Surfactant-induced friction reduction for hydrogels in the boundary lubrication regime

Kamada, Kosuke; Furukawa, Hidemitsu; Kurokawa, Takayuki; Tada, Tomohiro; Tominaga, Taiki; Nakano, Yoshiro; Gong, Jian Ping

doi:10.1088/0953-8984/23/28/284107

Cited by 19 publications

(18 citation statements)

References 37 publications

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“…Now artificial gels have become tough like as natural gels of the human body. While the articular cartilage of our knee has both quite low surface frictional coefficient lower than 0.01 and high compression stress higher than several MPa, the DN gels have exceeded both the properties (2)(3)(4) . These properties should be studied quantitatively to broaden the application of the artificial gels especially in mechanical engineering.…”

Section: Introductionmentioning

confidence: 69%

Surface and Bulk Mechanical Properties of Soft and Wet Materials

Wada

Hidema

Chiba

et al. 2013

JMMP

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The frictional behavior of the two kinds of high-strength gels, which were double network (DN) gels and shape memory gels (SMG), was studied. By using a commercial measuring instrument with an empirical fitting function, the coefficient of dynamical friction for the DN gels and the SMG was determined. The velocity dependence of the coefficient looked roughly similar for both the DN gels and the SMG, however the details of the dependence were different. The coefficient of the DN gels was smaller than that of the SMGs. The coefficient decreased as the normal force increased. This normal force dependence was observed for the DN gels previously, however for the first time for the SMGs. The differences of both the velocity and normal-force dependences between the DN gels and SMG were discussed in relation to their mechanical properties determined in the previous studies. It implied that the difference of the dependences was possibly related to the different softness of the gels.

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Section: Introductionmentioning

confidence: 69%

Surface and Bulk Mechanical Properties of Soft and Wet Materials

Wada

Hidema

Chiba

et al. 2013

JMMP

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“…The lubricating properties of hydrogels are recognized to involve a complex interplay between the physical-chemistry of the surfaces, their ability to deform under hydrodynamic flow and stress-induced water transport phenomena within the gel network [1]. Among various physico-chemical aspects, experiments with polyelectrolyte gels have demonstrated friction can be affected by electrostatic repulsion between surface charges or adsorption-desorption of polymer chains at the interface [2][3][4][5]. Another important phenomenon is the ability of the soft gel surface to deform under the action of hydrodynamical forces, thus allowing for the formation of a water lubricating film at the contact interface [6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Friction of Poroelastic Contacts with Thin Hydrogel Films

et al. 2018

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We report on the frictional behavior of thin poly(dimethylacrylamide) hydrogel films grafted on glass substrates in sliding contact with a glass spherical probe. Friction experiments are carried out at various velocities and normal loads applied with the contact fully immersed in water. In addition to friction force measurements, a novel optical setup is designed to image the shape of the contact under steady-state sliding. The velocity dependence of both friction force F and contact shape is found to be controlled by a Péclet number, Pe, defined as the ratio of the time τ needed to drain the water out of the contact region to a contact time a/ v, where v is the sliding velocity and a is the contact radius. When Pe < 1, the equilibrium circular contact achieved under static normal indentation remains unchanged during sliding. Conversely, for Pe > 1, a decrease in the contact area is observed together with the development of a contact asymmetry when the sliding velocity is increased. A maximum in F is also observed at Pe ≈1. These experimental observations are discussed in the light of a poroelastic contact model based on a thin-film approximation. This model indicates that the observed changes in contact geometry are due to the development of a pore pressure imbalance when Pe > 1. An order-of-magnitude estimate of the friction force and its dependence on normal load and velocity are also provided under the assumption that most of the frictional energy is dissipated by poroelastic flow at the leading and trailing edges of the sliding contact.

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“…For practical applications involving aqueous lubrication, it is often not convenient to graft polymer brushes from the sliding substrates, and other boundary layers, including surfactants, self‐assembling polymer brushes, or liposomes were often used as vectors to deliver hydrated interfaces for efficient boundary lubrication. Among these materials, liposomes have been proved as particularly efficient boundary lubricants.…”

Section: Introductionmentioning

confidence: 99%

Normal and shear forces between surfaces bearing phosphocholinated polystyrene nanoparticles

Lin

Nietzel

Klapper

et al. 2016

Polymers for Advanced Techs

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Extending earlier studies where phosphocholinated brushes and phosphocholine-exposing phosphatidylcholine lipid bilayer vesicles (PC-liposomes) were shown to be very efficient boundary lubricants in aqueous media by virtue of the highly-hydrated phophocholine groups, we examined interactions between surfaces bearing phosphocholinated polystyrene nanoparticles (pc-PS-NPs). We synthesized such particles by incorporation of alkyl chains terminated with phosphocholine groups in the PS-NP, with the hydrophilic phosphocholines exposed at the NP surface. These were then allowed to adsorb onto mica surfaces, and the normal and shear interactions between them were examined in a surface force balance. On moderate compressions (contact pressures > 9 atm) the pc-PS-NPs were squeezed out, leaving a single layer between the surfaces. Shear of the surfaces revealed a large frictional dissipation, with a friction coefficient μ ≈ 0.2, in contrast to our expectations that such phosphocholinated NPs would provide highly lubricating analogues of PC-liposomes (for which μ ≈ 10 À3 -10 À4 ). This is attributed to a number of factors, including the inherent roughness of the NP multilayers at low compressions and the relatively low areal density of the phosphocholine groups on the PS-NP surfaces. In particular, at higher compressions, sliding results in energy-dissipating breaking and reforming of phosphocholine/mica (dipole/charge) bonds at the mica surfaces (and thus high friction), because of bridging of the surfaces by a single layer of pc-PS-NPs.

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Surfactant-induced friction reduction for hydrogels in the boundary lubrication regime

Cited by 19 publications

References 37 publications

Surface and Bulk Mechanical Properties of Soft and Wet Materials

Surface and Bulk Mechanical Properties of Soft and Wet Materials

Friction of Poroelastic Contacts with Thin Hydrogel Films

Normal and shear forces between surfaces bearing phosphocholinated polystyrene nanoparticles

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