Molecular View on Mechanical Reinforcement in Polymer Nanocomposites

Sun, Ruikun; Melton, Matthew; Safaie, Niloofar; Ferrier, Robert C.; Cheng, Shiwang; Liu, Yun; Zuo, Xiaobing; Wang, Yangyang

doi:10.1103/physrevlett.126.117801

Cited by 29 publications

(33 citation statements)

References 40 publications

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“…Previous studies showed that the bulk rheological behavior of the linear PNC melts involving attractive polymer–NP interactions is largely controlled by the interfacial polymer layer (also called as “bound” layer) on NPs . The role of the interfacial layer in these systems is twofold.…”

Section: Resultsmentioning

confidence: 99%

Nonlinear Architectures Can Alter the Dynamics of Polymer–Nanoparticle Composites

et al. 2021

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Polymer nanocomposites exhibit remarkable physical properties that are attractive for many applications. These systems have been so far investigated using linear polymer chains; the role of polymer matrix architecture in local dynamics, bulk rheology, and nanoparticle (NP) motion remains unexplored. Here, using quasi-elastic neutron scattering, bulk rheology, and Xray photon correlation spectroscopy, we investigated nanocomposites with spherical silica nanoparticles well dispersed in poly(ethylene oxide) matrices having different architectures (specifically linear, stars, and hyperbranched). The results reveal that the mechanical reinforcement of the nanocomposites with the nonlinear polymers can be altered by orders of magnitude with respect to the conventional nanocomposite with the linear polymer. Polymer compactness and interpenetrability are found to play crucial roles in determining their bulk rheology. At the microscopic level, average segmental dynamics is remarkably slowed down by the attractive NPs in the matrices of high degree of branching, whereas no significant effect is observed in the linear polymer matrix at the same NP loading. In addition, the nanoscale dynamics of particles in the compact nonlinear matrices exhibits strong decoupling from the bulk viscoelasticity, allowing their fast relaxation even at ≈30% by volume. These results provide an experimental evidence that macromolecular architecture is a powerful new tool for tuning the bulk rheological properties as well as the nanoscale dynamics of polymer nanocomposites (PNCs) without the need for changing polymer molecular weight, nanoparticle size, shape, loading, or dispersion state.

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Section: Resultsmentioning

confidence: 99%

Nonlinear Architectures Can Alter the Dynamics of Polymer–Nanoparticle Composites

et al. 2021

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“…Yet, a consensus has emerged over the past few years that chain conformation is mostly unaffected by the presence of filler particles (Crawford et al, 2013) and that the origin of the polluting signal could be due to statistical effects of local H-D fluctuations (Banc et al, 2015). Sun et al (2021) have used ZAC to measure the anisotropic chain deformation, arguing that on the timescale of observation, they do not see any strain amplification which might explain the reinforcement effect. The hydrodynamic effect on single NP may be responsible, but further investigations of the particle structure are needed to clarify if the latter exists in the sample.…”

Section: Open Access Edited Bymentioning

confidence: 99%

Recent scattering approaches to structure and dynamics of polymer nanocomposites

Kruteva¹,

Genix²,

Holderer³

et al. 2022

Front. Soft. Matter

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The characterization of polymer nanocomposites on molecular length scales and timescales is a challenging task, which is also indispensable for the understanding of macroscopic material's properties. Neutron scattering is one of the techniques which are very well-suited for studying the structure and molecular motion in such soft matter systems. X-rays can also be used for the same purpose, however, with higher energy and thus a different focus on dynamics, where they are better suited for nanoparticle motion. In this mini-review, we aim at highlighting recent results in the field of polymer nanocomposites, including nanoparticle structure in various experimental systems, from model to industrial, and polymer and particle dynamics. This allows establishing the link between microscopic and macroscopic properties, in particular rheology.

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“…The addition of solid nanoparticles into polymers is an indispensable step toward improving their mechanical, thermal, and other physical properties for many industrial applications. − Together with the hydrodynamic effect induced by the presence of nanoparticles, the formation of an interfacial region surrounding the nanoparticle with structural and dynamic properties different from the neat polymer is thought to be the origin of the mechanical reinforcement of polymer nanocomposites (PNCs) at low filler loadings. ,,− As the filler volume fraction increases by more than 10%, an abrupt enhancement in the mechanical reinforcement has been frequently reported, which cannot be simply interpreted by relying on the hydrodynamic and interfacial layer effects. ,,− , Instead, this enhancement is largely related to the formation of a percolating filler network (PFN) within the polymer matrix. ,,,− The presence of such a PFN in various PNCs has been revealed using different techniques. − In addition, many physical phenomena, including the Payne and Mullins effects, , which have been widely observed in PNCs at high filler loadings, have been proven to mainly result from the formation and breakdown of PFNs. ,,,,,, …”

Section: Introductionmentioning

confidence: 99%

Evidence of the Transition from a Flexible to Rigid Percolating Network in Polymer Nanocomposites

Nguyen

Nakajima

2022

Macromolecules

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The formation of a percolating filler network (PFN) in polymer nanocomposites is critical in explaining the substantial improvement of their mechanical properties in comparison to neat polymer systems. However, the structural mechanism underlying the formation and development of the PFN has remained under active debate. Here, we report a direct observation of microstructure development of the PFN in a model isoprene rubber filled with various nanoparticle fractions by means of nanoscale loss tangent (tan δ) imaging with amplitude-modulated atomic force microscopy. Tanδ imaging revealed, for the first time in real space, the formation of a flexible PFN when the filler volume fraction was increased to ∼16%, which subsequently developed to a rigid PFN at the fraction of ∼24%. Importantly, the observed transition agrees well with a marked increase in the mechanical reinforcement in macroscopic measurements.

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Molecular View on Mechanical Reinforcement in Polymer Nanocomposites

Cited by 29 publications

References 40 publications

Nonlinear Architectures Can Alter the Dynamics of Polymer–Nanoparticle Composites

Nonlinear Architectures Can Alter the Dynamics of Polymer–Nanoparticle Composites

Recent scattering approaches to structure and dynamics of polymer nanocomposites

Evidence of the Transition from a Flexible to Rigid Percolating Network in Polymer Nanocomposites

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