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.
Disalvo, Anthony L.; (Bernardsville, NJ); Mordas, Carolyn J.; (Princeton, NJ)
Correspondence Name and Address:
PHILIP S. JOHNSON
JOHNSON & JOHNSON
ONE JOHNSON & JOHNSON PLAZA
November 1, 2004
U.S. Current Class:
U.S. Class at Publication:
B32B 015/02; B32B 018/00; A61K 007/00
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
2. The composite material of claim 1, wherein the metal is loaded onto the
surface of the nanoparticle by intercalation.
3. The composite material of claim 1, wherein the metal is loaded onto the
surface of the nanoparticle by adsorption.
4. The composite material of claim 1, wherein the metal is loaded onto the
surface of the nanoparticle by ion exchange.
5. The composite material of claim 1, wherein the metal is selected from
the group consisting of silver, copper, zinc, manganese, platinum,
palladium, gold, calcium, barium, aluminum, iron, and mixtures thereof.
6. The composite material of claim 1, wherein the nanoparticle comprises a
7. The composite material of claim 1, wherein the nanoparticle comprises
8. A solution comprising the composite material of claim 1.
9. A solid comprising the composite material of claim 1.
10. A gel comprising the composite material of claim 1.
11. A composition comprising the composite material of claim 1.
12. The composition of claim 11, further comprising one or more adjunct
ingredients and a carrier medium.
13. The composition of claim 12, wherein the adjunct ingredients are
selected from surfactants and charged functionalized molecules.
14. The composition of claim 12, wherein the carrier medium comprises is
an aqueous carrier medium.
15. A cosmetic or pharmaceutical composition comprising the composite
material of claim 1.
16. The composition of claim 15, further comprising an active agent
selected from skin lightening agents, skin pigmentation darkening agents,
anti-acne agents, sebum modulators, shine control agents, anti-microbial
agents, anti-fungals, anti-inflammatory agents, anti-mycotic agents,
anti-parasite agents, external analgesics, sunscreens, photoprotectors,
antioxidants, keratolytic agents, detergents, surfactants, moisturizers,
nutrients, vitamins, energy enhancers, anti-perspiration agents,
astringents, deodorants, hair removers, firming agents, anti-callous
agents, and agents for hair, nail, or skin conditioning.
17. A method of making a composite material comprising an exfoliated
nanoparticle having a metal coating, which method comprises: (a) reducing
a metal ion to metal; (b) exfoliating a starting material to form an
exfoliated nanoparticle; and (c) contacting the metal with the exfoliated
nanoparticle, whereby steps (a) and (b) may be performed sequentially in
any order or simultaneously and the metal is loaded onto the surface of
the exfoliated nanoparticle.
18. The method of claim 17, wherein the metal is loaded onto the surface
of the nanoparticle by intercalation.
19. The method of claim 17, wherein the metal is loaded onto the surface
of the nanoparticle by adsorption.
20. The method of claim 17, wherein the metal is loaded onto the surface
of the nanoparticle by ion exchange.
21. The method of claim 17, wherein the metal is selected from the group
consisting of silver, copper, zinc, manganese, platinum, palladium, gold,
calcium, barium, aluminum, iron, and mixtures thereof.
22. The method of claim 17, wherein the nanoparticle comprises a nanoclay.
23. The method of claim 22, wherein the nanoparticle comprises exfoliated
CROSS-REFERENCE TO RELATED APPLICATION
 This application claims priority from U.S. provisional application
Ser. No. 60/515,758 filed Oct. 30, 2003.
FIELD OF THE INVENTION
 The present invention relates to composite materials that are
functionalized nanoparticles and in particular, metal-loaded nanoclays.
Additionally, the present invention relates to a method of forming such
BACKGROUND OF THE INVENTION
 For centuries, silver metal has been known to be an agent capable
of killing many different microbial species. It was commonly used to
purify drinking solutions or administered to sick individuals before the
existence of modern antibiotics. Even after the discovery of penicillin
and its descendents, colloidal silver solutions were often used in cases
in which troublesome bacteria had become resistant to antibiotics.
 Colloidal silver solutions are commercially available today. They
are often unstable, however, and have a short shelf life. This is due to
the tendency of the silver particles to aggregate and form clusters so
large that they are no longer suspended in solution. For this reason,
undesirable gelling agents are added to solutions to keep the silver
particles suspended by preventing particle aggregation. Another problem
of the commercially available solutions is that the majority of the
silver content is usually found to be silver ions. This poses a large
problem in medical applications where silver ions rapidly combine with
ubiquitous chloride to form an insoluble white precipitate.
 Nanoparticles have been known to be used as fillers as disclosed in
U.S. Pat. No. 6,492,453, as coatings as disclosed in U.S. 2003/0185964
and as foam components as disclosed in U.S. Pat. No. 6,518,324.
 Nanoparticle systems are disclosed in U.S. 2002/0150678 as being
used in a composition and a method to impart surface modifying benefits
to soft and hard surfaces. In particular, this application discloses a
soft surface coating for articles such as fabrics and garments.
 Inorganic particulates, such as, clays, silicates, and alumina have
been widely used in combination with adjunct detergent and laundry
compounds to impart some form of antistatic control and/or fabric
 The present invention relates to composite materials comprising
metal loaded onto exfoliated nanoparticles. Such functionalized
nanoparticles may be incorporated into solid and liquid materials to
enhance or modify their bulk physical and performance characteristics. In
one embodiment, the metal is silver and the nanoparticle comprises a
nanoclay. Silver ion is reduced to its neutral metal state (Ag.sup.0) 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 solid silver particles, making them
more cost efficient.
SUMMARY OF THE INVENTION
 The invention provides 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.
 The invention also provides a method of making a composite material
comprising an exfoliated nanoparticle having a metal coating, which
method comprises: (a) reducing a metal ion to metal; (b) exfoliating a
starting material to form a nanoparticle; and (c) contacting the metal
with the exfoliated nanoparticle, whereby steps (a) and (b) may be
performed sequentially in any order or simultaneously and the metal is
loaded onto the surface of the exfoliated nanoparticle.
 The invention further provides solutions, solids, gels, coating
compositions, cosmetic and pharmaceutical compositions, and articles of
manufacture comprising such a composite material.
BRIEF DESCRIPTION OF THE DRAWINGS
 FIG. 1 shows the particle size distribution of the material of
 FIG. 2 shows the particle size distribution of the material of
 FIG. 3 shows the particle size distribution of the material of
 FIG. 4 shows the particle size distribution of the material of
DETAILED DESCRIPTION OF THE INVENTION
 Every limit given throughout this specification includes every
lower or higher limit, as the case may be, as if such lower or higher
limit was expressly written herein. Every range given throughout this
specification includes every narrower range that falls within such
broader range, as if such narrower ranges were all expressly written
 Nanoparticles as used herein means particles (including but not
limited to rod-shaped particles, disc-shaped particles, platelet-shaped
particles, tetrahedral-shaped particles), fibers, nanotubes, or any other
materials having dimensions on the nano scale. In one embodiment, the
nanoparticles have an average particle size of about 1 to about 1000
nanometers, preferably 2 to about 750 nanometers. That is, the
nanoparticles have a largest dimension (e.g., a diameter or length) of
about 1 to 1000 nm. Nanotubes can include structures up to 1 centimeter
long, alternatively with a particle size from about 2 to about 50
nanometers. Nanoparticles have very high surface-to-volume ratios. The
nanoparticles may be crystalline or amorphous. A single type of
nanoparticle may be used, or mixtures of different types of nanoparticles
may be used. If a mixture of nanoparticles is used they may be
homogeneously or non-homogeneously distributed in the composite material
or a system or composition containing the composite material.
 Non-limiting examples of suitable particle size distributions of
nanoparticles are those within the range of about 2 nm to less than about
750 nm, alternatively from about 2 nm to less than about 200 nm, and
alternatively from about 2 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 (for instance, color enhancement
requires a different particle size range than the other properties). The
average particle size of a batch of nanoparticles may differ from the
particle size distribution of those nanoparticles. For example, a layered
synthetic silicate can have an average particle size of about 25
nanometers while its particle size distribution can generally vary
between about 10 nm to about 40 nm. It should be understood that the
particle size distributions described herein are for nanoparticles when
they are dispersed in an aqueous medium and the average particle size is
based on the mean of the particle size distribution.
 According to the invention, the nanoparticles are exfoliated. In
particular, a starting material is exfoliated or disbursed to form the
nanoparticles. Such starting material may have an average size of up to
about 50 microns (50,000 nanometers).
 The nanoparticle may comprise for example natural or synthetic
nanoclays, including those made from amorphous or structured clays.
 In one embodiment, the exfoliated nanoparticle is a nanoclay. In a
further embodiment, the nanoparticle is a swellable nanoclay or adduct
thereof. A swellable nanoclay has weakly bound ions in interlayer
positions that may be hydrated or may absorb organic solvents. These
swellable nanoclays generally possess a low cationic or anionic charge,
i.e. less than about 0.9 units of charge per unit cell.
 As used herein, "adducts" means oil swellable nanoclays, i.e. those
that swell in organic, non-aqueous solvents such as polar and nonpolar
solvents. They may be prepared by reacting a water swellable nanoclay
with an organic material that binds to the swellable nanoclay. Examples
of such binding organic materials include, but are not limited to, a
quaternary ammonium compound having the structure:
 R1, R2, R3 and R4 are each independently
selected from H, a C1 to C22 alkyl, a C1 to C22
alkenyl, and a C1 to C22 aralkyl, provided that at least one of
the R groups is such an alkyl, alkenyl or aralkyl; and
 X is the water swellable nanoclay.
 The swellable nanoclay may be amorphous or structured, i.e.,
including sheets or layers, wherein a combination of such layers is
referred to as a lattice structure. Examples of suitable nanoclays having
lattice structures include the pyrophillite (dioctahedral) type, the talc
(trioctahedral) type, or mixtures thereof. Classes of suitable structured
swellable nanoclays include, but are not limited to the smectite
nanoclays, sepiolite nanoclays, zeolite nanoclays, palygorskite
nanoclays, or mixtures thereof.
 Examples of amorphous swellable nanoclays include allophone and
 In one embodiment, the nanoparticles are made from a starting
material such as Nanomer 1.34TCN (available from Nanocor) having a
particle size of 10 to 18 microns (10000-18000 nanometers). In another
embodiment, the nanoparticles are made from PGV (also available from
Nanocor) having a particle size of 20 to 25 microns. In another
embodiment, exfoliated PGV having a particle size range of 1-3 nanometers
is used. In other embodiments, Nanomer 1.34TCN and Nanomer 1.30E having a
particle size range of 1-9 nanometers is used.
 Boehmite alumina can have an average particle size distribution
from 2 to 750 nm.
 Layered clay minerals can be used as starting materials for the
exfoliated nanoparticles. The layered clay minerals suitable for use in
the present invention include those in the geological classes of the
smectites, the kaolins, the illites, the chlorites, the attapulgites and
the mixed layer clays. Typical examples of specific clays belonging to
these classes are the smectices, kaolins, illites, chlorites,
attapulgites and mixed layer clays. Smectites, for example, include
montmorillonite, bentonite, pyrophyllite, hectorite, saponite, sauconite,
nontronite, talc, beidellite, volchonskoite, stevensite, and vermiculite.
In one embodiment, montmorillonite nanoclay is preferred. See U.S. Pat.
No. 5,869,033, which is incorporated by reference herein. Kaolins include
kaolinite, dickite, nacrite, antigorite, anauxite, halloysite, indellite
and chrysotile. Illites include bravaisite, muscovite, paragonite,
phlogopite and biotite. Chlorites include corrensite, penninite,
donbassite, sudoite, pennine and clinochlore. Attapulgites include
sepiolite and polygorskyte. Mixed layer clays include allevardite and
vermiculitebiotite. Variants and isomorphic substitutions of these
layered clay minerals offer unique applications.
 Layered clay minerals may be either naturally occurring or
synthetic. For example, natural or synthetic hectorites, montmorillonites
and bentonites may be used as the starting material for the
 Natural clay minerals typically exist as layered silicate minerals
and less frequently as amorphous minerals. A layered silicate mineral has
SiO4 tetrahedral sheets arranged into a two-dimensional network
structure. A 2:1 type layered silicate mineral has a laminated structure
of several to several tens of silicate sheets having a three layered
structure in which a magnesium octahedral sheet or an aluminum octahedral
sheet is sandwiched between two sheets of silica tetrahedral sheets.
 A sheet of an 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 sol with thixotropic properties.
Further, a complex variant of the smectite type clay can be formed by the
reaction with various cationic organic or inorganic compounds. An example
of such an organic complex, an organophilic clay in which a
dimethyldioctadecyl ammonium ion (a quaternary ammonium ion) is
introduced by cation exchange. This has been industrially produced and
used as a gellant of a coating.
 Synthetic nanoclays may be employed in the invention. With
appropriate process control, the processes for the production of
synthetic nanoclays does indeed yield primary particles that are
nanoscale. However, the particles are not usually present in the form of
discrete particles, but instead predominantly assume the form of
agglomerates due to consolidation of the primary particles. Such
agglomerates may reach diameters of several thousand nanometers, such
that the desired characteristics associated with the nanoscale nature of
the particles cannot be achieved. The particles may 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
 Synthetic materials for making suitable nanoclays include layered
hydrous silicate, layered hydrous aluminum silicate, fluorosilicate,
mica-montmorillonite, hydrotalcite, lithium magnesium silicate and
lithium magnesium fluorosilicate. An example of a substituted variant of
lithium magnesium silicate is where the hydroxyl group is partially
substituted with fluorine. Lithium and magnesium may also be partially
substituted by aluminum. Lithium magnesium silicate may 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 commercially marketed under the
trade name LAPONITE.TM. by Southern Clay Products, Inc., may be used as a
starting material for the nanoparticles. There are many grades or
variants and isomorphous substitutions of LAPONITE.TM. marketed. Examples
of commercial hectorites are LAPONITE B.TM., LAPONITE S.TM., LAPONITE
XLS.TM., LAPONITE RD.TM., LAPONITE XLG.TM., and LAPONITE RDS.TM..
 Synthetic hectorites do not contain any fluorine. An isomorphous
substitution of the hydroxyl group with fluorine will produce synthetic
clays referred to as sodium magnesium lithium fluorosilicates, which may
also be used as the starting material. These sodium magnesium lithium
fluorosilicates, marketed as LAPONITE.TM. and LAPONITE S.TM., may contain
fluoride ions of up to approximately 10% by weight. The fluoride ion
content useful in the compositions described herein is up to about 10 or
more percent. LAPONITE B.TM., a sodium magnesium lithium fluorosilicate,
has a flat, circular, plate-like shape, with an average particle size,
depending on fluoride ion content, of about 25-100 nanometers. For
example, in one non-limiting embodiment, LAPONITE B.TM. having a diameter
of about 25-40 nmand and thinkness of about 1 nm may be used. Another
variant, called LAPONITE S.TM., contains about 6% of tetrasodium
pyrophosphate as an additive.
 In one embodiment, Laponite XLS.TM. is used as the starting
material for the nanoparticle, and silver is loaded thereon as the metal.
Laponite XLS has tetrahedral silicate layers joined by octahedral
magnesium and lithium hydroxyl bridges. This structure allows for
exfoliation and modification by either intercalation or 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 nanoparticles with minimal effort. The surface of the
nanoparticle is covered with sodium ions to balance out the negative
charge of the many silicate groups.
 The aspect ratio of the exfoliated nanoparticles, in some cases, is
of interest in forming films comprising the composite material with
desired characteristics. The aspect ratio of dispersions can be
adequately characterized by TEM (transmission electron microscopy).
 The aspect ratio of nanoparticles in one embodiment can be in the
range of 100 to 250. In another embodiment, the aspect ratio of the
nanoparticles is 200 to 350.
 For example, the average aspect ratio of individual particles of
LAPONITE B.TM. is approximately 20-40 and the average aspect ratio of
individual particles of LAPONITE RD.TM. is approximately 10-15. LAPONITE
B.TM. occurs in dispersions as essentially single clay particles or
stacks of two clay particles. LAPONITE RD.TM. occurs essentially as
stacks of two or more single clay particles.
 In some embodiments, a high aspect ratio may be desirable for film
formation. The aspect ratio of exfoliated nanoparticles dispersed in a
suitable carrier medium, such as water, is also of interest. The aspect
ratio of the nanoparticles in a dispersed medium is lower where several
of the particles are aggregated.
 In certain embodiments, it may be desirable for at least some
individual (non-aggregated) platelet and disc-shaped nanoparticles to
have at least one dimension that is greater than or equal to about 0.5
nm, and an aspect ratio of greater than or equal to about 15. Larger
aspect ratios may be more desirable for platelet and disc-shaped
nanoparticles than for rod-shaped nanoparticles.
 The aspect ratio of rod-shaped nanoparticles can be lower than that
of disc-shaped or platelet-shaped nanoparticles while maintaining
adequate film-forming properties. In certain non-limiting embodiments, it
may be desirable for at least some of the individual rod-shaped
nanoparticles to have at least one dimension that is greater than or
equal to about 0.5 nm, and an aspect ratio of greater than or equal to
 The aspect ratio of spheroid-shaped nanoparticles is generally less
than or equal to about 5. Nanoparticles preferred for the embodiments
presented here have aspect ratios of less than or equal to about 250. In
other non-limiting embodiments, it may be desirable for the nanoparticles
to have an aspect ratio 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 valuble properties, for example in the case of silver its
anti-microbial properties, while on the nanoparticle. The term loaded, as
used herein, includes complete coverage of the surface of the
nanoparticle, or alternatively, only a portion thereof.
 In one embodiment, the metal is selected from Groups 3 to 12 of the
Periodic Table of 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 may be selected based on the desired effect to
be achieved through use of the composite material. For example, silver
may be selected for its known anti-microbial properties.
 The metal may be loaded onto the nanoparticle via intercalation.
For example, silver ions, in particular, can be inserted among the
various layers of layered nanoclay by positioning in a "hole" to maximize
favorable interactions between the positively charged silver ion and the
various types of oxygen in the silicate structure. Silver ions have been
shown to have anti-microbial properties and Laponite that contains
intercalated ionic silver, retains these properties. Intercalation is
also possible with other metal ions, such as copper, zinc, manganese,
 The metal may also be loaded onto the nanoparticle via ion
exchange. For example, the surface of Laponite platelets is composed
mainly of sodium ions, which exist to balance out the negatively charged
oxygen atoms donated by the silicate structure in the layer below. When
positively charged metal ions are added to a solution of exfoliated
Laponite, a fraction of the surface sodium ions are displaced by the
added metal cations.
 The metal may also be loaded onto the nanoparticle by adsorption.
For example, certain functional groups such as amine, ammonium, and
carboxyl groups are strong binders to the face or edge of a platelet of
Laponite. Metal ions can be modified by the addition of these ligands so
that they are able to bind strongly to the surface of Laponite. The
reaction sequence for one example is shown below:
 The final product, Ag(NH3)2OH, is contacted with
Laponite, whereby the Ag(NH3)2OH binds to the face of the
 In one embodiment of the invention a metal ion is reduced to a
metal (0) in the presence of a starting material, which is exfoliated to
form a nanoparticle. Reduction and exfoliation may take place in sequence
(either step happening first) or simultaneously upon contacting of the
metal with the starting material/exfoliated nanoparticle. The metal is
thereby 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's
reagent. The Tollen's reagent is a known silver species able to undergo
reduction by either an aldehyde or ketone to form silver metal (0):
 The composite material may in 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 may be incorporated into structures or
articles of manufacture such as absorbent articles, wound care articles,
soft surfaces, or hard surfaces. Compositions containing the composite
material may be solutions or dry materials, that are coated, applied,
extruded, sprayed, and so forth as further described below. Such
compositions may have end uses in manufacturing, commercial, industrial,
personal, or domestic applications.
 Systems comprising the composite material can be employed to bring
about certain, desired benefits, for example improved fluid absorbency,
wettability, strike-through, comfort, malodor control, lubricity,
anti-inflammatory properties, anti-microbial properties, anti-fungal
properties, modification of surface friction, flexibility, transparency,
modulus, tensile strength, color enhancement, viscosity, smoothness, or
 In certain embodiments, the presence of the composite material in a
composition does not affect the desirable properties of the composition,
for example transparency. Addition of the composite material to a liquid
composition, for instance, will not alter the transparency or color of
the resultant composition as compared to the original, liquid material
not containing the composite material. Moreover, since nanoparticles
possess large surface areas, the composite material will also allow for
higher concentrations of metals to be included in the overall
formulation, such as in the treatment of infections.
 Compositions of the invention may comprise the composite material
and any other ingredients appropriate for the intended 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
adjunct ingredients. The adjunct ingredients may be, for example,
surfactants or charged functionalized molecules exhibiting properties
selected from the group consisting of hydrophilic, hydrophobic and
mixtures thereof associated with at least some of the composite material,
 Alternatively, an effective amount of composite material described
above can 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 quantity of composite material
necessary to impart the desired benefit to the soft surface. Such
effective amounts are readily ascertained by one of ordinary skill in the
art and is based on many factors, such as the particular composite
material used, the nature of the soft surface whether a liquid or dry
(e.g., granular, powder) composition is required, and the like.
 The composition may be applied to the surface(s) by washing,
spraying, dipping, painting, wiping, or by other manner in order to
deliver a coating, especially a transparent coating that covers 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
about 100% of the surface. Accordingly, the coating may be continuous or
 If the coating composition is to be sprayed onto the surface, the
viscosity of the coating composition should be such that it will be
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 shear thinning so that it is capable of
 Suitable carrier mediums for the compositions containing the
composite material include liquids, solids and gases. One suitable
carrier medium is water, which can be distilled, deionized, or tap water.
Water is valuable due to its low cost, availability, safety, and
compatibility. The pH of the liquid, in particular water, may be adjusted
through the addition of acid or base. Aqueous carrier mediums are also
easy apply to a substrate and then dried. Though aqueous carrier mediums
are more common than dry, nonaqueous mediums, the composition can exist
as a dry powder, granule or tablet or encapsulated complex form.
 Optionally, in addition to or in place of water, the carrier medium
can comprise a low molecular weight organic solvent. Preferably, the
solvent is highly soluble in water, e.g., ethanol, methanol, propanol,
isopropanol, ethylene glycol, acetone, and the like, and mixtures
thereof. The solvent can be used at any suitable level. Several
non-limiting examples, include a level of up to about 50%, or more; 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. Factors to consider when a
high level of solvent is used in the composition are odor, flammability,
dispersancy of the nanoparticles and environmental impact.
 The carrier medium may also comprise a film former, which when
dried, forms a continuous film. Examples of film formers are polyvinyl
alcohol, polyethylene oxide, polypropylene oxide, acrylic emulsions,
 Adjunct ingredients that may be used in compositions 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 that serves to provide additional character to
the polymer, such as hydrophilic or hydrophobic properties.
 Examples of the anchoring segments or groups include: polyamines,
quaternized polyamines, amino groups, quaternized amino groups, and
corresponding amine oxides; zwitterionic polymers; polycarboxylates;
polyethers; polyhydroxylated polymers; polyphosphonates and
polyphosphates; and polymeric chelants.
 Examples of the hydrophilizing segments or groups include:
ethoxylated or alkoxylated polyamines; polyamines; polycarboxylated
polyamines; water soluble polyethers; water soluble polyhydroxylated
groups or polymers, including saccharides and polysaccharides; water
soluble carboxylates and polycarboxylates; water soluble anionic groups
such as carboxylates, sulfonates, sulfates, phosphates, phosphonates and
polymers thereof; water soluble amines, quaternaries, 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 the hydrophobizing segments or groups include: alkyl,
alkylene, and aryl groups, and polymeric aliphatic or aromatic
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(dodecyl glycidyl ether); and hydrophobic polyesters such as
polycaprolactone and poly(3-hydroxycarboxylic acids).
 Examples of hydrophilic surface polymers that may be incorporated
into the compositions of the invention include, but are not limited to:
ethoxylated or alkoxylated polyamines; polycarboxylated polyamines;
polycarboxylates including but not limited to polyacrylate; polyethers;
polyhydroxyl materials; polyphosphates and phosphonates.
 Examples of hydrophobic surface polymers that may be incorporated
into the compositions of the invention include alkylated polyamines
include, but are not limited to: polyethyleneimine alkylated with fatty
alkylating agents such as dodecyl bromide, octadecyl bromide, oleyl
chloride, dodecyl glycidyl ether and benzyl chloride or mixtures thereof;
and polyethyleneimine 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
including as monomers (meth)acrylate esters of perfluorinated or highly
fluorinated alkyl groups.
 Non-polymeric surface modifying materials that may be used as
adjunct ingredients include fatty amines and quaternized amines
including: ditallowdimethylammonium chloride; octadecyltrimethylammonium
bromide; dioleyl amine; and benzyltetradecyldimethylammonium chloride.
Silicone-based surfactants, fatty zwitterionic surfactants and fatty
amine oxides may also be incorporated into the composition.
 Surfactants are also optional adjunct ingredients. Surfactants are
especially useful in the composition as wetting agents to facilitate the
 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 semi-polar nonionic surfactants are
disclosed in U.S. Pat. Nos. 5,707,950 and 5,576,282. Nonionic surfactants
may be characterized by an HLB (hydrophilic-lipophilic balance) of from 5
to 20, alternatively from 6 to 15.
 Mixtures of anionic and nonionic surfactants are especially useful.
Other conventional useful surfactants are listed in standard texts.
 Another class of adjunct ingredients that may be useful are
silicone surfactants and/or silicones. They can be used alone and/or
alternatively in combination with other surfactants described herein
above. Nonlimiting examples of silicone surfactants are the polyalkylene
oxide polysiloxanes having a dimethyl polysiloxane hydrophobic moiety and
one or more hydrophilic polyalkylene side chains
 If used, the surfactant is should be formulated to be compatible
with the composite material, carrier medium and other adjunct ingredients
present in the composition.
 The compositions can contain other adjunct ingredients, including
but not limited to alkalinity sources, antioxidants, anti-static agents,
chelating agents, aminocarboxylate chelators, metallic salts, photoactive
inorganic metal oxides, odor-controlling materials, perfumes,
photoactivators, polymers, preservatives, processing aids, pigments, and
pH control agents, solubilizing agents, zeolites, and mixtures thereof.
These optional ingredients may be included at any desired level.
 Coating compositions comprising the composite material can be used
on all types of soft surfaces, including but not limited to woven fibers,
nonwoven fibers, leather, plastic (for example, toothbrush handles,
synthetic film, filaments, toothbrush bristles), and mixtures thereof.
The soft surfaces of interest herein may comprise any known type of soft
surface, including but not limited to those associated with disposable
absorbent articles including but not limited to covers or topsheets,
absorbent cores, transfer layers, absorbent inserts, and backsheets
including those outer layers made from breathable and nonbreathable
 It should be understood that in certain embodiments, such a coating
composition can be applied to hard surfaces, and provide benefits
 In certain embodiments, the soft surface may comprise one or more
fibers. A fiber is defined as a fine hairlike structure, of vegetable,
mineral, or synthetic origin. Commercially available fibers have
diameters ranging from less than about 0.001 mm (about 0.00004 in) to
more than about 0.2 mm (about 0.008 in) and they come in several
different forms: short fibers (known as staple, or chopped), continuous
single fibers (filaments or monofilaments), untwisted bundles of
continuous filaments (tow), and twisted bundles of continuous filaments
(yarn). Fibers are classified according to their origin, chemical
structure, or both. They can be braided into ropes and cordage, made into
felts (also called nonwovens or nonwoven fabrics), woven or knitted into
textile fabrics, or, in the case of high-strength fibers, used as
reinforcements in composites-that is, products made of two or more
 The soft surfaces may comprise fibers made by nature (natural
fibers), made by man (synthetic or man-made), or combinations thereof.
Example of natural fibers include but are not limited to: animal fibers
such as wool, silk, fur, and hair; vegetable fibers such as cellulose,
cotton, flax, linen, and hemp; and certain naturally occurring mineral
fibers. 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. Example synthetic fibers derived
from natural sources include but are not limited to polysaccharides such
as starch. Example 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 processes (e.g., extruding, drawing, or spinning a
fluid such as a resin or a solution). Synthetic fibers are also formed by
solid handling size reduction processes (e.g., mechanical chopping or
cutting of a larger object such as a monolith, a film, or a fabric).
 Disposable absorbent articles, such as pantiliners, sanitary
napkins, interlabial devices, adult incontinent devices, breast pads,
shoe insoles, bandages, and diapers typically are made from absorbent,
nonwoven materials (including fibers) and are well known in the art.
These articles typically have a fluid permeable body-facing side and
fluid impermeable garment facing side. Additionally, such articles may
include an absorbent core for retaining fluids therebetween. Addition of
the composite material to an article of manufacture such as the absorbent
core of a disposable, absorbent article may help control malodor
formation and increase absorbency.
 Other uses for the composite material include but are not limited
to use in dental abrasives for toothpaste, odor absorbents, and oral
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 including skin, hair, nails, and
mucosa such as vaginal or oral mucosa. Such compositions may be
formulated as either leave-on products or rinse-off products.
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 disclosed in U.S. Ser. Nos. 10/137,509; 10/390,511; and
10/389,871, filed May 1, 2002; Mar. 17, 2003; Mar. 17, 2003,
respectively. These applications describe warming lubricant 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, such compositions increase in temperature or generate
warmth. This has a soothing 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 into these personal lubrications,
the resultant compositions have a smoother characteristic and remain as
clear solutions, as the composite material does not detract from the
transparency of the compositions.
 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, sebum modulators, shine
control agents, anti-microbial agents, anti-fungals, anti-inflammatory
agents, anti-mycotic agents, anti-parasite agents, external analgesics,
sunscreens, photoprotectors, antioxidants, keratolytic agents,
detergents, surfactants, moisturizers, nutrients, vitamins, energy
enhancers, anti-perspiration agents, astringents, deodorants, hair
removers, firming agents, anti-callous agents, and agents for hair, nail,
or skin conditioning.
 Formulations for topical or mucosal application are well known in
the art. Excipients used by those skilled in the art in such formulations
may be used with the composite material herein, provided they are
 The compositions of the present invention can be applied to a
surface and optionally allowed to dry on the surface, optionally
repeating the application and drying steps as needed. In some embodiments
of the methods described herein, including, but not limited to when
applying more than one coating, it is not necessarily required to dry the
coating(s) between applications.
 In order to deposit silver metal on nanoclay, silver ions were
reduced in the presence of Laponite using the Tollen's reagent, which is
able to undergo reduction by either an aldehyde or ketone to form silver
metal via the following reaction:
 The Tollen's reagent was prepared by adding two drops of 10% NaOH
to 5 mL of 5% AgNO3 to form a gray-brown precipitate. This
precipitate was then dissolved by the dropwise addition of 2% NH4OH
to yield a total Tollen's reagent volume of 30 mL.
 A solution of silver-loaded Laponite XLS was prepared by adding 600
mg of Laponite XLS to 50 mL of distilled water and using a magnetic
stirrer to exfoliate for 20 minutes. To this solution, 800 mg of glucose
were added and the stirring continued for 10 minutes to ensure complete
dissolution of the glucose. To this, 10 mL of Tollen's reagent as
prepared above were added. After two hours of continuous stirring, the
solution turned golden yellow in color. Further reaction time yielded a
dark amber-brown solution. Samples prepared for particle size analysis
and TEM analysis were diluted by a factor of 10 to prevent particle
aggregation. The particle size of the nanoparticles dictates the color of
the solution caused by a surface plasmon resonance phenomenon. For silver
particles, a yellow color has been determined to have the smallest
particle size possible. The particle size distribution of the resulting
nanoparticles is shown in FIG. 1.
 The formation of silver metal from silver ions was also
investigated using NaBH4:
 Dropwise addition of 32 mg of AgNO3 dissolved in 5 mL of
H2O to a solution containing 500 mg of exfoliated Laponite XLS and 4
mg NaBH4 yielded a golden yellow solution. This addition order for
this particular reaction was determined to give the smallest particle
 Nanoparticles of silver-laponite were prepared by reduction with
sodium citrate, although the reduction by this method was more difficult
to control. Citric acid was added to an exfoliated Laponite XLS solution,
followed by the addition of silver nitrate. 10% NaOH was added dropwise
to form the sodium salt of citric acid until the solution turned faintly
yellow. In many cases, the over-addition of sodium hydroxide caused the
silver particles to fall out of solution.
 Nanoparticles of silver-loaded Laponite XLS can be prepared by
hydrazine reduction as follows: 5 g of Laponite XLS are added to 995 g of
deionized water and stirred for 20 minutes to exfoliate the Laponite XLS.
20 mg of 55% hydrazine hydrate is added to the Laponite XLS dispersion
and the solution is stirred for 1 minute. 77 mg of AgNO3 is
dissolved in deionized water. The AgNO3 solution is added dropwise
to the Laponite--hydrazine solution to form a golden-yellow solution
containing 0.005% silver-loaded Laponite XLS.
 Another solution of silver-loaded Laponite XLS was prepared
similarly to Example 1, but the order of the components was altered.
Glucose and Tollen's reagent were mixed in a separate vessel and once the
color of the solution turned faintly gray, this mixture was added to the
solution of exfoliated Laponite XLS. After a short period of stirring,
the solution turned amber-yellow. This solution was diluted by a factor
of 10 for particle size analysis. The particle size distribution of the
resulting material is shown in FIG. 2.
 A sample was prepared by adding 200 mg of Laponite XLS to 100 mL of
water and stirring to exfoliate. The sample was analyzed for particle
size. The results are shown in FIG. 3.
 The sample of Example 6 was diluted by a factor of 50. The sample
was analyzed for particle size. The results are shown in FIG. 4.
 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 silver-loaded Laponite XLS was smaller, on average, than
Laponite XLS alone, indicating that the addition of silver to the
solution aided in the Laponite XLS exfoliation process.
 The data for Example 1 shows a single particle size distribution,
averaging 4.1 nm in size. Example 5, on the other hand, showed a bimodal
particle size distribution with the averages centered on 4.1 nm and 11
nm. This indicates the formation of two different types of particles. It
is possible that this solution contained silver-loaded Laponite XLS and
colloidal silver with no Laponite core.
 To verify that the Laponite XLS was being coated with silver, TEM
(transmission electron microscopic) images and EDX (Energy Dispersive
X-Ray) analysis were performed on Examples 1 and 6. The data confirmed
that the composite material of Example 1 contained silver-loaded Laponite
XLS particles, as opposed to a mixture of colloidal silver and Laponite
XLS. Elemental analysis showed the presence of Na, Mg, Si, and Ag (Cu was
present in the TEM grid). The data also revealed that particles of very
small size (.apprxeq.1 nm), determined to be uncoated Laponite XLS, were
 A solution containing silver-loaded Laponite XLS particles was
prepared as follows. 4.51 g of Laponite XLS was added to 900 mL of
deionized water. The solution was stirred for 1 hour and labeled Solution
A. To 400 mL of Solution A, 15 mg of NaBH4 was added. This solution
was labeled Solution B. 124 mg of AgNO3 was dissolved in 5 mL of
deionized water; and this was added dropwise to Solution B to form an
amber brown solution of 0.02% silver loaded onto Laponite XLS. Following
the above procedure, 0.01 %, 0.005% and 0.0025% silver loaded Laponite
XLS solutions were prepared. These solutions were analyzed for biocidal
activity against the organisms Staphylococcus aureus and Escherichia coli
as follows. The silver-loaded Laponite XLS solutions were inoculated with
the bacteria and neutralized with Letheen Broth containing 1.5% to
neutralize the activity after the appropriate time. Aliquots were plated
using Letheen Agar. The bacterial log reduction is given in the Table