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

Zhang, H.; Mitsuya, Yasunaga; Imamura, Masashi; Fukuoka, Natsuko; Fukuzawa, Kenji

doi:10.1007/s11249-005-8326-7

Cited by 20 publications

(18 citation statements)

References 22 publications

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“…Note that lubricant bonding in this sense does not refer to chemical bonds. For measurement of film thickness using ellipsometry, knowing the optical constants (refractive index n and extinction coefficient k) of the lubricant film and the disk is necessary [7,8]. In these studies, n = 1.30 and k = 0 were used for the lubricant film, and the values measured with the ellipsometer prior to lubricant application were used for the disk [9].…”

Section: Measurement Of Film Compositionmentioning

confidence: 99%

Changes in Friction Properties of Monolayer Lubricant Films Induced by Development of Molecules’ Bonding

et al. 2007

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Functional perfluoropolyether (PFPE) films consisting of mobile and bonded molecules are widely used for lubrication of magnetic disks. In order to clarify the influence of film composition (mobile/bonded) on tribological performance, we measured the friction properties of two types of 2 nm-thick PFPE films (functional Zdol2000 and nonfunctional Z03) under lightly loaded (loading force: 0-1 mN) and quasi-static (low rotational speed: 2.1 mm/s) conditions as a function of elapsed time. The friction force of Z03 remained unchanged with time and increased linearly with loading force as described by Amontons' law. In contrast, induced by the development of the molecules' bonding in time, the friction force of Zdol2000 increased and transited to a nonlinear increase with loading force as time proceeded. The nonlinear friction-load relationship of Zdol2000 in the equilibrium state was characterized by the Johnson-Kendall-Roberts model.

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Section: Measurement Of Film Compositionmentioning

confidence: 99%

Changes in Friction Properties of Monolayer Lubricant Films Induced by Development of Molecules’ Bonding

et al. 2007

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“…Nakakawaji et al suggested that the bonding mechanism between PFPE chains and diamond-like carbon (DLC) surfaces was affected by factors other than photoelectrons from the DLC surface [4]. Zhang et al discussed the interaction between the PFPE molecules and the carbon surface after UV irradiation in air [5]. Because of the presence of oxygen, ozone was generated during the UV treatment.…”

Section: Introductionmentioning

confidence: 99%

Bonding Mechanism of Perfluoropolyether Lubricant Film with Functional Endgroup on Magnetic Disks by Ultraviolet Irradiation

2011

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We studied the bonding mechanism of ultrathin perfluoropolyether (PFPE) lubricant (Fombline Z-tetraol and Moresco D-4OH) films with hydroxyl end groups by measuring the bonding film thickness after ultraviolet (UV) irradiation. Nonfunctional PFPE lubricants (Z-03 and D2 N) were compared to two types of functional PFPE lubricants. The bonded thickness of both functional lubricants increased after a short period of UV irradiation, whereas that of the nonfunctional lubricants did not increase after the same treatment. This result suggests the occurrence of three kinds of mechanisms. First, Z-tetraol and D-4OH bond because of the photodissociation of the end groups by the UV light. Second, they bond because of the interaction between the end groups and the photoelectron from the carbon surface generated by UV irradiation. Third, they bond because of the photodissociation of the main chain by the UV light. In contrast, the dynamic reaction coordinate calculations suggest that the end groups in the PFPE lubricant dissociate because of the electron capture by the lubricant. As a result, we infer that the bonding of PFPE lubricant films with hydroxyl end groups on magnetic disks occurs by selective dissociation of the end groups because of UV irradiation.

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“…Earlier papers attribute the UV bonding of PFPEs to originate from the underlying substrate via UV-induced photoelectrons emitted by the substrate [1][2][3][4][5][6]. The emitted photoelectrons are assumed to attach to the PFPE molecules causing dissociation (e.g., dissociative electron attachment).…”

Section: Introductionmentioning

confidence: 99%

The Photodissociation of Perfluoropolyethers by Ultraviolet Light

Waltman

Guo

2007

Tribol Lett

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Abstact The 172 nm ultraviolet (UV) photodissociation of perfluoropolyether (PFPE) boundary lubricants is examined experimentally and theoretically. Carbonyl fluoride, COF 2 , is the major gas phase product that results from the UV irradiation of non-functionalized perfluoropolyethers containing the perfluoromethylene oxide, perfluoroethylene oxide, and the perfluoro-n-propylene oxide monomer units. The energetics for COF 2 evolution from the carbon centered radicals R-OCF 2 OCF 2 Á , R-CF 2 CF 2 OCF 2 Á ; and from the oxygen centered radicals R-CF 2 OCF 2 O Á , R-CF 2 CF 2 O Á are quantified via ab initio calculations. The electronic structure of the transition state geometries leading to COF 2 dissociation is characterized. COF 2 originating from oxygen-centered radicals, leaving behind a carbon-centered radical on the PFPE main chain, appears to be the most energetically favorable dissociation pathway.

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

Cited by 20 publications

References 22 publications

Changes in Friction Properties of Monolayer Lubricant Films Induced by Development of Molecules’ Bonding

Changes in Friction Properties of Monolayer Lubricant Films Induced by Development of Molecules’ Bonding

Bonding Mechanism of Perfluoropolyether Lubricant Film with Functional Endgroup on Magnetic Disks by Ultraviolet Irradiation

The Photodissociation of Perfluoropolyethers by Ultraviolet Light

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