Local Viscosity of Interfacial Layers in Polymer Nanocomposites Measured by Magnetic Heating

Wu, Di; Weiblen, Donovan; Ozisik, Rahmi; Akcora, Pinar

doi:10.1021/acsapm.0c00889

Cited by 9 publications

(13 citation statements)

References 40 publications

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“…The properties of the interfacial region are significantly different from those of a neat polymer, which provides an opportunity to tune the macroscopic properties of PNCs by controlling interfacial regions. In general, macroscopic properties of PNCs are ascribed to the large volume fraction of the interfacial regions due to the relatively high surface area of NPs. − However, despite the significant recent progress in studies of the interfacial region, ,− a fundamental understanding of parameters controlling the interfacial layer structure and properties remains limited, which hinders the rational design of PNCs with desired properties.…”

Section: Introductionmentioning

confidence: 99%

Tuning the Properties of Nanocomposites by Trapping Them in Deep Metastable States

Zhou

Bocharova

Kumar

et al. 2022

ACS Appl. Polym. Mater.

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The interfacial region formed in a polymer matrix around nanoparticles (NPs) controls many macroscopic properties of polymer nanocomposites (PNCs). However, understanding the factors controlling the structure and properties of the interfacial region remains a challenge. We demonstrated that the initial trapping of polymer chains at surfaces of NPs in solution strongly affects the macroscopic properties of PNCs. The most surprising result is that the differences in properties of PNCs persist even after an extremely long thermal annealing time. We ascribe the observed changes to the formation of an interfacial layer that is trapped in a deep metastable state already in solution. Furthermore, the presented analysis suggests that the PNC equilibration time is defined by the chain desorption time that can be extremely long and, in some cases, even not accessible on a reasonable experimental time scale. These results highlight the importance of polymer solution concentrations on the formation of an interfacial layer and the macroscopic properties of PNCs.

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Section: Introductionmentioning

confidence: 99%

Tuning the Properties of Nanocomposites by Trapping Them in Deep Metastable States

Zhou

Bocharova

Kumar

et al. 2022

ACS Appl. Polym. Mater.

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“…Iron oxide (Fe 3 O 4 ) nanoparticles (15 ± 3 nm in diameter) purchased from Rosecreek Technologies Inc. were surface-modified with (3-aminopropyl)triethoxysilane (APTES, 99%, Sigma-Aldrich), following the procedures reported in our previous work. 27 The modified particles were mixed with 143 kDa PMMA (PDI: 1.3) in acetonitrile (15 mg/mL) and then sonicated for 10 min, followed by 30 min of rigorous stirring. PMMA-adsorbed Fe 3 O 4 nanoparticles were collected by centrifugaration and washed with the corresponding solvent several times to remove all free polymers.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…In previous studies, we studied the role of chain rigidity on the reinforcement of PEO and poly(methyl acrylate) (PMA) nanocomposites. 20,27,39 We showed that particles adsorbed with less rigid polymers improved the entanglement density of PMA matrix chains. 20 Consequently, the dense interphase layer slowed down the matrix polymer dynamics and the particle diffusion.…”

Section: ■ Introductionmentioning

confidence: 92%

“…Furthermore, the composite can be responsive to magnetic field-induced internal heating with the addition of magnetic nanoparticles. 27 Dynamic asymmetry in miscible blends as in poly(ethylene oxide) (PEO)−poly(methyl methacrylate) (PMMA) blend has been studied to optimize their mechanical and conducting properties. 32−37 This complex dynamic heterogeneity governs the linear viscoelastic behavior of polymer nanocomposites.…”

Section: ■ Introductionmentioning

confidence: 99%

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Thermally Activated Shear Stiffening in Polymer-Grafted Nanoparticle Composites for High-Temperature Adhesives

Yang

et al. 2022

ACS Appl. Polym. Mater.

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Thermally activated shear stiffening viscoelastic fluid can help to improve the performance of viscoelastic dampers and high-temperature adhesives. Polymer nanocomposites with heterogeneous interphases are applied to design such adaptive materials. In this work, shear stiffening in polymer-grafted nanoparticle composites is investigated. We report the linear rheological responses of grafted particle composites before and after large-amplitude oscillatory shear application. We found that interfacial mixing of short grafts with chemically different long matrix chains led to the enhancement of plateau moduli and terminal relaxations, unlike with the long grafts. Moreover, we showed that the elastic modulus of grafted chains was enhanced upon deformation through inter-diffusion and entanglements of interfacial layers with the short matrix chains in both grafted systems. These results suggest that dynamic coupling between chemically different polymers away from nanoparticle surfaces is a design strategy to achieve the thermally stiffening behavior in polymer nanocomposites.

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“…Effect of K loop on the Chain Conformation and Entanglement. Considering that the rigidity of polymer chains is also an important factor affecting polymer dynamics, 49,50 the effect of the rigidity of the loop chains on the linear chain dynamics is also investigated. The number of the loop chains is 32, and the length of loop chains is 60.…”

Section: ■ Model and Simulation Methodsmentioning

confidence: 99%

Heterogeneous Dynamics of Polymer Melts Exerted by Chain Loops Anchored on the Substrate: Insights from Molecular Dynamics Simulation

et al. 2021

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Understanding polymer–substrate interfacial dynamics at the molecular level is crucial for tailoring the properties of polymer ultrathin films (PUFs). Herein, through coarse-grained molecular dynamics simulation, the effect of length (N loop) and rigidity (K loop) of loop chains on the dynamics of linear chains is systematically explored, in which the loop chains are adsorbed on a solid substrate and the linear chains are covered on the loop chains. It is found that there is an optimal K loop, which strongly confines the motion of the linear chains. Meanwhile, compared to increasing the rigidity of the loop chains, increasing the length of the loop chains can more effectively confine the motion of the linear chains. More interestingly, we observe that the mismatch of the length (ΔN) and rigidity (ΔK) between the loop and linear chains leads to dynamic asymmetry (ΔD c). The relationship between the ΔN, ΔK, and ΔD c are found to follow the mathematical expression of ΔD c ∼ (ΔN)α(ΔK)β, in which the values of α and β are around 4.58 and 0.83, separately. Remarkably, using the Gaussian process regression model, we construct a master curve of diffusion coefficient on the segmental and chain length scales of the linear chains as a function of N loop and K loop, which is further validated by our simulated prediction. In general, this work provides a fundamental understanding of polymer interfacial dynamics at the molecular level, enlightening some rational principles for manipulating the physical properties of PUFs.

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Local Viscosity of Interfacial Layers in Polymer Nanocomposites Measured by Magnetic Heating

Cited by 9 publications

References 40 publications

Tuning the Properties of Nanocomposites by Trapping Them in Deep Metastable States

Tuning the Properties of Nanocomposites by Trapping Them in Deep Metastable States

Thermally Activated Shear Stiffening in Polymer-Grafted Nanoparticle Composites for High-Temperature Adhesives

Heterogeneous Dynamics of Polymer Melts Exerted by Chain Loops Anchored on the Substrate: Insights from Molecular Dynamics Simulation

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