Preparation of new perfluoro ether fluids exhibiting excellent thermal-oxidative stabilities

Abstract

A series of low molecular weight perfluoroalkyl ethers (PFAEs) were synthesized by direct fluorination. Viscosity-temperature properties and oxidation stabilities were determined. Viscosity-temperature correlations indicated that increases in branching and increases in the size of the branching substituent caused a deterioration in viscometric properties (i.e., an increase in ASTM slope). In addition, increasing the ratio of carbon to oxygen in these compounds also increased the ASTM slope. Preliminary oxidation stability measurements indicated that highly branched PFAE fluids (i.e., those containing quaternary carbons) may be less stable than either those containing a single trifluoromethyl pendant group or those containing no branching at all. Perfluoroalkyl ethers are a class of fluids which exhibits excellent thermal and oxidative stabilities (Gumprecht,

The interaction of short-chain model lubricants with the surfaces of hydrogenated amorphous carbon films

“…We postulate that the electron withdrawing nature of the fluorine substituents or steric hindrances of the large CF2 groups prevent an interaction of the oxygen lone pairs with surface and thus have little effect on desorption energies. While relatively inactive in the adsorption process, oxygen linkages do improve the oxidation stability and tailor characteristics such as viscosity, lubricity, surface tension and fluid density and are considered a vital component of the lubricant system [21].…”

Estimation and analysis of the rheological properties of a perfluoropolyether through molecular dynamics simulation

“…There is a general, macroscopic understanding of the structure-property relationship of the constituent units in PFPE molecules and the rheological behavior. For example, as the amount of branching and the size of the substituent increase, the viscosity-temperature dependence will be adversely affected [3,4]. However, the properties of lubricants measured experimentally combine the effect of various aspects of molecules, such as orientation and intermolecular and intramolecular interactions.…”

Mechano-responsive microcapsules with uniform thin shells

“…26 Additionally, fluorinated polymers typically have a low surface tension and a low friction coefficient. [30][31][32] These features, combined with render them attractive shell materials for capsules that display a low permeability towards hydrophilic and hydrophobic encapsulants. Hence, these capsules can be employed even in products encompassing a wide range of different solvents.…”