Collective motion in Poly(ethylene oxide)/poly(methylmethacrylate) blends

Faragó, B.; Chen, Chunxia; Maranas, Janna K.; Kamath, Sudesh; Colby, Ralph H.; Pasquale, Anthony J.; Long, Timothy Edward

doi:10.1103/physreve.72.031809

Cited by 41 publications

(51 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This behavior of this process is consistent with previous observations: the primary relaxation of PMMA is significantly influenced by environment, while that of PEO is not. [30][31][32][33][34][35][36][37] In particular, the observation that PEO mobility is slowed slightly when mixed with PMMA, with the extent independent of composition is consistent with deuterium NMR experiments on this system. 31 To summarize the decays for the entire temperature and spatial scale range of our simulations, we extract a characteristic time from I PEO (q,t) or I PMMA (q,t) using the empirical KolrauschWilliams-Watts [KWW] expression:…”

Section: Simulation Detailssupporting

confidence: 71%

A Molecular View of Dynamic Responses When Mixing Poly(ethylene oxide) and Poly(methyl methacrylate)

Chen

Maranas

2009

Macromolecules

Self Cite

View full text Add to dashboard Cite

We use explicit atom molecular dynamics to investigate mobility in poly(methyl methacrylate) [PMMA] when blended with 10%, 20%, and 30% weight percent poly(ethylene oxide) [PEO]. The responses to blending of main chain motion, rotation of the two methyl groups, and rotation of the entire ester side chain, which is associated with the -relaxation, are individually assessed at temperatures well above the glass transition temperature where their characteristic times overlap. We also consider the response of main chain motion in PEO to blending with PMMA. We find three classes of behavior: methyl group rotation is not influenced by blending, ester group rotation and the main chain motion of PEO are slightly altered by the change in environment, and a substantial change in dynamics is observed for main chain motion in PMMA. The observation that the -relaxation in PMMA changes with mixing is unusual, as this is a local motion thought to be insensitive to blending. This is discussed in light of the spatial extent of localized motion and that of mixing of the two components.

show abstract

Section: Simulation Detailssupporting

confidence: 71%

A Molecular View of Dynamic Responses When Mixing Poly(ethylene oxide) and Poly(methyl methacrylate)

Chen

Maranas

2009

Macromolecules

Self Cite

View full text Add to dashboard Cite

show abstract

“…In addition, we note that results obtained on IN11C (IN11 with a multidetector option) on deuterated PMMA below T g (at 393 K) display a slight quasielastic decay. 20 In that study the T dependence of the relaxation times around T g was found to be very similar to that of the -process. On the other hand, we recall that 2D-NMR data on the PMMA side-group motion by Schmidt-Rohr et al 11 showed that the main-chain and the ester side-group dynamics of this polymer are coupled.…”

Section: S S H Sg (Qt) By S I (Qt) ) S H Mc (Qt)/a H Mc (Q) the Rmentioning

confidence: 81%

“…The second work 8 did not report on the homopolymer dynamics. Finally, in the neutron spin-echo study on collective motion, 20 the temperature range was restricted to only two temperatures very close to T g for pure PMMA.…”

Section: Introductionmentioning

confidence: 99%

Self- and Collective Dynamics of Syndiotactic Poly(methyl methacrylate). A Combined Study by Quasielastic Neutron Scattering and Atomistic Molecular Dynamics Simulations

et al. 2006

View full text Add to dashboard Cite

We have investigated the molecular dynamics of syndiotactic poly(methyl methacrylate) well above the glass transition by combining quasielastic neutron scattering and fully atomistic computer simulations. The incoherent scattering measured by backscattering on a sample with deuterated ester methyl groups has revealed the single-particle motions of hydrogens in the main chain and in the R-methyl groups. Moreover, with neutron spin-echo experiments on the fully deuterated sample we have accessed the collective motions at the two first maxima of the structure factor. The simulated cell, which has been previously validated regarding the structural properties et al. Macromolecules 2006, 39, 3947], shows a dynamical behavior that, allowing a shift in temperature, reproduces very accurately all the experimental results. The combined analysis of both sets of data has shown that: (i) The segmental relaxation involving backbone atoms deviates from Gaussian behavior.(ii) The dynamics is extremely heterogeneous: in addition to the subdiffusion associated with the R-process and the methyl group rotations, we have found indications of a rotational motion of the ester side group around the main chain. (iii) At a given momentum transfer and depending on the molecular groups considered, the time scales for collective motion are spread over about 1 order of magnitude, the correlations involving the main chain decaying much more slowly than those relating side groups. (iv) At the length scale characteristic for the overall periodicity of the system (that corresponding to the first structure factor peak), the experimentally observed collective dynamics relates to the backbone motions and is of interchain character; there, coherency effects are observed for all correlations, though side groups display weaker collectivity. (v) At the second structure factor peak, coherency remains only for correlations involving the main chains.

show abstract

“…These times have been extracted using the Kolraush-Williams- (9) QENS slow process data for the 20% blend at Q ) 1.3 Å -1 (this work), (b) QENS fast process data for the 20% blend at Q ) 1.3 Å -1 (this work), (×) dielectric spectroscopy data for the R-relaxation of neat PEO, 11 (+) dielectric spectroscopy data for the -relaxation of PEO in a 20% blend, and (-) dielectric spectroscopy data for the γ-relaxation of PEO in a 20% blend. 11 Watts 41 The relaxation times show no sign of a modulation with Q, but rather the -2/ scaling with a spatial scale characteristic of incoherent relaxation times 44 is observed. The characteristic times obtained without accounting for an elastic fraction are similar for the 20% and 30% blends, which is consistent with prior measurements on this system.…”

Section: Resultsmentioning

confidence: 99%

Dynamics of PEO in Blends with PMMA: Study of the Effects of Blend Composition via Quasi-Elastic Neutron Scattering

et al. 2008

Self Cite

View full text Add to dashboard Cite

We address the dynamic behavior of poly(ethylene oxide) [PEO] in miscible blends with poly(methyl methacrylate) [PMMA] by using quasi-elastic neutron scattering [QENS] with isotopic labeling. The data reveal two dynamic processes in the picosecond-nanosecond time scales: a slow process that is consistent with previous measurements of the segmental relaxation and a composition independent fast process occurring on the picosecond time scale. The composition dependence of the slow process differs from previous measurements, particularly at low PEO content. The fast process is similar to the fast process observed in pure polymers and is insensitive to blending with PMMA. Relaxation times extracted from Kolraush-Williams-Watts [KWW] fits to the data are used to test the applicability of the chain connectivity and coupling models as a function of spatial scale. Both models describe slow process relaxation times within a small range of spatial scales near the Kuhn length of PEO. The effective concentration, when obtained as a fit parameter in chain connectivity model fits, is not a constant, but it decreases with increasing spatial scale.

show abstract

Collective motion in Poly(ethylene oxide)/poly(methylmethacrylate) blends

Cited by 41 publications

References 45 publications

A Molecular View of Dynamic Responses When Mixing Poly(ethylene oxide) and Poly(methyl methacrylate)

A Molecular View of Dynamic Responses When Mixing Poly(ethylene oxide) and Poly(methyl methacrylate)

Self- and Collective Dynamics of Syndiotactic Poly(methyl methacrylate). A Combined Study by Quasielastic Neutron Scattering and Atomistic Molecular Dynamics Simulations

Dynamics of PEO in Blends with PMMA: Study of the Effects of Blend Composition via Quasi-Elastic Neutron Scattering

Contact Info

Product

Resources

About