Hydrogen-Bond-Induced Supermolecular Assemblies in a Nanoconfined Tertiary Alcohol

Abstract

International audienceTert-butanol is the molecular archetype of a variety of H-bonded systems that form micelle-like supermolecular clusters in the liquid state. This self-association process is characterized by a prepeak in the static structure factor. Recently, it has been shown by neutron scattering that this prepeak is totally suppressed in a nanoconfined geometry [Morineau, D.; Alba-Simionesco, C. J. Phys. Chem. Lett. 2010, 1, 7155.]. The authors have shown that excluded volume effects was one main ingredient of this suppression, but the question of the survival of H-bonded self-association in nanochannels has remained unresolved experimentally. From molecular dynamics simulations, we prove that self-association survives under confinement despite the absence of the prepeak. Furthermore, we show that its apparent suppression is due to a negative contribution arising from the liquid-porous solid correlations, which cannot be disentangled experimentally. Strikingly, the stability of micelle-like clusters surpasses the putative formation of interfacial H-bonds with surface silanols, leading to an unexpected hydrophobic interaction of tert-butanol with surface silica. This work highlights the foremost interest of combining neutron scattering and molecular simulations with a careful account of the complex situation encountered under confinement to better understand the molecular microstructure of H-bonded liquids

Microstructure and concentration fluctuations in alcohol–Toluene and alcohol-Cyclohexane binary liquids: A small angle neutron scattering study

“…On the contrary, the spatial correlations between these neighboring micellar clusters seem much more sensitive to dilution. This phenomenon was revealed in the neutron diffraction structure factor by the suppression of a pre-peak, located at a momentum transfer qPP=0.7Å -1 , which is a well-known signature of TBA intermediate range order and the existence of correlations between H-bonded units [10,22,23,24,25,26,27,28,29,30]. It was shown that the addition of a small amount of aprotic solvent is sufficient to turn off the prepeak intensity with a complete extinction for x<0.6-0.8 for TBA-TOL and TBA-MCY [10].…”

Computational Assessment of Water Desalination Performance of Multi‐Walled Carbon Nanotubes

“…Let us note that the RDFs inside the CNT have higher intensity than in the bulk phase, which results from excluded volume effects. [ 55,72–75 ]…”

“…Let us note that the RDFs inside the CNT have higher intensity than in the bulk phase, which results from excluded volume effects. [55,[72][73][74][75] Eventually, the RDF between the hydrogen and the oxygen atoms of water molecules were computed and are reported in Figure 10d. This latter suggests that the strength of interactions is conserved under confinement since the typical distance corresponding to hydrogen bonds in the bulk phase, that is, 2.5 Å, is also observed under confinement.…”

Microphase separation of a miscible binary liquid mixture under confinement at the nanoscale

“…For three decades confinement effects at the nanoscale on the physics of fluids have been been intensively studied. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Many new properties have been then discovered such as the giant diffusion of liquids, [16][17][18] the apparition of new phases and new transitions, [19][20][21][22] giant dielectric properties, 11,12,[23][24][25] the increase of optical properties, 26 and the possible mixing of non-miscible mixtures. 27 These observations indicated that the classical understanding of the physics of liquids should be revisited in confined geometry.…”

“…27 These observations indicated that the classical understanding of the physics of liquids should be revisited in confined geometry. Whereas these effects have been largely investigated in the case of confined single components [1][2][3][4][5][6][7][8][9][10][11][12][13][14] and immiscible binary mixtures, [28][29][30] less works have been devoted to the confinement of miscible liquid mixtures. 15,[31][32][33] Recently, Muthulakshmi et al 34 reported an experimental evidence of a partial phase separation of an ethanol-water mixture confined in mesoporous silica using positron annihilation lifetime spectroscopy.…”