United States of America As Represented by the Secretary of the Air Force

Raymond Campos

Joseph M Mabry

Andrew J Guenthner

Timothy S Haddad

Treated, mesoporous aggregates comprising a plurality of coated particles that comprise an inorganic oxide core having a surface area of about 50 to about 500 square meters per gram and a shell or coating consisting of an array of fluoroalkyl molecular chains covalently bonded to the core at a density of at least one chain per square nanometer. The aggregates are formed by the chemical attachment of fluoroalkyl-alkylsilanes after exposure to an alkylamine and followed by an extraction to remove any unbound organic material. The dense packing of molecular chains in the fluoroalkyl shell combined with a mesoporous structure imparts a very low surface energy, a very high specific surface area, and surface texture over a wide range of length scales. Such features are highly desirable for the creation of, for example, superhydrophobic and superoleophobic surfaces, separation media, and release films.

Fluoroalkylsilanated mesoporous metal oxide particles and methods of preparation thereof

Coated particles comprise a core of fumed or precipitated inorganic metal oxide having a surface area of about 50 to about 500 square meters per gram and a shell consisting of an array of fluoroalkyl molecular chains at a density of at least 1 chain per square nanometer, joined to the core by covalent chemical bonds and with a total organic content of at least 9.9 percent by weight. These particles are formed by the chemical attachment of fluoroalkyl-alkylsilanes after exposure to an alkylamine and followed by an extraction to remove any organic material not covalently bound. The dense packing of molecular chains in the fluoroalkyl shell combined with a mesoporous structure imparts a very low surface energy, a very high specific surface area, and surface texture over a wide range of length scales. Such features are highly desirable for the creation of, for example, superhydrophobic and superoleophobic surfaces, separation media, and release films.

Fluoroalkylsilane-treated metal oxide particles and a fluoroelastomeric binder are dispersed in a fluorinated solvent with a low boiling point and applied to a substrate via spray deposition. The spray deposition process rapidly produces a conformal coating that features low surface energy and surface topography with a large range of characteristic length scales and re-entrant curvature, thereby imparting superoleophobicity. The degree of superoleophobicity is readily adjusted by means of altering the ratio of particles to binder. The choice of particle and binder result in coatings with thermal stability for thousands of hours at temperatures up to 200 degrees Celsius as well as desirable mechanical characteristics.

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Lancaster, CA, United States of America

Raymond Campos