Glycerol condensed phases Part I. A molecular dynamics study

Chelli, Riccardo; Procacci, Piero; Cardini, Gianni; Valle, Raffaele Guido Della; Califano, S.

doi:10.1039/a808958b

Cited by 123 publications

(146 citation statements)

References 41 publications

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“…Chelli et al have performed a molecular dynamics (MD) simulation for glycerol. They reported that there are large clusters of glycerol molecules connected through hydrogen bonds, and that the lifetime of these clusters is strongly correlated with diffusion time [21]. On the basis of this network picture, our experimental result suggests that the topology of the hydrogen-bonding network (coordination number) plays a key role in the glass transition of a hydrogen-bonding liquid.…”

Section: Resultsmentioning

confidence: 56%

“…Although such composition dependence of coordination number is frequently discussed for covalent network glasses, the temperature dependence is rarely discussed. On the other hand, in hydrogen-bondingnetwork glasses, the probability for hydrogen-bonding formation depends significantly on temperature, as shown by MD simulation [21]. Therefore, the mean coordination number of a hydrogen-bonding molecule is also dependent on temperature, and cannot be fixed at any given value.…”

Section: Resultsmentioning

confidence: 99%

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Systematic study of the glass transition in polyhydric alcohols

Nakanishi

Nozaki

2011

Phys. Rev. E

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We have investigated the glass transitions of trihydric alcohols using broadband dielectric spectroscopy, and compare the results with those previously reported for sugar alcohols. Although a systematic glass transition feature related to molecular size has been reported for sugar alcohols, the essential factor governing this feature is still unclear because the number of carbon atoms (N C ) and the number of OH groups (N OH ) per molecule are identical in sugar alcohols. By examining trihydric alcohols (N C = N OH ), we conclude that N OH is dominant for the characteristics of the slow dynamics, such as fragility and glass transition temperature. This result suggests that the topological structure of the hydrogen-bonding network (coordination number) plays an important role in the glass transition of polyhydric alcohols. Furthermore, the orientational correlation factor evaluated using the Kirkwood-Fröhlich theory reveals a similarity in hydrogen bond formation among a variety of polyhydric alcohols. Based on these two experimental results, we discuss a possible physical picture of the glass transition of polyhydric alcohols.

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Section: Resultsmentioning

confidence: 56%

Section: Resultsmentioning

confidence: 99%

Systematic study of the glass transition in polyhydric alcohols

Nakanishi

Nozaki

2011

Phys. Rev. E

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“…In crystals an extended structure with backbone torsion angles close to 180°has been found and justified theoretically, similarly as for other polyhydroxy compounds. 16 However, controversial theoretical and experimental models have been proposed for the liquid phase, mostly suggesting a large conformational flexibility. [16][17][18][19][20][21] Almost free rotation of the hydroxyl groups (between the three preferable staggered positions) was predicted for the glycerol molecule, which is in many aspects similar to the gluconate.…”

Section: Introductionmentioning

confidence: 99%

“…16 However, controversial theoretical and experimental models have been proposed for the liquid phase, mostly suggesting a large conformational flexibility. [16][17][18][19][20][21] Almost free rotation of the hydroxyl groups (between the three preferable staggered positions) was predicted for the glycerol molecule, which is in many aspects similar to the gluconate. 22 The high degree of flexibility also best corresponds to the results presented below.…”

Section: Introductionmentioning

confidence: 99%

Interpretation of Raman and Raman Optical Activity Spectra of a Flexible Sugar Derivative, the Gluconic Acid Anion

et al. 2009

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Raman scattering and its polarized extension, Raman optical activity (ROA), are commonly used for monitoring of molecular conformational equilibria in solutions. This is complicated for saccharides due to extensive motions of the hydroxyl groups and other molecular parts. Standard interpretation procedures involving ab initio spectral simulations for a limited set of conformers are not adequate. In this study, a more general approach is proposed for the gluconic acid anion taken as a model compound, where quantum simulations of the spectra are directly coupled with molecular dynamics (MD) techniques. Such a multiscale approach reveals how the structural information is encoded in the broadened spectral lines. The spectra were simulated for solvent-solute clusters generated by MD. Conformational averaging was enabled by a limited library of conformers for which the spectral parameters could be calculated ab initio and moved on the MD geometries by Cartesian coordinate tensor transfer techniques. The B3LYP/CPCM/6-31+G** approximation was used as a default for computation of the source force fields and polarizability derivatives. The spectra thus obtained relatively faithfully reproduced most of the experimental features. The Amber and polarizable Amoeba MD force fields produced similar results; application of the latter, however, was limited by the long time necessary to achieve a converged conformational equilibrium. Both MD simulation and spectral averaging suggest that the hydroxyl groups as well as the backbone C-C bonds rotate relatively freely, with some restrictions in the vicinity of the carboxyl group. In spite of the averaging, spectral response of characteristic vibrational normal mode families, such as CH and OH bending, can clearly be identified in the spectra. The simulations thus confirm the experimental fact that flexible saccharides exhibit significant vibrational activity that reveals precious information about molecular structure and dynamics encoded in the Raman and ROA spectral shapes.

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“…For PTFE and others fluorinated polymers it is well known that surface properties, in particular SFE, are related with weak molecular forces and the existence of C-F bonds from CF 2 groups [16,17]. The properties of these surfaces depend not only on the coverage by the fluorocarbons but also on the degree of order of the surface [18,19].…”

Section: A Linear Dependence Betweenmentioning

confidence: 99%

Simple measurement of surface free energy using a web cam

Vicente

André

Ferreira

2012

Rev. Bras. Ensino Fís.

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Neste trabalho, descrevemos uma experiência simples e pedagógica para medir a energia livre de superfície (SFE) queé um tema dominante no ensino da Física, a nível de estudos de graduação e pós-graduação. A vantagem desta experiência baseia-se na simplicidade dos materiais utilizados, ou seja, produtos de baixo custo e não prejudiciais, comoágua, glicerol, etileno glicol e propanol, que oferecem uma boa oportunidade para discutir pedagogicamente conceitos básicos, mas relevantes sobre fenómenos de superfície. Como exemplo, medidas dê angulo de contacto foram utilizadas para estimar a SFE e a molhabilidade de diferentes superfícies sólidas, tais como o vidro e o politetrafluoretileno (PTFE, TeflonPalavras-chave: práticas pedagógicas, energia livre de superfície,ângulo de contacto.In this paper we describe a simple and pedagogical experiment to measure surface free energy (SFE), which is a mainstream subject to teach undergraduate and graduate level Physics science. Beyond this, the advantage of this work relies on the simplicity of the materials used, namely non-harmful and low cost products such as water, glycerol, ethylene glycol and propanol, offering a useful pedagogical opportunity to discuss basic but relevant concepts regarding surface science phenomena. As example, contact angle measurements were used to estimate SFE and the wetting behavior of distinct solid surfaces such as glass and polytetrafluoroethylene (PTFE, Teflon R ⃝ ).

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Glycerol condensed phases Part I. A molecular dynamics study

Cited by 123 publications

References 41 publications

Systematic study of the glass transition in polyhydric alcohols

Systematic study of the glass transition in polyhydric alcohols

Interpretation of Raman and Raman Optical Activity Spectra of a Flexible Sugar Derivative, the Gluconic Acid Anion

Simple measurement of surface free energy using a web cam

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