Fluorinated oxide surface

One mole of Mg (24.31 g) reacts with one mole of fluorine gas (38.00 g) to form one mole of magnesium fluoride (62.31 g). Since the oxidation reaction occurs at the surface of each Mg particle, the particles become coated with an oxidized surface layer of Mgp2. The thickness of such an Mgp2 surface layer has been calculated as 0.19 pm.l l... 

When fluorine is deposited onto a silicon oxide surface from a plasma process, it cannot be completely removed even after an extensive period in elevated temperature water. 

Hydrazine (anhydrous) exhibits flammable, explosive, and toxic properties. It is a flammable liquid and bums in air with a violet flame the closed cup flash point is 38°C ( 100°F). The vapors of hydrazine form explosive mixtures with air over a very wide range, between 4.7 and 100% by volume in air. It ignites spontaneously when brought in contact with many porous substances, such as earth, wood, or cloth. Ignition occurs on contact with many metal oxide surfaces and on mixing with oxidizers such as nitric acid or hydrogen peroxide. It forms shock-sensitive explosive products when combined with metal perchlorates, alkali metals, or their dichromates. Spontaneous ignition occurs with fluorine, chlorine, bromine vapors, or nitrous oxide. 

Shibuichi and co-workers prepared super water- and oil-repellent aluminum oxide surfaces by anodic oxidation [19, 21]. Two-aluminum plates were used as the working and the counter electrodes, respectively. After anodic oxidation of aluminum in 0.5 M H2SO4 solution at a constant current density of 10 mA/cm for 3 h, a fractal aluminum oxide was formed on the working electrode. After hydrophobization with fluorinated monoalkylphosphate or IH, IH, 2H, 2H-perfluorodecyltrichlorosilane, the WCA on the surface was measured to be larger than 160°. 

Fabricating Chemical Gradients on Oxide Surfaces by Means of Fluorinated, Catechol-Based, Self-Assembled Monolayers ... 

Recently, capillary action has been used to self-assemble macroscopic objects. Objects of various shapes were cut from polydimethylsiloxane, a polymer that is not wettable by water but is wetted by fluorinated hydrocarbons. Designated surfaces were then made wettable by water by using controlled oxidation. These objects were then floated at an interface between perfluorodecalin (CioFig) and water. When two non-oxidized surfaces (wettable by CioFis) approached each other within a distance of approximately 5 mm, they moved into contact, which with time created an ordered, self-assembled pattern of the objects. The movement and self-assembly was driven by the solvent adhesive forces that produce the capillary action, thereby leading to an elimination of the curved menisci between non-oxidized surfaces. One such pattern is shown to the right. 

Surface modification of polymers involves altering the characteristics of the material. A polymer may be given a low surface tension by fluorinating the surface, or a reactive surface may be introduced. For example, the surface may be exposed to plasma or corona treatments. A plasma is defined as a partially ionized gas, with equal number densities of electrons and positive ions (98). A corona involves a controlled discharge of electrons. Depending on the atmosphere and/or ions used, the surface of a polymer may be oxidized or specific moieties placed on the surface. Thus the bondability of polymers to a surface can be altered significantly. 

Litinskii et al. investigated the contact between the fluoropolymer SKF 32 (fluorine-containing rubber) and three oxide surfaces molybdenum oxide and solid solutions of molybdenum-niobium oxides and molybdenum-technetium oxide [115], Contact appeared when a bond was created between a metal atom and a carbon that lost its fluorine atom. Molecular orbitals on clusters simulating the contact between the fluoropolymer and the oxide surfaces have been computed using the DFT B3LYP/3-21g. Nine contacts between the three available metal atoms (molybdenum, niobium, and technetium) and the three carbon atoms of the fluoropolymer have been studied. Electronic spectra revealed that the molybdenum atom leads to the most favorable contact with the SKF 32 fluoropolymer. A similar analysis has been carried out with ferric and nickel oxides [116]. 

ESCA should be regarded as a powerful technique providing information complementary to that from other branches of spectroscopy, but with unique advantages which mean that for many studies of polymeric systems it may well be the most important. In particular aspects of polymer chemistry, such as dynamic studies of thermal or photochemical degradation, and in studies of polymeric films produced at surfaces by chemical reaction (e.g. fluorination, oxidation, etc.) the information derived from ESCA studies is not obtainable by other techniques. The application of ESCA to such problems is considered briefly in this article, however, more extensive discussion of particular aspects are given in the paper on surface fluorination. 

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