Surface Damage Influences the JKR Contact Mechanics of Glassy Low-Molecular-Weight Polystyrene Films

Degen, George D.; Cristiani, Thomas R.; Cadirov, Nicholas; Eguiluz, Roberto C. Andresen; Kristiansen, Kai; Pitenis, Angela A.; Israelachvili, Jacob N.

doi:10.1021/acs.langmuir.9b02037

Cited by 8 publications

(9 citation statements)

References 46 publications

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“…In N 2 , adhesive failure occurs at less than 3% strain, while in water, the film does not stretch beyond the equilibrium swollen thickness during retraction. Failure appears to be adhesive, but we cannot rule out the possibility of some small transfer to the other surface . After detachment, we do not observe significant changes either in the surface profile or in the contact region if we make subsequent contact at the same spot, consistent with adhesive failure.…”

Section: Resultsmentioning

confidence: 57%

Cooperative Tridentate Hydrogen-Bonding Interactions Enable Strong Underwater Adhesion

Lamberty

Tran

Engers

et al. 2023

ACS Appl. Mater. Interfaces

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Multidentate hydrogen-bonding interactions are a promising strategy to improve underwater adhesion. Molecular and macroscale experiments have revealed an increase in underwater adhesion by incorporating multidentate H-bonding groups, but quantitatively relating the macroscale adhesive strength to cooperative hydrogen-bonding interactions remains challenging. Here, we investigate whether tridentate alcohol moieties incorporated in a model epoxy act cooperatively to enhance adhesion. We first demonstrate that incorporation of tridentate alcohol moieties leads to comparable adhesive strength with mica and aluminum in air and in water. We then show that the presence of tridentate groups leads to energy release rates that increase with an increase in crack velocity in air and in water, while materials lacking these groups do not display rate-dependent adhesion. We model the ratedependent adhesion to estimate the activation energy of the interfacial bonds. Based on our data, we estimate the lifetime of these bonds to be between 2 ms and 6 s, corresponding to an equilibrium activation energy between 23k B T and 31k B T. These values are consistent with tridentate hydrogen bonding, suggesting that the three alcohol groups in the Tris moiety bond cooperatively form a robust adhesive interaction underwater.

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Section: Resultsmentioning

confidence: 57%

Cooperative Tridentate Hydrogen-Bonding Interactions Enable Strong Underwater Adhesion

Lamberty

Tran

Engers

et al. 2023

ACS Appl. Mater. Interfaces

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“…On the other hand, in terms of the JKR adhesion contact theory, i.e., F pull‑off = (3π/2) RW ad , the effective work of adhesion W ad was also computed by combining the measured pull-off forces and the known indenter radius R . The JKR theory is generally used to determine the effective work of adhesion of viscoelastic polymers to describe the hysteretic adhesion property. , …”

Section: Methodsmentioning

confidence: 99%

“…On the other hand, in terms of the JKR adhesion contact theory, 39 i.e., F pull-off = (3π/2)RW ad , the effective work of adhesion W ad was also computed by combining the measured pull-off forces and the known indenter radius R. The JKR theory is generally used to determine the effective work of adhesion of viscoelastic polymers to describe the hysteretic adhesion property. 40,41 ■ RESULTS AND DISCUSSION Results of Adhesion Measurements. Figure 4a shows the force−displacement curves of ESMP sheet under the same contact displacement (∼242 μm) and different preset temperatures.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Thermal-Regulated Adhesion Enhancement and Fast Switching within the Viscoelastic Glass Transition Zone of a Shape Memory Polymer

Gong

Wang

2021

Langmuir

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The effects of temperature and preload on adhesion of an epoxy-based shape memory polymer (ESMP) were investigated experimentally. The ESMP sheet and polydimethylsiloxane (PDMS) control sample were prepared by mold casting. The adhesion measurements were carried out on a home-built adhesion tester using a hemispherical glass indenter as the counter-surface. The reduced modulus was determined by the Oliver–Pharr method and Hertz theory. The viscoelastic energy dissipation was extracted, and the effective work of adhesion was calculated by the fitting method and JKR theory. In the vicinity of glass transition temperature (T g), the viscoelastic enhancement factor (1 + f(v, T)) is as high as 955 because of the strong viscoelastic effect of the ESMP sheet. The adhesion strength of the ESMP sheet is about 589 kPa under a relatively smaller contact displacement condition (∼44.6 μm). The strong viscoelastic effect induces more viscoelastic energy dissipation that contributes to the effective work of adhesion and leads to strong preload dependence of the adhesion. The pull-off force F pull‑off is demonstrated to linearly depend on F m 1/3 E r 2/3. In the sharp half glass transition zone (T > T g), the viscoelasticity and rigidity rapidly decrease with the temperature increasing about 10 °C, leading to a 6-fold reduction in adhesion. The results indicate that the adhesion of the ESMP sheet can be significantly enhanced and meanwhile rapidly switched within the viscoelastic glass transition zone.

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“…The frequency and dissipation changes can be related to the mass oscillating with the crystal and the viscoelastic properties of the layer through various models. 35 Surfaces Forces Apparatus (SFA). The SFA allows to measure normal forces (e.g., forces due to the surface and liquid structure, polymer, steric) between macroscopic surfaces with high force sensitivity while simultaneously monitoring the absolute surface distance (film thickness) and contact shape.…”

Section: Quartz Crystal Microbalance With Dissipation (Qcm-d)mentioning

confidence: 99%

Glycosaminoglycans and glycoproteins influence the elastic response of synovial fluid nanofilms on model oxide surfaces

Mann

Smith

Saltzherr

et al. 2021

Preprint

Self Cite

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Synovial fluid (SF) is the natural lubricant found in articulated joints, providing unique cartilage surface protecting films under confinement and relative motion. While it is known that the synergistic interactions of the macromolecular constituents provide its unique load-bearing and tribological performance, it is not fully understood how two of the main constituents, glycosaminoglycans (GAGs) and glycoproteins, regulate the formation and mechanics of robust load-bearing films. Here, we present evidence that the load-bearing capabilities, rather than the tribological performance, of the formed SF films depend strongly on its components’ integrity. For this purpose, we used a combination of enzymatic treatments, quartz crystal microbalance with dissipation (QCM-D) and the surface forces apparatus (SFA) to characterize the formation and load-bearing capabilities of SF films on model oxide (i.e., silicates) surfaces. We find that, upon cleavage of proteins, the elasticity of the films is reduced and that cleaving GAGs results in irreversible (plastic) molecular re-arrangements of the film constituents when subjected to confinement. Understanding thin film mechanics of SF can provide insight into the progression of diseases, such as arthritis, but may also be applicable to the development of new implant surface treatments or new biomimetic lubricants.GRAPHICAL ABSTRACT

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Surface Damage Influences the JKR Contact Mechanics of Glassy Low-Molecular-Weight Polystyrene Films

Cited by 8 publications

References 46 publications

Cooperative Tridentate Hydrogen-Bonding Interactions Enable Strong Underwater Adhesion

Cooperative Tridentate Hydrogen-Bonding Interactions Enable Strong Underwater Adhesion

Thermal-Regulated Adhesion Enhancement and Fast Switching within the Viscoelastic Glass Transition Zone of a Shape Memory Polymer

Glycosaminoglycans and glycoproteins influence the elastic response of synovial fluid nanofilms on model oxide surfaces

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