Perfluoropolyether Boundary Lubricants Based on the Star Architecture

Star PFPE (perfluoropolyether) polymers based on an aromatic benzene core and a non-aromatic cyclotriphosphazene (CTP) core are investigated as boundary lubricant films on rigid magnetic media. The effect of the benzene and CTP cores on head-disk spacing are measured by the changes in the acoustic e...

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Autores principales:	Robert J. Waltman, Connie Wiita, Roberto Valsecchi
Formato:	article
Lenguaje:	EN
Publicado:	Japanese Society of Tribologists 2018
Materias:	star polymer perfluoropolyether disk lubricants electronic structure tribology Physics QC1-999 Engineering (General). Civil engineering (General) TA1-2040 Mechanical engineering and machinery TJ1-1570 Chemistry QD1-999
Acceso en línea:	https://doaj.org/article/4e45e1742dec4b2bb118c130cb5cb729
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spelling	oai:doaj.org-article:4e45e1742dec4b2bb118c130cb5cb7292021-11-05T09:19:00ZPerfluoropolyether Boundary Lubricants Based on the Star Architecture1881-219810.2474/trol.13.262https://doaj.org/article/4e45e1742dec4b2bb118c130cb5cb7292018-12-01T00:00:00Zhttps://www.jstage.jst.go.jp/article/trol/13/5/13_262/_pdf/-char/enhttps://doaj.org/toc/1881-2198Star PFPE (perfluoropolyether) polymers based on an aromatic benzene core and a non-aromatic cyclotriphosphazene (CTP) core are investigated as boundary lubricant films on rigid magnetic media. The effect of the benzene and CTP cores on head-disk spacing are measured by the changes in the acoustic emission signal as a function of head-disk spacing at similar lubricant film thicknesses. The earlier head-disk contact observed with the CTP core is attributed in part to its larger size perpendicular to the plane of the disk surface. The adhesion of the benzene and CTP cores to the underlying carbon film is investigated by ab initio quantum chemistry. The non-aromatic nature of the CTP ring and the lack of steric accessibility to the CTP core nitrogen atoms prevent good adhesive interactions with the underlying carbon film. Conversely, the π-electrons of aromatic benzene create a quadrupole moment in the direction perpendicular to the plane of the benzene that can interact with the underlying carbon surface and hence provide weak adhesion. Electron-withdrawing and -donating substituents on the benzene ring can be used to exert a “push-pull” effect on the π-electrons to alter the strength of the intermolecular interactions to specific functional groups of the underlying carbon surface. These effects are visualized by mapping the electrostatic potential of the benzene core as a function of electron-withdrawing and -donating substituents and computing model dimer optimized geometries and intermolecular interaction energies. Finally, the thermal stability of the star PFPE polymers are quantified by measuring the evaporation rate of thin films (11 Å) as a function of time at the HDD temperature (~ 60℃). Thermogravimetric analyses (TGA) of the neat polymers also provide direction for improvement of the synthetic lubricants.Robert J. WaltmanConnie WiitaRoberto ValsecchiJapanese Society of Tribologistsarticlestar polymerperfluoropolyetherdisk lubricantselectronic structuretribologyPhysicsQC1-999Engineering (General). Civil engineering (General)TA1-2040Mechanical engineering and machineryTJ1-1570ChemistryQD1-999ENTribology Online, Vol 13, Iss 5, Pp 262-274 (2018)
institution	DOAJ
collection	DOAJ
language	EN
topic	star polymer perfluoropolyether disk lubricants electronic structure tribology Physics QC1-999 Engineering (General). Civil engineering (General) TA1-2040 Mechanical engineering and machinery TJ1-1570 Chemistry QD1-999
spellingShingle	star polymer perfluoropolyether disk lubricants electronic structure tribology Physics QC1-999 Engineering (General). Civil engineering (General) TA1-2040 Mechanical engineering and machinery TJ1-1570 Chemistry QD1-999 Robert J. Waltman Connie Wiita Roberto Valsecchi Perfluoropolyether Boundary Lubricants Based on the Star Architecture
description	Star PFPE (perfluoropolyether) polymers based on an aromatic benzene core and a non-aromatic cyclotriphosphazene (CTP) core are investigated as boundary lubricant films on rigid magnetic media. The effect of the benzene and CTP cores on head-disk spacing are measured by the changes in the acoustic emission signal as a function of head-disk spacing at similar lubricant film thicknesses. The earlier head-disk contact observed with the CTP core is attributed in part to its larger size perpendicular to the plane of the disk surface. The adhesion of the benzene and CTP cores to the underlying carbon film is investigated by ab initio quantum chemistry. The non-aromatic nature of the CTP ring and the lack of steric accessibility to the CTP core nitrogen atoms prevent good adhesive interactions with the underlying carbon film. Conversely, the π-electrons of aromatic benzene create a quadrupole moment in the direction perpendicular to the plane of the benzene that can interact with the underlying carbon surface and hence provide weak adhesion. Electron-withdrawing and -donating substituents on the benzene ring can be used to exert a “push-pull” effect on the π-electrons to alter the strength of the intermolecular interactions to specific functional groups of the underlying carbon surface. These effects are visualized by mapping the electrostatic potential of the benzene core as a function of electron-withdrawing and -donating substituents and computing model dimer optimized geometries and intermolecular interaction energies. Finally, the thermal stability of the star PFPE polymers are quantified by measuring the evaporation rate of thin films (11 Å) as a function of time at the HDD temperature (~ 60℃). Thermogravimetric analyses (TGA) of the neat polymers also provide direction for improvement of the synthetic lubricants.
format	article
author	Robert J. Waltman Connie Wiita Roberto Valsecchi
author_facet	Robert J. Waltman Connie Wiita Roberto Valsecchi
author_sort	Robert J. Waltman
title	Perfluoropolyether Boundary Lubricants Based on the Star Architecture
title_short	Perfluoropolyether Boundary Lubricants Based on the Star Architecture
title_full	Perfluoropolyether Boundary Lubricants Based on the Star Architecture
title_fullStr	Perfluoropolyether Boundary Lubricants Based on the Star Architecture
title_full_unstemmed	Perfluoropolyether Boundary Lubricants Based on the Star Architecture
title_sort	perfluoropolyether boundary lubricants based on the star architecture
publisher	Japanese Society of Tribologists
publishDate	2018
url	https://doaj.org/article/4e45e1742dec4b2bb118c130cb5cb729
work_keys_str_mv	AT robertjwaltman perfluoropolyetherboundarylubricantsbasedonthestararchitecture AT conniewiita perfluoropolyetherboundarylubricantsbasedonthestararchitecture AT robertovalsecchi perfluoropolyetherboundarylubricantsbasedonthestararchitecture
_version_	1718444408567758848

Perfluoropolyether Boundary Lubricants Based on the Star Architecture

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