Crowded, Confined, and Frustrated: Dynamics of Molecules Tethered to Nanoparticles

Agarwal, Praveen; Kim, Sung‐A; Archer, Lynden A.

doi:10.1103/physrevlett.109.258301

Cited by 59 publications

(102 citation statements)

References 32 publications

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“…Such negative deviations in T g of PEG/PMMA mixtures, relative to the Fox relation, have been reported previously and argued to be a consequence of the segmental-scale attraction of PEG and PMMA42. At the same time, a more pronounced decrease observed for free PEG chains relative to tethered chains can be understood both in terms of the lower number of chain ends43 and lower mobility near SiO 2 particle surface44 for the latter.…”

Section: Resultssupporting

confidence: 74%

“…48; ∼1.7 nm for PEG 2k ), as shown by the dashed line. However, it is known from previous measurements44 that because of the high grafting density of tethered chains, this height can be substantially larger. Hence, we also evaluated η r assuming the polymer brush to be comprising fully stretched out PEG chains with Δ∼ N * b (∼16 nm), as shown in solid line, here N is the number of kuhn monomers in entire chain length and b is the length of a polymer chain segment.…”

Section: Resultsmentioning

confidence: 95%

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Phase stability and dynamics of entangled polymer–nanoparticle composites

2015

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Nanoparticle–polymer composites, or polymer–nanoparticle composites (PNCs), exhibit unusual mechanical and dynamical features when the particle size approaches the random coil dimensions of the host polymer. Here, we harness favourable enthalpic interactions between particle-tethered and free, host polymer chains to create model PNCs, in which spherical nanoparticles are uniformly dispersed in high molecular weight entangled polymers. Investigation of the mechanical properties of these model PNCs reveals that the nanoparticles have profound effects on the host polymer motions on all timescales. On short timescales, nanoparticles slow-down local dynamics of the host polymer segments and lower the glass transition temperature. On intermediate timescales, where polymer chain motion is typically constrained by entanglements with surrounding molecules, nanoparticles provide additional constraints, which lead to an early onset of entangled polymer dynamics. Finally, on long timescales, nanoparticles produce an apparent speeding up of relaxation of their polymer host.

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Section: Resultssupporting

confidence: 74%

Section: Resultsmentioning

confidence: 95%

Phase stability and dynamics of entangled polymer–nanoparticle composites

2015

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“…Motion of the chains from/to the particle surface can produce gradual changes in the properties of the nanocomposite over time, where either coarsening of particle aggregates or improvement in the dispersion state of the nanoparticles might occur depending on the form of interactions between the particle and the polymer . These effects are further complicated by the rich milieu of conformational and dynamic transitions polymer chains experience near adsorbing surfaces …”

Section: Structure Phase Behavior and Mechanical Propertiesmentioning

confidence: 99%

25th Anniversary Article: Polymer–Particle Composites: Phase Stability and Applications in Electrochemical Energy Storage

Srivastava

Schaefer

Yang³

et al. 2013

Advanced Materials

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Polymer-particle composites are used in virtually every field of technology. When the particles approach nanometer dimensions, large interfacial regions are created. In favorable situations, the spatial distribution of these interfaces can be controlled to create new hybrid materials with physical and transport properties inaccessible in their constituents or poorly prepared mixtures. This review surveys progress in the last decade in understanding phase behavior, structure, and properties of nanoparticle-polymer composites. The review takes a decidedly polymers perspective and explores how physical and chemical approaches may be employed to create hybrids with controlled distribution of particles. Applications are studied in two contexts of contemporary interest: battery electrolytes and electrodes. In the former, the role of dispersed and aggregated particles on ion-transport is considered. In the latter, the polymer is employed in such small quantities that it has been historically given titles such as binder and carbon precursor that underscore its perceived secondary role. Considering the myriad functions the binder plays in an electrode, it is surprising that highly filled composites have not received more attention. Opportunities in this and related areas are highlighted where recent advances in synthesis and polymer science are inspiring new approaches, and where newcomers to the field could make important contributions.

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“…The introduction of boundary effects, [18][19][20][21][22] finite size effects, 23,24 conformation and chain packing effects [25][26][27][28] and other associated new mechanisms, [29][30][31][32][33] due to thinning of the nanometer films, usually results in sufficiently more complex rheological behaviors that are not easily predictable using the bulk rules. The introduction of boundary effects, [18][19][20][21][22] finite size effects, 23,24 conformation and chain packing effects [25][26][27][28] and other associated new mechanisms, [29][30][31][32][33] due to thinning of the nanometer films, usually results in sufficiently more complex rheological behaviors that are not easily predictable using the bulk rules.…”

Section: Introductionmentioning

confidence: 99%

Probing the rheological properties of supported thin polystyrene films by investigating the growth dynamics of wetting ridges

et al. 2016

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Despite its importance in the processing of nanomaterials, the rheological behavior of thin polymer films is poorly understood, partly due to the inherent measurement challenges. Herein, we have developed a facile method for investigating the rheological behavior of supported thin polymeric films by monitoring the growth of the "wetting ridge"-a microscopic protrusion on the film surface due to the capillary forces exerted by a drop of ionic liquid placed on the film surface. It was found that the growth dynamics of the wetting ridge and the behavior of polystyrene rheology are directly linked. Important rheological properties, such as the flow temperature (Tf), viscosity (η), and terminal relaxation time (τ0) of thin polystyrene films, can be derived by studying the development of the height of the wetting ridge with time and the sample temperature. Rheological studies using the proposed approach for supported thin polystyrene (PS) films with thickness down to 20 nm demonstrate that the PS thin film exhibits facilitated flow, with reduced viscosity and lowered viscous temperature and a shortened rubbery plateau, when SiOx-Si was used as the substrate. However, sluggish flow was observed for the PS film supported by hydrogen-passivated silicon substrates (H-Si). The differences in enthalpic interactions between PS and the substrates are the reason for this divergence in the whole-chain mobility and flow ability of thin PS films deposited on SiOx-Si and H-Si surfaces. These results indicate that this approach could be a reliable rheological probe for supported thin polymeric films with different thicknesses and various substrates.

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Crowded, Confined, and Frustrated: Dynamics of Molecules Tethered to Nanoparticles

Cited by 59 publications

References 32 publications

Phase stability and dynamics of entangled polymer–nanoparticle composites

Phase stability and dynamics of entangled polymer–nanoparticle composites

25th Anniversary Article: Polymer–Particle Composites: Phase Stability and Applications in Electrochemical Energy Storage

Probing the rheological properties of supported thin polystyrene films by investigating the growth dynamics of wetting ridges

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