WO2010038066A1

WO2010038066A1 - Hair care compositions comprising porous silicon

Info

Publication number: WO2010038066A1
Application number: PCT/GB2009/051280
Authority: WO
Inventors: Leigh Canham; Armando Loni; Sean Smith; Tanya Monga; Daniel Johnson
Original assignee: Intrinsiq Materials Global Limited
Priority date: 2008-09-30
Filing date: 2009-09-30
Publication date: 2010-04-08
Also published as: GB0817939D0

Abstract

A hair care composition comprising porous silicon is described.

Description

HAIR CARE COMPOSITIONS COMPRISING POROUS SILICON

Field of the Invention

This invention relates to hair care compositions comprising porous silicon and methods of making said compositions. This invention also relates to various uses of said hair care compositions. This invention also relates to methods of loading porous silicon with one or more ingredients.

Background of the Invention

Human hair becomes "soiled" due to its contact with the surrounding environment and from the continuous secretion of sebum via the scalp. Shampooing cleans the hair by removing such contaminants and excess sebum, but can also remove much of the hair's natural moisturizing agents, oils and conditioning agents. Undesirable effects include leaving the dried hair in a rough, lustreless or frizzy state with increased levels of static charge.

Modern hair care formulations, such as shampoo and conditioner, have evolved to meet the complex requirements of effective cleaning with desired hair properties and appearance. Specific ingredients or so-called actives are included in such formulations to promote effective cleaning, softness, appropriate colour, sheen, combability, body, volume, stylability, anti-static properties and manageability. The delivery and the retention of such actives on hair follicles, hair roots and the scalp remains a significant technical challenge. Studies have shown, for example, that often only 5wt% of a specific ingredient or active is retained after typical rinsing.

Other problems associated with hair care include dandruff and split ends. Dandruff is due to the excessive shedding of dead skin cells from the scalp. Excessive flaking can be a symptom of fungal infection, psoriasis or seborrhoeic dermatitis. Trichoptilosis ("split-ends") are a common form of hair damage that is the result of either physical or chemical traumatizing of the hair. Prevention generally involves supplementation of hair care products with cationic surfactants in order to improve lubricity or with plasticizing agents like humectants in order to raise moisture levels. There is a continued need for alternative and preferably improved formulations for effectively delivering specific ingredients to human or animal hair and/or the scalp.

The present invention is based partly on the surprising finding that porous silicon may be used in hair care formulations for the effective and controlled delivery of active ingredients.

Summary of the Invention

According to a first aspect of the present invention, a hair care composition comprising porous silicon is provided.

According to a second aspect of the present invention, there is provided a production process for said hair care composition according to the first aspect of the present invention, comprising blending said porous silicon and other components of the hair care composition.

According to a third aspect of the invention, the use of porous silicon in a hair care composition is provided.

According to a further aspect of the present invention a method of treating and/or cleaning the hair and/or scalp of a human or animal comprising applying a hair care composition according to the first aspect of the present invention is provided. The method may be a cosmetic method. The hair care composition may be an anti- dandruff shampoo and/or suitable for treating split ends. The present invention extends to hair care compositions for use in the prevention and/or treatment of dandruff and/or split ends and/or head-lice and/or hair-loss.

The porous silicon may comprise at least one ingredient for delivery to human and/or animal hair and/or the scalp and/or the animal body. The porous silicon may comprise at least one ingredient for delivery to human hair only. Suitable ingredients include actives such as one or more of: anti-dandruff agents, natural hair root nutrients, antifungal agents, sunscreens, hair fibre agents, fragrances, moisturisers, oils, vitamins, structural agents, natural actives. The porous silicon may be loaded with the ingredient which may be entrapped in the silicon pores. According to a further aspect of the present invention, there is provided a method of loading porous silicon with at least one ingredient, the method comprising contacting porous silicon with said at least one ingredient wherein the ingredient is present as a complex with a chelator.

The ingredient and chelator may be dissolved in a suitable solvent, e.g. water. The solution, which may have been heated may then be added to the porous silicon. The chelator may subsequently be removed by, for example, thermal evaporation.

The use of porous silicon in hair care compositions according to the present invention seeks to provide one or more of the following: targeted delivery of ingredients; treatment and/or prevention of "split ends", hair loss, head-lice, dandruff, "frizziness"; imparting colour, fragrance, sheen, volume, manageability; extended release of ingredients including burst fragrance release, for example, during hair drying; improved bioavailability of hydrophobic actives; beneficial degradation products such as orthosilicic acid; retention of significant levels of active ingredients on the hair and/or scalp over extended periods of time, enhanced UV protection of hair with or without the inclusion of loaded ingredients.

Detailed Description of the Invention

Porous Silicon

As used herein, and unless otherwise stated, the term "silicon" refers to solid elemental silicon. For the avoidance of doubt, and unless otherwise stated, it does not include silicon-containing chemical compounds such as silica, silicates or silicones, although it may be used in combination with these materials.

The physical forms of porous silicon which are suitable for use in the present invention may be chosen from or comprise amorphous silicon, single crystal silicon and polycrystalline silicon (including nanocrystalline silicon, the grain size of which is typically taken to be 1 to 100nm) and including combinations thereof. The silicon may be surface porosified, for example, using a stain etch method or more substantially porosified, for example, using an anodisation technique. Following porosification some non-porosified silicon, such as bulk silicon, may be present with the porous silicon.

The porous silicon is advantageously selected from microporous and/or mesoporous silicon. Mesoporous silicon contains pores having a diameter in the range of 2 to 50nm. Microporous silicon contains pores possessing a diameter less than 2nm.

The average pore diameter is measured using a known technique. Mesopore diameters are measured by very high resolution electron microscopy. This technique and other suitable techniques which include gas-adsorption-desorption analysis, small angle x-ray scattering, NMR spectroscopy or thermoporometry, are described by R.

Herino in "Properties of Porous Silicon", chapter 2.2, 1997. Micropore diameters are measured by xenon porosimetry, where the Xe¹²⁹ nmr signal depends on pore diameter in the sub 2nm range.

The porous silicon may have a BET surface area of 10m²/g to 800m²/g for example 100m²/g to 400m²/g. The BET surface area is determined by a BET nitrogen adsorption method as described in Brunauer et al., J. Am. Chem. Soc, 60, p309, 1938. The BET measurement is performed using an Accelerated Surface Area and Porosimetry Analyser (ASAP 2400) available from Micromeritics Instrument Corporation, Norcross, Georgia 30093. The sample is outgassed under vacuum at 350⁰C for a minimum of 2 hours before measurement.

The purity of the porous silicon may be about 95 to 99.99999% pure, for example about 95 to 99.99% pure. Any particular metals which may cause scalp irritation may be minimised, these include nickel, copper and silver. For example, any nickel which may be present preferably does not exceed 100ppm. So-called metallurgical silicon which may also be used in the hair care compositions has a purity of about 98 to 99.5%.

The use of porous silicon according to the present invention may impart a visually appealing appearance to the hair and, as such, according to a further aspect of the present invention, the use of porous silicon in a hair care composition for modifying the appearance of hair is provided. This may include a glittering or glinting appearance. By using mirrors, which reflect different wavelengths of light, specific colouration of hair may be effected. This may be achieved by varying the porosities of adjacent layers comprising porous silicon between low and high porosity layers. Typically, the low porosity layers may have a porosity of up to about 65vol%, for example about 25vol% to 65vol% and the high porosity layers have a porosity of at least about 60vol%, for example about 60vol% to 95vol%. Each mirror may comprise greater than 10 layers or greater than 100 layers, or greater than 200 layers or greater than or equal to 400 layers. Each layer from which the mirrors are formed has a different refractive index to its neighbouring layer or layers such that the combined layers form a Bragg stack mirror. Specific colours may also be imparted to silicon particles by surface porosification using stain etching or partial oxidation. In general, porous silicon possessing a particle size less than 1 μm may be used in connection with the present invention in providing optical effects.

The total amount of silicon present in the hair care composition may be about 0.01wt% to 20wt% based on the total weight of the hair care composition and the unloaded weight of the silicon, for example 0.01 wt% to 5wt%.

Silicon manufacture and processing

Methods for making various forms of silicon which are suitable for use in the present invention are described below. The methods described are well known in the art.

In PCT/GB96/01863, the contents of which are incorporated herein by reference in their entirety, it is described how bulk crystalline silicon can be rendered porous by partial electrochemical dissolution in hydrofluoric acid based solutions. This etching process generates a silicon structure that retains the crystallinity and the crystallographic orientation of the original bulk material. Hence, the porous silicon formed is a form of crystalline silicon. Broadly, the method involves anodising, for example, a heavily boron doped CZ silicon wafer in an electrochemical cell which contains an electrolyte comprising a 20% solution of hydrofluoric acid in an alcohol such as ethanol, methanol or isopropylalcohol (IPA). Following the passing of an anodisation current with a density of about 50mAcm^~2, a porous silicon layer is produced which may be separated from the wafer by increasing the current density for a short period of time. The effect of this is to dissolve the silicon at the interface between the porous and bulk crystalline regions. Porous silicon may also be made using the so-called stain-etching technique which is another conventional method for making porous silicon. This method involves the immersion of a silicon sample in a hydrofluoric acid solution containing a strong oxidising agent. No electrical contact is made with the silicon, and no potential is applied. The hydrofluoric acid etches the surface of the silicon to create pores. Mesoporous silicon may be generated from a variety of non-porous silicon powders by so-called "electroless electrochemical etching techniques", as reviewed by K. Kolasinski in Current Opinions in Solid State & Materials Science 9, 73 (2005). These techniques include "stain-etching", "galvanic etching", "hydrothermal etching" and "chemical vapour etching" techniques. Stain etching results from a solution containing fluoride and an oxidant. In galvanic or metal-assisted etching, metal particles such as platinum are also involved. In hydrothermal etching, the temperature and pressure of the etching solution are raised in closed vessels. In chemical vapour etching, the vapour of such solutions, rather than the solution itself is in contact with the silicon. Mesoporous silicon can be made by techniques that do not involve etching with hydrofluoric acid. An example of such a technique is chemical reduction of various forms of porous silica as described by Z. Bao et al in Nature vol. 446 8th March 2007 p172-175 and by E. Richman et al. in Nano Letters vol. 8(9) p3075-3079 (2008). If this reduction process does not proceed to completion then the mesoporous silicon contains varying residual amounts of silica.

Following its formation, the porous silicon may be dried. For example, it may be supercritically dried as described by Canham in Nature, vol. 368, (1994), pp133-135. Alternatively, the porous silicon may be freeze dried or air dried using liquids of lower surface tension than water, such as ethanol or pentane, as described by Bellet and Canham in Adv. Mater, 10, pp487-490, 1998.

Silicon hydride surfaces may, for example, be generated by stain etch or anodisation methods using hydrofluoric acid based solutions. When the silicon, prepared, for example, by electrochemical etching in HF based solutions, comprises porous silicon, the surface of the porous silicon may or may not be suitably modified in order, for example, to improve the stability of the porous silicon in the hair care composition. In particular, the surface of the porous silicon may be modified to render the silicon more stable in alkaline conditions. The surface of the porous silicon may include the external and/or internal surfaces formed by the pores of the porous silicon.

In certain circumstances, the stain etching technique may result in partial oxidation of the porous silicon surface. The surfaces of the porous silicon may therefore be modified to provide: silicon hydride surfaces; silicon oxide surfaces wherein the porous silicon may typically be described as being partially oxidised; or derivatised surfaces which may possess Si-O-C bonds and/or Si-C bonds. Silicon hydride surfaces may be produced by exposing the porous silicon to HF.

Silicon oxide surfaces may be produced by subjecting the silicon to chemical oxidation, photochemical oxidation or thermal oxidation, as described for example in Chapter 5.3 of Properties of Porous Silicon (edited by L.T. Canham, IEE 1997). PCT/GB02/03731 , the entire contents of which are incorporated herein by reference, describes how porous silicon may be partially oxidised in such a manner that the sample of porous silicon retains some elemental silicon. For example, PCT/GB02/03731 describes how, following aπodisation in 20% ethanoic HF, the anodised sample was partially oxidised by thermal treatment in air at 500⁰C to yield a partially oxidised porous silicon sample.

Following partial oxidation, an amount of elemental silicon will remain. The silicon particles may possess an oxide content corresponding to between about one monolayer of oxygen and a total oxide thickness of less than or equal to about 4.5nm covering the entire silicon skeleton. The porous silicon may have an oxygen to silicon atomic ratio between about 0.04 and 2.0, and preferably between 0.60 and 1.5. Oxidation may occur in the pores and/or on the external surface of the silicon.

Derivatised porous silicon is porous silicon possessing a covalently bound monolayer on at least part of its surface. The monolayer typically comprises one or more organic groups that are bonded by hydrosilylation to at least part of the surface of the porous silicon. Derivatised porous silicon is described in PCT/GBOO/01450, the contents of which are incorporated herein by reference in their entirety. PCT/GBOO/01450 describes derivatisation of the surface of silicon using methods such as hydrosilyation in the presence of a Lewis acid. In that case, the derivatisation is effected in order to block oxidation of the silicon atoms at the surface and so stabilise the silicon. Methods of preparing derivatised porous silicon are known to the skilled person and are described, for example, by J. H. Song and MJ. Sailor in Inorg. Chem. 1999, vol 21 , No. 1-3, pp 69-84 (Chemical Modification of Crystalline Porous Silicon Surfaces). Derivitisation of the silicon may be desirable when it is required to increase the hydrophobicity of the silicon, thereby decreasing its wettability. Preferred derivatised surfaces are modified with one or more alkyne groups. Alkyne derivatised silicon may be derived from treatment with acetylene gas, for example, as described in "Studies of thermally carbonized porous silicon surfaces" by J. Salonen et al in Phys Stat. Solidi (a), 182, pp123-126, (2000) and "Stabilisation of porous silicon surface by low temperature photoassisted reaction with acetylene", by S.T. Lakshmikumar et al in Curr. Appl. Phys. 3, pp185-189 (2003). Mesoporous silicon may be derivatised during its formation in HF-based electrolytes, using the techniques described by G. Mattei and V. Valentini in Journal American Chemical Society vol 125, p9608 (2003) and Valentini et al., Physica Status Solidi (c) 4 (6) p2044-2048 (2007).

The surface chemistry of the porous silicon may be adapted depending on the particular application. For example, in connection with anti-dandruff or split ends treatments, such as shampoos, the surface chemistry may be tailored in order to promote skin binding and hence scalp retention and/or hair binding.

The porous silicon may also comprise a capping layer in order to prevent release of the loaded ingredient prior to application to the human or animal or too soon following application. In particular, the porous silicon may be capped using ultrathin capping layers or beads around the loaded porous silicon. The capping layers may provide retention of the loaded ingredient over a number of months of storage in liquid media, for example from about 1 year up to about 5 years. After the container has been opened, retention may be for a shorter period but may still be up to about 1 year after opening. The capping layer may also be designed to trigger active release of the loaded ingredient through site-specific degradation when in contact with the human or animal hair or scalp. Suitable capping materials include one or more of glyceryl oleate, seed oil, cyclopentasiloxane or paraffin. Suitable methods for capping the porous silicon include spray drying, fluidized bed coating, pan coating, modified microemulsion techniques, melt extrusion, spray chilling, complex coacervation, vapour deposition, solution precipitation, emulsification, supercritical fluid techniques, physical sputtering, laser ablation, and thermal evaporation. The capping layer, may for example be degraded by a sudden increase in temperature, such as that provided by warm water. The capping layer may comprise two overlying distinct capping layers, with each layer possessing different properties. A suitable shampoo formulation according to the present invention may comprise microparticles of mesoporous silicon (possessing a d₅o of about 50μm), loaded with an anti-dandruff agent such as ketaconazole and coated with a layer of glyceryl oleate of about 2-5μm thickness. An example of a capping layer for use in anti-dandruff shampoos is one that is selectively recognised by the micro-organism which is responsible for dandruff, i.e. the fungi M. Restricta and M. Globosa. A suitable capping layer comprises one or more triglycerides. The lipases in the fungi degrade the triglycerides and the anti-dandruff agent is released, particularly in high regions of fungal activity.

Paniculate silicon

The silicon is typically present in particulate form. Methods for making silicon powders such as silicon microparticles and silicon nanoparticles are well known in the art. Silicon microparticles are generally taken to mean particles of about 1 to 1000μm in diameter and silicon nanoparticles are generally taken to mean particles possessing a diameter of about 100nm and less. Silicon nanoparticles therefore typically possess a diameter in the range of about 1 nm to about 100nm, for example about 5nm to about 100nm. Fully biodegradable mesoporous silicon typically has an interconnected silicon skeleton with widths in the 2-5nm range. In connection with the present invention, mesoporous silicon particles possessing a diameter of 50nm-1000nm and particularly 100-500nm may be employed. Methods for making silicon powders are often referred to as "bottom-up" methods, which include, for example, chemical synthesis or gas phase synthesis. Alternatively, so-called "top-down" methods refer to such known methods as electrochemical etching or comminution (e.g. milling as described in Kerkar et al. J. Am. Ceram. Soc, vol. 73, pages 2879-2885, 1990.). PCT/GB02/03493 and PCT/GB01 /03633, the contents of which are incorporated herein by reference in their entirety, describe methods for making particles of silicon, said methods being suitable for making silicon for use in the present invention. Such methods include subjecting silicon to centrifuge methods, or grinding methods. Porous silicon powders may be ground between wafers or blocks of crystalline silicon. Since porous silicon has lower hardness than bulk crystalline silicon, and crystalline silicon wafers have ultrapure, ultrasmooth surfaces, a silicon wafer/porous silicon powder/silicon wafer sandwich is a convenient means of achieving for instance, a 1-10 μm particle size from much larger porous silicon particles derived, for example, via anodisation.

The surface of silicon particles prepared by "top down" or "bottom up" methods may also be a hydride surface, a partially oxidised surface, a fully oxidised surface or a derivatised surface. Milling in an oxidising medium such as water or air will result in silicon oxide surfaces. Milling in an organic medium may result in, at least partial derivatisation of the surface. Gas phase synthesis, such as from the decomposition of silane, will result in hydride surfaces. The surface may or may not be suitably modified in order, for example, to improve the stability of the particulate silicon in the hair care composition.

Other examples of methods suitable for making silicon nanoparticles include evaporation and condensation in a subatmospheric inert-gas environment. Various aerosol processing techniques have been reported to improve the production yield of nanoparticles. These include synthesis by the following techniques: combustion flame; plasma; laser ablation; chemical vapour condensation; spray pyrolysis; electrospray and plasma spray. Because the throughput for these techniques currently tends to be low, preferred nanoparticle synthesis techniques include: high energy ball milling; gas phase synthesis; plasma synthesis; chemical synthesis; sonochemical synthesis.

Some methods of producing silicon nanoparticles are described in more detail below.

High-energy ball milling

High energy ball milling, which is a common top-down approach for nanoparticle synthesis, has been used for the generation of magnetic, catalytic, and structural nanoparticles, see Huang, "Deformation-induced amorphization in ball-milled silicon", Phil. Mag. Lett., 1999, 79, pp305-314. The technique, which is a commercial technology, has traditionally been considered problematic because of contamination problems from ball-milling processes. However, the availability of tungsten carbide components and the use of inert atmosphere and/or high vacuum processes has reduced impurities to acceptable levels. Particle sizes in the range of about 0.1 to 1 μm are most commonly produced by ball-milling techniques, though it is known to produce particle sizes of about 0.01 μm.

Ball milling can be carried out in either "dry" conditions or in the presence of a liquid, i.e. "wet" conditions. For wet conditions, typical solvents include water or alcohol based solvents.

Gas phase synthesis

Silane decomposition provides a very high throughput commercial process for producing polycrystalline silicon granules. Although the electronic grade feedstock

(currently about $30/kg) is expensive, so called "fines" (microparticles and nanoparticles) are a suitable waste product for use in the present invention. Fine silicon powders are commercially available. For example, NanoSi™ Polysilicon is commercially available from Advanced Silicon Materials LLC and is a fine silicon powder prepared by decomposition of silane in a hydrogen atmosphere. The particle size is 5 to 500nm and the BET surface area is about 25m²/g. This type of silicon has a tendency to agglomerate, reportedly due to hydrogen bonding and Van der Waals forces.

Plasma synthesis

Plasma synthesis is described by Tanaka in "Production of ultrafine silicon powder by the arc plasma method", J. Mat. Sci., 1987, 22, pp2192-2198. High temperature synthesis of a range of metal nanoparticles with good throughput may be achieved using this method. Silicon nanoparticles (typically 10-100nm diameter) have been generated in argon-hydrogen or argon-nitrogen gaseous environments using this method.

Chemical synthesis

Solution growth of ultra-small (<10nm) silicon nanoparticles is described in US 20050000409, the contents of which are incorporated herein in their entirety. This technique involves the reduction of silicon tetrahalides such as silicon tetrachloride by reducing agents such as sodium napthalenide in an organic solvent. The reactions lead to a high yield at room temperature.

Sonochemical synthesis

In sonochemistry, an acoustic cavitation process can generate a transient localized hot zone with extremely high temperature gradient and pressure. Such sudden changes in temperature and pressure assist the destruction of the sonochemical precursor (e.g., organometallic solution) and the formation of nanoparticles. The technique is suitable for producing large volumes of material for industrial applications. Sonochemical methods for preparing silicon nanoparticles are described by Dhas in "Preparation of luminescent silicon nanoparticles: a novel sonochemical approach", Chem. Mater., 10, 1998, pp 3278-3281. Mechanical synthesis

Lam et al have fabricated silicon nanoparticles by ball milling graphite powder and silica powder, this process being described in J. Crystal Growth 220(4), p466-470 (2000), which is herein incorporated by reference in its entirety. Arujo-Andrade et al have fabricated silicon nanoparticles by mechanical milling of silica powder and aluminium powder, this process being described in Scripta Materialia 49(8), p773-778 (2003).

An alternative method for making porous silicon from nanoparticles includes exposing nanoparticulate elemental silicon to a pulsed high energy beam. The high energy beam may be a laser beam or an electron beam or an ion beam. Preferably, the high energy beam creates a condition wherein the elemental silicon is rapidly melted, foamed and condensed. Preferably, the high energy beam is a pulsed laser beam.

In the present invention, particle size distribution measurements, including the mean particle size (d₅₀/μm) of the porous silicon particles are measured using a Malvern Particle Size Analyzer, Model Mastersizer, from Malvern Instruments. A helium-neon gas laser beam is projected through a transparent cell which contains the silicon particles suspended in an aqueous solution. Light rays which strike the particles are scattered through angles which are inversely proportional to the particle size. The photodetector array measures the quantity of light at several predetermined angles. Electrical signals proportional to the measured light flux values are then processed by a microcomputer system, against a scatter pattern predicted from theoretical particles as defined by the refractive indices of the sample and aqueous dispersant to determine the particle size distribution of the silicon.

Ingredients

The porous silicon may be loaded with one or more active ingredients. These ingredients include one or more of the following: an anti-dandruff agent or agents, a natural hair root nutrient or nutrients, sunscreen or sunscreens, hair fibre agent or agents, fragrance or fragrances, moisturiser or moisturisers, oil or oils, hair-loss ingredient or ingredients, vitamin or vitamins, head lice agent or agents, structural agent or agents, natural active or actives. Typically, the one or more ingredients are present in the range, in relation to the loaded silicon, of 0.01 to 60wt%, for example 1 to 40wt% and for example 2 to 10wt%.

The ingredient to be loaded with the porous silicon may be dissolved or suspended in a suitable solvent, and porous silicon particles may be incubated in the resulting solution for a suitable period of time. Both aqueous and non-aqueous slips have been produced from ground silicon powder and the processing and properties of silicon suspensions have been studied and reported by Sacks in Ceram. Eng. Sci. Proc, 6, 1985, pp1109-1 123 and Kerkar in J. Am. Chem. Soc. 73, 1990, pp2879-85. The wetting of solvent will result in the ingredient penetrating into the pores of the silicon by capillary action, and, following solvent removal, the ingredient will be present in the pores. Preferred solvents are water, ethanol, and isopropyl alcohol, GRAS solvents and volatile liquids amenable to freeze drying. Alternative methods of loading may comprise the use of one or more chelators. For example, the ingredient to be loaded may be combined with a chelator prior to the ingredient being loaded with the porous silicon. The chelator may then be removed, by for example, thermal evaporation.

In general, if the ingredient to be loaded has a low melting point and a decomposition temperature significantly higher than that melting point, then an efficient way of loading the ingredient is to melt the ingredient.

Higher levels of loading, for example, at least about 15wt% of the loaded ingredient based on the loaded weight of the silicon may be achieved by performing the impregnation at an elevated temperature. For example, loading may be carried out at a temperature which is at or above the melting point of the ingredient to be loaded. Quantification of gross loading may conveniently be achieved by a number of known analytical methods, including gravimetric, EDX (energy-dispersive analysis by x-rays), Fourier transform infra-red (FTIR), Raman spectroscopy, UV spectrophotometry, titrimetric analysis, HPLC or mass spectrometry. If required, quantification of the uniformity of loading may be achieved by techniques that are capable of spatial resolution such as cross-sectional EDX, Auger depth profiling, micro-Raman and micro-FTIR.

The loading levels can be determined by dividing the volume of the ingredient taken up during loading (equivalent to the mass of the ingredient taken up divided by its density) by the void volume of the porous silicon prior to loading multiplied by one hundred. Anti-dandruff agents

Suitable examples of anti-dandruff agents include zinc pyrithione (ZnPT), selenium sulphide, tea tree oil, coal tar, sulphur, salicylic acid, 1 hydroxy pyridone. Further examples are the imidazole anti-fungals including miconazole, imidazole, fluconazole, piroctone, clotrimazole, bifonazole, ketaconazole, climbazole, olamine(octopirox), rilopirox, ciclopirox, olamine.

In order to facilitate loading of the anti-dandruff agent with the porous silicon, the anti- dandruff agent may be combined with a chelator. A suitable example of a chelator is ethanolamine. Advantageously, for use in connection with delivering anti-dandruff agents the d₅₀ of the loaded porous silicon particles is 1 to 45μm, for example 1 to 10μm. Advantageously, the use of porous silicon facilitates the use of larger particles than those usually considered appropriate when ZnPT is used in conventional shampoos. The anti-dandruff agent may be loaded with the porous silicon in amounts of about 20 to 50wt%. The amounts of loaded porous silicon may be loaded in shampoo at about 0.01 to 2wt%, preferably 0.05 to 1wt%. Release of the anti-dandruff agent may be facilitated by one or more of a number of effects, including, frictional forces, an increase in salt level or a change in pH on application to the scalp. Release may also be facilitated by the choice of an appropriate capping layer which reacts with the microorganisms which are responsible for dandruff.

Sunscreens

Suitable sunscreens include camphor derivatives, benzophenone compounds such as 4,4'-tetrahydroxy-benzophenone which is sold commercially as Uvinul D50, and 2- hydroxy-4-methoxybenzophenone, sold commercially as Eusolex 4360, dibenzoyl methane derivatives such as t-butyl-4-methoxydibenzoylmethane, sold commercially as Parsol 1789, and isopropyldibenzoyl methane, sold commercially as Eusolex 8020. Further suitable types of sunscreen materials are cinnamates, such as 2-ethylhexyl-p- methoxy cinnamate, sold commercially as Parsol MCX, 2-ethoxy ethyl-p-methoxy cinnamate, sold commercially as Giv-Tan F and isoamyl-p-methoxy cinnamate, sold commercially as Neo-Heliopan E1000. The compositions in accordance with the present invention are particularly useful for delivering one or more sunscreens to the hair only rather than the scalp. Natural hair root nutrients

Suitable natural hair root nutrients include amino acids and sugars. Examples of suitable amino acids include arginine, cysteine, glutamine, glutamic acid, isoleucine, leucine, methionine, serine and valine, and/or precursors and derivatives thereof. The amino acids may be added singly, in mixtures, or in the form of peptides, e.g. di- and tripeptides. The amino acids may also be added in the form of a protein hydrolysate, such as a keratin or collagen hydrolysate. Suitable sugars are glucose, dextrose and fructose. These may be added singly or in the form of, e.g. fruit extracts.

Hair fibre benefit agents

Suitable examples of hair fibre benefit agents include ceramides, for moisturising the fibre and maintaining cuticle integrity. Ceramides are available including by extraction from natural sources, or as synthetic ceramides.

Other suitable materials include fatty acids, for cuticle repair and damage prevention. Particular examples include branched chain fatty acids such as 18-methyleicosanoic acid and other homologues of this series, straight chain fatty acids such as stearic, myristic. and palmitic acids, and unsaturated fatty acids such as oleic acid, linoleic acid, linolenic acid and arachidonic acid.

Split ends may be treated and/or prevented by using a lubricating or plasticizing agent. The surface chemistry of the porous silicon may be adapted to promote hair binding.

Hair-loss ingredients

One or more ingredients suitable for the prevention and/or treatment of hair-loss may be included. Suitable hair loss preventive agents include non-steroidal antiinflammatories such as piroxicam, ketoprofen, ibuprofen, circulation stimulators such as capsicum or gotu kola, minoxidil or zinc pyridinethione (ZPT), plant extracts such as aloe vera, ginko biloba, olive oil, vitamin E, vitamin B3 and amino acids.

Head-lice agents Suitable actives include insecticides and/or pesticides such as pyrethrins, essential oils, malathion compounds, avermectin compounds.

Fragrances

Suitable fragrances, or perfuming ingredients, include compounds belonging to varied chemical groups such as aldehydes, ketones, ethers, nitrites, terpenic hydrocarbons, alcohols, esters, acetals, ketals, nitriles. Natural perfuming agents are preferred such as essential oils, resinoids and resins.

With regard to fragrant oils, sustained release may be carried out using microporous silicon or mesoporous silicon possessing a pore diameter in the range of about 1- 10nm. The small pore size suppresses the release of the fragrant volatiles.

The compositions in accordance with the present invention are particularly useful for delivering one or more fragrances to the hair only rather than the scalp.

Moisturisers

Suitable moisturisers or emollients include glycerine, mineral oil, petrolatum, urea, lactic acid or glycolic acid.

Oils

Suitable oils include plant oils, essential oils.

Vitamins

Suitable vitamins include vitamin A, B5, C, E.

Structural agents

Suitable structural agents include oils, proteins, polymers that thicken and add body to hair and/or make it feel smoother. Structural agents which add body may be referred to as bulking agents or bulk agent coatings and may be suitable for use with fine hair follicles. These may be colour matched and/or provide a muted glitter appearance with the hair and/or combined with one or more fragrances.

Natural actives

Suitable natural actives include herb or plant extracts. Light sensitive plant actives are suitable for use in accordance with the present invention. Entrapment within porous silicon and gradual release provides for improved shelf-life and on-hair photostability.

Mixtures of any of the above active ingredients may also be used.

Hair care compositions

The term hair care composition as used herein includes shampoos, gels, creams, conditioners (including leave-on conditioners), combined shampoo/conditioners, hair dyes, mousses, foams, waxes, creme rinses, masks, muds, semi-solid structured styling pastes (also known as putties), styling sprays, hot oil treatments, rinses, lotions, all suitable for use on the hair of humans and animals, particularly on human hair, especially hair on the human head. The general constituents of these compositions are well known to the skilled person.

The pH of the hair care composition is advantageously such that the silicon does not dissolve in the composition over a significant period of time and will thus afford an acceptable shelf-life. The pH of the hair care composition is typically less than about 7.5 (though may be as high as about 8.5) and preferably less than or equal to about 7 for example less than or equal to about 6 and may be less than about 4.6. Most commercially available shampoos are, for example, about pH 5-6.5 and the pH of the hair care composition may lie in this range. The lower limit of pH may be about 2. For mesoporous silicon, a suitable pH range may be 2 to 6. For use in higher pH environments, such as up to about pH 8.5 the porous silicon may advantageously be stabilised, for example, by partial oxidation. This may be achieved by heating the porous silicon to about 500⁰C over 1 hour in air or an oxygen rich atmosphere.

Shampoos typically comprise water, surfactant, plus a host of optional further constituents. Water may be present in an amount of about 25% to about 99wt%, for example about 50% to about 98wt% based on the weight of the total composition. Shampoo formulations typically contain high concentrations of surfactants, e.g. up to about 50wt% based on the total weight of the shampoo. Surfactants may provide a number of functions. For example, they make the removal of dirt easier by reducing the surface tension between the water and the greasy matter on the hair. Any foam produced by the surfactant may hold the dirt in it, and prevent it from being re- deposited on the hair. Surfactants may stabilise the shampoo mixture, and help retain the other ingredients in solution. They may also thicken the shampoo and make it easier to use. Shampoos may contain several surfactants which may provide different types of cleaning, according to the type of hair. One commonly used surfactant is ammonium lauryl sulphate, another is ammonium laureth sulphate, which is milder. Many of the ingredients in shampoos are traditionally soft organic materials.

Most modern shampoos may contain conditioning agent. Other typical ingredients include lather boosters, viscosity modifiers and additives for controlling the pH. The pH of commercially available shampoos may vary quite widely, for example, some shampoos are formulated to be acidic, e.g. about pH 3.5-4.5. Other ingredients may include preservative such as sodium benzoate or parabens. Aesthetic ingredients include colours, perfumes, pearlescing agents.

The compositions according to the present invention may comprise one or more surfactants. The surfactant may be selected from any of a wide variety of anionic, amphoteric, zwitterionic and non-ionic surfactants. The surfactant may be detersive. The amount of surfactant in, for example, the shampoo composition may be from 1 to 50wt%, for example from 3 to 30wt%, for example from 5% to 20wt% based on the total weight of the composition.

Suitable anionic surfactants include alkyl sulphates, alkyl ether sulphates, alkaryl sulphonates, alkanoyl isethionates, alkyl succinates, alkyl sulphosuccinates, N-alkoyl sarcosinates, alkyl phosphates, alkyl ether phosphates, alkyl ether carboxylates, alpha- olefin sulphonates and acyl methyl taurates, for example, their sodium, magnesium ammonium and mono-, di- and triethanolamine salts. The alkyl and acyl groups may contain from 8 to 18 carbon atoms and may be unsaturated. The alkyl ether sulphates, alkyl ether phosphates and alkyl ether carboxylates may contain from 1 to 10 ethylene oxide or propylene oxide units per molecule, and may contain 2 to 3 ethylene oxide units per molecule.

Particular examples of suitable anionic surfactants include sodium lauryl sulphate, sodium lauryl ether sulphate, ammonium lauryl sulphosuccinate, ammonium lauryl sulphate, ammonium lauryl ether sulphate, sodium dodecylbenzene sulphonate, triethanolamine dodecylbenzene sulphonate, sodium cocoyl isethionate, sodium lauroyl isethionate, sodium N-lauryl sarcosinate, and mixtures thereof.

Examples of anionic detersive surfactants which may provide cleaning and lather performance to the composition include sulfates, sulfonates, sarcosinates and sarcosine derivatives.

The composition according to the present invention may also include co-surfactants, to help impart aesthetic, physical or cleansing properties to the composition. Suitable examples include amphoteric, zwitterionic and/or non-ionic surfactants, which can be included in an amount ranging up to about 10wt% based on the total weight of the shampoo composition. Examples of amphoteric or zwitterionic surfactants include alkyl amine oxides, alkyl betaines, alkyl amidopropyl betaines, alkyl sulphobetaines (sultaines), alkyl glycinates, alkyl carboxyglycinates, alkyl amphopropionates, alkylamphoglycinates, alkyl amidopropyl hydroxysultaines, acyl taurates and acyl glutamates, wherein the alkyl and acyl groups have from 8 to 19 carbon atoms. Typical amphoteric and zwitterionic surfactants for use in shampoos of the invention include lauryl amine oxide, cocodimethyl sulphopropyl betaine and lauryl betaine, cocamidopropyl betaine, sodium cocamphopropionate, and mixtures thereof.

Suitable non-ionic surfactants include condensation products of aliphatic (C₈ to Ci₈) primary or secondary linear or branched chain alcohols or phenols with alkylene oxides, usually ethylene oxide and generally having from 6 to 30 ethylene oxide groups. Other suitable non-ionic surfactants include mono- or di-alkyl alkanolamides. Examples include coco mono- or di-ethanolamide and coco mono-isopropanolamide. Further non-ionic surfactants which can be included in shampoo compositions of the invention are the alkyl polyglycosides (APGs).

Further surfactant may also be present as emulsifier for emulsified components of the composition, e.g. emulsified particles of silicone. This may be the same surfactant as the anionic surfactant or the co-surfactant, or may be different. Suitable emulsifying surfactants are well known in the art and include anionic and non-ionic surfactants. Examples of anionic surfactants used as emulsifiers for materials such as silicone particles are alkylarylsulphonates, e.g., sodium dodecylbenzene sulphonate, alkyl sulphates e.g., sodium lauryl sulphate, alkyl ether sulphates, e.g., sodium lauryl ether sulphate nEO, where n is from 1 to 20 alkylphenol ether sulphates, e.g., octylphenol ether sulphate nEO where n is from 1 to 20, and sulphosuccinates, e.g., sodium dioctylsulphosuccinate.

Examples of non-ionic surfactants used as emulsifiers for materials such as silicone particles are alkylphenol ethoxylates, e.g., nonylphenol ethoxylate nEO, where n is from 1 to 50, alcohol ethoxylates, ester ethoxylates, e.g., polyoxyethylene monostearate where the number of oxyethylene units is from 1 to 30.

The composition of the invention may also include one or more conditioning agents. As used herein, the term "conditioning agent" includes any material which is used to give a particular conditioning benefit to hair and/or the scalp or skin. For example, in shampoo compositions for use in washing hair, suitable materials are those which deliver one or more benefits relating to shine, softness, combability, wet-handling, anti- static properties, protection against damage, body, volume, stylability and manageability.

Conditioning agents for use in the present invention include emulsified silicones, used to impart, for example, wet and dry conditioning benefits to hair such as softness, smooth feel and ease of combability. The conditioning agent may be present in a level of from about 0.01wt% to about 25wt%, for example about 0.05 to about 10wt%, for example about 0.1 to 5wt% based on the total weight of the composition. The lower limit may be determined by the minimum level to achieve conditioning and the upper limit by the maximum level to avoid making the hair and/or skin unacceptably greasy. About 1 wt% is typically suitable.

A further class of silicones for inclusion in shampoos and conditioners of the invention are amino functional silicones. By "amino functional silicone" is meant a silicone containing at least one primary, secondary or tertiary amine group, or a quaternary ammonium group. A further class of conditioning agents are peralkyl and peralkenyl hydrocarbon materials, used to enhance the body, volume and stylability of hair. Suitable materials include polyisobutylene materials available from Presperse, Inc. The amount of peralkyl or peralkenyl hydrocarbon material incorporated into the compositions of the invention may depend on the level of body and volume enhancement desired and the specific material used. A suitable amount is from 0.01 to about 10wt% by weight of the total composition. The lower limit is determined by the minimum level to achieve the body and volume enhancing effect and the upper limit by the maximum level to avoid making the hair unacceptably stiff. An amount of per-alk(en)yl hydrocarbon material of from 0.5 to 2wt% of the total composition is a suitable level.

A cationic deposition polymer is an ingredient which may be included in shampoo compositions of the invention, for enhancing conditioning performance of the shampoo. By "deposition polymer" is meant an agent which enhances deposition of active ingredients and/or conditioning components (such as silicones) from the shampoo composition onto the intended site during use, i.e. the hair and/or the scalp.

The deposition polymer may be a homopolymer or be formed from two or more types of monomers. The molecular weight of the polymer may typically be at least 10,000, for example, in the range 100,000 to about 2,000,000. The polymers will have cationic nitrogen containing groups such as quaternary ammonium or protonated amino groups, or a mixture thereof. The cationic amines can be primary, secondary or tertiary amines.

As further optional components for inclusion in the compositions of the invention one or more of the following may be included: pH adjusting agents, viscosity modifiers, pearlescers, opacifiers, suspending agents, preservatives, colouring agents, dyes, proteins, herb and plant extracts, and other moisturising and/or conditioning agents.

Any viscosity modifier suitable for use in hair care compositions may be used herein. Generally, the viscosity modifier may comprise from about 0.01 to 10wt%, for example 0.05wt% to about 5wt%, e.g. about 0.1 to 3wt% based on the weight of the total composition. A non-limiting list of suitable viscosity modifiers can be found in the CTFA International Cosmetic Ingredient Dictionary and Handbook, 7^th edition, edited by Wenninger and McEwen (The Cosmetic, Toiletry and Fragrance Association, Inc., Washington D. C, 1997). A wide variety of additional ingredients can be formulated into the compositions according to the present invention. These include: other hair conditioning ingredients such as panthenol, pantethine, pantotheine, panthenyl ethyl ether, and combinations thereof; other solvents such as hexylene glycol; hair-hold polymers such as those described in WO-A-94/08557; viscosity modifiers and suspending agents such as xanthan gum, guar gum, hydroxyethyl cellulose, triethanolamine, methyl cellulose, starch and starch derivatives; viscosity modifiers such as methanolamides of long chain fatty acids such as cocomonoethanol amide; crystalline suspending agents; pearlescent aids such as ethylene glycol distearate; opacifiers such as polystyrene; preservatives such as phenoxyethanol, benzyl alcohol, methyl paraben, propyl paraben, imidazolidinyl urea and the hydantoins; polyvinyl alcohol; ethyl alcohol; pH adjusting agents, such as lactic acid, citric acid, sodium citrate, succinic acid, phosphoric acid, sodium hydroxide, sodium carbonate; salts, in general, such as potassium acetate and sodium chloride; colouring agents; hair oxidising (bleaching) agents, such as hydrogen peroxide, perborate and persulfate salts; hair reducing agents, such as the thioglycolates; perfumes; sequestering agents, such as disodium ethylenediamine tetra-acetate; antioxidants/ultra-violet filtering agents such as octylmethoxycinnamate, benzophenone-3 and DL-alpha tocopherol acetate and polymer plasticizing agents, such as glycerine, diisobutyl adipate, butyl stearate, and propylene glycol. Such optional ingredients generally are used individually at levels from about 0.001 wt% to about 10.0wt%, preferably from about 0.05wt% to about 5.0wt% by weight of the composition.

Mousses, foams and sprays can be formulated with propellants such as propane, butane, pentane, dimethylether, hydrofluorocarbon, CO₂, N₂O, nitrogen or without specifically added propellants (using air as the propellant in a pump spray or pump foamer package).

Examples

The invention will now be described by way of example only with reference to the following example. Example 1 : Anti-dandruff shampoo

0.125g of zinc pyrithione is added to 2g of ethanolamine and 2g of water. The solution is heated in an air convector oven at 95⁰C for 20 minutes. The container containing the solution is lidded but vented to limit loss through evaporation. The contents are stirred to create a yellow/lime green solution. The hot solution is pipetted onto 1g of oxidised mesoporous silicon powder and allowed to dry. The oxidised mesoporous silicon powder is prepared by either oxidation of anodised silicon wafers, stain etching of silicon powder or partial chemical reduction of porous silica. The dried cake returns to the original powder colour (pale brown) through evaporation of the ethanolamine. It is then ground into a powder with solid ZnPT entrapped in the mesopores. The loaded porous silicon is blended to form a shampoo.

Claims

1. A hair care composition comprising porous silicon.

2. A hair care composition according to claim 1 , wherein the porous silicon comprises mesoporous silicon and/or microporous silicon.

3. A hair care composition according to claim 2, wherein the porous silicon consists of or consists essentially of mesoporous silicon.

4. A hair care composition according to claim 2, wherein the porous silicon consists of or consists essentially of microporous silicon.

5. A hair care composition according to any one of the previous claims, wherein the porous silicon comprises microparticles and/or nanoparticles.

6. A hair care composition according to any one of claims 1 to 4, wherein the porous silicon consists or consists essentially of microparticles.

7. A hair care composition according to any one of claims 1 to 4, wherein the porous silicon consists or consists essentially of nanoparticles.

8. A hair care composition according to any one of the previous claims, wherein the porous silicon has been surface modified.

9. A hair care composition according to the previous claim wherein the surface modified porous silicon comprises or consists essentially of one or more of: derivatised porous silicon, partially oxidised porous silicon, porous silicon modified with silicon hydride surfaces, a capping layer.

10. A hair care composition according to any one of the previous claims, wherein the hair care composition is any one of a shampoo, gel, cream, conditioner, shampoo and conditioner, hair dye, creme rinse, mousse, foam, wax, mask, mud, putty, styling spray, hot oil treatment, rinse, lotion.

1 1. A hair care composition according to the previous claim, wherein the hair care composition is a shampoo.

12. A hair care composition according to claim 10, wherein the hair care composition is a shampoo and conditioner.

13. A hair care composition according to claim 10, wherein the hair care composition is a conditioner.

14. A hair care composition according to any one of the previous claims, wherein the pH of the hair care composition is about 2 to 8.5.

15. A hair care composition according to the previous claim, wherein the pH of the hair care composition is about 5 to 6,5.

16. A hair care composition according to any one of the previous claims, wherein the porous silicon is present in an amount of from 0.01wt% to 20wt% based on the total weight of the hair care composition.

17. A hair care composition according to any one of the previous claims, wherein the porous silicon comprises at least one ingredient for delivery to hair and/or the scalp.

18. A hair care composition according to the previous claim wherein the ingredient is selected from one or more of: an anti-dandruff agent, a natural hair root nutrient, a sunscreen, a hair-loss agent, a hair fibre agent, a fragrance, an anti-fungal agent, a moisturiser, an oil, a vitamin, a hair-loss agent, a head-lice agent, a structural agent, a natural active.

19. A hair care composition according to claim 17 or 18, wherein the at least one ingredient is present in the range, in relation to the loaded porous silicon, of 0.01 to

60wt%.

20. A hair care composition according to the previous claim, wherein the at least one ingredient is present in the range, in relation to the loaded porous silicon, of 2 to 10wt%.

21. A production process for preparing the hair care composition according to any one of the previous claims comprising blending the porous silicon and other components of the hair care composition.

22. Use of porous silicon for delivering at least one active ingredient to the hair and/or scalp of a human or animal.

23. A method of treating and/or cleaning the hair and/or scalp of a human or animal comprising applying a hair care composition to said hair and/or scalp as claimed in any one of claims 1 to 20.

24. A method according to the previous claim, wherein the method is a cosmetic method.

25. A method according to either of claims 23 or 24, wherein the hair care composition is an anti-dandruff shampoo

26. A method according to either of claims 23 or 24, wherein the hair care composition is for treating split ends.

27. A method according to claim 23, wherein the method is for the treatment of dandruff.

28. A method according to claim 27, wherein the porous silicon is loaded with zinc pyrithione.

29. A method according to claim 27, wherein the porous silicon is loaded with climbazole, ketoconazole, piroctone olamine, or combinations thereof.