Positron annihilation and broadband dielectric spectroscopy: A series of propylene glycols

Bartoš, Josef; Šauša, O.; Köhler, Mateus H.; Švajdlenková, Helena; Lunkenheimer, P.; Krištiak, J.; Loidl, A.

doi:10.1016/j.jnoncrysol.2010.07.030

Cited by 19 publications

(20 citation statements)

References 71 publications

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“…16) to calculate the static dielectric constant, for the force fields showing a better performance in the prediction of the dielectric spectrum in every case (water SPC, ethanol TraPPE.UA, ethylene glycol OPLS, propylene glycol GAFF, glycerol OPLS and MEA OPLS). Black circles represent experimental values obtained from different sources for the following systems: water [9.12], ethanol [16.18, 97], ethylene glycol [98], propylene glycol [99], glycerol [95,96,100,101] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 …”

Section: Discussionmentioning

confidence: 99%

Molecular dynamics simulations for the prediction of the dielectric spectra of alcohols, glycols and monoethanolamine

Cardona

Fartaria

Sweatman

et al. 2015

Molecular Simulation

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This version is available at https://strathprints.strath.ac.uk/54062/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the The response of molecular systems to electromagnetic radiation in the microwave region (0.3-300 GHz) has been principally studied experimentally, using broadband dielectric spectroscopy. However, relaxation times corresponding to reorganisation of molecular dipoles due to their interaction with electromagnetic radiation at microwave frequencies are within the scope of modern molecular simulations. In this work, fluctuations of the total dipole moment of a molecular system, obtained through molecular dynamics simulations, are used to determine the dielectric spectra of water, a series of alcohols and glycols, and monoethanolamine. Although the force fields employed in this study have principally been developed to describe thermodynamic properties, most them give fairly good predictions of this dynamical property for these systems. However, the inaccuracy of some models and the long simulation times required for the accurate estimation of the static dielectric constant can sometimes be problematic. We show that the use of the experimental value for the static dielectric constant in the calculations, instead of the one predicted by the different models, yields satisfactory results for the dielectric spectra, and hence the heat absorbed from microwaves, avoiding the need for extraordinarily long simulations or re-calibration of molecular models.

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Section: Discussionmentioning

confidence: 99%

Molecular dynamics simulations for the prediction of the dielectric spectra of alcohols, glycols and monoethanolamine

Cardona

Fartaria

Sweatman

et al. 2015

Molecular Simulation

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“…17 Recently, the structure of c-t-1,4-PBD has been studied by neutron diffraction and molecular dynamics, 47 but unfortunately, the small q region has not been addressed, so that a check on the medium range order in the spirit of TOP model as for Pc and salol could not be performed. On the other hand, some of us have discussed the M-VFTH parameters of the viscosity or structural relaxation in relation to various effects in the PALS response in small molecule (glycerol, Pc, and three propylene glycols) 37,39,61 as well as one polymer (poly(propylene glycol)) glass-formers. 38 These findings describing simultaneously both the o-Ps annihilation reflecting the free volume microstructure and the structural relaxation from the different dynamic techniques prompt us to test the potential of the TOP model for c-t-1,4-PBD.…”

Section: B Structural Relaxation In Terms Of the Top Model And Its Cmentioning

confidence: 99%

“…Recent instrumental and spectral analytical advances in BDS [29][30][31] enable to reveal further connections between the various features of the PALS response and the glassy dynamics. 26,[32][33][34][35][36][37][38][39][40] Two empirical T b2 and T L b1 rules establish the specific relationships between the o-Ps lifetime, τ 3 , and the primary α relaxation time, τ α , namely, τ α (T b2 )∼ 10 −9 s or τ α (T b1 ) ∼ 10 −6±1 s, respectively. 26,32 In the former case, for many glass-formers at the onset of the plateau or quasi-plateau effect in the PALS response the relation τ 3 ∼ = τ α has been often found.…”

Section: Introductionmentioning

confidence: 99%

Positron annihilation and relaxation dynamics from dielectric spectroscopy and nuclear magnetic resonance: Cis–trans-1,4-poly(butadiene)

Bartoš

Šauša²,

Schwartz

et al. 2011

The Journal of Chemical Physics

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The electronic spectrum of SiH4: Jahn-Teller Rydberg series J. Chem. Phys. 135, 214304 (2011) Electronic states of tetrahydrofuran molecules studied by electron collisions J. Chem. Phys. 135, 134317 (2011) Dyson orbitals of N2O: Electron momentum spectroscopy and symmetry adapted cluster-configuration interaction calculations J. Chem. Phys. 134, 204304 (2011) Electronic excitations of potassium intercalated manganese phthalocyanine investigated by electron energy-loss spectroscopy J. Chem. Phys. 134, 194504 (2011) Experimental and theoretical study on generalized oscillator strengths of the valence-shell electronic excitations in CF4 J. Chem. Phys. 134, 064307 (2011) Additional information on J. Chem. Phys. We report a joint analysis of positron annihilation lifetime spectroscopy (PALS), dielectric spectroscopy (BDS), and nuclear magnetic resonance (NMR) on cis-trans-1,4-poly(butadiene) (c-t-1, 4-PBD). Phenomenological analysis of the orthopositronium lifetime τ 3 − T dependence by linear fitting reveals four characteristic PALS temperatures:. Slight bend effects in the glassy and supercooled liquid states are related to the fast or slow secondary β process, from neutron scattering, respectively, the latter being connected with the trans-isomers. In addition, the first bend effect in the supercooled liquid coincides with a deviation of the slow effective secondary β eff relaxation related to the cis-isomers from low-T Arrhenius behavior to non-Arrhenius one and correlates with the onset of the primary α process from BDS. The second plateau effect in the liquid state occurs when τ 3 becomes commensurable with the structural relaxation time τ α (T b2 ). It is also approximately related to its crossover from non-Arrhenius to Arrhenius regime in the combined BDS and NMR data. Finally, the combined BDS and NMR structural relaxation data, when analyzed in terms of the two-order parameter (TOP) model, suggest the influence of solidlike domains on both the annihilation behavior and the local and segmental chain mobility in the supercooled liquid. All these findings indicate the influence of the dynamic heterogeneity in both the primary and secondary relaxations due to the cis-trans isomerism in c-t-1,4-PBD and their impact into the PALS response.

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“…In Figure 13 , the relationships between the mean o -Ps lifetimes at the characteristic PALS temperature in the liquid state and the mean characteristic segmental α relaxation times, τ α , and the mean secondary relaxation, τ β are showed [ 68 , 69 , 70 ]. In the former case it can be seen that the so-called equivalent α temperature, T α,eq , i.e., the temperature at which the PALS time scale equals to LS and BDS [ 33 , 34 , 35 , 36 , 37 , 38 ], being 303 K is not too distant from the second characteristic PALS temperature, T b2 L = 291 K. This plausible match of T findings suggests that an onset of the quasi-plateau effect in the PALS response is related to the segmental α dynamics of cis -1,4-PIP10k sample. Moreover, this is fully consistent with the generally accepted bubble concept of the o -Ps annihilation in low viscous organic media [ 73 ].…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, the comparison between the characteristic PALS temperatures with afore-mentioned dynamic characteristic temperatures, T DYN , and the dynamic time scales, the two bend effects in the PALS response above the glass-to-liquid transition at T b2 L and T b1 L are related to the structural α-relaxation or sometimes, to the secondary β-process [ 31 , 32 , 33 , 34 , 35 , 36 ]. On the other hand, concerning the characteristic ESR temperatures, their mutual relationships with dynamic ones appears to be more complicated.…”

Section: Introductionmentioning

confidence: 99%

On the Mutual Relationships between Molecular Probe Mobility and Free Volume and Polymer Dynamics in Organic Glass Formers: cis-1,4-poly(isoprene)

et al. 2021

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We report on the reorientation dynamics of small spin probe 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO) in cis-1,4-poly(isoprene) (cis-1,4-PIP10k) from electron spin resonance (ESR) and the free volume of cis-1,4-PIP10k from positron annihilation lifetime spectroscopy (PALS) in relation to the high-frequency relaxations of cis-1,4-PIP10k using light scattering (LS) as well as to the slow and fast processes from broadband dielectric spectroscopy (BDS) and neutron scattering (NS). The hyperfine coupling constant, 2Azz′(T), and the correlation times, τc(T), of cis-1,4-PIP10k/TEMPO system as a function of temperature exhibit several regions of the distinct spin probe TEMPO dynamics over a wide temperature range from 100 K up to 350 K. The characteristic ESR temperatures of changes in the spin probe dynamics in cis-1,4-PIP10k/TEMPO system are closely related to the characteristic PALS ones reflecting changes in the free volume expansion from PALS measurement. Finally, the time scales of the slow and fast dynamics of TEMPO in cis-1,4-PIP10k are compared with all of the six known slow and fast relaxation modes from BDS, LS and NS techniques with the aim to discuss the controlling factors of the spin probe reorientation mobility in polymer, oligomer and small molecular organic glass-formers.

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Positron annihilation and broadband dielectric spectroscopy: A series of propylene glycols

Cited by 19 publications

References 71 publications

Molecular dynamics simulations for the prediction of the dielectric spectra of alcohols, glycols and monoethanolamine

Molecular dynamics simulations for the prediction of the dielectric spectra of alcohols, glycols and monoethanolamine

Positron annihilation and relaxation dynamics from dielectric spectroscopy and nuclear magnetic resonance: Cis–trans-1,4-poly(butadiene)

On the Mutual Relationships between Molecular Probe Mobility and Free Volume and Polymer Dynamics in Organic Glass Formers: cis-1,4-poly(isoprene)

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