The interest in the preparation and application of nanometer size materials is increasing since they can exhibit properties of great industrial interest. Several techniques have been proposed to produce nanomaterials using supercritical fluids. These processes, taking advantage of the specific properties of supercritical fluids, are generally flexible, more simplified and with a reduced enviromental impact. The result is that nanomaterials with potentially better performances have been obtained. We propose a critical review of the supercritical based techniques applied to the production of nanoparticles, nanofibers, nanowires, nanotubes, nanofilms and nanostructured materials. The most relevant characteristics of each process and the kind of nanomaterial that can be produced are highlighted.

Nanomaterials and supercritical fluids

This invention relates to a process of forming a polymeric nanocomposite comprising a continuous polymeric phase formed from a melt processible polymer having a melt processing temperature equal to or greater than about 220 °C and platelet particles having an average thickness equal to or less than about 50 A, and a maximum thickness of about 100 A having a secondary or primary ammonium cationic complex, a quaternary phosphonium cationic complex bonded to surface of said particles, the composite material formed by said process and an article formed from the composite material.

Melt process formation of polymer nanocomposite of exfoliated layered material

An ink-jet recording material comprising an ink receiving layer (A) present near a supporting material which comprises precipitation method silica particles having an average secondary particle diameter of 500 nm or less, or precipitation method silica particles having an average secondary particle diameter of 500 nm or less and gas phase method silica particles having an average secondary particle diameter of 500 nm or less, and further comprises poly(vinyl alcohol) in an amount of less than 20 parts by weight relative to 100 parts by weight of the total silica particles in the ink receiving layer (A), and an ink receiving layer (B) being apart form the supporting material which comprises at least one type of particles selected from among those of a gas phase method silica, alumina and an alumina hydrate and poly(vinyl alcohol) in an amount of less than 25 parts by weight relative to 100 parts by weight of the at least one type of particles.

Ink-jet recording material

Nanocomposites are manufactured by combining a host material, such as an organic solvent or a matrix polymer and exfoliated intercalates formed by contacting a phyllosilicate with a polymer to adsorb or intercalate the polymer between adjacent phyllosilicate platelets. Sufficient polymer is adsorbed between adjacent phyllosilicate platelets to expand the adjacent platelets to a spacing of at least about 5 A, preferably at least about 10 A (as measured after water removal), up to about 100 A and preferably in the range of about 30-40 A, so that the intercalate easily can be exfoliated, e.g., when mixed with an organic solvent or a polymer melt, to provide a carrier material for drugs and the like, or to provide a matrix polymer/platelet composite (nanocomposite) material - the platelets being exfoliated from the intercalate.

Intercalates and exfoliates formed with oligomers and polymers and composite materials containing same

We review recent developments in the preparation of mesoporous metals and related metal-based nanomaterials. Among the many types of mesoporous materials, mesoporous metals hold promise for a wide range of potential applications, such as in electronic devices, magnetic recording media, and metal catalysts, owing to their metallic frameworks. Mesoporous metals with highly ordered networks and narrow pore-size distributions have traditionally been produced by using mesoporous silica as a hard template. This method involves the formation of an original template followed by deposition of metals within the mesopores and subsequent removal of the template. Another synthetic method is the direct-template approach from lyotropic liquid crystals (LLCs) made of nonionic surfactants at high concentrations. Direct-template synthesis creates a novel avenue for the production of mesoporous metals as well as related metal-based nanomaterials. Many mesoporous metals have been prepared by the chemical or electrochemical reduction of metal salts dissolved in aqueous LLC domains. As a soft template, LLCs are more versatile and therefore more advantageous than hard templates. It is possible to produce various nanostructures (e.g., lamellar, 2D hexagonal (p6mm), and 3D cubic (Ia\3d)), nanoparticles, and nanotubes simply by controlling the composition of the reaction bath.

Rational Design of Mesoporous Metals and Related Nanomaterials by a Soft-Template Approach

A composite material comprising a resin other than polyamide resin and a layered silicate dispersed therein, said layered silicate having a layer thickness of 7 to 12 Å and an interlayer distance of 30 Å or above. Owing to the layered silicate uniformly dispersed in the resin matrix, the composite material is superior in mechanical characteristics and heat resistance. It also has good water resistance and chemical resistance.

Composite material containing a layered silicate

Porous platinum fibers synthesized using supercritical fluid

Micropipe defects existing in a silicon carbide single crystal are closed within the single crystal. At least a portion of the micropipe defects opened on the surface of the silicon carbide single crystal (SiC substrate) is sealed up with a coating material. Then heat treatment is performed so as to saturate the inside of the micropipe defects with silicon carbide vapors. By this, the micropipe defects existing in the SiC substrate can be closed within the SiC substrate, not in a newly grown layer. Further, the micropipe defects can be efficiently closed by filling the micropipe defects with a silicon carbide material by preliminarily using super critical fluid and the like.

Method of manufacturing silicon carbide single crystal and silicon carbide single crystal manufactured by the same

A porous material composed of many SiO 4 tetrahedra sheets having interlayer bridges of SiO 2 . It has pores having a diameter of 10 Å or above, and possesses the properties of a solid acid formed by the isomorphous substitution of metal atoms for Si of SiO 4 frameworks. It is made by a process including introducing an organic substance into interlayer space of crystals of layered silicates to expand the spacing between crystal layers, as well as forming bridges of SiO 2 therebetween, bringing the intercalated compounds into contact with a metal salt to link metal atoms to the SiO 4 frameworks, and firing the products. The material can withstand a temperature of 800° C., has a pore diameter larger than that of zeolites, etc., and is useful in making an adsorbent or catalyst for molecules having a high molecular weight, such as a catalyst for the catalytic cracking of petroleum.

Porous material composed of layered silica and metal oxide and a process for manufacturing the same

PURPOSE:To improve hygroscopic capacity, water resistance and humidity conditioning capacity, by using an integral solidified substance consisting of a specific amount of a cellulose fiber, hydrated magnesium silicate clay mineral and an org. binder as a malodor absorbing material. CONSTITUTION:100pts.wt. of a cellulose fiber, 100-3,000pts.wt. of hydrated magnesium silicate clay mineral and 1,000-300,000pts.wt. of water are mixed to prepare a slurry. An org. binder is added to and mixed with said slurry in an amount of 1-20pts.wt. to 100pts.wt. of hydrated magnesium silicate clay mineral on a solid basis. Next, the slurry mixture is dehydrated and molded to form a semi-filter material which is, in turn, dried and solidified to obtain an integrally solidified malodor absorbing material. As hydrated magnesium silicate clay mineral, there is sepiolite or white tile and, as the org. binder, there is acrylonitrile butadiene latex.

Yoshiaki Fukushima

Papers

Composite material containing a layered silicate

Porous platinum fibers synthesized using supercritical fluid

Method of manufacturing silicon carbide single crystal and silicon carbide single crystal manufactured by the same

Porous material composed of layered silica and metal oxide and a process for manufacturing the same

Malodor absorbing material and its preparation