Initial Solvent-Driven Nonequilibrium Effect on Structure, Properties, and Dynamics of Polymer Nanocomposites

Oh, Sol Mi; Abbasi, Mozhdeh; Shin, Tae Joo; Saalwächter, Kay; Kim, So Youn

doi:10.1103/physrevlett.123.167801

Cited by 24 publications

(47 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…twice as much in the BDS (see Figure ). Note that no evidence for a dead layer, which would be represented by a signal contribution resembling that of bulk P2VP measured below 400 K, was found in the present work. , Furthermore, since such nanocomposites are not expected to be thermodynamically equilibrated, , differences in the studied samples may well arise due to potential differences in preparation procedures.…”

Section: Resultscontrasting

confidence: 56%

“…Note that no evidence for a dead layer, which would be represented by a signal contribution resembling that of bulk P2VP measured below 400 K, was found in the present work. 33,34 Furthermore, since such nanocomposites are not expected to be thermodynamically equilibrated, 35,36 differences in the studied samples may well arise due to potential differences in preparation procedures. This discussion to this point on the IFL model is based on the hypothesis that the segmental dynamics of the IFL is isotropic (S = 0 in eq 2), as in the bulk polymer.…”

Section: Nmr Datamentioning

confidence: 99%

See 1 more Smart Citation

On the Immobilized Polymer Fraction in Attractive Nanocomposites: T_g Gradient versus Interfacial Layer

et al. 2021

Self Cite

View full text Add to dashboard Cite

We study the slowing down of polymer dynamics in canonical nanocomposites made of strongly interacting mixtures of poly-2-vinyl pyridine and silica nanoparticles (radius R = 7 ± 2 nm) by means of low-field NMR relaxometry. We demonstrate that this technique enables the accurate quantification of the fraction of immobilized (irreversibly adsorbed) polymer on to the filler surface, in a manner that complements data from broadband dielectric spectroscopy (BDS) and differential scanning calorimetry (DSC). We rationalize the slowing down using two previously developed approaches to model the immobilized layer. The first one is based on a glass-transition temperature (T g) gradient, while the second one assumes a single interfacial component with a distribution of relaxation times. While both models convincingly fit the NMR data providing us with robust and complementary conclusions, the former approach is found to fit more accurately previously published DSC experiments. Quantitatively, NMR results indicate that the segmental relaxation of the immobilized layer is ca. 1 decade slower than in the bulk polymer, while earlier BDS analyses were equivocal on this point, indicating either 1 or 2 decades. These discrepancies highlight the difficulties and potential model dependencies in quantifying the dynamics of the minority polymer fraction in the immobilized layer, necessitating a systematic multi-technique approach to properly characterize dynamical heterogeneities in polymer-based materials.

show abstract

Section: Resultscontrasting

confidence: 56%

Section: Nmr Datamentioning

confidence: 99%

On the Immobilized Polymer Fraction in Attractive Nanocomposites: T_g Gradient versus Interfacial Layer

et al. 2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…In our case, it is possible that short chains were trapped in a nonequilibrium or metastable state. A few studies ,, have reported that nonequilibrium effects can be induced by different environmental factors during PNC processing. Although the exact mechanisms for trapping the short chains at the interface are not known, following the ideas of Granick et al, they might be related to the steric pinning of weakly adsorbed short chains by the strongly adsorbed long chains.…”

Section: Discussionmentioning

confidence: 99%

“…In our case, it is possible that short chains were trapped in a nonequilibrium or metastable state. A few studies 22,68,69 have reported that nonequilibrium effects can be induced by different environmental factors during PNC processing.…”

Section: ■ Discussionmentioning

confidence: 99%

Addition of Short Polymer Chains Mechanically Reinforces Glassy Poly(2-vinylpyridine)–Silica Nanoparticle Nanocomposites

Bocharova

Genix

Carrillo

et al. 2020

ACS Appl. Nano Mater.

View full text Add to dashboard Cite

The addition of hard fillers to a polymer matrix is a well-known process for achieving mechanical reinforcement. With a decrease in the size of the fillers, the contribution from polymer–particle nanometer-sized interfaces becomes significant, and these interfaces affect the mechanical performance of polymer nanocomposites (PNCs) beyond the limits established for conventional composites. However, the molecular mechanisms underlying the improvement in the mechanical performance of glassy PNCs remain unresolved, necessitating a deeper understanding of the structure–property relationships in these intrinsically heterogeneous systems. In this effort, by using Brillouin light scattering (BLS) and dynamic mechanical analysis (DMA), we demonstrated that adding shorter chains to a PNC prepared with high molecular weight polymers significantly improved the mechanical properties of the PNC in the glassy state. The strongest enhancement of mechanical properties occurred at an optimum concentration of short chains. This is in contrast to the behavior of the glass transition temperature of PNCs which shows a monotonic decrease with an increase in the concentration of shorter chains. Using experimental data and coarse-grained molecular dynamics (MD) simulations, we have identified the molecular mechanism leading to the observed nonmonotonic changes in mechanical reinforcement. This mechanism includes changes in the nanoscale organization at the interface combined with chain stretching amplified by the addition of the short chains. Overall, our approach paves a simple and cost-effective pathway to fabricating glassy PNCs with significantly improved mechanical properties that will fill various practical needs.

show abstract

“…Thus, particle interactions and the resulting NP structure may be altered during solvent evaporation [ 22 , 23 , 24 ]. Previous studies have shown evidence of improved NP dispersion by polymer adsorption on the NP surface in solution-casted PNC films [ 13 , 25 , 26 , 27 , 28 , 29 , 30 ]. A previous study performed by us revealed that polymer adsorption resulted in improved dispersion of NPs in PNC films, suggesting that adsorbed polymers suppress NP aggregation during drying by introducing steric repulsion between the NPs [ 31 ].…”

Section: Introductionmentioning

confidence: 99%

Role of Adsorbed Polymers on Nanoparticle Dispersion in Drying Polymer Nanocomposite Films

Kim

et al. 2021

Polymers

Self Cite

View full text Add to dashboard Cite

Polymers adsorbed on nanoparticles (NPs) are important elements that determine the dispersion of NPs in polymer nanocomposite (PNC) films. While previous studies have shown that increasing the number of adsorbed polymers on NPs can improve their dispersion during the drying process, the exact mechanism remained unclear. In this study, we investigated the role of adsorbed polymers in determining the microstructure and dispersion of NPs during the drying process. Investigation of the structural development of NPs using the synchrotron vertical-small-angle X-ray scattering technique revealed that increasing polymer adsorption suppresses bonding between the NPs at later stages of drying, when they approach each other and come in contact. On the particle length scale, NPs with large amounts of adsorbed polymers form loose clusters, whereas those with smaller amounts of adsorbed polymers form dense clusters. On the cluster length scale, loose clusters of NPs with large amounts of adsorbed polymers build densely packed aggregates, while dense clusters of NPs with small amounts of adsorbed polymers become organized into loose aggregates. The potential for the quantitative control of NP dispersion in PNC films via modification of polymer adsorption was established in this study.

show abstract

Initial Solvent-Driven Nonequilibrium Effect on Structure, Properties, and Dynamics of Polymer Nanocomposites

Cited by 24 publications

References 54 publications

On the Immobilized Polymer Fraction in Attractive Nanocomposites: T_g Gradient versus Interfacial Layer

On the Immobilized Polymer Fraction in Attractive Nanocomposites: T_g Gradient versus Interfacial Layer

Addition of Short Polymer Chains Mechanically Reinforces Glassy Poly(2-vinylpyridine)–Silica Nanoparticle Nanocomposites

Role of Adsorbed Polymers on Nanoparticle Dispersion in Drying Polymer Nanocomposite Films

Contact Info

Product

Resources

About

Initial Solvent-Driven Nonequilibrium Effect on Structure, Properties, and Dynamics of Polymer Nanocomposites

Cited by 24 publications

References 54 publications

On the Immobilized Polymer Fraction in Attractive Nanocomposites: Tg Gradient versus Interfacial Layer

On the Immobilized Polymer Fraction in Attractive Nanocomposites: Tg Gradient versus Interfacial Layer

Addition of Short Polymer Chains Mechanically Reinforces Glassy Poly(2-vinylpyridine)–Silica Nanoparticle Nanocomposites

Role of Adsorbed Polymers on Nanoparticle Dispersion in Drying Polymer Nanocomposite Films

Contact Info

Product

Resources

About

On the Immobilized Polymer Fraction in Attractive Nanocomposites: T_g Gradient versus Interfacial Layer

On the Immobilized Polymer Fraction in Attractive Nanocomposites: T_g Gradient versus Interfacial Layer