Spreading Profiles of Molecularly Thin Perfluoropolyether Films

Tyndall, George W.; Karis, T. E.; Jhon, Myung S.

doi:10.1080/10402009908982242

Cited by 97 publications

(51 citation statements)

References 31 publications

(7 reference statements)

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“…The Zdol spreading profile shoulder height corresponds to the film thickness at which ¶P/ ¶h < 0 and P changes sign from positive to negative. The shoulder heights for two of the Zdol fractions were close to those expected from analysis of the disjoining pressure isotherm [56].…”

Section: Disjoining Pressuresupporting

confidence: 58%

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Spreading and dewetting in nanoscale lubrication

Karis

Kim

2005

Tribol Lett

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This article critically reviews the fundamental scientific tools, as well as constructs cohesive schemes for potential applications, relevant to the molecularly-thin liquid film technology. Our focus is to understand the nanoscale dynamic behavior of thin lubricant films, relevant to the emerging field of nanotechnology, especially for achieving durability and reliability in the nanoscale devices. Our goal is to present a unified and hybrid description of perfluoropolyether (PFPE) experiment, mesoscopic interpretation, microscopic simulation tools, and molecular design tools available up to now. The experimentation and theory for the physicochemical properties of ultra-thin PFPE films are used to examine liquid film in the sub-monolayer to multilayer regime. Methods for extracting spreading properties from the scanning microellipsometry (SME) for various PFPE/solid surface pairs and the surface rheological characterization of PFPEs are examined. The interrelationships among SME spreading profiles, rheology, surface energy, and tribology, are given. Mesoscopic theories, including thermodynamics of evaporation and flow, stability analysis, microscale mass transfer, and capillary waves are introduced to describe thin PFPE film dynamics. Estimation of thin film viscosity enhancement from vapor pressure suppression by dispersion force is reviewed. The method for experimental derivation of lubricant spreading profiles from contact angles is summarized. The implications of capillary waves, or thermal fluctuations, at the surface of polymeric lubricant films are also discussed. The lattice-based, simple reactive sphere Monte Carlo (MC) technique for examining the fundamentals of PFPE dynamics is illustrated. An off-lattice based bead-spring MC model is also introduced to capture a detailed internal structure of the PFPE molecules, and the molecular dynamics method is implemented for a full-scale nanostructural analysis of PFPE ultra-thin films. By systematically tuning the endgroup strengths of PFPE, we examined the physicochemical properties for thin liquid films of the various PFPE/solid surface pairings. These tools accurately describe the static and dynamic behavior of ultra-thin liquid films consistent with experimental findings and thus are suitable for examining the fundamental mechanisms of lubrication in nanoscale devices. Application of the next generation head-disk interface design in information storage device is briefly considered.

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Section: Disjoining Pressuresupporting

confidence: 58%

“…Our results provide a direct interpretation of the experimental surface energy data for PFPE films with functional endgroups [56]. Most remarkably the MC simulation can predict equilibrium properties, including the molecular roughness of the surface ( figure 7(a)).…”

Section: Bead-spring Modelmentioning

confidence: 81%

Spreading and dewetting in nanoscale lubrication

Karis

Kim

2005

Tribol Lett

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“…However, the first local minimum in the polar surface energy occurs at a thickness smaller than the monolayer thickness reported in the literature [23]. We propose the following explanation.…”

Section: Polar Surface Energymentioning

confidence: 92%

Effect of Ultraviolet Irradiation on the Interactions between Perfluoropolyether Lubricant and Magnetic Disk Surfaces

et al. 2005

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To tailor the characteristics of molecularly thin lubricant films, magnetic disk surfaces coated with nanometer-thick perfluoropolyether AM3001 lubricant films were irradiated with 184.9 and 253.7 nm ultraviolet (UV) rays. We elucidated the effect of UV irradiation on the interactions between the lubricant and the magnetic disk surface via surface energy, bonded lubricant thickness and lubricant spreading measurements for films with and without UV irradiation. We found that UV irradiation decreased the dispersive and polar surface energies of the lubricant films by 20 and 80%, respectively; increased bonded lubricant thickness; and decelerated lubricant spreading. These results indicated that dispersion and polar interactions between lubricant molecules and the magnetic disk surface were strengthened by UV irradiation.

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“…6. Generally this assumption does not hold true for PFPE Zdol2000 because of its functional end groups (Tyndall et al 1999). However, considering that the disk surfaces are nearly hydrophobic as indicated by the water contact angle in Table 1, we simply neglected the pressure originating from polar interactions.…”

Section: Models For Lubricant Distribution On Grooved Surfacesmentioning

confidence: 99%

Measurement of spreading characteristics of molecularly thin lubricant films over grooved solid surfaces based on diffraction simulations

et al. 2006

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Characteristics of molecularly thin lubricant films are basically determined by their interactions with solid surfaces. Since these interactions can be modified by engineered microscopic surface textures, it is expected that rational design of the textures will make it possible to attain desired tribological functions and performance. In this research, with the aim of applying it to head-disk interface of hard disk drives, we propose a method based on diffraction simulations that enables thickness measurement of molecularly thin films coated on grooved solid surfaces. Using this method, we experimentally investigate the spreading characteristics of nanometer-thick polymeric liquid lubricant films on grooved surfaces. The results revealed that the average thicknesses of the films dipcoated on the grooved and smooth surfaces under identical conditions were approximately the same, whereas lubricant spreading on grooved surfaces was significantly faster than that on smooth surfaces.

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Spreading Profiles of Molecularly Thin Perfluoropolyether Films

Cited by 97 publications

References 31 publications

Spreading and dewetting in nanoscale lubrication

Spreading and dewetting in nanoscale lubrication

Effect of Ultraviolet Irradiation on the Interactions between Perfluoropolyether Lubricant and Magnetic Disk Surfaces

Measurement of spreading characteristics of molecularly thin lubricant films over grooved solid surfaces based on diffraction simulations

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