Relaxation dynamics of deformed polymer nanocomposites as revealed by small-angle scattering and rheology

Sun, Ruikun; Yang, Jie; Patil, Shalin; Liu, Yun; Zuo, Xiaobing; Lee, André; Wang, Yangyang; Cheng, Shiwang

doi:10.1039/d2sm00775d

Cited by 2 publications

(2 citation statements)

References 108 publications

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“…[27][28][29][30][31][32][33] As was recalled above, we can go beyond the mechanical characterization because the interfacial properties of PNC can be probed by a large variety of scattering and microscopy techniques with the aim of identifying their characteristic length and time scales, for example, NMR, [3,10,11,34,35] differential scanning calorimetry (DSC), [36] dynamic mechanical thermal analysis (DMTA), [28,[37][38][39] rheology, [40,41] neutron and positron annihilation spectroscopies, [42,43] atomic force microscopy (AFM), [26,40] small-angle neutron (SANS), [42,43] and small-angle X-ray scattering (SAXS). [44][45][46] One important question in this field concerns the observed similarities amongst PNC. Transmission electron microscopy (TEM) indicated that CB exists as aggregates of spherical particles.…”

Section: Characterization Of the Interface Between Phases In Dense Po...mentioning

confidence: 99%

Modeling the Interface Between Phases in Dense Polymer‐Carbon Black Nanoparticle Composites by Dielectric Spectroscopy: Where Are We Now and What are the Opportunities?

Brosseau

2024

Macro Theory & Simulations

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The macroscopic properties of polymer nanocomposites (PNC) rely largely on the interphase between the polymer chains and the filler particles. One significant difficulty to solve this issue is to quantitatively model the structure‐property correlations due to the interfacial region in these complex materials. While dielectric spectroscopy (DS) measurements are routinely used to characterize the effective permittivity of filled polymers, fitting standard effective medium models and mixing equations to these data remains notoriously difficult to interpret. This is due to the absence of explicit reference to internal length scales characterizing the interfaces in the PNC. As an illustrative example, a two‐level homogenization framework is proposed which enables the extraction of useful information on the impact of a thin interphase confined on a nanometer length scale based on broadband DS data. This model leads to new ways of tuning the interphase so as to optimize the material's response to electric field, a situation relevant for electromagnetic shielding. This approach provides guidance on how to observe directly and experimentally the actual properties of the interface between the phases (as opposed to model‐based inference). Aside from its secure physical foundation in the theory of effective medium, a significant advantage of this approach is that a genetic algorithm (GA) technique applied to this physics‐based model enables the uniqueness of the fit parameters to be considered, as the GA method is robust in terms of finding globally optimum solutions, therefore placing confidence in non‐universal values of the percolation exponents. Recent work in physics‐informed machine learning indicates that the effective dielectric properties of PNC with many degrees of freedom due to their complex morphology can be described by considering only a few degrees of freedom describing the interface features between the phases in these composites.

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Section: Characterization Of the Interface Between Phases In Dense Po...mentioning

confidence: 99%

Modeling the Interface Between Phases in Dense Polymer‐Carbon Black Nanoparticle Composites by Dielectric Spectroscopy: Where Are We Now and What are the Opportunities?

Brosseau

2024

Macro Theory & Simulations

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“…In this sense, such model-free analysis of the scattering anisotropy fails to produce microstructural information that can be directly interpreted at the molecular level and compared to molecular models. Alternatively, mathematical approaches such as the method of spherical harmonic expansion − have been developed to describe scattering anisotropy from deformed polymers, but require simplifying assumptions about the chain segment density distribution to obtain information about the molecular configuration. Therefore, the development of accurate, molecularly informed models for anisotropic scattering in deformation and flow is critically important for understanding the microstructural changes encoded in the anisotropic scattering patterns.…”

Section: Introductionmentioning

confidence: 99%

Self-Consistent Connected-Rod Model for Small-Angle Scattering from Deformed Semiflexible Chains in Flow

Zhang,

Smith,

Corona

et al. 2023

Macromolecules

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Quantifying the microstructure and dynamics under nonlinear deformations is critical for designing flow processes and rheological models for semiflexible polymers and molecular assemblies. Although flow-small angle neutron and X-ray scattering (flow-SANS/SAXS) are suitable for studying how a material's microstructure deforms in flow, scattering models to describe the molecular anisotropy of semiflexible chains in flow have yet to be developed due to the challenge of describing the coupled effects of global (chain-level) deformation and local (segment-level) orientation. To address this challenge, we develop a detailed scattering model for anisotropic semiflexible chains based on a connected-rod chain model that incorporates an orientation distribution for the segments that is thermodynamically self-consistent with the overall stretch and orientation of the chain. We validate the model by comparing its predictions with flow-SANS experiments on wormlike surfactant micelles and find excellent quantitative agreement for the shape of the scattering anisotropy between experiment and simulation across a large range of shear rates. The development of a thermodynamically consistent scattering model for semiflexible chains in flow opens up new possibilities for obtaining microstructural information from flow-SANS/SAXS experiments that can be compared with molecular theories and simulations of flowing polymers and complex fluids.

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Relaxation dynamics of deformed polymer nanocomposites as revealed by small-angle scattering and rheology

Abstract: The relaxation dynamics of polystyrene (PS)/silica nanocomposites after a large step deformation are studied by a combination of small-angle scattering techniques and rheology. Small-angle x-ray scattering measurements and rheology show...

Cited by 2 publications

References 108 publications

Modeling the Interface Between Phases in Dense Polymer‐Carbon Black Nanoparticle Composites by Dielectric Spectroscopy: Where Are We Now and What are the Opportunities?

Modeling the Interface Between Phases in Dense Polymer‐Carbon Black Nanoparticle Composites by Dielectric Spectroscopy: Where Are We Now and What are the Opportunities?

Self-Consistent Connected-Rod Model for Small-Angle Scattering from Deformed Semiflexible Chains in Flow

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