The effect of dynamically heterogeneous interphases on the particle dynamics of polymer nanocomposites

Wu, Di; Narayanan, Suresh; Li, Ruhao; Feng, Yuanyue; Akcora, Pinar

doi:10.1039/d2sm01617f

Cited by 4 publications

(5 citation statements)

References 52 publications

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“…X-ray photocorrelation spectroscopy (XPCS) has been used to study structure and dynamics in polymers, gels, and nanocomposites. − In XPCS, an intensity–intensity autocorrelation function is measured in gels and nanocomposites that is related to the intermediate scattering function . Two-time correlation functions are employed to observe time-dependent slowing down of the dynamics.…”

Section: Conclusion and Future Outlookmentioning

confidence: 99%

Two-Dimensional Fluctuation Correlation Spectroscopy (2D-FlucCS): A Method to Determine the Origin of Relaxation Rate Dispersion

Gupta,

Verma

2024

ACS Meas. Sci. Au

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Relaxation rate dispersion, i.e., nonexponential or multicomponent kinetics, is observed in complex systems when measuring relaxation kinetics. Often, the origin of rate dispersion is associated with the heterogeneity in the system. However, both homogeneous (where all molecules experience the same rate but inherently nonexponential) and heterogeneous (where all molecules experience different rates) systems can exhibit rate dispersion. A multidimensional correlation analysis method has been demonstrated to detect and quantify rate dispersion observed in molecular rotation, diffusion, solvation, and reaction kinetics. One-dimensional (1D) autocorrelation function detects rate dispersion and measures its extent. Two-dimensional (2D) autocorrelation function measures the origin of rate dispersion and distinguishes homogeneous from heterogeneous. In a heterogeneous system, implicitly there exist subensembles of molecules experiencing different rates. A three-dimensional (3D) autocorrelation function measures subensemble exchange if present and reveals if the system possesses static or dynamic heterogeneity. This perspective discusses the principles, applications, and potential and also presents a future outlook of twodimensional fluctuation correlation spectroscopy (2D-FlucCS). The method is applicable to any experiment or simulation where a time series of fluctuation in an observable (emission, scattering, current, etc.) around a mean value can be obtained in steady state (equilibrium or nonequilibrium), provided the system is ergodic.

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Section: Conclusion and Future Outlookmentioning

confidence: 99%

Two-Dimensional Fluctuation Correlation Spectroscopy (2D-FlucCS): A Method to Determine the Origin of Relaxation Rate Dispersion

Gupta,

Verma

2024

ACS Meas. Sci. Au

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“…The Q range in which this transformation takes place slightly broadens with increasing temperature. The Q –2 dependence is characteristic of diffusive motion, where the decreasing exponent is indicative of confinement . At lower Q values, ⟨τ( Q )⟩ scales as Q –1.5 at room temperature (Figure b), where the scaling exponent increases only slightly to 1.6, at the highest temperature measured.…”

mentioning

confidence: 94%

“…The Q −2 dependence is characteristic of diffusive motion, where the decreasing exponent is indicative of confinement. 41 At lower Q values, ⟨τ(Q)⟩ scales as Q −1.5 at room temperature (Figure 3b), where the scaling exponent increases only slightly to 1.6, at the highest temperature measured. With increasing temperature, the scaling exponent hardly changes, and at 360 K, a Q −1.6 scaling is observed.…”

mentioning

confidence: 95%

“…Polymers tethered to nanoparticles exhibit similar constraint dynamics. 41 Here, however, the confined chains are tethered to dynamic assemblies that change shape during the measurements. Further studies are on the way to addressing this challenge.…”

mentioning

confidence: 99%

“…This is consistent with the QENS results at Q = 0.3 Å –1 . Polymers tethered to nanoparticles exhibit similar constraint dynamics . Here, however, the confined chains are tethered to dynamic assemblies that change shape during the measurements.…”

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confidence: 99%

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Molecular Insight into the Effects of Clustering on the Dynamics of Ionomers in Solutions

et al. 2023

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Quasi‐elastic neutron scattering study on dynamically asymmetric polymer blends

Mbonu,

Osti,

et al. 2024

Journal of Polymer Science

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Compatibility between polymers with different glass transition temperatures controls the thermomechanical properties of blends. This work explores the segmental dynamics of poly(methyl acrylate) (PMA) chains when they are blended with polymers of different rigidities and miscibility. Inspired by the intriguing dynamic asymmetry of chains within the interfacial layer of nanoparticles, this study aims to understand dynamic heterogeneity in dynamically asymmetric blends of PMA/poly(methyl methacrylate) (PMMA), PMA/polystyrene (PS), and PMA/poly(ethylene oxide) (PEO) using the differential scanning calorimetry (DSC) and quasi‐elastic neutron scattering (QENS) measurements below and above the glass transition temperature of PMMA or PS. Results revealed that the segmental jump distance of PMA increased on blending due to volume enhancement. The reduced effective diffusivity of PMA in PMMA is attributed to PMMA's enhanced flexibility (lower characteristic ratio, ) and superior interaction (lower ) when compared with the PS environment. The results demonstrate that the chain rigidity and miscibility affect the free volume, interchain cooperativity, and segmental dynamics in dynamically asymmetric blends.

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The effect of dynamically heterogeneous interphases on the particle dynamics of polymer nanocomposites

Abstract: The entanglements of dynamically asymmetric polymer layers influence relaxations of nanoparticles in polymer nanocomposites. In this work, dynamics of polymer-adsorbed and polymer-grafted nanoparticles in poly(methyl acrylate) matrix polymer was investigated...

Cited by 4 publications

References 52 publications

Two-Dimensional Fluctuation Correlation Spectroscopy (2D-FlucCS): A Method to Determine the Origin of Relaxation Rate Dispersion

Two-Dimensional Fluctuation Correlation Spectroscopy (2D-FlucCS): A Method to Determine the Origin of Relaxation Rate Dispersion

Molecular Insight into the Effects of Clustering on the Dynamics of Ionomers in Solutions

Quasi‐elastic neutron scattering study on dynamically asymmetric polymer blends

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