Nanodiamond Applications

Being extremely small and with high amount of surface atoms, nanodiamond has diversified applications. Some applications involve using the superhard properties of diamond. The others may adapt low frictional coefficient of diamond (Table 7.1).

7.1 LUBRICATION OF ENGINE OIL AND MACHINE GREASE

Nanodiamond can reduce significantly the frictional coefficient by coating on the sliding surface. The nanodiamond coating reduces the contact area. Moreover, the inertness of the diamond surface reduces the atomic drag force across the interface of the two relatively moving surfaces (Fig. 7.1).

Nanodiamond used as engine oil additive have demonstrated reduced gasoline consumption and increased engine life (Fig. 7.2). These benefits are attributed to the coating of nanodiamond on the walls of the cylinder. As a result, the frictional coefficient is reduced.

The electroplating of metal coating using electrolyte with nan-odiamond dispersion allows the impregnation of nanodiamond. However, the incorporation may be small (e.g. 5V%) due to the Brownian motion of the nanodiamond in the liquid medium. The incorporation of nanodiamond can be boosted by electrophoresis with charged nanodiamond in electrolyte. More than 20 V% may be attained after the metal coating. The impregnation of nanodia-mond in metal coating can increase the hardness and significantly improve the wear resistance.

Diamond Nanotechnology: Synthesis and Applications by James C Sung & Jianping Lin

Copyright © 2009 by Pan Stanford Publishing Pte Ltd

www.panstanford.com

978-981-4241-36-6

Table 7.1. Mechanical applications of nanodiamond

Super smooth polishing of gems, ceramics, glass, silicon wafers, and surgical knives Impregnation in coatings of gold, silver, copper, and chromium for hard facing

Reinforcement of rubber, resins, plastic, PTFE, and metals (Cu, Al)

Figure 7.1. The pin-on-disc sliding experiments and their results in improvements of the tribological properties of nanodiamond coated surfaces.

An application of nanodiamond impregnated coating is for gilding the watch wands or other ornaments. Because the gold is soft, the impregnation of nanodiamond can prevent the scratching of gold (Fig. 7.3). Due to the dramatically increased hardness and strength, the gilded thickness can be reduced in half so the overall cost is comparable with coating with thicker gold.

For conventional nickel coating, nanodiamond addition may also improve the wear resistance and corrosion resistance (Table 7.2

Figure 7.2. The schematic illustration of nanodiamond lubrication of two moving parts.

and 7.3). The reduced frictional coefficient is also obvious. Moreover, nanodiamond is conductive. Due to its conductivity, nickel may deposit much quicker and with a finer finish. Such quality may also aid the value of nanodiamond impregnated nickel hardfacing.

7.2 SINTERING OF MICRON AND NANODIAMONDS

Most micron diamonds are formed by pulverizing larger diamond formed under high pressure. There are tons of micron diamonds that are pressed again, this time to sinter them together to form polycrystalline diamond (PCD). There are also tons of mesh or micron diamonds that are used to grind or polish the PCD formed.

For sintering to proceed relatively fast and to eliminate most porosity present in the original powder mix, the temperature

Figure 7.3. The increase of gold hardness with nanodiamond impregnation.

ought to be about 3/4 of the melt point of the powder. Because diamond will not melt below 4000°C, so it means the sintering may have to be performed above 3000°C. However, if diamond were heated to such a high temperature, it would have been graphi-tized so the PCD cannot be made unless the pressure is applied to reach diamond's stability field. The pressure for reaching the diamond stability field increases with the increasing temperature, at a temperature of about 3000°C, the pressure ought be about 10 GPa to keep diamond stable. Such a high pressure would make industrial sintering impractical as most ultrahigh pressure apparatuses used today to synthesis diamond can reach a pressure of about 5 GPa.

In order to sinter diamond at a pressure of about 5 GPa, molten cobalt is used to infiltrate micron diamond. In this case, cobalt can dissolve diamond at the contact points of micron diamond where the pressure is high and it then precipitate dissolved carbon atoms in regions of original pores. As a result, micron diamond grains are

Table 7.2. The properties enhancement of nanodiamond dispersed nickel coating

Electric Plating Brush Plating

Electric Plating Brush Plating

Table 7.2. The properties enhancement of nanodiamond dispersed nickel coating

Nickel-

Nickel-

black

Nickel-

Prush

Nickel

graphite

powder

Nickel-

black

Plating

(3-5 iim)

(3-5 iim)

(0.2-0.5 fim)

Nickel

graphite

powder

Micro

3180

1291

4785

2293

2304

5123

hardness

(Mpa)

Dynamic

0.75-0.90

0.14-0.16

0.18-0.20

0.22-0.30

0.15-0.20

0.21-0.27

friction

coefficient

Static

0.25-0.37

0.20-0.25

0.25-0.31

friction

coefficient

Wearing rate

18.53

11.06

10.61

(MM3/Nm)

Wearing

5

4

0

depth (/u,m)

Adhesive

30

30

30

strength (N)

gradually merging together with new diamond forming bridges across all voids. Such a PCD contains inter-grown micron diamond particles.

Normally, cobalt may come from the melting of a cemented tungsten carbide substrate that is placed adjacent to the volume of micron diamond. When the temperature becomes higher than the melting point of cobalt, it will melt and infiltrate into micron diamonds where sintering is taking place. This method is ideal in making PCD/cWC compact that is widely used as cutting tools, drill bit cutters, and wire drawing dies. The composite will allow the hard diamond to cut but it is supported by a tough cWC that does not break.

Alternatively, cobalt may be mixed with the diamond powder beforehand. In this case, the path of infiltration is shorter. This is particularly useful for sintering smaller diamond grains, such as for making PCD with submicron grain size.

An important consideration of high pressure sintering of PCD is grain size. Normally, the larger the size of the diamond grains, the easier for cobalt to infiltrate. But for precision cutting applications

Table 7.3. The effects of doping chromium coating with nanodiamond

Tool Material being processed Efficiency increased by

Tool Material being processed Efficiency increased by

Table 7.3. The effects of doping chromium coating with nanodiamond

(times)

$8 ~ 20 drill

Glass reinforced plastic,

1.9-20.0

Stamping die, coldextruded,

copper, stainless steel Steel, aluminum glass

1.6-1.80,2.0-3.0

sheared, extended

reinforced plastic,

1.6-2.40,2.0-4.0

brass steel

1.4-1.8

Cold stamping die

Pig iron powder, stainless

9-15

Steel powder, ceramic Powder for radio, bakelite

4-5 2-3

Saw blade, needle

4.0-8.0

file

Internal

2-3

combustion engine cylinder combustion engine cylinder and wire drawing practices, the finer the diamond grains, the better finish of the work surface. Hence, a choice of grain size has to be made for making PCD for various applications.

The presence of cobalt in PCD, although useful for many mechanical applications, has severely limited the applicability of PCD. As cobalt is the catalyst for making diamond, it can also catalyze the back conversion unless the PCD is pressed in the stability field of diamond. So for all applications performed at low pressures, there is threshold temperature at about S that may not cross, otherwise, diamond will be back converted to amorphous carbon. Such back conversion cannot only soften the diamond cutter, but also, the sudden volume expansion (up to 50%) may easily crack the PCD, or cause delamination of the compact.

Most applications would expose PCD to temperature above 700°C. For example, the cutter's tip will be hotter than this temperature if the cutting speed is high or if the work material is abrasive. Alternatively, the process of making PCD tools, e.g. brazing it to join the shank, will also expose PCD above the threshold temperature. Hence, the industry has been scrambling on the best way to avoid such a problem of thermal degradation. So far the approaches have been to eliminate (e.g. by acid dissolution) or replace cobalt (e.g. by silicon) as the sintering aid of PCD. But these so called thermally stable PCD have their own weaknesses. For one thing they are not as tough and finer grained PCD cannot be produced. Hence, cobalt sintered PCD is still dominates the market.

However, the sintering is a process of powder consolidation by eliminating surface area or grain boundaries. So the smaller the grain size, the faster the powder can sinter. As a consequence, a lower temperature is needed to sinter a finer grained powder. In fact, by reducing the size from 10 to 1 fim, the sintering temperature may decrease by 200°C. However, as the grain size become smaller, more dramatic decrease of sintering temperature may be realized. Hence, by using nano-grained diamond, the sintering temperature may be lowered to about 1500°C. In this case, no sintering aid is necessary because the increase of diamond surface area itself can drive the sintering (Fig. 7.4).

Commercial PCD contain grains of from 50 fim down to about 2 fim. Even with the grain as small as 1 fim, its surface area is only about 0.02m2/gm. On the other hand, nanodiamond (e.g. 5nm) may have a surface area of 400m2/gm. The sintering of nanodi-amond with such a high surface area may require a much lower temperature and so the sintering may be performed by using conventional ultrahigh pressure apparatuses.

The direct sintered nano-PCD has many advantages. For example, it has a much higher thermal stability, most likely >1200°C. Moreover, its hardness and wear resistance must be much higher than conventional PCD so the tool life can be dramatically increased. In addition, with its nano grains in random orientation, the isotropic wear pattern should allow it to produce a mirror finish without requiring further polishing.

There are other possible novel properties of this nano-PCD. For example, it may be highly transparent in a wide spectrum of electromagnetic radiations. In fact, with proper sintering and to allow enough grain coarsening, optical transparent PCD may be made. Such an optical transparent PCD can be used as window materials for electromagnetic radiation of different energies.

Another possibility is that nano PCD may become the best heat spreader ever invented. With the trend of increasing power of many electronic devices (e.g. CPU, laser diode), the semiconductor chip can no longer be cooled by conventional copper heat spreader. Although CVD diamond may be an excellent heat spreader, but the cost of deposition may be prohibitive. Moreover, the larger sized electronic devices now require a heat spreader thicker than 2 mm. No CVD diamond film today has been able to penetrate this thickness barrier. Hence, nano PCD with its thickness that can be designed will be the heat spreader for the future.

The cost of nanodiamond used to be more than $10/carat, so their price would be prohibitive for making nano PCD. But today the commercial products of nanodiamond is down to less than $1/carat that is on par with a high grade pulverized micron diamond. Hence, the time to make nano PCD has come.

In order to make good use of a cemented tungsten substrate to reinforce the brittle nano PCD, cobalt infiltration may still apply. But this time the micron PCD is used to support nano PCD. For example, micron PCD may form an interlayer between nano PCD and cWC. There are many possibilities to make products based on this three-layer concept.

7.3 ADAMANTANE MOLECULES

A simple carbon structure that may be formed with high stability is adamantane that contains 10 carbon atoms in diamondoid structure. In fact, the very word "diamond" was derived from the Greek admas that means invincible or unbreakable. Adamantane or its derivatives may be found in petroleum residue. The first artificial synthesis of adamantine was accomplished by V. Prelog in 1941 (Prelog, V., Seiwerth, R., 1941, Uber die Synthese des Adamantane, Berichte 74,1769-1772).

Adamantane melts at 270°C that is a small fraction of about 4000°C for diamond. This shows the power of suppressing melting point by moving carbon atoms to the surface with hydrogen termination (Fig. 7.5).

Adamantane and its derivatives (e.g. amantadine, remanta-dine, memantine) have been used as drugs for killing influenza viruses and for treating brain diseases (e.g. Alzheimer, Parkinson). It has been noticed that such drugs are not poisonous to human body.

Figure 7.4. Novel designs of future nano-PCD with the interlayer of micron PCD that is supported by conventional cWC. Such designs can combine the longest tool life with the most smooth surface finish.
Properties

Molecular formula Molar mass Appearance Density Melting point Solubility in water

270°C (543 K) Poorly soluble

C10H16 136.23 g/mol

White to off-white powder 1.07 g/cm3 (20°Q, solid

Solubility in other solvents Soluble in hydrocarbons

Figure 7.5. The molecular structures and properties of adamantane Source: Wikipedia.

Figure 7.6. Adamantane moiety used as photoresist.

Adamantane molecules may be further bonded to absorbents (e.g. H, OH, NH2) or organic radicals (e.g. CH3, NH3Cl). Being diamondoid, the compound is strong and it can be transparent. Such features allow diamondoid derivatives to be used as optical lenses. For example, adamantane polymers are used as UV photoresist materials for ArF excimer laser with a wavelength of 193 nm (Fig. 7.6).

Additionally, such derived molecules may be polymerized to form strong threads that can be weaved into fabrics (Fig. 7.7). Such

Figure 7.6. Adamantane moiety used as photoresist.

Nanodiamond Structure
Figure 7.7. Adamantane derivatives (top) and the polymerization of diamantine derivatives (bottom). Source: Industrial Diamond Review, 2008, 1,20-22.

nanodiamond-impregnated fabrics are superhard cloths that are scratch free and water repelling. Moreover, they can be stacked up to make bulletproof vests that are lighter and softer than Kevlar or Nomex. Nanodiamond impregnated fabrics may also be used as armor protected seats for helicopters.

With further additions and repetitions, diamondoid structure can be augmented to take forms of real diamond.

Diamondoid molecules are stable to body fluids and they are benign to human body. An ideal application is to use diamondoid structure as the anchor for the delivery of amino acids, proteins, genes, and drugs.

7.4 OTHER DIAMONDOIDS

A methane (CH4) molecule contains a carbon atom with diamondoid bonds (sp3). It is the simplest molecule with carbon caged by hydrogen termination. More complicated cage structures may be derived from the collisions of methane molecules. In addition, bucky ball structures or non-hydrocarbons may be incorporated as well (Fig. 7.8).

Adamantane Diamantarie Triamantane

Nanodiamond Structure

Figure 7.8. Additional diamondoid structures. Source: Industrial Diamond Review, 2008,1, 20-22.

iso-Tetramantane Pentamantane Cyclohexamantane

Figure 7.8. Additional diamondoid structures. Source: Industrial Diamond Review, 2008,1, 20-22.

7.5 NANODIAMOND COSMETICS

Nanodiamond is the best hardener for polymers. The wetting and dispersing of diamond by organic materials are excellent, particularly with diamond surfaces terminated by hydrogen or fluorine. One example of nanodiamond-dispersed polymer is diamond-impregnated Teflon (DiT). DiT can be used to coat on metals or glass to render scratch free surface that is also water repelling. Another example is nanodiamond-impregnated paint (DiP) that may be applied on automobile's exterior. Again, the paint can be scratch free and rain dry. As nanodiamond is non-poisonous, a big area of application is nanodiamond-impregnated cosmetics.

Nanodiamond Surface
Figure 7.9. The diamondoid carrier with DNA strands anchoring on its surface.

Each carbon atom on the surface of nanodiamond has at least one dangling electron that may bond to a light element, such as H, N, or O. As biological materials are made of carbon compounds, almost all life sustaining chemicals can be absorbed by nanodi-amond. Thus, nanodiamond is an excellent absorbent for amino acids, proteins, platelets, and DNA (Fig. 7.9), to name a few example. Due to the smallness of dynamite nanodiamond compared to even a virus, nanodiamond may be used as a drug to exterminate virus.

Human body contains about 1/4 of carbon by weight. Nanodiamond as carbon is non-poisonous (Fig. 7.10). Moreover, it is not only cancer inactive, but also a catalyst for promoting drug effectiveness. For examples, nanodiamond has been used to treat burning skin infections, food poisons, and intestine malfunctions with good results.

Figure 7.10. Various carbon structures that may be derived by the collision of simple molecules of carbon compounds.

Visible

Virus (w-aoonm) Germs

IQttm_IQOnm_l|un_10

Cells lOOjirn tp

1-liti in r

jrjM>nd f.l-hnrn) IjQi.d Cryril (V?A| I'ff F (H:nKli; 'J-il ; 11 i-.TI

Figure 7.11. The relative scale of nanodiamond compared to microbes and cells.

In comparison to tiny nanodiamond particles, the human cells appear to be colossal (Fig. 7.11). Much larger than microbes, nanodiamond cannot harm normal cells. Nanodiamond cannot penetrate the cell's membrane. One the contrary, nanodiamond can stick to the NDA of bacteria or RNA of viruses. For example, nan-odiamond has been used to cure gum diseases. It is conceivable that nanodiamond may also be effective in attaching genes and hence it is capable to kill drug resistant viruses (e.g. HIV, SARS).

Nanodiamond is perceived to be able to inhibit the growth of malignant, or to kill cancer cells. It has also been reported that nan-odiamond may relieve mental stresses and body pains. Additional remedies include the restoration of digestion disorders, improvements of blood circulations, the enhancement of immune systems, or even the extension of patient's lives.

Nanodiamond surfaces may be modified by the termination of various chemical radicals (Fig. 7.12). If the termination is nonpolar (e.g. H or F), the surface is hydrophobic. On the other hand, if hydrogen bonds may be formed on the absorbents (e.g. O or S), the surface is hydrophilic. The water repelling or wetting behavior is important for dispersion in liquid. The surface modification also allows the attachment of organic molecules, such as amine, carboxyl, carbonyl, hydroxyl, amide, nitrile, sulfide, epoxyl, phos-phryl, sulfate, imide, etc.

For nanodiamond just formed, the surface contain ample C-O, C=O, C-N, C=N, and OH. Although these radicals are wettable by water, they tend to agglomerate. After boiling in sulfuric acid, the dispersion in water improved, so is the dispersion. However, if an organic polymer is used to as the matrix material, nanodiamond should be heat treated beforehand in hydrogen, fluorine or chlorine to render the surface hydrophobic.

Nanodiamond
Figure 7.12. The attachment of surface absorbents on nanodiamond (top diagram) and the major surfactant radicals (bottom diagram).

7.6 COSMETIC APPLICATIONS OF NANODIAMOND

A remedial healthcare nanodiamond composition can include a biologically acceptable carrier and a plurality of nanodiamond particles dispersed in the carrier. Depending on the carrier, an optional dispersant can be used. The remedial healthcare composition can be formulated as a dental filling, lotion, deodorant, toothpaste, shampoo, antibiotic, dermal strip, skin cleanser, or exfoliant. Other similar compositions can also be formulated to incorporate nan-odiamond particles given the disclosure herein. Of course, the particular biologically acceptable carriers and other components may vary depending on the specific formulation. However, the following discussion illustrates several currently preferred nanodiamond compositions and associated benefits.

Nanodiamond particles typically carry an electrical charge that leads to aggregation and flocculation of particles. In most cases, this aggregation of nanodiamond particles is undesirable. Therefore, an optional dispersant can be included which improves the uniformity of nanodiamond distribution. In this way, a colloidal suspension can be formed in which the nanodiamond particles remain substantially uniformly dispersed over an extended period of time, e.g. typically months or years. Preferably, the nanodiamond particles remain dispersed during the useful shelf life of the particular composition. The dispersant can be provided in the form of a specific compound separate from the carrier in a liquid nanodiamond composition. However, for highly viscous compositions the carrier can also be the dispersant. Thus, in some embodiments such as a solid deodorant, toothpaste, soaps, viscous nail polish, and the like, the carrier can provide sufficient viscous support to prevent agglomeration and/or settling of the nanodiamond particles.

Any suitable dispersant can be used which is compatible with a particular carrier. However, several non-limiting examples of dispersants include anionic surfactants, electrolytes, alcohols, metal chlorides and nitrates such as Al, Na, Ca, and Fe chlorides and nitrates, and the like. Other suitable nanodiamond dispersants include isopropyl triisosteroyl titanate, polyethylene-oxides, and other anionic surfactants. One specific suitable surfactant that can be used is stearalkonium hectorite. The dispersant can also provide other properties to a composition such as pH control. Further, the amount of dispersant can depend on the amount of nanodiamond present and the viscosity of the composition. However, as a general guideline, the remedial healthcare composition can include from 1 wt.% to about 30 wt.% dispersant.

Suitable nanodiamond particles can have an average size of from about 0.5 nm to about 50 nm. In some embodiments the plurality of nanodiamond particles can have an average size from 1 nm to about 10 nm, preferably from about 4 nm to about 8 nm, and most preferably about 5 nm. The concentration of nanodia-mond particles will vary depending on the composition and the desired effect, as discussed in more detail below. As a practical matter, the plurality of nanodiamond particles is typically about 1 wt.% to about 80 wt.% of the composition. Nanodiamond particles can be formed using a number of known techniques such as shock wave synthesis, CVD, and the like. Currently preferred nanodiamond particles are produced by shock wave synthesis.

7.7 THE DENTAL USE OF NANODIAMOND

The remedial healthcare composition may be formulated as a dental material. The dental material can be formulated for use as a filling, veneer, reconstruction, and the like. The dental material can include an acceptable carrier and a plurality of nanodiamond particles. Acceptable carriers are known in the art and can include, for example, composite resins, polymeric resins, ceramics, and other known carriers. In addition, the dental material can include additives such as colorants, fillers, etc. Although dental compositions can include colorants or additives to provide whiteness for cosmetic purposes, the primary purpose of the dental material is remedying a defect in a tooth and preventing future decay. Such dental materials are known and a more detailed description can be found in US Patent Nos. 6,020,395; 6,121,344; and 6,593,395, which are each incorporated herein by reference in their respective entireties.

Dental compositions include a plurality of nanodiamond particles. The nanodiamond particles can provide additional mechanical strength, as well as an appearance that approximates natural enamel when dry. The nanodiamond particles can be present in the composition at from about 1 wt.% to about 60 wt.%, and preferably from about 10 wt.% to about 40 wt.%.

In addition to mechanical strength, introduction of nanodia-mond particles to a composition can provide a number of beneficial properties. One of such beneficial properties is an impressive ability of nanodiamonds to absorb oil and other organic materials. Carbon atoms are very small (about 1.5 A); thus, various forms of carbon can pack to form a high atomic concentration. In fact, diamond has the highest atomic concentration (176 atom/nm3) of all known materials. This high atomic concentration contributes to the exceptional hardness of diamond. As a result, any given surface area of a nanodiamond particle can include many more atoms than other nanoparticles of the same size.

Diamond is among the most inert materials known. Specifically, at temperatures below about 500°C, diamond typically does not react with other materials. Further, diamond is compatible with most biological systems. This is due, at least in part, to the sp3 bonding of diamond and the similar bonding of most biological materials containing roughly around 25% carbon in sp3 bonding. As such, diamond is ideal for use in medical applications, e.g. artificial replacements (joint coatings, heart valves, etc.), and will not deteriorate over time.

Although diamond is highly stable, if the nanodiamond surface is free of adsorbent or absorbent, i.e. clean, it is thought that carbon atoms on the surface contain unpaired electrons that are highly reactive. As a result, nanodiamond particles can readily bond to and effectively absorb a variety of atomic species. For example, small atoms such as H, B, C, N, O, and F can be readily adsorbed on the nanodiamond surface, although other atoms can also be absorbed. Hence, nanodiamond particles, with their vast number of surface atoms, can hold a large amount of such adsorbed atoms. For example, nanodiamond particles are capable of absorbing almost as many hydrogen atoms as the number of carbon atoms. Thus, nanodiamond particles can be used as storage sites for hydrogen. In addition, those small atoms are building blocks, e.g. H, CO, OH, COOH, N, CN and NO, of organic materials including biological molecules. Consequently, nanodiamond particles can readily attach to amino acids, proteins, cells, DNA, RNA, and other biological materials, and nanodiamond particles can be used to remove skin oils, facial oils, compounds that result in body odor, bacteria, etc.

Further, nanodiamonds are typically smaller than most viruses (10-100 nm) and bacteria (10-100 ¡m). Therefore, nanodiamond can be used to penetrate the outer layers of viruses and bacteria and then attach to RNA, DNA or other groups within the organism to prevent the virus or bacteria from functioning. Similarly, nan-odiamond can be used in conjunction with known drug delivery mechanisms to treat cancer or acquired immune deficiency syndrome.

7.8 NANODIAMOND SKIN LOTION

A method of binding biological molecules can include formulating a nanodiamond composition containing a plurality of nanodiamond particles. The nanodiamond particles can be dispersed in a biologically acceptable carrier. The nanodiamond composition can then be contacted with a biological material such that at least a portion of the biological material is bonded to the nanodiamond composition. Examples of biological materials include organic oils, sebum, bacteria, epithelial cells, amino acids, proteins, DNA, and combinations thereof. Once the biological material is bonded to nanodiamond, the nanodiamond composition can be removed from the surface or environment. The nanodiamond composition can then be discarded or further treated to identify or otherwise utilize the absorbed biological material. In one embodiment, the nanodiamond composition can be formulated as any of the following products: deodorant, toothpaste, shampoo, antibiotic, dermal strip, DNA test strip, or skin cleanser.

Similarly, nanodiamond compositions can be remedial healthcare compositions formulated for skin care. Examples of skin care formulations include lotions, facial tissue lotion, deodorant, dermal strip, skin cleanser, soap, antibiotic, and exfoliant. Alternatively, the remedial healthcare composition can be formulated as toothpaste, shampoo, or other similar product.

The remedial healthcare composition can be formulated as a lotion. The lotion can include an acceptable carrier and a plurality of nanodiamond particles. Acceptable carriers are known in the literature, and can include, for example, glycerin, alcohols, water, gels, combinations of these materials, and other known carriers. In addition, the lotion can include additives such as fragrance, colorants, vitamin E, herbal supplements, antibiotics, UV absorbers, sun-block agents, and the like. A more detailed description of various lotions can be found in US Patent Nos. 6,207,175 and 6,248,339, which are each incorporated herein by reference in their respective entireties. The nanodiamond particles can be present in the composition at from about 1 wt.% to about 40 wt.%, and preferably from about2wt.% to about 15 wt.%.

In a similar embodiment, the remedial healthcare composition can be formulated as a lotion for application in a facial tissue. The facial tissue lotion can include an acceptable carrier and a plurality of nanodiamond particles. Acceptable carriers are known in the art and can include, for example, glycerin, alcohols, water, gels, combinations of these materials, and other known carriers. In addition, the lotion can include additives such as fragrance, colorants, vitamin E, herbal supplements, antibiotics, UV absorbers, sun-block agents, and the like. A more detailed description of facial lotion formulations can be found in US Patent No. 6,428,794, which is incorporated herein by reference in its entirety. The presence of nanodiamond particles can improve absorption of oils and undesirable deposits from the skin without abrasiveness associated with larger diamond particles. The nanodiamonds can be present in the facial tissue lotion composition at from about 1 wt.% to about 30 wt.%, and preferably from about 2 wt.% to about 15 wt.%.

The remedial healthcare composition can be formulated as a deodorant. The deodorant can include an acceptable carrier and a plurality of nanodiamond particles. Acceptable carriers can vary considerably depending on the specific formulation. For example, deodorants can be formulated as a solid, gel, cream or the like. Suitable carriers can include, but are not limited to, dime-thicones, silicone fluids (e.g. siloxanes), glycerin, alcohols, water, gels, sorbitols, and other known carriers. In addition, the deodorant can include additives such as fragrance, stabilizing agents, pH or buffer agents, solvents, antiperspirant agents, and the like. A more detailed description of various deodorant formulations can be found in US Patent Nos. 5,968,490; 6,358,499; and 6,503,488, which are each incorporated herein by reference in their respective entireties. When included in deodorant compositions, the nanodi-amond particles can be present in the composition at from about 1 wt.% to about 40 wt.%, and preferably from about 2 wt.% to about 20 wt.%.

The remedial healthcare composition can be formulated as a dermal strip. Dermal strips are typically formed having a backing substrate with an oil or sebum absorbing composition coated thereon or within the substrate. The dermal strip can include an acceptable carrier and a plurality of nanodiamond particles on the substrate. Acceptable carriers are known in the literature and can include, for example, hemp, pulp papers, porous polymeric thermoplastics, and other known carriers. Additives such as herbal extracts, vitamins, antibiotics, anti-inflammatories, fragrance, and the like can also be included. The nanodiamond particles can be present in the composition at from about 1 wt.% to about 40 wt.%, and preferably from about 2 wt.% to about 15 wt.%.

The remedial healthcare composition can be formulated as a skin cleanser. The skin cleanser can include an acceptable carrier and a plurality of nanodiamond particles. Acceptable carriers are known in the literature and can include, for example, glycerin, alcohols, collagen, elastin, gels, copolymeric materials, and other known carriers. In addition, the skin cleanser can include additives such as fragrance, colorants, vitamin E, herbal supplements, antibiotics, UV absorbers, hydrating agents, sun-block agents, exfoliating agents, and the like. A more detailed description of various skin cleansers can be found in US Patent Nos. 3,944,506; 4,048,123; 4,737,307; and 6,518,228, which are each incorporated herein by reference in their respective entireties. The nanodiamond particles can be present in the skin cleanser composition at from about 1 wt.% to about 50 wt.%, and preferably from about5 wt.% to about 30 wt.%.

The remedial healthcare composition can be formulated as an antibiotic composition. Such antibiotic compositions can be formed as a skin cleanser, lotion, wound dressing, and the like similar to the other compositions described herein. Nanodiamonds in antibiotic and lotion compositions can also increase healing of skin and removal of damaged skin such as with sunburns and scar tissue.

7.9 TOOTHPASTE AND NAIL POLISH

Alternatively, the remedial healthcare composition can be formulated as toothpaste including an acceptable carrier and a plurality of nanodiamond particles. Basic formulation of toothpastes is known in the literature. Common acceptable carriers can include, for example, glycerin, sorbitol, silicas (e.g. amorphous, hydrated, etc.), thickening agents such as carrageenan and salts of cellulose ethers, alcohols, water, gels, combinations of these materials, and other known carriers. In addition, the toothpaste can include additives such as sodium fluoride, fragrance, flavors, colorants, herbal supplements, and the like. The nanodiamond particles can be present in the composition at from about 1 wt.% to about 40 wt.%, and preferably from about 2 wt.% to about 15 wt.%. Nanodiamond added toothpaste has another advantage, as nan-odiamond is known to cure gum disease.

The remedial healthcare compositions can also be formulated as a shampoo. The shampoo can include an acceptable carrier and a plurality of nanodiamond particles. Acceptable carriers are known in the literature and can include, for example, surfactants, alcohols, water, glycerin, gels, combinations of these materials, and other known carriers. In addition, the shampoo can include additives such as fragrance, colorants, vitamin E, herbal supplements, and the like. The nanodiamond particles can be present in the composition at from about 1 wt.% to about 40 wt.%, and preferably from about 2 wt.% to about 15 wt.%.

Optional bubbling agents can also be added to the nanodia-mond compositions. Suitable bubbling agents can be included to increase contact of unsaturated nanodiamonds with a biological material. For example, over time, nanodiamond particles near a surface can become saturated with biological or other material. The presence of vapor bubbles can improve the rate at which such saturated nanodiamonds are removed from a surface. This can be advantageous in maximizing the effect of nanodiamonds in skin cleansers, deodorants, shampoos, soaps, toothpaste, and the like.

Another cosmetic nanodiamond composition can be formulated including a cosmetically acceptable carrier and a plurality of nanodiamond particles dispersed in the carrier with a dispersant. For example, the cosmetic composition can be formulated as a nail polish, eyeliner, lip-gloss, or exfoliant (Fig. 7.13).

Preferably, the cosmetic nanodiamond composition can be formulated as a nail polish. A nanodiamond nail polish composition can include a cosmetically acceptable carrier and a plurality of nanodiamonds dispersed therein. Additives can also be included such as, but not limited to, dispersant, pigment, plasti-cizer, bubbling agent, solvent, stabilizer, UV stabilizer, moisturizers, fragrances, and combinations thereof. Additional considerations and materials for nail enamel compositions generally are discussed in US Patent Application No. 2003/0064086 and U.S. Patent Nos. 5,725,866; 5,882,636; and 6,352,687, which are incorporated herein by reference in their entireties. In one specific embodiment, the nanodiamond nail composition can include a polymeric resin, plasticizer, pigment, nanodiamonds, dispersant, solvent, and a UV stabilizer.

Suitable cosmetically acceptable carriers can include, but are not limited to, polymeric resins such as nitrocellulose resins, cellulose acetate resins, vinyl resins, acrylate resins, polyester resins, aldehyde derivatives such as tosylamide/formaldehyde resins, and other similar polymeric resins. Other resins can also be used which provide mechanical strength to the nail composition upon drying. Typically, such carriers can comprise from about 5 wt.% to about 60 wt.% of the nanodiamond nail polish composition.

Many of the above listed cosmetically acceptable carriers are somewhat rigid. Thus, softer resins can be combined with more rigid resins in order to provide mechanically sound nail enamel with some degree of flexibility. Additionally, optional plasticiz-ers can be added to further increase the flexibility of the nail enamel upon drying. Addition of such softer resins and plasticizers can reduce premature cracking and chipping. Examples of suitable plasticizers can include benzoates, stearates, phosphates such as tricresyl phosphate, phthalates such as dibutyl phthalate and dioctyl phthalate, camphor, and the like.

The nanodiamond nail compositions typically include a solvent that provides a fluid, or spreadable composition that is suitable for application to a nail. The solvent then evaporates once applied to provide a durable hardened film on the nail, wherein the resin acts as a binder for the remaining components, e.g. pigments, nanodiamonds, etc. Non-limiting examples of common solvents that are suitable include acetates such as butyl acetate and ethyl acetate, alcohols such as isopropyl alcohol, ketones, toluene, xylene, and combinations of these solvents.

One of the primary purposes of nail compositions can be to provide an aesthetically pleasing appearance. Specifically, various additives can be included which provide a wide range of colors and/or effects to the applied nail composition. For example, pigments can be included which provide a specific color to the applied nail composition. Organic pigments are most common; however, inorganic pigments can also be used. Such pigments are well known in the literature and can be chosen accordingly to provide a desired color and consistency. Optional particulate materials such as mica, metal oxides, diamonds and the like can be added to provide a sparkle or other effects. For example, larger particulates create a sparkle appearance, while progressively smaller particulates can create a shimmer, or even pearlescent appearance.

The cosmetic nanodiamond composition can also include a dispersant such as those discussed above. One specific suitable dispersant for nanodiamond nail compositions is stearalkonium hectorite.

In addition to the above-recited advantages of including nanodiamondparticles in a nail formulation, the nanodiamond particles can also improve the durability of the applied nail compositions. Specifically, nanodiamonds can provide increased resistance to chipping and wear, e.g. typically a nanodiamond nail polish can last from about three to ten times longer than typical nail lacquer formulations. The nanodiamonds can be included in the cosmetic nanodiamond compositions at about 1 wt.% to about 50wt.% of the composition, and preferably from about 2 wt.% to about 30 wt.%.

One example of nail polish composition is prepared including 20 wt.% nitrocellulose resin, 20 wt.% ethyl acetate, 25 wt.% toluene and 10 wt.% isopropyl alcohol solvents, 9 wt.% dibutyl phthalate plasticizer, 5 wt.% stearalkonium hectorite, and 3 wt.% benzophe-none UV stabilizer. The remaining weight percent includes an aqueous aluminum chloride suspension of 60 wt.% nanodiamond particles.

Nanodiamond Film
Figure 7.13. Nanodiamond cosmetic products and the Chinese product instruction.

Chapter Eight

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