube walls Nanopores Using molecular dynamics experiments, we have extended our previous analysis of equimolar mixtures of water and acetonitrile confined between silica walls [J. Phys. Chem. B 2009, 113, 12744] to examine similar solutions trapped within carbon nanotubes and cylindrical silica pores. Two different carbon tube sizes were investigated, (8,8) tubes, with radius Rcnt = 0.55 nm, and (16,16) ones, with Rcnt = 1.1 nm. In the narrowest tubes, we found that the cylindrical cavity is filled exclusively by acetonitrile; as the radius of the tube reaches ∼1 nm, water begins to get incorporated within the inner cavities. In (16,16) tubes, the analysis of global and local concentration fluctuations shows a net increment of the global acetonitrile concentration; in addition, the aprotic solvent is also the prevailing species at the vicinity of the tube walls. Mixtures confined within silica nanopores of radius ∼1.5 nm were also investigated. Three pores, differing in the effective wall/solvent interactions, were analyzed, (i) a first class, in which dispersive forces prevail (hydrophobic cavities), (ii) a second type, where oxygen sites at the pore walls are transformed into polar silanol groups (hydrophilic cavities), and (iii) finally, an intermediate scenario, in which 60% of the OH groups are replaced by mobile trimethylsilyl groups. Within the different pores, we found clear distinctions between the solvent layers that lie in close contact with the silica substrate and those with more central locations. Dynamical modes of the confined liquid phases were investigated in terms of diffusive and rotational time correlation functions. Compared to bulk results, the characteristic time scales describing different solvent motions exhibit significant increments. In carbon nanotubes, the most prominent modifications operate in the narrower tubes, where translations and rotations become severely hindered. In silica nanopores, the manifestations of the overall retardations are more dramatic for solvent species lying at the vicinity of trimethylsilyl groups. © 2010 American Chemical Society. Fil:Rodriguez, J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Elola, M.D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Laria, D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_15206106_v114_n23_p7900_Rodriguez
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	Acetonitrile Carbon nanotubes Hydrophobicity Mixtures Molecular dynamics Organic solvents Oxygen Silica Tubes (components) Aprotic solvents Carbon tube Characteristic time Concentration fluctuation Confined liquids Cylindrical cavities Different solvents Dispersive forces Equimolar mixtures Hydrophobic cavities Inner cavities Nano-cavities OH group Oxygen site Pore wall Silanol groups Silica pores Silica substrate Similar solution Solvent species Time correlation functions Trimethylsilyl groups Tube walls Nanopores
spellingShingle	Acetonitrile Carbon nanotubes Hydrophobicity Mixtures Molecular dynamics Organic solvents Oxygen Silica Tubes (components) Aprotic solvents Carbon tube Characteristic time Concentration fluctuation Confined liquids Cylindrical cavities Different solvents Dispersive forces Equimolar mixtures Hydrophobic cavities Inner cavities Nano-cavities OH group Oxygen site Pore wall Silanol groups Silica pores Silica substrate Similar solution Solvent species Time correlation functions Trimethylsilyl groups Tube walls Nanopores Rodriguez, J. Elola, M.D. Laria, D. Confined Polar Mixtures within Cylindrical Nanocavities
topic_facet	Acetonitrile Carbon nanotubes Hydrophobicity Mixtures Molecular dynamics Organic solvents Oxygen Silica Tubes (components) Aprotic solvents Carbon tube Characteristic time Concentration fluctuation Confined liquids Cylindrical cavities Different solvents Dispersive forces Equimolar mixtures Hydrophobic cavities Inner cavities Nano-cavities OH group Oxygen site Pore wall Silanol groups Silica pores Silica substrate Similar solution Solvent species Time correlation functions Trimethylsilyl groups Tube walls Nanopores
description	Using molecular dynamics experiments, we have extended our previous analysis of equimolar mixtures of water and acetonitrile confined between silica walls [J. Phys. Chem. B 2009, 113, 12744] to examine similar solutions trapped within carbon nanotubes and cylindrical silica pores. Two different carbon tube sizes were investigated, (8,8) tubes, with radius Rcnt = 0.55 nm, and (16,16) ones, with Rcnt = 1.1 nm. In the narrowest tubes, we found that the cylindrical cavity is filled exclusively by acetonitrile; as the radius of the tube reaches ∼1 nm, water begins to get incorporated within the inner cavities. In (16,16) tubes, the analysis of global and local concentration fluctuations shows a net increment of the global acetonitrile concentration; in addition, the aprotic solvent is also the prevailing species at the vicinity of the tube walls. Mixtures confined within silica nanopores of radius ∼1.5 nm were also investigated. Three pores, differing in the effective wall/solvent interactions, were analyzed, (i) a first class, in which dispersive forces prevail (hydrophobic cavities), (ii) a second type, where oxygen sites at the pore walls are transformed into polar silanol groups (hydrophilic cavities), and (iii) finally, an intermediate scenario, in which 60% of the OH groups are replaced by mobile trimethylsilyl groups. Within the different pores, we found clear distinctions between the solvent layers that lie in close contact with the silica substrate and those with more central locations. Dynamical modes of the confined liquid phases were investigated in terms of diffusive and rotational time correlation functions. Compared to bulk results, the characteristic time scales describing different solvent motions exhibit significant increments. In carbon nanotubes, the most prominent modifications operate in the narrower tubes, where translations and rotations become severely hindered. In silica nanopores, the manifestations of the overall retardations are more dramatic for solvent species lying at the vicinity of trimethylsilyl groups. © 2010 American Chemical Society.
format	JOUR
author	Rodriguez, J. Elola, M.D. Laria, D.
author_facet	Rodriguez, J. Elola, M.D. Laria, D.
author_sort	Rodriguez, J.
title	Confined Polar Mixtures within Cylindrical Nanocavities
title_short	Confined Polar Mixtures within Cylindrical Nanocavities
title_full	Confined Polar Mixtures within Cylindrical Nanocavities
title_fullStr	Confined Polar Mixtures within Cylindrical Nanocavities
title_full_unstemmed	Confined Polar Mixtures within Cylindrical Nanocavities
title_sort	confined polar mixtures within cylindrical nanocavities
url	http://hdl.handle.net/20.500.12110/paper_15206106_v114_n23_p7900_Rodriguez
work_keys_str_mv	AT rodriguezj confinedpolarmixtureswithincylindricalnanocavities AT elolamd confinedpolarmixtureswithincylindricalnanocavities AT lariad confinedpolarmixtureswithincylindricalnanocavities
_version_	1782025560412651520

Confined Polar Mixtures within Cylindrical Nanocavities

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