Temperature effects on the nanoindentation characterization of stiffness gradients in confined polymers

Song, Jake; Kahraman, Rıdvan; Collinson, David W.; Xia, Wenjie; Brinson, L. Catherine; Keten, Sinan

doi:10.1039/c8sm01539b

Cited by 16 publications

(16 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The profiles acquired at each applied load were then translated horizontally so that the inflection point of each profile was aligned, providing a single coordinate system for all of the profiles across the graphite−rubber interface. Even though the modulus measurements are made assuming JKR contact mechanics, we believe that the scaling of the substrate effect with x and F max is effectively described by the Hertzian contact radius ( a FF ), as calculated by eq , consistent with the recent MD simulations that show the substrate effect is not affected by changes to tip−sample adhesion strength …”

Section: Resultssupporting

confidence: 82%

“…This particular behavior is commonly termed as the substrate effect or “thin film effect”. The size and extent of structural effects are highly dependent on the size of the tip used and indentation depth, the relative stiffness and location , of neighboring phases relative to the indentation, the viscoelastic state, and the incompressibility of the indented material. In particle–matrix composites, the indentation measurement can be further complicated due to the shape of the particle targeted for analysis or the presence of other nearby or subsurface particles .…”

Section: Introductionmentioning

confidence: 99%

“…In particle–matrix composites, the indentation measurement can be further complicated due to the shape of the particle targeted for analysis or the presence of other nearby or subsurface particles . The particle geometry itself can influence the magnitude of the stress interaction effect if the particle shape and subsurface geometry are such that the material between the particle and the indenting tip becomes highly confined . In addition, a nanoparticle is a nonideal substrate and is expected to deflect or rotate under load.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Deconvolution of Stress Interaction Effects from Atomic Force Spectroscopy Data across Polymer−Particle Interfaces

Collinson¹,

Eaton²,

Shull³

et al. 2019

Macromolecules

Self Cite

View full text Add to dashboard Cite

Atomic force microscopy (AFM) is a powerful technique for imaging polymer nanocomposites as well as other systems with heterogeneous material properties on the nanoscale. However, the quantitative measurement of modulus is highly susceptible to convoluting structural effects due to the finite tip radius and stress field interactions with particles and substrates which are often termed the "substrate effect" or "thin film effect". We present an empirical master curve that can model the change in measured modulus (E MC ) due to structural effects in an AFM indentation on a soft material near a stiff filler, using N121 and N660 carbon black−styrene−butadiene rubber nanocomposites as examples. Finite element analysis is combined with experimental AFM data across an interface at increasing indentation depths to create a robust method for confirming or rejecting the presence of an interphase layer in AFM. From the raw data, which is initially inconclusive, we reasonably estimate the width of the loosely bound layer (ξ int ) surrounding each (strongly interacting) N121 particle to be 50−60 nm after deconvolving the substrate effect. In comparison, we found no significant loosely bound layer around the (weakly interacting) N660 particles. While we have demonstrated this technique for polymer nanocomposites, we believe the strategy is broadly applicable to multiphase soft materials.

show abstract

Section: Resultssupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Deconvolution of Stress Interaction Effects from Atomic Force Spectroscopy Data across Polymer−Particle Interfaces

Collinson¹,

Eaton²,

Shull³

et al. 2019

Macromolecules

Self Cite

View full text Add to dashboard Cite

show abstract

“…23,37,58,59 Quasi-static finite-element simulations 59 of the AFM experiment assuming elastic properties of the substrate and the glassy polymer (PMMA) film indicate stiffening near the rigid substrate. Very recent molecular dynamics simulations 60 have further suggested that the stiffness gradient length scale increases with temperature from below to above the polymer glass transition. Both simulations are based on several elastic and energetic parameters for the polymer interactions with the substrate and the indenter.…”

Section: Resultsmentioning

confidence: 98%

Shell Architecture Strongly Influences the Glass Transition, Surface Mobility, and Elasticity of Polymer Core-Shell Nanoparticles

et al. 2019

View full text Add to dashboard Cite

Despite the growing application of nanostructured polymeric materials, there still remains a large gap in our understanding of polymer mechanics and thermal stability under confinement and near polymer–polymer interfaces. In particular, the knowledge of polymer nanoparticle thermal stability and mechanics is of great importance for their application in drug delivery, phononics, and photonics. Here, we quantified the effects of a polymer shell layer on the modulus and glass-transition temperature ( T g ) of polymer core–shell nanoparticles via Brillouin light spectroscopy and modulated differential scanning calorimetry, respectively. Nanoparticles consisting of a polystyrene (PS) core and shell layers of poly( n -butyl methacrylate) (PBMA) were characterized as model systems. We found that the high T g of the PS core was largely unaffected by the presence of an outer polymer shell, whereas the lower T g of the PBMA shell layer decreased with increasing PBMA thickness. The surface mobility was revealed at a temperature about 15 K lower than the T g of the PBMA shell layer. Overall, the modulus of the core–shell nanoparticles decreased with increasing PBMA shell layer thickness. These results suggest that the nanoparticle modulus and T g can be tuned independently through the control of nanoparticle composition and architecture.

show abstract

“…Nevertheless, much less attention has been paid to the confinement of SRPs inside the spherical container, especially considering SRP mixtures with polydispersity. The physical effects from the topological constraints and confinements play significant roles in the structure and function of individual genetic materials [34][35][36][37][38], such as chromosome shape in elongated bacterial cells [39], DNA (or DNA-actin filament mixtures) self-organization in a cell-size confinement [40], and drug delivery from spherical vesicles [41,42], etc.…”

Section: Introductionmentioning

confidence: 99%

Entropy-Induced Separation of Binary Semiflexible Ring Polymer Mixtures in Spherical Confinement

Zhou¹,

Guo²,

Li³

et al. 2019

Polymers

View full text Add to dashboard Cite

Coarse-grained molecular dynamics simulations are used to investigate the conformations of binary semiflexible ring polymers (SRPs) of two different lengths confined in a hard sphere. Segregated structures of SRPs in binary mixtures are strongly dependent upon the number density of system (ρ), the bending energy of long SRPs (Kb, long), and the chain length ratio of long to short SRPs (α). With a low ρ or a weak Kb, long at a small ratio α, long SRPs are immersed randomly in the matrix of short SRPs. As ρ and bending energy of long SRPs (Kb, long) are increased up to a certain value for a large ratio α, a nearly complete segregation between long and short SRPs is observed, which can be further characterized by the ratio of tangential and radial components of long SRPs velocity. These explicit segregated structures of the two components in spherical confinement are induced by a delicate competition between the entropic excluded volume (depletion) effects and bending contributions.

show abstract

Temperature effects on the nanoindentation characterization of stiffness gradients in confined polymers

Abstract: Stiffness gradients in geometrically confined polymers as measured by nanoindentation are influenced by opposing roles of the polymers viscoelastic state and the degree of confinement.

Cited by 16 publications

References 34 publications

Deconvolution of Stress Interaction Effects from Atomic Force Spectroscopy Data across Polymer−Particle Interfaces

Deconvolution of Stress Interaction Effects from Atomic Force Spectroscopy Data across Polymer−Particle Interfaces

Shell Architecture Strongly Influences the Glass Transition, Surface Mobility, and Elasticity of Polymer Core-Shell Nanoparticles

Entropy-Induced Separation of Binary Semiflexible Ring Polymer Mixtures in Spherical Confinement

Contact Info

Product

Resources

About