The study of dielectric relaxation in propylene glycol–poly(propylene glycol) mixtures

Sengwa, R. J.; Chaudhary, Rakhee; Mehrotra, S. C.

doi:10.1016/s0032-3861(01)00662-0

Cited by 31 publications

(8 citation statements)

References 22 publications

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“…In the MARTINI model, atoms can be classified as charged (Q), polar (P), nonpolar (N), or apolar (C), and there are subtypes denoting hydrogen bonding and degree of polarity. We can assign a MARTINI type to each of our bead types according to the mapping suggestions in the literature . We set the interaction parameters for the PPG bead to equal those of N0 from the MARTINI model, the three‐carbon PE bead uses C2, and the charged beads Br − and C 2 N + use the Qa and Q0 parameters, respectively.…”

Section: Methodsmentioning

confidence: 99%

Modeling the Effect of Polymer Composition on Ionic Aggregation in Poly(propylene glycol)‐Based Ionenes

Vijayaraghavan

Brown

Hall

2016

Macromol. Chem. Phys.

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Ionenes are polymers that contain a small fraction of charged groups in their backbone. These form ionic aggregates that act like reversible cross-links, conferring interesting material properties to the system. Here, poly(propylene glycol)-based ammonium ionenes are modeled containing varying amounts of alkyl groups, referred to as hard segments. Experimental results show that hard segment content strongly affects the temperature at the onset of fl ow, which is related to the dissociation of ionic aggregates. This study aims to show the ionic aggregation and microscopic morphology and how these relate to polymer relaxation behavior. Therefore, we perform molecular dynamics simulations using a simple coarse-grained model of the system. The aggregate morphology and dynamics as a function of hard segment content is quantifi ed and related to experimental observations. their counterions, in the melt state with no solvent. In general in dry ion containing polymers, the bulk properties of the polymer are determined in large part by the ionic aggregates, which provide mechanical stability because when multiple chains participate in the same aggregate, they effectively act as temporary cross-links. When the temperature is increased above the ionic dissociation temperature, the ionic aggregates are no longer stable, and the material can fl ow more easily. [ 3,4 ] This temperaturedependent cross-linking ability has led to interest in ion containing polymers, [5][6][7][8] including potentially ammonium ionenes, [ 9 ] as self-healing materials.Ammonium ionenes, containing charged nitrogen groups in the chain backbone, have been well studied and the work on both standard and segmented (with different types of monomer segments present along the chain) has been reviewed. [ 10 ] This area continues to be of signifi cant interest, and specialty segmented ionene materials based on urethanes [ 11 ] or including nucleobases [ 12 ] have been created recently. Segmented ionenes can be synthesized

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Section: Methodsmentioning

confidence: 99%

Modeling the Effect of Polymer Composition on Ionic Aggregation in Poly(propylene glycol)‐Based Ionenes

Vijayaraghavan

Brown

Hall

2016

Macromol. Chem. Phys.

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“…Sengwa et al [4] studied the dielectric relaxation in propylene glycol-poly propylene glycol mixtures over three concentrations in the frequency range 10 MHz to 4 GHz at 298 K using Time Domain Reflectometry (TDR). The effective Dielectric relaxation is shown to depend exponentially on the number density of dipoles or molecules.…”

Section: Introductionmentioning

confidence: 99%

Dielectric dispersion in 1,2-diaminopropane–dimethylaminoethanol mixtures as a function of composition and temperature

Undre¹,

Khirade²

2011

Lith. J. Phys.

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The dielectric dispersion ε' and dielectric loss ε" of binary mixture of 1,2-diaminopropane-dimethylaminoethanol were measured by employing the time domain reflectometry technique over a frequency range from 10 MHz to 20 GHz at 288, 298, 308, and 318 K temperatures. The accuracy in the measurement of the ε' and ε" values obtained from this technique is within ±5%. To evaluate various dielectric parameters, the frequency dependents complex permittivity (ε*(ω) = ε' -iε") data, viz., static permittivity ε 0 , relaxation time τ, and permittivity at high frequency ε ∞ were fitted by the nonlinear least-squares fit method to Debye expression. Temperature dependent ε 0 , τ, Kirkwood correlation factor g, free energy of activation ΔG, and enthalpy of activation ΔH have been determined and discussed in terms of the effect of -NH 2 and -CH 3 side-group on molecular dynamics and intermolecular hydrogen bonds. The dielectric behaviour of 1,2-diaminopropane and dimethylaminoethanol liquid molecules and their conformations as well as molecular dynamics of the system can be explored only by comparing the dielectric data of the mixture system with the dielectric data of the individual molecules and their dynamics.

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“…In the past, these three substances have been extensively studied by dielectric spectroscopy, in pure state [1][2][3][4][5][6][7][8][9][10][11], in mixtures with non-polar solvents [12][13][14][15][16][17][18][19], in aqueous solutions [20][21][22][23][24] or in mixtures with other polar liquids [25][26][27][28], in all the range of liquids temperatures, and also in the super-cooled state [29][30][31].…”

Section: Introductionmentioning

confidence: 99%

A new representation of permittivityversustemperature for alkanols of the same chain length

Catenaccio

2009

Physics and Chemistry of Liquids

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The alkanols of three carbon length have been studied by dielectric methods during many years and they do not obey any theoretical model. These substances have the same chain length and have one, two or three dipoles per molecule, so their ability to form hydrogen bridges changes from one substance to other, and one can obtain information by comparative studies. In previous works, we have measured the thermal dependence of permittivity of these substances and analysed the results with an empirical modification of the Onsager equation. Now we shall analyse and compare the results using a different representation. In this representation, the data shows straight lines, whose slopes depend on the quantity of dipoles of each molecule encouraging the high quality of the fittings obtained with the three substances, and also that they behave in the same dielectric way with the rise of temperature. IntroductionIn the past, these three substances have been extensively studied by dielectric spectroscopy, in pure state [1][2][3][4][5][6][7][8][9][10][11], in mixtures with non-polar solvents [12][13][14][15][16][17][18][19], in aqueous solutions [20][21][22][23][24] or in mixtures with other polar liquids [25][26][27][28], in all the range of liquids temperatures, and also in the super-cooled state [29][30][31].In these systems, the hydrogen bonding between molecules and the dielectric behaviour is present and is governed by this association. At the present time there is still a controversy in the detailed explanation of how these clusters form and evolve [32][33][34][35][36][37][38]. Despite this lack of an explicit model, one can obtain valuable information by doing comparative studies of the dielectric behaviour of these substances.Static permittivity brings information about the molecular associations, and its variations with temperature gives knowledge on the dynamics of the structures made by the hydrogen bonding.In previous works, we have measured the static permittivity as a function of temperature in pure and diluted alcohols, and also in this family of alkanols, and analysed the results obtained with an empirical modification of the Onsager equation [39][40][41][42][43]. Now the objective is to compare the results obtained with a new representation [44] that put in evidence the differences in the dielectric behaviour of liquids that have the same chain length and an increasing number of dipoles per molecule.

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The study of dielectric relaxation in propylene glycol–poly(propylene glycol) mixtures

Cited by 31 publications

References 22 publications

Modeling the Effect of Polymer Composition on Ionic Aggregation in Poly(propylene glycol)‐Based Ionenes

Modeling the Effect of Polymer Composition on Ionic Aggregation in Poly(propylene glycol)‐Based Ionenes

Dielectric dispersion in 1,2-diaminopropane–dimethylaminoethanol mixtures as a function of composition and temperature

A new representation of permittivityversustemperature for alkanols of the same chain length

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