Mechanism of ultraviolet and electron bonding of perfluoropolyethers

Vurens, G.H.; Gudeman, Christopher S.; Lin, Li-Shin; Foster, John S.

doi:10.1021/la00040a024

Cited by 58 publications

(46 citation statements)

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“…The technique of enhancing adhesion of PFPE lubricants to the carbon overcoat by irradiation with short-UV (185 nm) was first reported by Saperstein and Lin some time ago [9]. Later, Vurens et al suggested that photoelectrons emanating from the carbon layer were responsible for the observed efficacy [10]. Capture of one of these low energy electrons by a PFPE molecular chain would lead to detachment of a fluoride anion and formation of a radical center on the polymer backbone.…”

Section: A20h and C2: Tof-sims Studymentioning

confidence: 99%

Disk Lubricant Additives, A20H and C2: Characteristics and Chemistry in the Disk Environment

Kasai

Wakabayashi

2008

Tribol Lett

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Disk lubricant additives A20H and C2 are Fomblin Z type perfluoropolyether with the hydroxyl endgroup, -O-CF 2 -CH 2 -OH, at one end, and the cyclo-triphosphazene end-group, R 5 (PN) 3 -O-, at the other end. Here, R is an m-trifluoromethyl-phenoxy group for A20H and a trifluoroethoxy group for C2. These additives were examined for miscibility with benzene, spin-off rate, water contact angle, and the diffusion rate over the carbon overcoat. It is revealed that A20H adheres to the carbon overcoat spontaneously. The attractive interaction arises from the charge-transfer type interaction between the aromatic rings of the phosphazene end and the graphitic regime of the carbon overcoat. No spontaneous adherence occurs between the lubricant C2 and the carbon overcoat. A TOF-SIMS study of disks coated with A20H and C2, respectively, with and without subsequent curing by short-UV (185 nm) was performed. It is revealed: (1) if presented with a low energy electron, the phenoxy groups of A20H readily undergo the dissociative electron capture, while the trifluoroethoxy group does not, and (2) photoelectrons generated by short-UV have little kinetic energy and the electron capture occurs only if an electrophilic molecular sector is in intimate contact with the carbon. Thus, in the case of disks coated with A20H, UV-curing results in detachment of a phenoxy group in contact with the carbon, generation of a radical center at the phosphorus atom and subsequent formation of a bona fide chemical bond between the phosphor and the carbon overcoat. No reaction of consequence occurs when disks coated with C2 are irradiated with short-UV.

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Section: A20h and C2: Tof-sims Studymentioning

confidence: 99%

Disk Lubricant Additives, A20H and C2: Characteristics and Chemistry in the Disk Environment

Kasai

Wakabayashi

2008

Tribol Lett

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“…Liu et al [32] studied the catalytic decomposition of Fomblin Zdol in the presence of the Lewis acid Al 2 O 3 using thermogravimetric analysis (TGA). Lewis acid catalysis [33][34][35], triboelectrons [36], and tribomechanical shearing [37,38] have all been demonstrated to decompose PFPEs. The environment has noticeable influence on performance and durability of the PFPE lubricant that can be weakened at high humidity [39].…”

Section: Introductionmentioning

confidence: 99%

Study of the Thermal Decomposition of PFPEs Lubricants on a Thin DLC Film Using Finitely Extensible Nonlinear Elastic Potential Based Molecular Dynamics Simulation

Nath

Wong

2014

Journal of Nanotechnology

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Perfluoropolyethers (PFPEs) are widely used as hard disk lubricants for protecting carbon overcoat reducing friction between the hard disk interface and the head during the movement of head during reading and writing data in the hard disk. Due to temperature rise of PFPE Zdol lubricant molecules on a DLC surface, how polar end groups are detached from lubricant molecules during coating is described considering the effect of temperatures on the bond/break density of PFPE Zdol using the coarse-grained bead spring model based on finitely extensible nonlinear elastic potential. As PFPE Z contains no polar end groups, effects of temperature on the bond/break density (number of broken bonds/total number of bonds) are not so significant like PFPE Zdol. Effects of temperature on the bond/break density of PFPE Z on DLC surface are also discussed with the help of graphical results. How bond/break phenomenonaffects the end bead density of PFPE Z and PFPE Zdol on DLC surface is discussed elaborately. How the overall bond length of PFPE Zdol increases with the increase of temperature which is responsible for its decomposition is discussed with the help of graphical results. At HAMR condition, as PFPE Z and PFPE Zdol are not suitable lubricant on a hard disk surface, it needs more investigations to obtain suitable lubricant. We study the effect of breaking of bonds of nonfunctional lubricant PFPE Z, functional lubricants such as PFPE Zdol and PFPE Ztetrao, and multidented functional lubricants such as ARJ-DS, ARJ-DD, and OHJ-DS on a DLC substrate with the increase of temperature when heating of all of the lubricants on a DLC substrate is carried out isothermally using the coarse-grained bead spring model by molecular dynamics simulations and suitable lubricant is selected which is suitable on a DLC substrate at high temperature.

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“…Another approach to improve the durability of PFPE is UV bonding (Bhushan 1996;. Vurens et al (1992) reported that UV light could cause photoelectrons emission from the substrate, which will interact with the PFPE molecules to form a negative ion resonance state followed by a possible dissociative electron attachment (see Fig. 6c).…”

Section: Durability Of Lubricant Filmsmentioning

confidence: 99%

Lubrication of advanced metal evaporated tape using novel perfluoropolyether lubricants

Bhushan

Tao

2006

Microsyst Technol

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In order to reduce the failure of advanced metal evaporated (AME) tape, novel perfluoropolyether (PFPE) lubricants, Z-TETRAOL and A20H, were deposited on an unlubricated AME tape. The degradation mechanisms of the PFPE lubricants applied on AME tape were studied using a mass spectrometer in high vacuum. The durability of various lubricants was compared using pin-on-disk experiments in high vacuum and using an accelerated tape tester in ambient air. It was found that PFPE lubricants were mainly degraded by tribochemical reaction and mechanical shear. The durability of Z-TETRAOL and A20H are higher than conventional PFPE lubricant and lubricant on experimental tape. By using ultraviolet light treatment and by applying a stearic acid overcoat, the durability of PFPE lubricants could be improved.

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Mechanism of ultraviolet and electron bonding of perfluoropolyethers

Cited by 58 publications

References 0 publications

Disk Lubricant Additives, A20H and C2: Characteristics and Chemistry in the Disk Environment

Disk Lubricant Additives, A20H and C2: Characteristics and Chemistry in the Disk Environment

Study of the Thermal Decomposition of PFPEs Lubricants on a Thin DLC Film Using Finitely Extensible Nonlinear Elastic Potential Based Molecular Dynamics Simulation

Lubrication of advanced metal evaporated tape using novel perfluoropolyether lubricants

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