Reduction of frictional forces between solid surfaces bearing polymer brushes

Klein, Jacob; Kumacheva, Eugenia; Mahalu, D.; Perahia, Dvora; Fetters, Lewis J.

doi:10.1038/370634a0

Cited by 563 publications

(543 citation statements)

References 13 publications

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“…A polymer-free HEPES-glycerol solution with a glycerol 75% v/v showed a 55% (from 0.45 to 0. 2) reduction in friction at a sliding velocity of 0.1 mm/s in comparison to pure HEPES solution at the same speed. The coefficient of friction values in the absence of polymer appear to converge at 150 mm/s irrespective of the viscosity of the operating fluid, suggesting that asperity contacts between surfaces are no longer occurring; the frictional forces originate only from viscous dissipation within the fluid film, and thus the coefficient of friction at the interface diminishes to a very low value.…”

Section: Tribological Studies Of Pll-g-peg In Aqueousmentioning

confidence: 88%

“…Klein et al have studied the shear forces between polymer-bearing surfaces with the surface-forces apparatus, to understand the frictional forces at the interface. These studies show that when two surfaces covered with a high density of terminally attached polymers are immersed in a good solvent and brought into contact, the swollen polymer brushes reduce interfacial frictional forces [2]. As they approach each other, opposing polymer brushes exhibit repulsive forces due to osmotic effects on the one hand and the free-energy penalty (due to reduced configurational entropy) resulting from the overlap of the brush layers on the other.…”

Section: Introductionmentioning

confidence: 97%

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Macrotribological Studies of Poly(L-lysine)-graft-Poly(ethylene glycol) in Aqueous Glycerol Mixtures

et al. 2009

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We have investigated the tribological properties of surfaces with adsorbed poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) sliding in aqueous glycerol solutions under different lubrication regimes. Glycerol is a polar, biocompatible liquid with a significantly higher viscosity than that of water. Macrotribological performance was investigated by means of pin-on-disk and mini-tractionmachine measurements in glycerol-PLL-g-PEG-aqueous buffer mixtures of varying compositions. Adsorption studies of PLL-g-PEG from these mixtures were conducted with the quartz-crystal-microbalance technique. The enhanced viscosity of the glycerol-containing lubricant reduces the coefficient of friction due to increased hydrodynamic forces, leading to a more effective separation of the sliding partners, while the presence of hydrated polymer brushes at the interface leads to an entropically driven repulsion, which also helps mitigate direct asperity-asperity contact between the solid surfaces under boundary-lubrication conditions. The combination of polymer layers on surfaces with aqueous phases of enhanced viscosity thus enables the friction to be reduced by several orders of magnitude, compared to the behavior of pure water, over a large range of sliding speeds. The individual contributions of the polymer and the aqueous glycerol solutions in reducing the friction have been studied across different lubrication regimes.

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Section: Tribological Studies Of Pll-g-peg In Aqueousmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 97%

Macrotribological Studies of Poly(L-lysine)-graft-Poly(ethylene glycol) in Aqueous Glycerol Mixtures

et al. 2009

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“…[9][10][11] This is essentially due to the fluid character of the layer formed by the grafted chains that reduces the frictional forces. 12 In addition comb-like polymers increase the solubility of complexes formed by polyelectrolytes and surfactants of opposite charges. 13 These particular properties make comb-like polymers attractive for applications such as the fabrication of biomedical devices, 14 or as conditioning agents in cosmetic applications.…”

Section: Introductionmentioning

confidence: 99%

Influence of the molecular architecture on the adsorption onto solid surfaces: comb-like polymers

Guzmán

Ortega

Prolongo

et al. 2011

Phys. Chem. Chem. Phys.

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“…Measurements of the frictional forces between neutral polymer brushes have shown them to have remarkable lubricating properties [1][2][3][4] . These properties have been attributed to the very limited interpenetration between opposing polymer brushes even at quite high compressions suggested by some theoretical studies [5][6][7] .…”

Section: Introductionmentioning

confidence: 99%

Direct Measurement of Normal and Shear Forces between Surface-Grown Polyelectrolyte Layers

et al. 2009

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This paper presents measurements, using the surface force balance (SFB), of the normal and shear forces in aqueous solutions between polyelectrolyte layers grown directly on mica substrates (grafted-from). The grafting-from was via surface-initiated atom transfer radical polymerization (surface-initiated ATRP) using a positively-charged methacrylate monomer. Xray reflectometry measurements confim the successful formation of polyelectrolyte layers by this method. Surface-inititated ATRP has the advantages that the polymer chains can be strongly grafted to the substrate, and that high grafting densities should be achievable. Measured normal forces in water showed a long-range repulsion arising from an electrical double layer that extended beyond the polyelectrolyte layers, and a stronger, shorter-range repulsion when the polyelectrolyte brushes were in contact. Swollen layer thicknesses were in the range 15 -40 nm. Upon addition of ~10 -2 M -10 -1 M sodium nitrate, screening effects reduced the electrical double layer force to an undetectable level. Shear force measurements in pure water were performed, and the measured friction may arise from polymer chains bridging between the surfaces.2

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Reduction of frictional forces between solid surfaces bearing polymer brushes

Cited by 563 publications

References 13 publications

Macrotribological Studies of Poly(L-lysine)-graft-Poly(ethylene glycol) in Aqueous Glycerol Mixtures

Macrotribological Studies of Poly(L-lysine)-graft-Poly(ethylene glycol) in Aqueous Glycerol Mixtures

Influence of the molecular architecture on the adsorption onto solid surfaces: comb-like polymers

Direct Measurement of Normal and Shear Forces between Surface-Grown Polyelectrolyte Layers

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