Experimental aspects of polymer dynamics

Richter, D.; Monkenbusch, M.; Willner, Lutz; Wischnewski, A.; Arbe, Arantxa; Colmenero, Juan

doi:10.1002/pi.908

Cited by 5 publications

(9 citation statements)

References 34 publications

(54 reference statements)

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“…This behavior has often been observed for flexible polymers at intermediate Q, for internal motions where the observed length scale is given by 1/Q. This behaviour can be described in the framework of the Rouse-Zimm model and the deviation from a Q 2 -dependence of the relaxation rate can be attributed to hydrodynamic interactions [37].…”

Section: Materials and Methods -Sans Experiments Were Performed On Th...mentioning

confidence: 63%

“…To investigate the dynamics of the system on the length scale of the rodlike aggregates, NSE measurements have been performed with pure PE, and samples with added h-or d-SDS. A number of studies, using NSE to investigate PE containing systems has been performed [37][38][39][40][41][42][43] but to the best of our knowledge, this is the first study using NSE to investigate such viscous, oppositely charged polyelectrolyte systems, and NSE allows to obtain unique insights into the mesoscopic dynamics of the respective systems.…”

Section: Materials and Methods -Sans Experiments Were Performed On Th...mentioning

confidence: 99%

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Structure and dynamics of polyelectrolytes in viscous polyelectrolyte-surfactant complexes at the mesoscale

Hoffmann¹,

Faragó²,

Schweins³

et al. 2013

EPL

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Rather dilute mixtures of oppositely charged polyelectrolyte and surfactant can form highly viscous solutions for an excess of polyelectrolyte charges present, with viscosities up to 4 orders of magnitude above the pure polyelectrolyte solution. These changes in macroscopic behavior should originate from changes in the mesoscopic properties. Therefore, the structure and dynamics of such mixtures, namely JR 400 and SDS (h-or d-SDS) have been investigated using small-angle neutron scattering (SANS) and neutron-spin echo (NSE), where contrast matching allows to selectively study the behavior of the polyelectrolyte in these complexes. This combination of SANS and NSE allows to obtain uniquely detailed information on the individual components of the complex, showing that the polyelectrolyte to a high extent conserves its local mobility even in these highly viscous complexes and the high viscosity arises from the overall connectivity, information that is relevant for future potential applications of such systems.

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Section: Materials and Methods -Sans Experiments Were Performed On Th...mentioning

confidence: 63%

Section: Materials and Methods -Sans Experiments Were Performed On Th...mentioning

confidence: 99%

Structure and dynamics of polyelectrolytes in viscous polyelectrolyte-surfactant complexes at the mesoscale

Hoffmann¹,

Faragó²,

Schweins³

et al. 2013

EPL

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“…[34][35][36][37] Among the central subjects intimately related to important physical properties of these materials in the bulk 31 is the temperature dependence of their structural/ conformational and dynamic features, particularly close to the characteristic temperature where a glasslike transition associated with a "freezing-in" of motional degrees of freedom takes place. 29,[34][35][36][37] The significance of glass-transition-related phenomena in the behavior of polymeric [38][39][40] and colloidal [41][42][43][44] systems cannot be overemphasized, as it has beensand continues to bes a subject of intense scientific effort over the years. Considering that a combination of polymer/colloidal features is manifested in dendrimer behavior (and even more so in a "tunable" manner), elucidation of the mechanisms leading to vitrification of these materials appears as a challenging task.…”

Section: ι Introductionmentioning

confidence: 99%

Static and Dynamic Behavior in Model Dendrimer Melts: Toward the Glass Transition

Karatasos

2005

Macromolecules

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Molecular dynamics (MD) simulations were employed in order to explore the static and dynamic response of model AB2 dendrimer melts of generations 3 and 4, in a temperature range covering the states of enhanced mobility, as well as the states where a significant dynamic slowdown led to a virtual freezing-in of the dendrimer motion. Particular emphasis was given to the investigation of the motional and conformational changes of the models in the proximity of a glasslike transition observed upon temperature decrease. The qualitative picture emerging from this study is consistent with recent pertinent experiments, offering thus the possibility for a better understanding of basic mechanisms responsible for the observed behavior.

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“…Figure presents the steady-shear viscosity measured as studied by rheology in the temperature range from 278 to 358 K, with 20 K as temperature interval for PPO-THY/DAT and from 283 to 363 K, in 10 K steps for PPO-UPY, respectively. However, while for PPO-THY/DAT, the measured viscosity is independent of shear rate for all temperatures expected in the Newtonian regime, − under steady shear, PPO-UPY exhibits a shear thickening behavior at the lowest temperatures, as shown in parts a and b of Figure , respectively. Shear thickening is characterized by an increase in effective viscosity when the shear rate increases past a certain critical value as evident in Figure b for T = 283 K and T = 293 K. Shear thickening effects are also observed for PEO-UPY and are commonly observed in complex fluids including dense suspensions, wormlike micelles, and associating polymer solutions. − In fact, shear thickening is not yet well understood in the literature, − and thus several theoretical models have been proposed to describe the shear thickening behavior. − Marrucci et al .…”

Section: Resultsmentioning

confidence: 87%

“…We assume that these values reflect the mass-averaged number of associated building blocks ⟨ N assc ⟩ w , which clearly, as a consequence of the hydrogen bond interactions weakening, decreases with temperature. Moreover, in the Rouse regime, using the zero-shear viscosity, both the segmental relaxation time τ s , as well as the expected Rouse time τ R , can be extracted for PPO polymer by the following equations: ,,, τ s = 12 M n η 0 N A N 2 ρ π 2 k B T τ normalR = N 2 τ normals where ρ is the density of the polymer melt, N A the Avogadro number, k B the Boltzmann constant and M n and N are given above (these results for τ s and τ R are shown in Figure a). In order to extract the terminal relaxation time, τ t and compare it with the calculated Rouse time, a function composed of a generic peak function ,, to account for contributions of the chain dynamics is adjusted to the master curve data for PPO backbone (see Figure a): G ′ = normalG normale ω 2 τ t 2 ω 2 τ t 2 …”

Section: Resultsmentioning

confidence: 99%

Influence of Polymer Polarity and Association Strength on the Properties of Poly(alkyl ether)-Based Supramolecular Melts

et al. 2022

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The present work focuses on the impact of polymer polarity and hydrogen-bonding (H-bonding) end groups association strength on the structure and dynamics of poly(alkyl ether)-based supramolecular model polymers studied by means of small angle scattering (SAS), rheology, dielectric relaxation spectroscopy (DRS), and differential scanning calorimetry (DSC). These consist of poly-(propylene oxide) (PPO) or poly(ethylene oxide) (PEO) backbone that selfassembly in the bulk via hydrogen bonding (H-bonding). Diaminotriazine (DAT) and thymine-1-acetic acid (THY) as well as 2-ureido-4[1H]-pyrimidinone (UPY) are the H-bonding end groups of choice. Both PPO and PEO bearing either DAT or THY as end groups associate into linear chains, but PPO-THY/DAT forms longer chains in comparison with PEO-THY/DAT. The lower polarity of the backbone results in stronger associations for the same end groups. However, the temperature dependence of the association/dissociation lifetimes for this H-bonding type is independent of the different main chain polarity as these breaking times do not exceed the rouse chain dynamics as expected within the Cates model. PPO-UPY forms a transient network characterized by the interplay between small transient bonds controlled by the characteristic times of association/dissociation between pairs of UPY groups involving probably just two ends, revealed by the similar dielectric spectra with PPO backbone, and a more stable bond type of associate that forms phase separated UPY clusters. The latter are responsible for the physical cross-links in the network and result in the rubbery-like plateau of the rheological spectra. PPO-UPY has similar structure to PEO-UPY, as validated by small angle scattering, but the UPY detachment times in the clusters are longer for PEO-UPY than for PPO-UPY, though the activation energies are very close and match the typical energy barrier specifically imposed by the hydrogen bonds. Moreover, while the segmental relaxation times and the glass transition temperature (T g ) of PPO-UPY is similar to PPO, PEO-UPY has the highest T g value and a much slower segmental relaxation as compared to PEO and PPO based supramolecular polymers. This seems to indicate that the Hbonding association dynamics of the UPY groups is strongly influenced by the main chain polarity that play a fundamental role in defining the time scale of the association process.

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Experimental aspects of polymer dynamics

Cited by 5 publications

References 34 publications

Structure and dynamics of polyelectrolytes in viscous polyelectrolyte-surfactant complexes at the mesoscale

Structure and dynamics of polyelectrolytes in viscous polyelectrolyte-surfactant complexes at the mesoscale

Static and Dynamic Behavior in Model Dendrimer Melts: Toward the Glass Transition

Influence of Polymer Polarity and Association Strength on the Properties of Poly(alkyl ether)-Based Supramolecular Melts

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