Bonding of Ethers and Alcohols to a-CN_x Films

Abstract

The surface chemistry of fluorinated ethers and fluorinated alcohols adsorbed on amorphous nitrogenated carbon (a-CN x ) have been studied as models for the interaction of perfluoropolyalkyl ether (PFPE) lubricants with the surfaces of magnetic data storage media. Temperature-programmed desorption experiments conducted in ultrahigh vacuum using small fluorinated ethers and fluorinated alcohols have measured their desorption energies and have provided insight into the nature of bonding between PFPEs and a-CN x films. Preliminary results indicate that ether linkages interact with a-CN x films through electron donation from the oxygen lone pair electrons. In contrast, alcohol end groups show evidence of hydrogen bonding with a-CN x films. The models derived from this study can aid in the future development of both lubricants and protective overcoats to ensure that the magnetic hard disks display optimal wear resistance and performance.

Tribology of Confined Fomblin-Z Perfluoropolyalkyl Ethers: Role of Chain-End Chemical Functionality

“…It is, however, unlikely that a polar group like carboxylic acid 21,42 would fail to physisorb to a polar surface as, for example, the hydroxyl groups in DOL, [19][20][21][22][23][24][25][26]28,29,[32][33][34][35][38][39][40]73 the piperonyl groups in AM2001, 30,31 or the p-phenoxyanilinium group 41 are expected to do.…”

Effect of Heat Treatment Temperature on PFPE Molecules Bonded on DLC Surface

“…One of the features of bonding will be PFPE bonding which occurs when a hydrogen atom is transferred from the hydroxyl end to a dangling bond on the DLC surface 13) . In addition to bonding, hydrogen bonding between the hydroxyl end of the PFPE and an amine terminated sites on the DLC surface may occur because the desorption energy between the hydroxyl end and an amine terminated sites is higher than that between the hydroxyl end and an oxidized site on the DLC surface 5,6) . In this study, the amount of covalent bonding and hydrogen bonding were not quantitatively determined, therefore, a quantitative analysis for the covalent bonds and the hydrogen bonding must be a future study in order to clarify these features.…”

“…For vacuum vapor deposition, the PFPE film can be lubricated on the DLC surface without exposure to the atmosphere, therefore, contamination from the atmosphere does not affect the adsorption between the PFPE molecules and the active sites of the DLC surface during the lubrication process. On the other hand, in the traditional dip-coating method for PFPE lubrication, the heat treatment process can effectively increase the thickness of the bonded layer of the PFPE film [6][7][8][9][10][11] . In this study, the PFPE bonded layer is formed on the DLC surface as a function of the heat treatment time by the dip-coating method and compared to that by the vacuum vapor deposition method.…”

Combined Theoretical and Experimental Investigation of Mechanisms and Kinetics of Vapor-Phase Mercury Uptake by Carbonacoues Surfaces

“…(79) TPD has been used to study oxide formation on tungsten surfaces at high temperature, e.g., > 1200 K. (80,81) At low coverage on tungsten surface, oxygen mainly desorbed as oxygen atoms with first order kinetics. However, as oxygen coverage increased, oxygen desorbed as oxide form.…”

“…(115) Propane was chosen as the adsorbate because it is a representative of non-polar organics and lower hydrocarbons that have received significant research attention. (79) However, to my knowledge, no experimental work has been done on the adsorption behavior of propane on graphite at low temperatures and vacuum pressure.…”