MXPA06004819A - Composite materials comprising metal-loaded nanoparticles - Google Patents

Abstract

Composite materials comprising nanoparticles functionalized with metals are disclosed. The composite materials may be used in a variety of applications, including in coating compositions, cosmetic and pharmaceutical compositions, absorbent articles, and the like.

Description

COMPOSITE MATERIALS THAT COMPRISE NANOPARTICLES CHARGED WITH METAL INTERREFERENC1A TO RELATED REQUEST This application claims the priority of the provisional application of E.U.A. Serial No. 60 / 515,758 filed on October 30, 2003.

FIELD OF THE INVENTION The present invention relates to composite materials that are functionalized nanoparticles and in particular to metal-loaded nanoclays. Additionally, the present invention relates to a method for forming such composite materials.

BACKGROUND OF THE INVENTION During cycles it has been known that metallic silver is an agent capable of killing many different microbial species. It has been commonly used to purify beverage solutions or to be administered to sick people before the existence of modern antibiotics. Even after the discovery of penicillin and its derivatives, colloidal silver solutions are often used in cases in which problematic bacteria become resistant to antibiotics. Colloidal silver solutions are commercially available today. Often, however, they are unstable and have a short shelf life. This is due to the tendency of silver particles to aggregate and form groups so large that they are no longer suspended in solution. For this reason, undesirable gelling agents are added to the solutions to keep the silver particles suspended avoiding aggregation of the particles. Another problem with commercially available solutions is that most of the silver content is usually found as silver ions. This generates a big problem in medical applications and where the silver ions combine rapidly with the ubiquum chloride to form an insoluble white precipitate. It has been known that nanoparticles can be used as fillers, as described in the U.S. Patent. Do not. 6,492,453, as coatings as described in the document of E.U.A. 2003/0185964 and as foam components, as described in Patent of E.U.A. No. 6,518,324. The nanoparticle systems are described in the document of E.U.A. 2002/0150678 are used in a composition and method for imparting surface modification benefits to soft and hard surfaces.

In particular, this application describes a smooth surface coating for articles such as fabrics and garments.

Inorganic particulate materials such as clays, silicates and alumina have been used extensively in combination with detergent auxiliaries and laundry compounds to impart some form of antistatic control and / or a fabric softening benefit. The present invention relates to composite materials comprising a metal loaded on exfoliated nanoparticles. Such functionalized nanoparticles can be incorporated in solid and liquid materials to improve or modify their physical characteristics in bulk and their operation. In one embodiment, the material is silver and the nanoparticle comprises a nanoclay. The silver ion is reduced to its neutral metal state (Ag °) and loaded onto the nanoclay. Silver-coated nanoclays in particular have excellent antimicrobial properties and represent a less expensive alternative to the use of colloidal silver solutions. Such nanoparticles made according to the invention are stable and use less silver metal to generate the same surface area as the solid silver particles, which makes them more cost-effective.

BRIEF DESCRIPTION OF THE INVENTION The invention provides a composite material comprising: (a) an exfoliated nanoparticle having a surface, and (b) a metal selected from groups 13 to 12, aluminum and magnesium, wherein the metal is loaded onto the surface of the nanoparticle.

The invention also provides a method for producing a composite material comprising an exfoliated nanoparticle having a metal coating, which method comprises: (a) reducing a metal ion to metal; (b) exfoliate an initial material to form a nanoparticle; and (c) contacting the metal with the exfoliated nanoparticle, such that steps (a) and (b) can be performed sequentially in any order or simultaneously and the metal is loaded onto the surface of the exfoliated nanoparticle. The invention also provides solutions, solids, gels, coating compositions, cosmetic and pharmaceutical compositions as well as articles of manufacture comprising said composite material.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows the particle size distribution of the material of example 1. Figure 2 shows the particle size distribution of the material of example 5. Figure 3 shows the particle size distribution of the material of example 6. The figure 4 shows the particle size distribution of the material of example 7.

DETAILED DESCRIPTION OF THE INVENTION Each limit provided in this specification includes a lower or upper limit, as the case may be, as if said lower or upper limit was expressly written herein. Each interval that is provided in this specification includes a narrower range within said wider range and said narrower ranges are considered to be all expressly written herein. Nanoparticles, as used herein, means particles (including, but not limited to, rod-shaped particles, disk-shaped particles, flake-like particles, tetrahedral-shaped particles), fibers, nanotubes or any other material that has nanoscale dimensions. In one embodiment, the nanoparticles have an average particle size of from about 1 to about 1000, preferably from 2 to about 750 nanometers. That is, the nanoparticles having a larger dimension (for example a diameter or length) of about 1 to 1000 nm. The nanotubes can include structures up to 1 centimeter long, alternatively with a particle size of from about 2 to about 50 nanometers. The nanoparticles have very high proportions of surface with respect to volume. The nanoparticles can be crystalline or amorphous. A unique type of nanoparticle can be used, or mixtures of different types of nanoparticles can be used. If a mixture of nanoparticles is used, they can be homogeneously or non-homogeneously distributed in the composite material or a system or composition containing the composite material. Non-limiting examples of nanoparticle distributions of suitable particle size are those in the range of about 2 nm to less than about 750 nm, alternatively of about 2 nm to less than about 200 nm, and alternatively of about 2 nm. nm to less than about 150 nm. It should also be understood that certain particle size distributions may be useful to provide certain benefits, and other ranges of particle size distributions may be useful to provide other benefits (eg, color improvement requires a different particle size range). in comparison with other properties). The average particle size of a batch of nanoparticles may differ from the particle size distribution of those nanoparticles. For example, a stratified synthetic silicate can have an average particle size of about 25 nanometers while its particle size distribution can generally vary between about 10 nm and about 40 nm. It should be understood that the particle size distributions described herein are for nanoparticles when dispersed in an aqueous medium and the average particle size is based on the average particle size distribution.

According to the invention, the nanoparticles are exfoliated. In particular, an initial material is exfoliated or distributed to form the nanoparticles. Such initial material can have an average size of up to about 50 micrometers (50,000 nanometers). The nanoparticle may comprise, for example, natural or synthetic nanoclays that include those made from amorphous or structured clays. In one embodiment, the exfoliated nanoparticle is a nanoclay.

In a further embodiment, the nanoparticle is an expandable nanoclay or an adduct thereof. An expandable nanoclay has ions weakly bound in positions between layers that can be hydrated or that absorb organic solvents. These expandable nanoclays generally have a low cationic or anionic charge, that is, less than about 0.9 units of charge per unit cell. As used herein, the term "adducts" means oil expandable nanoclays, i.e., those that expand in non-aqueous organic solvents such as polar and non-polar solvents. They can be prepared by reacting an expandable nanoclay with water, with an organic material that binds to the expandable nanoclay. Examples of such organic binding materials include, but are not limited to a quaternary ammonium compound having the structure: wherein: R1.R2.R3 and 4 are each selected independently of H, an alkyl of 1 to 22 carbon atoms, an alkenyl of 1 to 22 carbon atoms and an aralkyl of 1 to 22 carbon atoms, with the proviso that at least one of the groups R is such as an alkyl , alkenyl or aralkyl; and X is the nanoclay expandable in water. The expandable nanoclay can be amorphous or structured, that is, it can include sheets or layers, wherein a combination of such layers is referred to as a crosslinked structure. Examples of suitable nanoclays having cross-linked structures include pyrophyllite (d-octahedral), talc (trioctahedral) type or mixtures thereof. Suitable classes of structured expandable nanoclays include, but are not limited to, smectite nanoclays, sepiolite nanoclays, zeolite nanoclays, paigorcita nanoclays or mixtures thereof. Examples of amorphous expandable nanoclays include allophane and mogolite. In one embodiment, the nanoparticles are made from an initial material such as Nanomer 1.34TCN (available from Nanocor) having a particle size of 10 to 18 nanometers (10000 - 18000 nanometers). In another embodiment, the nanoparticles are made of PGB (also available from Nanocor) having a particle size of 20 to 25 microns. In another embodiment, exfoliated PGV is used which has a particle size range of 1-3 nanometers. In other embodiments, Nanomer 1.34TCN and Nanomer1.30E having a particle size range of 1-9 nanometers are used. The boehmite alumina may have an average particle size distribution of 2 to 750 nm. Stratified clay minerals can be used as initial materials for exfoliated nanoparticles. Stratified clay minerals suitable for use in the present invention include those in the geological classes of smectites, kaolins, ilutas, cloritas, atapulguitas and mixed stratified clays. Typical examples of specific clays that belong to these classes are smectites, kaolins, ¡Hitas, cloritas, atapulguitas and mixed stratified clays. Smectites, for example, include montmorillonite, bentonite, pyrophyllite, hectorite, saponite, sauconite, nontronite, talc, beidellite, volchonskoite, stevensite, and vermiculite. In one embodiment, the montmorillonite nanoclay is preferred. See U.S. Pat. No. 5,869,033, which is hereby incorporated by reference. Kaolins include kaolinite, dickite, nacrite, antigorite, anauxite, halloisite, indellite and chrysotile. Ilitas include bravaisite, muscovite, paragonite, phlogopite and biotite. The chlorites include corrensite, penninite, donbasita, sudoite, penin and clinochlore. Attapulguitas include sepiolita and polyigorsquita. Mixed stratified clays include allevardite and vermiculitebiotite. The variants and isomorphic substitutions of these stratified clay minerals offer unique applications.

Stratified clay minerals can be as found in nature or synthetic. For example, natural or synthetic hectorites, montmorillonites and bentonites can be used as the starting material for nanoparticles. Natural clay minerals typically exist as stratified silicate minerals and less frequently as amorphous minerals. A stratified silicate mineral has tetrahedral sheets of SiO distributed in a two-dimensional network structure. A layered silicate mineral of type 2: 1 has a laminated structure of several to several tens of silicate sheets having a stratified structure in which an octahedral magnesium sheet or an octahedral aluminum sheet is interposed between two sheets of tetrahedral sheets of silica. A sheet of expandable layer silicate has a negative electric charge and the electric charge is neutralized by the existence of alkali metal cations and / or alkaline earth metal cations. Smectite or expandable mica can be dispersed in water to form a sun with thixotropic properties. In addition, a complex variant of smectite-like clay can be formed by reaction with various organic or inorganic cationic compounds. An example of such an organic complex, an organophilic clay in which a dimethyldioctadecylammonium ion (a quaternary ammonium ion) is introduced by cation exchange. This has been produced industrially and is used as a gelling agent for a coating.

Synthetic nanoclays can be used in the invention. With appropriate procedural controls, the process for the production of synthetic nanoclays actually provides primary particles that are at the nanoscale. However, the particles are usually not present in the form of discrete particles, but rather predominantly assume the form of agglomerates due to the consolidation of the primary particles. Such agglomerates can reach diameters of several thousand nanometers such that the desired characteristics associated with the nanoscale nature of the particles can not be obtained. The particles can be deagglomerated, for example by grinding, as described in EP-A 637,616 or by dispersion in a suitable carrier medium, such as water or water / alcohol and mixtures thereof. Synthetic materials for producing suitable nanoclays include layered hydrous silicate, layered hydrated aluminum silicate, fluorosilicate, mica-montmorillonite, hydrotalcite, lithium magnesium silicate and lithium magnesium fluorosilicate. An example of a substituted variant of lithium magnesium silicate is that in which the hydroxyl group is partially substituted with fluorine. Lithium and magnesium may also be partially substituted with aluminum. The lithium magnesium silicate can be isomorphically substituted by any member selected from the group consisting of magnesium, aluminum, lithium, iron, chromium, zinc and mixtures thereof.

Synthetic hectorite, for example as marketed under the tradename LAPONITEMR by Southern Clay Products, Inc., can be used as starting material for the nanoparticles. There are many grades or variants and isomorphic substitutions of the LAPONITEMR marketed. Examples of commercial hectorites are LAPONITE BMR, LAPONITE S R, LAPONITE XLSMR, LAPONITE RDMR, LAPONITE XLG R and LAPONITE RDMR. Synthetic hectorites do not contain any fluorine. An isomorphic substitution of the hydroxyl group with fluorine will produce synthetic clays called sodium, magnesium and lithium fluorosillcates, which can also be used as the starting material. These sodium, magnesium and lithium fluorosilicts, marketed as LAPONITE R and LAPONITE SMR may contain fluorine ions of up to about 10% by weight. The useful fluorine ion content in the compositions described herein is up to about 10 or more percent. LAPONITE BMR, a sodium, magnesium and lithium fluorosilicate, has a flat, circular and similar flat shape with an average particle size, depending on the fluorine ion content, of about 25-100 nanometers. For example, in a non-limiting embodiment, LAPONITE BMR having a diameter of about 25-40 nm and a thickness of about 1 nm can be used. Another variant, called LAPONITE SMR contains approximately 6% tetrasodium pyrophosphate as an additive. In one embodiment, Laponite XLSMR is used as the initial material for the nanoparticle and silver is loaded therein as the metal.

Laponite XLS has layers of tetrahedral silicate joined by octahedral magnesium and lithium hydroxyl bridges. This structure allows exfoliation and modification either by intercalation or by adsorption of metal to the nanoclay surface. In the case of intercalation, the metal is inserted between the layers of nanoclay. In the case of surface adsorption, the metal binds to the surface of the nanoclay. Laponite XLS is advantageous because it is synthetically consistent and pure, and exfoliates to form nanoclays with minimal effort. The surface of the nanoclay is covered with sodium ions to balance the negative charge of the many silicate groups. The dimensional proportion of the exfoliated nanoparticles, in some cases, is of interest to form films comprising the composite material with the desired characteristics. The dimensional proportion of proportions can be adequately characterized by TEM (transmission electron microscopy). The dimensional proportion of the nanoparticles in one modality can be in the range of 100 to 250. In another embodiment, the dimensional proportion of the nanoparticles is 200 to 350. For example, the average dimensional proportion of individual particles of LAPONITE BMR is of about 20-40 and the average dimensional proportion of individual particles of LAPONITE RDMR is about 10-15. LAPONiTE BMR is found in dispersions as clay particles essentially alone or stacked with 2 clay particles.

LAPONITE RDMR is essentially presented as stacks of two or more unique clay particles. In some embodiments, a high dimensional ratio for film formation may be desirable. The dimensional proportion of exfoliated nanoparticles dispersed in a suitable carrier medium, such as water, are also of interest. The dimensional proportion of the nanoparticles in a dispersed medium is lower when several of the particles are added. In some embodiments, it may be desirable for at least some individual (non-aggregated) nanoparticles in the form of flake and disk having at least one dimension that is greater than or equal to about 0.5 nm, and a dimensional ratio greater than or equal to Equal to about 15. Larger dimensional proportions for nanoparticles in the form of flake and disc than for nanoparticles in the form of a bar may be more desirable. The dimensional proportion of the bar-shaped nanoparticles may be less than those of the disk-shaped or flaked nanoparticles while maintaining the proper film-forming properties. In some non-limiting embodiments, it may be desirable that at least some of the individual rod-shaped nanoparticles have at least one dimension that is greater than or equal to about 0.5 nm and a dimensional ratio greater than or equal to about 3.

The dimensional proportion of nanoparticles in spheroid form is generally less than or equal to about 5. Preferred nanoparticles for the embodiments presented here have dimensional proportions of less than or equal to about 250. In other non-limiting embodiments, it may be desirable that the nanoparticles have a dimensional proportion of less than about 10. According to the invention, one or more metals are used to functionalize the nanoparticle. In particular, they are loaded onto the exfoliated nanoparticle by one of a variety of methods including intercalation, adsorption or ion exchange. Advantageously, the metal retains its useful properties, for example in the case of the antimicrobial properties of the silver while it is on the nanoparticle. The term "charge", as used herein, includes the complete coverage of the surface of the nanoparticle, or alternatively only a portion thereof. In a modality, the metal is selected from groups 3 to 12 of the periodic table of the elements, aluminum and magnesium. Preferably, the metal is selected from silver, copper, zinc, manganese, platinum, palladium, gold, calcium, barium, aluminum, iron and mixtures thereof. In a particularly preferred embodiment, the metal is silver. The metal or metals can be selected based on the desired effect that is to be obtained by using the composite material. For example, silver can be selected for its known antimicrobial properties.

The metal can be loaded onto the nanoparticle via intercalation. For example, silver ions, in particular, can be inserted between the various stratified nanoclay layers by placing it in an "orifice" to maximize the favorable interactions between the positively charged silver ion and the various types of oxygen in the silicate structure. It has been shown that silver ions have antimicrobial properties and Laponite containing intercalated ionic silver retains these properties. Intercalation with other metal ions, such as copper, zinc, manganese, etc., is also possible. The metal can also be loaded onto the nanoparticle via ion exchange. For example, the surface of the Laponite scales consists mainly of sodium ions, which exist to balance the negatively charged oxygen atoms donated by the silicate structure in the underlying layer. When the positively charged metal ions are added to an exfoliated Laponite solution, a fraction of the sodium ion surface is displaced by the added metal cations. The metal can also be loaded onto the nanoparticle by adsorption. For example, some functional groups such as amine, ammonium and carboxyl groups are strong binders for the face or edge of a Laponite scale. The metal ions can be modified by the addition of these ligands so that they are able to bind strongly to the Laponite surface. The reaction sequence for an example is shown in the following: 2AgNO3 + 2NaOH? Ag2O + 2NaN03 + H2O Ag2O + 4NH3 + H2O? 2Ag (NH3) 2OH The final product Ag (NH3) 2 is contacted with Laponite, whereby Ag (NH3) 2OH is bound to the Laponite cane. In one embodiment of the invention, a metal ion is reduced to metal (0) in the presence of an initial material, which is exfoliated to form a nanoparticle. The reduction and exfoliation can be carried out in sequence (either of the steps happens first) or simultaneously upon contacting the metal with the initial material / exfoliated nanoparticle. In this way the metal is loaded onto the surface of the exfoliated nanoparticle. In one embodiment of the invention, the metal is silver, which is loaded onto the nanoparticle via intercalation using the Tollen reagent. The Tollen reagent is a well-known species of silver capable of undergoing reduction either by an aldehyde or ketone to form metallic silver (0): + Ag (NH3) 2OH + glucose? Ag The composite material can be incorporated into a variety of systems, materials and compositions including liquids, solids, gels, coating compositions, cosmetic and pharmaceutical compositions and the like. The composite material can be incorporated into structures or articles of manufacture such as absorbent articles, items for wound care, soft surfaces or hard surfaces. The compositions containing the composite material can be solutions or dry materials that are coated, applied, extruded, sprayed, etc. as further described in the following. Such compositions can have end uses in the processing or in commercial, industrial, personal or domestic applications. The systems comprising the composite material can be used to carry out some desired benefits, for example improved fluid absorbency, susceptibility to wetting, penetration and dispersion, comfort, elimination of odors, lubricity and anti-inflammatory properties, antimicrobial properties, antifungal properties, modification of surface friction, flexibility, transparency, modulus, tensile strength, color improvement, viscosity, smoothness or gel strength. In some embodiments, the presence of the composite material in a composition does not affect the desirable properties of the composition, for example, transparency. The addition of the composite material to a liquid composition, for example, will not alter the transparency or color of the resulting composition compared to the original liquid material that does not contain the composite material. In addition, since the nanoparticles have large surface areas, the composite material will also allow higher concentrations of metals to be included in the general formulation, for example in the treatment of infections.

The compositions of the invention may comprise the composite and any other appropriate ingredient for the proposed use of the compositions. Some compositions of the invention may comprise: (a) the composite material, which may be an effective amount of the composite material; (b) a suitable carrier medium; and (c) optionally one or more auxiliary ingredients. Auxiliary ingredients may be, for example, surfactants or charged functionalized molecules having properties that are selected from the group consisting of hydrophilic, hydrophobic and mixtures thereof related to at least part of the composite, or both. Alternatively, an effective amount of the composite material described in the foregoing may be included in compositions useful for coating a variety of soft surfaces in need of treatment. As used herein, an effective amount of composite material refers to the amount of composite material necessary to impart the desired benefit to the smooth surface. Such effective amounts are easily determined by a person ordinarily skilled in the art and are based on many factors, such as the particular composite material used, the nature of the smooth surface, whether it is a liquid or dry composition (e.g. , dust) if required and similar. The composition can be applied to one or more of the surfaces by washing, spraying, dripping, painting, rubbing or by any other way in order to obtain a coating, especially a clear coating covering at least about 0.5% of the surface , or any greater percentage of the surface, including but not limited to at least about 5%, at least about 10%, at least about 30%, at least about 50%, at least about 80 % and at least approximately 100% of the surface. Accordingly, the coating can be continuous or discontinuous. If the coating composition is to be sprayed onto the surface, the viscosity of the coating composition must be such that it is capable of passing through the nozzle of a spray device. Such viscosities are well known and are incorporated herein by reference. The composition may be capable of undergoing dilution by shearing so that it is capable of being sprayed. Suitable carrier media for compositions containing the composite material include liquids, solids and gases. Another suitable carrier medium is water, which can be distilled, deionized or tap water. Water is useful because of its low cost, availability, safety and compatibility. The pH of the liquid, in particular water, can be adjusted by the addition of acid or base. Aqueous carrier media can also be easily applied to a substrate and then dried. Although aqueous carrier media is more common than dry non-aqueous media, the composition can exist as a dry powder, granule or tablet to a complex encapsulated form. Optionally, in addition to or in place of water, the carrier medium may comprise a low molecular weight organic solvent. Preferably, the solvent is highly soluble in water, for example ethanol, methanol, propanol, isopropanol, ethylene glycol, acetone and the like, and mixtures thereof. The solvent can be used in any suitable concentration. Various non-limiting examples include a concentration of up to about 50% or greater; from about 0.1% to about 25%; from about 2% to about 15% and from about 5% to about 10% by weight of the total composition. The factors to be considered when using a high concentration of solvent in the composition are the odor, the flammability, the dispersibility of the nanoparticles and the environmental impact. The carrier medium may also comprise a film former, which, when dry, forms a continuous film. Examples of film formers are polyvinyl alcohol, polyethylene oxide, polypropylene oxide, acrylic emulsions and hydroxypropylmethylcellulose. Auxiliary ingredients that can be used in composition containing the composite material include polymers and copolymers with at least one segment or group which comprises functionality that serves to anchor the composite material to a substrate. These polymers may also comprise at least one segment or group which serves to provide additional character to the polymer, such as hydrophilic or hydrophobic properties. Examples of the anchor segments or groups include: polyamines, quatemized polyamines, amino groups, quaternized amino groups and corresponding amide oxides; zwitterionic polymers; polycarboxylates; polyethers; polyhydroxylated polymers; polyphosphonates and polyphosphates; and polymeric chelators. Examples of the hydrophilizing segments or groups include: ethoxylated or alkoxylated polyamines; polyamines; polycarboxylated polyamines; water-soluble polyethers; soluble polyhydroxylated groups or polymers including saccharides and polysaccharides; water-soluble carboxylates and polycarboxylates; water-soluble anionic groups such as carboxylates, sulfonates, sulphates, phosphates, phosphonates and polymers thereof; water-soluble amines, quaternary substances, amine oxides and polymers thereof; water-soluble zwitterionic groups and polymers thereof; water-soluble amides and polyamides; and water-soluble polymers and copolymers of vinylimidazole and vinylpyrrolidone. Examples of hydrophobizing segments or groups include: alkyl, alkylene and aryl groups, as well as aliphatic or aromatic polymeric hydrocarbons; fluorocarbons and polymers comprising fluorocarbons; silicones; hydrophobic polyethers such as poly (styrene oxide), poly (propylene oxide), poly (butylene oxide), poly (tetramethylene oxide) and poly (dodecylglycidyl ether); and hydrophobic polyesters such as polycaprolactone and poly (3-hydroxycarboxylic acids). Examples of hydrophilic surface polymers that may be incorporated in the compositions of the invention include, but are not limited to: ethoxylated or alkoxylated polyamides; polycarboxylated polyamines; polycarboxylates including but not limited to polyacrylate; polyethers; polyhydroxyl materials; polyphosphates and phosphonates. Examples of hydrophobic surface polymers that can be incorporated into the compositions of the invention include alkylated polyamides and include, but are not limited to: polyethylenimine alkylated with fatty alkylating agents such as dodecyl bromide, octadecyl bromide, oleyl chloride, dodecyl glycidyl ether and benzyl chloride or mixtures thereof; and polyethylenimine acylated with fatty acylating agents such as methyl dodecanoate and oleoyl chloride; silicones including but not limited to: polydimethylsiloxane having pendant aminopropyl or aminoethylaminopropyl groups and fluorinated polymers including, but not limited to: polymers that include as monomers esters of (meth) acrylates of perfluorinated or highly fluorinated alkyl groups. The non-polymeric surface modifying materials that can be used as auxiliary ingredients include fatty amines and quaternized amines and include: ditallowdimethylammonium chloride; octadecyltrimethylammonium bromide; dioleilamine and benzyltetradecyldimethylammonium chloride.

Surfactants based on silicone, zwitterionic fatty surfactants and fatty amine oxide can also be incorporated into the composition. The surfactants are also optional auxiliary ingredients. The surfactants are especially useful in the composition as wetting agents to facilitate dispersion. Suitable surfactants can be selected from the group including anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, ampholytic surfactants, zwitterionic surfactants and mixtures thereof. Examples of suitable nonionic, anionic, cationic, ampholytic, zwitterionic and non-ionic semi-polar surfactants are described in U.S. Pat. Nos. 5,707,950 and 5,576,282. Nonionic surfactants can be characterized by a HLB (hydrophilic-lipophilic balance) of 5 to 20, alternatively 6 to 15. Mixtures of anionic and nonionic surfactants are especially useful. Other conventional useful surfactants are included in the standard texts. Another class of auxiliary ingredients that may be useful are silicone surfactants and / or silicones. They can be used alone and / or alternatively combined with other surfactants described hereinbefore. Non-limiting examples of silicone surfactants are polyalkylene oxide polysiloxanes having a hydrophobic dimethylpolysiloxane moiety and one or more polyalkylene hydrophilic side chains. If used, the surfactant must be formulated to be compatible with the composite, carrier medium or other adjuvant ingredients present in the composition. The compositions may contain other adjuvant ingredients including, but not limited to alkalinity sources, antioxidants, antistatic agents, chelating agents, aminocarboxylate chelators, metal salts, photoactive inorganic metal oxides, odor eliminating materials, perfumes, photoactivators , polymers, preservatives, processing aids, pigments and pH control agents, solubilizing agents, zeolites and mixtures thereof. These optional ingredients can be included at any desired concentration. The coating compositions comprising the composite material can be used on all types of soft surfaces including but not limited to woven fibers, non-woven fibers, leather, plastic (for example, toothbrush handles, synthetic films, filaments, bristles of toothbrushes) and mixtures thereof. The soft surfaces of interest herein may comprise any known type of soft surface including but not limited to those related to disposable absorbent articles including but not limited to top covers or canvases, absorbent cores, transfer layers, absorbent inserts and supporting or rear canvases that include those outer layers made of films that allow breathing or those that do not allow breathing. It should be understood that in certain embodiments, such a coating composition can be applied to hard surfaces and provide benefits thereto. In some embodiments, the smooth surface may comprise one or more fibers. A fiber is defined as a fine structure similar to hair, of vegetable, mineral or synthetic origin. Commercially available fibers have diameters ranging from less than about 0.001 mm (about 0.00004 inches) to more than about 0.2 mm (about 0.008 inches) and come in several different forms: short fibers (known as short or cut fibers), single fibers continuous (filaments or monofilaments), non-twisted sets of continuous filaments (bundle) and twisted sets of continuous filaments (yarn). The fibers are classified according to their origin, chemical structure or both. They can be braided into ropes or cordage, can be made into felts (also called nonwovens or non-woven fabrics), can be knitted or knitted on textile fabrics, or in the case of high strength, can be used as reinforcements in composite materials - that is, products made from two or more different materials. The smooth surfaces may comprise fibers made by nature (natural fibers), manufactured by man (synthetic or manufactured) or combinations thereof. Examples of natural fibers include, but are not limited to: animal fibers such as wool, silk, skin and hair; vegetable fibers such as cellulose, cotton, a variety of flax, another variety of flax and hemp; and certain mineral fibers that are found naturally. The synthetic fibers can be derived from natural fibers or not. Examples of synthetic fibers which are derived from natural fibers include but are not limited to rayon and lyocell, both of which are derived from cellulose, a natural polysaccharide fiber. Synthetic fibers which are not derived from natural fibers can be derived from other natural sources or from mineral sources. The example of synthetic fibers derived from natural sources includes, but is not limited to polysaccharides such as starch. Examples of fibers from mineral sources include, but are not limited to, polyolefin fibers such as polypropylene and polyethylene fibers, which are derived from petroleum, and silicate fibers such as glass and asbestos. Synthetic fibers are commonly formed, when possible, by fluid handling methods (eg extrusion, drawing or spinning of a fluid such as a resin or a solution). Synthetic fibers are also formed by solid size reduction methods (for example grinding or mechanical cutting of a larger object such as a monolith, a film or a fabric). Disposable absorbent articles such as panty liners, sanitary napkins, interlabial devices, adult incontinence devices, brassiere pads, shoe insoles, bandages and diapers are typically made of absorbent non-woven materials (including fibers) and they are well known in the art. These articles typically have a fluid-permeable, body-facing side and a garment-facing, waterproof side. Additionally, said articles may include an absorbent core for retaining fluids therebetween. The addition of the composite material to a manufacturing article such as an absorbent core of an absorbent and disposable article can help control odor formation and increase absorbency. Other uses for the composite material include, but are not limited to, use on tooth abrasives for odor absorbing toothpastes and mouth rinses. Other uses for the composite material include ophthalmic solutions and devices such as contact lenses. Another embodiment of the invention relates to cosmetic and pharmaceutical compositions comprising the composite material. These may be in the form of creams, lotions, gels, foams, oils, ointments or powders for application to tissues that include skin, hair, nails and mucosa such as the vaginal or buccal mucosa. Such compositions can be formulated as leaving products or as products that are rinsed off. Alternatively, such compositions may also be in the form of ophthalmic solutions or ointments, which are applied directly to the eye. In one embodiment, the composition contains an anti-acne agent such as salicylic acid or benzoyl peroxide.

In another embodiment, the composition is a personal lubricant such as those described in USSN Nos. Serial 10 / 137,509; 10 / 390,511 and 10 / 389,871 filed on 05/01/2002; 03/17/2003; 03/17/2003, respectively. These applications describe heated lubricating compositions that are non-toxic and non-irritating and that can be used as personal lubricants designed to come into contact with the skin or mucosa. When mixed with water, said compositions increase the temperature or generate a sensation of heat. This is a calming effect on the tissues to which these compositions are applied. These compositions are preferably substantially anhydrous and preferably contain at least one polyhydric alcohol. By incorporating the composite material in these personal lubricants, the resulting compositions have a smoother characteristic and remain as clear solutions, since the composite material does not reduce the transparency of the compositions. The cosmetic and pharmaceutical compositions may contain a variety of active agents known in the art such as skin lightening agents, skin pigmentation darkening agents, anti-acne agents, tallow modulators, gloss control agents, agents antimicrobials, antifungals, anti-inflammatory agents, antifungal agents, anti-parasite agents, external analgesics, sunscreens, sunscreens, antioxidants, keratolytic agents, detergents, surfactants, moisturizers, nutrients, vitamins, energy enhancers, antiperspirant agents, astringents, deodorants , hair removers, agents for firmness, anti-callus agents and agents for conditioning hair, nails or skin. Formulations for topical or mucosal application are well known in the art. The excipients used by those skilled in the art in such formulations can be used with the composite material herein, provided they are compatible. The compositions of the present invention can be applied to a surface and optionally allowed to dry on the surface, optionally repeat the application and the drying steps as needed. In some embodiments of the methods described herein, which include but are not limited to the time when more than one coating is applied, it is not necessarily required that one or more of the coatings dry between applications.

EXAMPLES EXAMPLE 1 In order to deposit metallic silver on nanoclay, silver ions are reduced in the presence of Laponite using the Tollen reagent which is capable of undergoing reduction either by an aldehyde or ketone to form metallic silver via the following reaction: Ag (NH3) OH + glucose? Ag The Tollen reagent is prepared by adding two drops of 10% NaOH to 5 ml of 5% AgNO3 to form a gray-brown precipitate. This precipitate is then dissolved by the dropwise addition of 2% NH 4 OH to provide the total Tollen reagent volume of 30 ml. A solution of Laponite XLS loaded with silver is prepared by adding 600 mg of Laponite XLS to 50 ml of distilled water and using a magnetic stirrer to exfoliate for 20 minutes. 800 mg of glucose are added to this solution and stirring is continued for 10 minutes to ensure complete dissolution of the glucose. To this is added 10 ml of the Tollen reagent prepared before. After 2 hours of continuous stirring, the solution turns golden yellow. The additional reaction time provides a dark amber-brown solution. Samples prepared for particle size analysis and TEM analysis are diluted by a factor of 10 to avoid particle aggregation. The particle size of the nanoparticles determines the color of the solution caused by the surface plasmon resonance phenomenon. For silver particles it has been determined that a yellow color has the smallest particle size possible. The particle size distribution of the resulting nanoparticles are shown in Figure 1.

EXAMPLE 2 We also investigated the formation of metallic silver from silver ions using NaBH: 4AgN03 + NaBH4? 4Ag ° The dropwise addition of 32 mg of AgNO3 dissolved in 5 ml of H20 to a solution containing 500 mg of Laponite XLS exfoliated and 4 mg of NaBH4 provides a golden yellow solution. This order of addition for this particular reaction is determined to provide the smallest particle size.

EXAMPLE 3 Silver-Laponite nanoparticles are prepared by reduction with sodium citrate, although reduction by this method is more difficult to control. Citric acid is added to an exfoliated solution of Laponite XLS, followed by the addition of silver nitrate. 10% NaOH is added dropwise to form the sodium salt of citric acid until the solution becomes slightly yellow. In many cases, the excessive addition of sodium hydroxide causes the silver particles to settle out of the solution. AgNO3 + sodium citrate? Ag ° EXAMPLE 4 Laponite XLS nanoparticles loaded with silver can be prepared by reduction with hydrazine as follows: 5 g of Laponite XLS are added to 995 g of deionized water and stirred for 20 minutes to exfoliate the Laponie XLS. 20 mg of hydrazine hydrate 55% is added to the Laponite XLS dispersion and the solution is stirred for 1 minute. 77mg of AgNO3 is dissolved in deionized water. The AgN03 solution is added dropwise to the Laponite-hydrazine solution to form a golden-yellow solution containing 0.005% Laponite XLS loaded with silver.

EXAMPLE 5 Another solution of Laponite XLS loaded with silver is prepared in a similar manner to Example 1 but the order of the components is altered. Glucose and Tollen's reagent are mixed in a separate container and once the color of the solution becomes slightly gray, this mixture is added to the exfoliated Laponite XLS solution. After a short period of agitation, the solution becomes amber-yellow. This solution is diluted by a factor of 10 for particle size analysis. Figure 2 shows the particle size distribution of the resulting material.

EXAMPLE 6 A sample is prepared by adding 200 mg of Laponite XLS to 100 ml of water and shaking to exfoliate. The sample is analyzed for particle size. The results are presented in figure 3.

EXAMPLE 7 The sample of example 6 is diluted by a factor of 50. The sample is analyzed for particle size. In Figure 4 the results are shown. The results of examples 1-7 indicate that as a solution of Laponite XLS in water is diluted, the distribution of particle sizes changes. The particle size of Laponite XLS loaded with silver is smaller, on average than Laponite XLS alone, which indicates that the addition of silver to the solution helps in the Laponite XLS exfoliation process. The data for Example 1 show that the single particle size distribution, which averages a size of 4.1 nm. On the other hand, in example 5, a bimodal particle size distribution is shown with the averages centered at 4.1 nm and 11 nm. This indicates the formation of two different types of particles. It is possible that this solution contains Laponite XLS loaded with silver and colloidal silver without Laponite core.

EXAMPLE 8 To verify that Laponite XLS is being coated with silver, images of TEM (transmission electron microscopy) and EDX (energy dispersive X-ray) analysis are carried out in examples 1 and 6. The data confirm that the composite material of Example 1 contains Laponite XLS particles loaded with silver, as opposed to a mixture of colloidal silver and Laponite XLS. The elemental analysis shows the presence of Na, Mg, Si and Ag (Cu is present in the TEM grid). The data also show that particles of very small size («1 nm) were determined to be uncoated Laponite XLS, and that they are also present.

EXAMPLE 9 A solution is prepared as follows containing particles of Laponite XLS loaded with silver. 4.51 g of Laponite XLS are added to 900 ml of deionized water. The solution is stirred for 1 hour and labeled as solution A. To 400 ml of solution A is added 15 mg of NaBH. This solution is labeled as solution B. 124 mg of AgNO3 are dissolved in 5 ml of deionized water and this is added dropwise to solution B to form a 0.02% silver-brown amber solution loaded in Laponite XLS. Following the above procedure, silver solutions of 0.01%, 0.005% and 0.0025% loaded in Laponite XLS are prepared. These solutions are analyzed to determine biocidal activity against the organisms Staphylococcus aureus and Escherichia coli, as follows. Laponite XLS solutions loaded with silver are inoculated with the bacteria and neutralized with Letheen broth containing 1.5% to neutralize the activity after the appropriate time. The aliquots are seeded on plates using Letheen agar. The logarithmic bacterial reduction is given in the following table. , 10

Claims (23)

NOVELTY OF THE INVENTION CLAIMS

1. A composite material comprising: (a) an exfoliated nanoparticle having a surface, and (b) a metal selected from groups 3 to 12, aluminum and magnesium, wherein the metal is loaded onto the surface of the nanoparticle.

2. The composite material according to claim 1, J O further characterized in that the metal is loaded onto the surface of the nanoparticle by intercalation.

3. The composite material according to claim 1, further characterized in that the metal is loaded onto the surface of the nanoparticle by adsorption.

4. The composite material according to claim 1, further characterized in that the metal is loaded onto the surface of the nanoparticle by ion exchange.

5. The composite material according to claim 1, further characterized in that the metal is selected from the group consisting of silver, copper, zinc, manganese, platinum, palladium, gold, calcium, barium, aluminum, iron and mixtures thereof. the same.

6. The composite material according to claim 1, further characterized in that the nanoparticle comprises a nanoclay.

7. - The composite material according to claim 1, further characterized in that the nanoparticle comprises exfoliated Laponite.

8. A solution comprising the composite material defined in claim 1.

9. A solid comprising the composite material defined in claim 1.

10. A gel comprising the composite material that is defined in claim 1.

11. A composition comprising the composite material that is defined in claim 1.

12. The composition according to claim 11, further characterized in that it comprises one or more auxiliary ingredients and a carrier medium. .

13. The composition according to claim 12, further characterized in that the auxiliary ingredients are selected from surfactants and charged functionalized molecules.

14. The composition according to claim 12, further characterized in that the carrier medium comprises an aqueous carrier medium.

15. A cosmetic or pharmaceutical composition comprising the composite material defined in claim 1.

16. The composition according to claim 15, further characterized in that it comprises an active agent that is selected from skin lightening agents. , skin pigmentation obscuring agents, anti-acne agents, sebum modulators, gloss control agents, antimicrobial agents, antifungals, anti-inflammatory agents, anti-fungal agents, anti-parasite agents, external analgesics, sunscreens, sunscreens , antioxidants, keratolytic agents, detergents, surfactants, humectants, nutrients, vitamins, energy enhancers, antiperspirant agents, astringents, deodorants, hair removers, agents for firmness, anti-callus agents and agents to condition hair, nails or hair skin.

OR 17.- A method for producing a composite material consisting of exfoliated nanoparticles having a metal coating, which method is characterized in that it comprises: (a) reducing a metal ion to metal; (b) exfoliating an initial material to form an exfoliated nanoparticle; and (c) contacting the metal with the exfoliated nanoparticle, whereby the steps (a) and (b) can be carried out sequentially in any order or simultaneously and the metal is loaded onto the surface of the exfoliated nanoparticle.

18. The method according to claim 17, further characterized in that the metal is loaded onto the surface of the nanoparticle by intercalation.

19. The method according to claim 17, further characterized in that the metal is loaded onto the surface of the nanoparticle by adsorption.

20. - The method according to claim 17, further characterized in that the metal is loaded onto the surface of the nanoparticle by ion exchange.

21. The method according to claim 17, further characterized in that the metal is selected from the group consisting of silver, copper, zinc, manganese, platinum, palladium, gold, calcium, barium, aluminum, iron and mixtures thereof. same.

22. The method according to claim 17, further characterized in that the nanoparticle comprises a nanoclay.

23. The method according to claim 22, further characterized in that the nanoparticle comprises exfoliated Laponite.