United States of America as Represented by the Administrator of Nasa

Ohio Aerospace Institute

National Institute of Aerospace Associates

Haiquan Guo

Mary Ann B Meador

Baochau N Nguyen

Frances I Hurwitz

Emilie J Siochi

Godfrey Sauti

Tian-Bing Xu

Mary Ann Meador

Charles L Bennett

Stephen P Wilkinson

Tobias Marriage

Thomas M Essinger-Hileman

The present invention relates to broadband and tunable infrared (IR)-blocking optical filters for millimeter and sub-millimeter astronomy composed of small diffusely scattered particles embedded in an aerogel substrate. The size of the scattering particles included in the aerogel filters can be tuned to give variable cutoff frequencies. In one embodiment, the aerogel scattering optical filters of the present invention have ultra-low density and index of refraction (typically n&#x3c;1.15), removing the need for anti-reflection coatings that limit bandwidth and increase filter complexity, and allowing for high transmission across an ultra-broad band from zero frequency to above 1 THz, and as much as 10 THz.

Optical filter having polyimide aerogel substrate and infrared radiation scattering particles

Aerogels, aerogel composites and methods of making the same are discussed. One example method can include the act of creating a Boehmite colloid and adding a hydrolyzed silicon precursor to form a sol. A reinforcement can be infused with the sol, gelled to form a gel, then dried to form an aerogel composite. Such a method can also include the acts of performing one or more solvent exchanges and subjecting the gel composite to subcritical drying. Additionally, such a method can include the act of heat treating the aerogel composite. The aerogel composite can be used in high temperature, flexible seals capable of withstanding temperatures, pressures, and compression levels associated with aerodynamic heating generated during flight and in aerospace applications. The aerogel composite also can be used in thermal protection systems designed for fire protection for structures or in personnel fire protective equipment.

High temperature, hydrophobic, flexible aerogel composite and method of making same

Porous cross-linked partially aliphatic polyimide networks are provided. The polyimide networks comprise a polyamic acid oligomer that (i) comprises a repeating unit of a dianhydride and a diamine and terminal functional groups, (ii) has an average degree of polymerization of 10 to 70, (iii) has been cross-linked via a cross-linking agent, comprising three or more cross-linking groups, at a balanced stoichiometry of the cross-linking groups to the terminal functional groups, and (iv) has been chemically imidized to yield the porous cross-linked polyimide network. The polyimide networks are partially aliphatic based on (a) the diamine comprising a first diamine and a second diamine, wherein the first diamine comprises a linear aliphatic backbone chain, and the second diamine does not, and/or (b) the dianhydride comprising a first dianhydride and a second dianhydride, wherein the first dianhydride comprises a linear aliphatic backbone chain, and the second dianhydride does not.

Porous cross-linked partially aliphatic polyimide networks

Aerogels, aerogel composites and methods of making the same are discussed. One example method can include the act of creating a Boehmite colloid and adding a hydrolyzed silicon precursor to form a sol. A reinforcement can be infused with the sol, gelled to form a gel, then dried to form an aerogel composite. Such a method can also include the acts of performing one or more solvent exchanges and subjecting the gel composite to supercritical drying. Additionally, such a method can include the act of heat treating the aerogel composite. The aerogel composite can be used in high temperature, flexible seals capable of withstanding temperatures, pressures, and compression levels associated with aerodynamic heating generated during flight and in aerospace applications. The aeorogel composite also can be used in thermal protection systems designed for fire protection for structures or in personnel fire protective equipment.

An aerogel and process of making the aerogel are provided. The aerogel is a polyimide aerogel having polyamide cross-links formed using a poly(maleic anhydride) cross-linker.

Polyalkylene imide aerogels and processes for making the same

Robust, flexible, lightweight, low profile enhanced performance dielectric barrier discharge actuators (plasma actuators) based on aerogels/nanofoams with controlled pore size and size distribution as well as pore shape. The plasma actuators offer high body force as well as high force to weight ratios (thrust density). The flexibility and mechanical robustness of the actuators allows them to be shaped to conform to the surface to which they are applied. Carbon nanotube (CNT) based electrodes serve to further decrease the weight and profile of the actuators while maintaining flexibility while insulating nano-inclusions in the matrix enable tailoring of the mechanical properties. Such actuators are required for flow control in aeronautics and moving machinery such as wind turbines, noise abatement in landing gear and rotary wing aircraft and other applications.

Robust, flexible and lightweight dielectric barrier discharge actuators using nanofoams/aerogels

Porous cross-linked polyimide networks are provided. The networks comprise an anhydride end-capped polyamic acid oligomer. The oligomer (i) comprises a repeating unit of a dianhydride and a diamine and terminal anhydride groups, (ii) has an average degree of polymerization of 10 to 50, (iii) has been cross-linked via a cross-linking agent, comprising three or more amine groups, at a balanced stoichiometry of the amine groups to the terminal anhydride groups, and (iv) has been chemically imidized to yield the porous cross-linked polyimide network. Also provided are porous cross-linked polyimide aerogels comprising a cross-linked and imidized anhydride end-capped polyamic acid oligomer, wherein the oligomer comprises a repeating unit of a dianhydride and a diamine, and the aerogel has a density of 0.10 to 0.333 g/cmand a Young's modulus of 1.7 to 102 MPa. Also provided are thin films comprising aerogels, and methods of making porous cross-linked polyimide networks.

Porous cross-linked polyimide networks

Ceramic oxide aerogels having improved flexibility are disclosed. Preferred embodiments exhibit high modulus and other strength properties despite their improved flexibility. The gels may be polymer cross-linked via organic polymer chains to further improve strength properties, without substantially detracting from the improved flexibility. Methods of making such aerogels are also disclosed.

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Avon, OH, United States of America

Haiquan Guo