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Titolo:
Molecular dynamics study of spherical aggregates of chain molecules at different degrees of hydrophilicity in water solution
Autore:
Sterpone, F; Briganti, G; Pierleoni, C;
Indirizzi:
Univ Aquila, INFM, I-67010 Laquila, Italy Univ Aquila Laquila Italy I-67010 v Aquila, INFM, I-67010 Laquila, Italy Univ Aquila, Dept Phys, I-67010 Laquila, Italy Univ Aquila Laquila ItalyI-67010 ila, Dept Phys, I-67010 Laquila, Italy CEA Saclay, DBCM, Sect Biophys Prot & Membranes, F-91191 Gif Sur Yvette, France CEA Saclay Gif Sur Yvette France F-91191 F-91191 Gif Sur Yvette, France Univ Roma La Sapienza, UdR Roma 1, INFM, Rome, Italy Univ Roma La Sapienza Rome Italy apienza, UdR Roma 1, INFM, Rome, Italy Univ Roma La Sapienza, Dept Phys, I-00185 Rome, Italy Univ Roma La Sapienza Rome Italy I-00185 Dept Phys, I-00185 Rome, Italy
Titolo Testata:
LANGMUIR
fascicolo: 16, volume: 17, anno: 2001,
pagine: 5103 - 5110
SICI:
0743-7463(20010807)17:16<5103:MDSOSA>2.0.ZU;2-#
Fonte:
ISI
Lingua:
ENG
Soggetto:
SODIUM OCTANOATE MICELLE; AQUEOUS-SOLUTION; NONIONIC SURFACTANTS; PHASE-BEHAVIOR; COMPUTER-SIMULATION; NEUTRON-SCATTERING; INTERNAL STRUCTURE; DODECYL-SULFATE; IONIC MICELLES; MODEL MICELLE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
48
Recensione:
Indirizzi per estratti:
Indirizzo: Pierleoni, C Univ Aquila, INFM, Via Vetoio, I-67010 Laquila, Italy Univ Aquila Via Vetoio Laquila Italy I-67010 Laquila, Italy
Citazione:
F. Sterpone et al., "Molecular dynamics study of spherical aggregates of chain molecules at different degrees of hydrophilicity in water solution", LANGMUIR, 17(16), 2001, pp. 5103-5110

Abstract

We present molecular dynamics simulations of three spherical aggregates constituted of the same number of monomeric chains of increasing hydrophilic character in water solution. The three different chains are dodecane, CH3(CH2)(10)CH3; dodecan-1-ol, CH3(CH2)(10)CH2OH; and oligoethylenoxide, CH3(CH2)(11)(OCH2CH2)(3)OH, and the systems are denoted C-12, C12E0, and C12E3, respectively. The three solutions are simulated at the same temperature and pressure and at about the same concentration in weight of the solute. We investigate the structural changes of the aggregate and the conformational changes of its chains after increasing the hydrophilicity of the monomers. In the C12 system, the density of the aggregate is higher than the density of the pure hydrocarbon liquid in the same thermodynamic conditions. Dodecane chains are quite rigid and mostly in the all-trans conformation. This is aneffect of the strong hydrophobic repulsion exerted on the aggregate by thewater. A density depletion develops at the interface between the oil core and the solvent because of the mismatch between the two components. This extra pressure is gradually released after increasing the hydrophilicity of the monomers. In the C12E3 system, the density depletion at the interface iscompletely canceled, and the system is homogeneous through the interface. In this system, the interfacial regions appear to be divided into an inner part, where methylene groups, oxyethylene groups, and water molecules are present, and into an outer region formed by a mixture of oxyethylene groups and water only. The local density of oxyethylene groups in the interfacial region is strongly fluctuating, and its histogram shows an effective attraction among those groups. Thus, a considerable portion of the interfacial volume is filled by the solvent only. We observe a strong tendency for the OCCO dihedrals in the hydrophilic tails to be in the gauche state, and at thesame time, we observe the presence of H-bond bridges that stabilize this structure.

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Documento generato il 28/09/20 alle ore 15:28:18