WO2013102657A1

WO2013102657A1 - Process for preparing particles of titanium oxide containing a phthalocyanine derivative, said particles and uses thereof

Info

Publication number: WO2013102657A1
Application number: PCT/EP2013/050098
Authority: WO
Inventors: Aurélien AUGER
Original assignee: Commissariat A L'energie Atomique Et Aux Energies Alternatives
Priority date: 2012-01-05
Filing date: 2013-01-04
Publication date: 2013-07-11
Also published as: FR2985510A1

Abstract

The present invention relates to a process for preparing a titanium oxide particle having a titanium oxide network and incorporating at least one phthalocyanine derivative, from at least one titanium phthalocyanine derivative via an inverse microemulsion; to said particles and to uses thereof.

Description

PROCESS FOR THE PREPARATION OF TITANIUM OXIDE PARTICLES CONTAINING PHTALOCYANINE DERIVATIVE, THE SAID PARTICLES AND USES THEREOF

DESCRIPTION TECHNICAL FIELD

The present invention relates to the field of materials having a good light and UV resistance and in particular nanoparticles or titanium oxide microparticles containing phthalocyanine dyes.

Indeed, the present invention relates to a process for preparing titanium oxide particles incorporating phthalocyanine and naphthalocyanine derivatives. It also relates to titanium oxide particles incorporating phthalocyanine and naphthalocyanine derivatives, capable of being prepared by this process and their various uses and applications.

STATE OF THE PRIOR ART

The materials having a good light and UV light, when associated with a product, can make it possible to extend the service life and to protect it vis-à-vis the solar irradiation. Thus, such materials find applications in various fields such as the paper industry, the textile industry, the pharmaceutical industry, the plastics industry and the photovoltaic industry.

Thus, considerable interest has developed in recent years regarding the light-fastness of materials. This interest comes from the fact that certain organic compounds such as pthalocyanines have the ability to absorb large doses of light without decomposing.

Pthalocyanines have been extensively studied for their excellent optical and electronic properties in the photoconductor and photovoltaic cell sectors. They have two important absorption regions: B-band (300-400 nm) and Q-band (600-800 nm). At present, the development of an organic / inorganic hybrid material of the titanium oxide type (Ti0 ₂ ) would be promising for the field of photovoltaics. In addition, a unidirectional electrical network is a significant property for the efficiency of photogenerated electron transport.

Methods for preparing an organic / inorganic phthalocyanine / TiO ₂ hybrid material have already been described in the state of the art.

Cheng et al. (2010) have published a method for preparing dye sensitized solar cells (DSSCs) based on an ordered matrix of TiO ₂ nanotubes and phthalocyanines as sensitizing dyes [1]. This method comprises two steps which are (1) the electrosynthesis of TiO ₂ hollow nanotubes and (2) the electrodeposition of phthalocyanine amino compounds, designated TAZnPc, thereon. Given the preparation process, there is no covalent bond between TAZnPc and TiO ₂ .

Giribabu et al. (2009) also proposes a new photosensitizer phosphor for DSSC based on asymmetric zinc phthalocyanine and implementing a Ti0 _{2 film} [2]. This film is made from nanoparticles of Ti0 ₂ and Ti0 ₂ paste. The phosphors are then adsorbed on the surface of these already synthesized films.

Machado et al. (2008) proposes nanocomposites based on Ti0 ₂ and zinc phthalocyanine as photocatalyst in the treatment of wastewater using solar radiation [3]. These composites are prepared by coating TiO ₂ particles with zinc phthalocyanines. As for [2], this preparation process involves adsorption of phthalocyanines to the surface of particles.

Li and Xin (2010) also describe a photocatalyst for photodegradation of organic pollutants in water, based on TiO ₂ and phthalocynanine and, more particularly, based on TiO ₂ nanoparticles sensitized by Zn (II) phthalocyanine. [4]. This photocatalyst is obtained by preparing nanoparticles of TiO ₂ in the anatase phase which are subsequently impregnated with phthalocyanine Zn (II). This impregnation comparable to adsorption does not imply any covalent bond. Similarly, Jang et al. (2009) prepared nanoparticles of Ti0 ₂ by sol-gel [5]. The latter are then encapsulated in a polymer shell (PMMA) and the material obtained is impregnated with phthalocyanine derivatives of the copper (II) phthalocyanine tetrasulfonate type.

Finally, Lopez et al. (2010) study Zn (ll) phthalocyanine stabilization for photodynamic therapy applications [6]. This stabilization is obtained via TiO ₂ nanoparticles prepared by two sol-gel synthesis variants, these nanoparticles incorporating, during the in situ synthesis, the phthalocyanine derivative. However, the organic aromatic compound is not covalently bonded to the network of nanoparticles, and may be subject to release to falsify any measurement.

A method of preparation comparable to that described in [6] has been described by Di et al. (2006) [7]. In this document, mesoporous TiO ₂ particles doped with copper phthalocyanines incorporated during the synthesis of the particles are prepared.

There is a real need for a simple, practical and industrially applicable process for preparing materials based on phthalocyanines and titanium oxide particles which do not have the disadvantages listed above.

DISCLOSURE OF THE INVENTION The present invention overcomes the disadvantages and technical problems listed above. Indeed, the latter proposes a process for preparing particulate materials based on titanium oxide and incorporating phthalocyanine derivatives, said process being applicable at the industrial level, not requiring heavy processes or steps and using easily accessible, non-hazardous and low-toxicity products.

The work of the inventors has demonstrated that the use of titanium phthalocyanine derivatives as precursors makes it possible to manufacture titanium oxide particles such as microparticles or nanoparticles of titanium oxide incorporating phthalocyanine derivatives. The availability of combined axial ligands with the presence of the Ti atom introduced into the cavity of the phthalocyanine macrocycle makes it possible to use it as a precursor necessary for a correct synthesis of titanium oxide particles in the reverse micellar pathway.

The present invention provides a novel method for preparing titanium phthalocyanine particles that allows the synthesis of nanoparticles and microparticles into platelets. These particles therefore possess the properties of the hydrophobic compound of titanium phthalocyanine while remaining dispersible in an aqueous medium. Therefore, these particles have an amphiphilic character allowing their dispersion in polymer matrices and other coatings.

Functionalization by phthalocyanine derivatives, covalently and at heart ie in the network of titanium oxide particles, can make it possible to extend the life of a product and to protect it against the solar irradiation. Indeed, in the context of the present invention, the inventors have shown that such particles have excellent light and UV holding properties. Similarly, these particles have, as shown in Figure 1, a unidirectional electrical network, giving them de facto a significant property for the photogenerated electron transport efficiency.

Thus, the present invention relates to a process for preparing a titanium oxide particle incorporating at least one phthalocyanine derivative, said particle being prepared from at least one titanium phthalocyanine derivative via an inverse microemulsion.

The titanium oxide particles prepared by the process according to the present invention have a titanium oxide network and incorporate at least one phthalocyanine derivative. In the titanium oxide lattice of the particles of the invention, each Ti atom is bonded to two oxygen atoms by means of single covalent bonds. Therefore, the titanium oxide particles according to the invention are clearly distinguishable from an oxotitane phthalocyanine crystal as described in the patent application CN 1,594,330 [8] and the patent application JP 08 134373 [ 9] and wherein the Ti atoms are bonded to oxygen atoms by means of a double bond.

By "reverse microemulsion", also called "water-in-oil" microemulsion, is meant a limpid, thermodynamically stable suspension of fines. droplets of a first polar liquid in a second non-polar liquid and therefore immiscible with the first liquid. The expression "reverse micellar pathway" is equivalent to the expression "via an inverse microemulsion".

By "titanium phthalocyanine derivative" is meant a compound of formula

(I):

(I)

in which

R 1, R ₂ , R 3 and R ₄ , which may be identical or different, represent an optionally substituted arylene group and

R ₅ and R ₅ , which are identical or different, are chosen from the group consisting of -Cl, -F, -OH and -OR 'with R' representing a linear or branched alkyl of 1 to 12 carbon atoms, and especially from 1 to 6 carbon atoms, optionally substituted.

By "substituted alkyl" is meant, in the context of the compounds of formula (I), an alkyl substituted by a halogen, an amino group, a diamine group, an amide group, an acyl group, a vinyl group or a hydroxyl group. an epoxy group, a phosphonate group, a sulfonic acid group, an isocyanate group, a carboxyl group, a thiol (or mercapto) group, a glycidoxy group or an acryloxy group and in particular a methacryloxy group. Advantageously, R 'represents a methyl or an ethyl.

For the purposes of the present invention, the term "arylene group" means an aromatic or heteroaromatic carbon structure, optionally mono- or polysubstituted, consisting of one or more aromatic or heteroaromatic rings each comprising from 3 to 8 atoms, the (or ) heteroatom (s) which can be N, O, P or S. "Substituted arylene" means an arylene group which may be mono- or polysubstituted by a group selected from the group consisting of a carboxylate; an aldehyde; an ester; an ether; a hydroxyl; a halogen; aryl such as phenyl, benzyl or naphthyl; alkyl, linear or branched, of 1 to 12 carbon atoms and in particular of 1 to 6 carbon atoms, optionally substituted such as methyl, ethyl, propyl or hydroxypropyl; an amine; a friend of ; a sulfonyl; a sulfoxide and a thiol.

Advantageously, the groups R 1, R ₂ , R 3 and R ₄ are identical or different, each representing a phenylene, a naphthylene or an anthracene. More particularly, the groups R 1, R ₂ , R 3 and R ₄ are identical and represent a phenylene, a naphthylene or an anthracene.

In particular, the titanium phthalocyanine derivative used in the context of the present invention is a compound of formula (II):

in which

the groups R ₇ to R 22, which are identical or different, are chosen from the group consisting of hydrogen; a carboxylate; an aldehyde; a ketone; an ester; an ether; a hydroxyl; a halogen; aryl such as phenyl, benzyl or naphthyl; an alkyl, linear or branched, of 1 to 12 carbon atoms and in particular from 1 to 6 carbon atoms, optionally substituted such as methyl, ethyl, propyl or hydroxypropyl; an amine; a friend of ; a sulfonyl; a sulfoxide and a thiol.

the groups R ₅ and R ₆ are as previously defined.

Alternatively, the titanium phthalocyanine derivative used in the context of the present invention is a compound of formula (III) of the naphthalocyanine type:

in which

the groups R ₂ 3 to R ₄₆ , which are identical or different, are chosen from the group consisting of hydrogen; a carboxylate; an aldehyde; a ketone; an ester; an ether; a hydroxyl; a halogen; aryl such as phenyl, benzyl or naphthyl; alkyl, linear or branched, of 1 to 12 carbon atoms and in particular of 1 to 6 carbon atoms, optionally substituted such as methyl, ethyl, propyl or hydroxypropyl; an amine; a friend of ; a sulfonyl; a sulfoxide and a thiol.

the groups R ₅ and R ₆ are as previously defined. A compound of formula (II I) which is preferred in the context of the present invention is the compound in which the groups R ₂ 3 to R ₄₆ represent a hydrogen and the groups R ₅ and R ₆ are as previously defined.

In the formulas (I), (II) and (II I), the dotted bonds represent coordination bonds or dative bonds.

Advantageously, the groups R ₅ and R ₆ in the compounds of formula (I), (II) or (II I) are identical and are chosen from the group consisting of -Cl, -F, -OH and -OR 'with R 'representing a linear or branched alkyl of 1 to 12 carbon atoms and in particular of 1 to 6 carbon atoms, optionally substituted and especially selected from the group consisting of -Cl, -F, -OH, -OCH ₃ and -OC ₂ H ₅ . More particularly, the groups R ₅ and R ₆ in the compounds of formula (I), (II) or (II I) are identical and represent -Cl.

The compounds of formula (I I) that can be particularly used in the context of the present invention are:

the compound of formula (IV) which is unsubstituted titanophthalocyanine chloride corresponding to a compound of formula (II) in which the groups R ₇ to R 22 are all hydrogen and the groups R ₅ and R ₅ are - Cl:

the compound of formula (V) which is the peripherally substituted titanium phthalocyanine chloride corresponding to a compound of formula (II) in which the groups R ₅ and R ₆ are -Cl, the groups R ₇ , Rio, Ru, R ₁₄ , R 15, R 18, R ₁₉ and R 22 all represent hydrogen and the groups R ₈ , R ₉ , R 12, R 13, R 16, R _17, R 20 and R ₂₁ are identical and selected from the group consisting of hydrogen; a carboxylate; a aldehyde; a ketone; an ester; an ether; a hydroxyl; a halogen; aryl such as phenyl, benzyl or naphthyl; alkyl, linear or branched, of 1 to 12 carbon atoms and in particular of 1 to 6 carbon atoms, optionally substituted such as methyl, ethyl, propyl or hydroxypropyl; an amine; a friend of ; a sulfonyl; a sulfo

the compound of formula (VI) which is non-peripherally substituted titanium phthalocyanine chloride corresponding to a compound of formula (II) in which the groups R ₅ and R ₅ are -Cl, the groups R ₈ , R ₆ , R12, R13, Ri6, R17, R20 and R21 are all hydrogen and the R ₇ groups, Rio, Ru, R14, R15, Ris, R19 and R22 are identical and are selected from the group consisting of hydrogen; a carboxylate; an aldehyde; a ketone; an ester; an ether; a hydroxyl; a halogen; aryl such as phenyl, benzyl or naphthyl; alkyl, linear or branched, of 1 to 12 carbon atoms and in particular of 1 to 6 carbon atoms, optionally substituted such as methyl, ethyl, propyl or hydroxypropyl; an amine; a friend of ; a sulfonyl; a sulfoxide and a thiol:

The process according to the invention comprises, more particularly, the following successive steps:

a) preparing a microemulsion (M _a ) of the water-in-oil type containing at least one titanium phthalocyanine derivative,

b) adding, to the microemulsion (M _a ) obtained in step (a), at least one compound allowing the hydrolysis of the titanium phthalocyanine derivative,

c) adding to the microemulsion (M _b ) obtained in step (b) a solvent for destabilizing said microemulsion,

d) recovering titanium oxide particles incorporating at least one phthalocyanine derivative precipitated in step (c).

Step (a) of the process according to the invention therefore consists in preparing a microemulsion (M _a ) of the water-in-oil type containing at least one titanium phthalocyanine derivative. Any technique making it possible to prepare such a microemulsion can be used in the context of the present invention. Thus, it is possible to:

- either prepare a first solution (Mi) and subsequently incorporate a (or) derivative (s) of titanium phthalocyanine to obtain the microemulsion (M _a );

- Or prepare the microemulsion (M _a ) directly by mixing together the various components and therefore a (or) derivative (s) phthalocyanine titanium.

Advantageously, step (a) of the process according to the invention consists in preparing a first solution (Mi) in which is (are) subsequently incorporated (s) a (or) titanium phthalocyanine derivative (s). This solution (M i) is obtained by mixing together:

at least one surfactant,

- optionally at least one co-surfactant and

at least one non-polar or slightly polar solvent.

Advantageously, the surfactant, the optional co-surfactant and the non-polar or weakly polar solvent are added one after the other and, in the following order, surfactant then optionally co-surfactant then non-polar or weakly polar solvent.

Mixing is carried out with stirring using a stirrer, a magnetic bar, an ultrasonic bath or a homogenizer, and may be carried out at a temperature between 10 and 40 ° C, preferably between 15 and 30 ° C and more particularly at ambient temperature (ie 23 ° C. ± 5 ° C.) for a period of between 1 and 45 minutes, in particular between 5 and 30 minutes and, in particular, for 15 minutes.

The surfactant (s) that may be used in the context of the present invention aims to introduce hydrophilic species in a hydrophobic environment and may be chosen from ionic surfactants, nonionic surfactants and mixtures thereof By "mixtures" is meant, in the context of the present invention, a mixture of at least two different ionic surfactants, a mixture of at least two different nonionic surfactants or a mixture of at least one nonionic surfactant. ionic agent and at least one ionic surfactant.

An ionic surfactant may in particular be in the form of a hydrocarbon chain, charged whose charge is counterbalanced by a counter-ion. As non-limiting examples of ionic surfactants, mention may be made of sodium bis (2-ethylhexyl sulfosuccinate) (AOT), cetyltrimethylammonium bromide (CTAB), cetylpyridinium bromide (CPB) and mixtures thereof.

A nonionic surfactant that may be used in the context of the present invention may be chosen from the group consisting of polyethoxylated alcohols, polyethoxylated phenols, oleates, laurates and their mixtures. By way of nonlimiting examples of commercial nonionic surfactants, mention may be made of Triton X such as Triton X. 100; Brij such as Brij-30; Igepal COs such as Igepal CO-720; Tween such as Tween 20; Spans such as the Span 85.

Advantageously, the surfactant used in the context of the present invention is Triton X-100.

A co-surfactant may optionally be added to the solution (Mi).

By "co-surfactant" is meant in the context of the present invention an agent capable of facilitating the formation of microemulsions and stabilize them. Advantageously, said co-surfactant is an amphiphilic compound chosen from the group consisting of a sodium alkyl sulphate of 8 to 20 carbon atoms, such as SDS (for "sodium dodecyl sulphate"); an alcohol such as an isomer of propanol, butanol, pentanol and hexanol; a glycol and their mixtures.

Advantageously, the co-surfactant used in the context of the present invention is n-hexanol.

Any non-polar or weakly polar solvent is usable in the context of the present invention. Advantageously, said non-polar or weakly polar solvent is a non-polar or weakly polar organic solvent and, in particular, chosen from the group consisting of n-butanol, hexanol, cyclopentane, pentane, cyclohexane, n-butanol and n-butanol. hexane, cycloheptane, n-heptane, n-octane, isooctane, hexadecane, petroleum ether, benzene, isobutylbenzene, toluene, xylene, cumene, diethyl ether, n-butyl acetate, isopropyl myristate and mixtures thereof.

Advantageously, the non-polar or weakly polar solvent used in the context of the present invention is cyclohexane.

In the solution (Mi), the surfactant is present in a proportion of between 1 and 30%, especially between 5 and 25% and, in particular, between 10 and 20% by volume relative to the total volume of said solution. The co-surfactant is optionally present in the solution (Mi) in a proportion of between 1 and 30%, especially between 5 and 25% and, in particular, between 10 and 20% by volume relative to the total volume of said solution. Thus, the non-polar or weakly polar solvent is present in the solution (Mi) in a proportion of between 40 and 98%, in particular between 50 and 90% and, in particular, between 60 and 80% by volume relative to to the total volume of said solution. Once the solution (M i) has been prepared, the titanium phthalocyanine derivative (s) as previously defined is (are) incorporated to form the microemulsion (M _a ) of the type water in oil.

The titanium phthalocyanine derivative (s) may be added in solid form, in liquid form or in solution in a polar solvent. When several different titanium phthalocyanine derivatives are used, they may be mixed at once or added one after the other or in groups.

Whatever the variant used, a polar solvent is added to the microemulsion (M _a ) after incorporation of said titanium phthalocyanine derivative (s) into the solution (M i). Advantageously, the titanium phthalocyanine derivative (s) is (are) added to the solution (Mi) in solution in a polar solvent and then the polar solvent, which is identical to or different from the first, is further added. More particularly, the two polar solvents used are identical. Alternatively, the two polar solvents used are different but at least partially miscible: for example THF and water. The addition of the titanium phthalocyanine derivative and optionally the polar solvent may be carried out with stirring using a stirrer, a magnetic bar, an ultrasonic bath or a homogenizer and may be used at a temperature of between 10 and 40 ° C. C, advantageously between 15 and 30 ° C and, more particularly, at room temperature (ie 23 ° C ± 5 ° C) for a period of between 5 min and 1 h, in particular between 15 and 45 min and, in particular, for 30 minutes.

By "polar solvent" is meant in the context of the present invention a solvent selected from the group consisting of water, deionized water, distilled water, acidified or basic, hydroxylated solvents such as methanol and sodium hydroxide. ethanol, low molecular weight liquid glycols such as ethylene glycol, dimethyl sulfoxide (DMSO), acetonitrile, acetone, tetrahydrofuran (THF) and mixtures thereof.

The polar solvent or the mixture of polar solvents (polar solvent in which the titanium phthalocyanine derivative (s) is (are) in solution and / or other polar solvent subsequently added) is present in the microemulsion ( M _a ), in a proportion of between 0.1 and 20%, especially between 0.5 and 15% and, in particular, between 1 and 10% by volume relative to the total volume of said microemulsion. The OR the titanium phthalocyanine derivative (s) is (are) present in this polar solvent or this mixture of polar solvents in a concentration of between 10 mM and 0.5 M, in particular between 20 mM and 0.4 M and, in particular, between 40 mM and 0.3 M. Step (b) of the process according to the invention aims to provide for the hydrolysis of the titanium phthalocyanine derivative (s) by adding to the microemulsion (M _a ) a compound allowing this hydrolysis, the microemulsion (M _b ) thus obtained being a water-in-oil microemulsion.

The compound allowing the hydrolysis of the titanium phthalocyanine derivative (s) is advantageously chosen from the group consisting of ammonia, potassium hydroxide (KOH), lithium hydroxide (LiOH) and sodium hydroxide (NaOH) and, advantageously, a solution of such a compound in a polar solvent, which is identical or different, to the polar solvent (s) used during step (a) . The compound allowing the hydrolysis of the titanium phthalocyanine derivative (s) is, more particularly, ammonia or a solution of ammonia in a polar solvent as defined above. Indeed, ammonia acts as a reagent (H ₂ 0) and as a catalyst (NH ₄ OH) hydrolysis of (or) derivative (s) phthalocyanine titanium.

The compound allowing the hydrolysis of the titanium phthalocyanine derivative (s), when it is in solution in the polar solvent, is present in a proportion of between 5 and 50%, in particular between 10 and 40%, and in particular between 20 and 30% by volume relative to the total volume of said solution. In addition, said solution is present in a proportion of between 0.01 and 10%, in particular between 0.05 and 5% and, in particular, between 0.75 and 2% by volume relative to the total volume of the microemulsion ( M).

Step (b) can be carried out with stirring using a stirrer, a magnetic bar, an ultrasonic bath or a homogenizer, and at a temperature of between 10 and 40.degree. C., advantageously between 15 and 30.degree. more particularly at room temperature (ie 23 ° C. ± 5 ° C.) for a period of between 6 and 48 hours, in particular between 12 and 36 hours and, in particular, for 24 hours. Step (c) of the process according to the invention aims at precipitating the titanium oxide particles by adding a solvent which does not denature the structure of the particles but which destabilizes or denatures the microemulsion (Mb) obtained at the step (b).

Advantageously, the solvent used is a polar solvent as defined above. A particular polar solvent to be used in step (c) is selected from the group consisting of ethanol, acetone and methanol. Even more advantageously, the solvent used in step (c) of the process according to the invention is ethanol. Thus, a volume of solvent greater than the volume of said microemulsion, in particular greater by a factor of 1.5, is added to the microemulsion (Mb); in particular, greater by a factor of 2; and even a factor of 3.

Any technique making it possible to recover titanium oxide particles incorporating at least one phthalocyanine derivative precipitated during step (c) may be implemented during step (d) of the process according to the invention. Advantageously, this step (d) implements one or more steps, identical or different, chosen from the centrifugation, sedimentation and washing steps. The washing step (s) is (are) carried out in a polar solvent as defined above. When the recovery step uses several washes, the same polar solvent is used for several or even all washes or several different polar solvents are used at each wash. Regarding one (or more) centrifugation stage (s), it (they) can be implemented by centrifuging the titanium oxide particles, in particular in a wash solvent at room temperature, at a temperature of a speed of between 4000 and 8000 rpm and, in particular, of the order of 6000 rpm (ie 6000 ± 500 rpm) and this, for a period of between 5 min and 2 h, in particular between 10 min and 1 h, and particular, for 15 min.

The method according to the present invention may comprise, following step (d), an additional step of purifying the titanium oxide particles obtained hereinafter referred to as "step (e)".

Advantageously, this step (e) consists in putting the titanium oxide particles recovered after step (d) of the process according to the invention in contact with a very wide volume of water. By "very large volume" is meant a volume greater by a factor of 50, in particular by a factor of 500 and, in particular, by a factor of 1000 to the volume of particles of titanium oxide, recovered after the step ( d) the process according to the invention. Step (e) may be a dialysis step, the titanium oxide particles being separated from the volume by a cellulose membrane, of the Spectra / Por ^® - MWCO3500 (Proud) type. Alternatively, an ultrafiltration step can be provided in place of the dialysis step, via a polyethersulfone membrane. Step (e) may, in addition, be carried out with stirring using a stirrer, a magnetic bar, an ultrasonic bath or a homogenizer, at a temperature between 0 and 30 ° C., advantageously between 2 and 20 ° C. ° C and, more particularly, cold (ie 6 ° C ± 2 ° C) and this, for a period of between 30 h and 15 d, especially between 3 and 10 days and, in particular, for 1 week.

The present invention also relates to the microemulsion (M _b) which can be implemented under the method according to the invention. This microemulsion of water-in-oil type comprises:

at least one surfactant, especially as defined above,

optionally at least one co-surfactant, especially as defined above,

at least one non-polar or weakly polar solvent, especially as defined above,

at least one polar solvent, in particular as previously defined,

at least one titanium phthalocyanine derivative, especially as defined above, and

at least one compound capable of hydrolyzing a titanium phthalocyanine derivative, in particular as defined above.

Advantageously, the water-in-oil microemulsion that is the subject of the present invention (M _b ) comprises:

at least one surfactant in an amount of between 1 and 30%, in particular between 5 and 25% and, in particular, between 10 and 20%; - optionally at least one co-surfactant in an amount of between 1 and 30%, especially between 5 and 25% and, in particular, between 10 and 20%;

at least one non-polar or slightly polar solvent in an amount of between 40 and 95%, especially between 50 and 90% and, in particular, between 60 and 80%;

at least one polar solvent in an amount of between 0.25 and 15%, especially between 0.5 and 10% and, in particular, between 1 and 5%;

at least one titanium phthalocyanine derivative in a concentration of between 50 μM and 50 mM, in particular between 100 μM and 10 μm, and in particular between 500 μM and 5 μm; and

at least one compound capable of hydrolyzing said titanium phthalocyanine derivative in an amount of between 0.01 and 5%, especially between 0.05 and 1% and, in particular, between 0.1 and 0.5%,

the percentages being expressed in volume relative to the volume of said microemulsion.

The present invention further relates to a titanium oxide particle capable of being prepared by the process of the present invention. This particle is a titanium oxide particle comprising at least one phthalocyanine derivative, as previously defined. It differs from the titanium oxide particles of the state of the art by the two covalent bonds which bind the Ti atom to the phthalocyanine derivative, the phthalocyanine derivative not being a group which functionalizes the particle of titanium oxide or adsorbed on it. Indeed, the covalent bonds which bind the Ti atom with the phthalocyanine derivative are retained in the titanium oxide particle formed at the end of the process according to the invention. Thus, there is a strong interaction between the structure of the titanium oxide particle and the phthalocyanine derivative (s) by the presence of the covalent bonds. Therefore, the phthalocyanine derivative is covalently bonded to the titanium oxide lattice of the particle according to the invention. In addition, the titanium oxide particles obtained according to the process of the invention are in the form of platelets and in particular in the form of nanoplates or chips.

By "nanoplate" is meant, in the context of the present invention, a rectangular parallelepiped having at least two of its characteristic dimensions less than or equal to 100 nm. Advantageously, a nanoplate, in the context of the present invention, comprises:

a length greater than 100 nm and in particular between 100 and

500 nm;

a thickness of between 2 and 20 nm and in particular between 5 and 10 nm; and

a width of between 20 and 80 nm and in particular between 40 and 60 nm. FIG. 1 is the representation of a nanoplate that can be obtained by the method of the invention.

For the purposes of the present invention, the term "microchip" means a rectangular parallelepiped having at least one of its characteristic dimensions greater than or equal to 1 μιη. Advantageously, a chip, in the context of the present invention, comprises:

a length greater than 1 μηι and in particular between 1 and 2 μιη; a thickness of between 2 and 20 nm and in particular between 5 and 10 nm; and

a width of between 80 nm and 1.2 μm and in particular between 100 nm and 1 μm.

In the context of the present invention, the terms "titanium particle", "titanium nanoparticle", "titanium nanopellet", "titanium oxide particle", "titanium oxide nanoparticle" and "nanopellet of titanium" titanium oxide "can be used in an equivalent manner to define the product prepared by carrying out the process according to the invention.

Similarly, in the context of the present invention, the terms "titanium particle", "titanium microparticle", "titanium chip", "titanium oxide particle", "titanium oxide microparticle" and " titanium oxide chip " can be used in an equivalent way to define the product prepared by implementing the method according to the invention.

Given that the titanium oxide particles according to the present invention or prepared according to the process of the present invention comprise compounds of TiO ₂ type and phthalocyanine type compounds, they can be used in each of the known applications of these compounds. . Examples include applications as photocatalysts and dyes.

Moreover and surprisingly, these microparticles and nanoparticles of titanium oxide phthalocyanine derivatives have remarkable properties of light and UV light, allowing to consider new applications.

Accordingly, the present invention relates to the use of a titanium oxide particle according to the present invention or prepared according to the process of the present invention in the paper industry, the textile industry, the pharmaceutical industry, the plastic industry and the photovoltaic industry and, more particularly, in the fields selected from the group consisting of coloring agents (inks, paints, paper and textiles); photocatalysis and photodegradation; UV protection agents; solar light-keeping agents; anti-light and anti-UV protection agents; and electronic, optical, sensor, conversion and energy storage devices.

More particularly, the present invention relates to the use of a titanium oxide particle according to the present invention or prepared according to the method of the present invention for UV protection.

Other features and advantages of the present invention will become apparent to those skilled in the art on reading the examples below given for illustrative and non-limiting, and with reference to the appended figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic representation of a titanium oxide nanoparticle nanoparticle prepared by the method according to the invention. FIG. 2 shows a view obtained by transmission electron microscopy (M ET) of titanium oxide nanoparticles prepared by the process according to the invention.

Figure 3 shows the energy dispersive analysis (EDS) of titanium oxide nanoparticles prepared by the process according to the invention.

FIGS. 4A and 4B show two independent examples of the UV resistance of a PVA film in which nanoparticles of titanium oxide, not prepared by the process according to the invention, were trapped before and after UV irradiation at 365 nm. In FIGS. 4A and 4B, the values plotted on the abscissa correspond to the absorbance without unit and the values plotted on the ordinate at the wavelength expressed in nm.

FIG. 5 shows the light resistance of a PVA film in which nanoparticles of titanium oxide prepared by the process according to the invention were trapped before and after artificial aging. In FIG. 5, the values plotted on the abscissa correspond to the absorbance without unit and the values carried in ordinates at the wavelength expressed in nm.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

I. Process for preparing titanium nanoparticles according to the invention

In this example, titanium oxide nanoparticles in the form of nanobits or nanoplates were prepared using the reverse microemulsion (water-in-oil) method. The microemulsion solution (three-phase melamine) was prepared by mixing the appropriate amounts of surfactant, organic solvent, aqueous solution (THF-containing), aqueous ammonia solution. Ammonia acts as a reagent (H ₂ 0) and as a catalyst (NH ₃ ) for the hydrolysis of the titanium phthalocyanine derivative.

A solution (solution M i according to the invention) was generated by adding, in this order, the following chemicals, the surfactant Triton X100 (8.4 mL, 9 g), the co-surfactant n-hexanol (8, 2 mL), cyclohexane organic solvent (38 mL). The solution was then stirred at room temperature for 15 minutes. Next, the titanium phthalocyanine derivative titanium IV phthalocyanine dichloride or titanium IV phthalocyanine dichloride (CAS No. 16903-42-7) in a THF solution was added (400 μΐ to 0). , 1 M in THF, ie 25 mg, M = 631.35 gmol ¹ , n = 4x10 ^-5 mol) followed by water (0.4 ml) It should be noted that a concentration of 0, 4 M phthalocyanine was also successfully tested and the resulting emulsion was stirred at room temperature for 30 min.

The hydrolysis of the titanium-based compound was initiated by the addition of 25% aqueous ammonia (500 μΐ) and the reaction mixture was stirred for 24 h at room temperature.

The emulsion was destabilized by the addition of ethanol (500 mL) and the nano-objects were washed three times with ethanol and once with water, each wash being followed by centrifuge sedimentation (15 min. at 6000 rpm).

After the washing step, the purification of the nanoparticles obtained was completed by dialysis (nominal MWCO3500 Daltons) in water (1 L) with magnetic stirring for one week.

II. Characterization of titanium oxide nanoparticles according to the invention.

The nanoparticles of titanium oxide dispersed in water (40 mL) prepared according to the method of Part I were then characterized by transmission electron microscopy (TEM) analysis which allows to appreciate the nanostructure of these nanoparticles.

According to the TEM images, the titanium oxide nanoparticles have the shape of nanobaggets or nanoplates, with a width of between 20-50 nm and a length of between 100-500 nm (FIG. 2).

According to the results of EDS analyzes, the Ti and O chemical elements are present in these blue-colored nanoparticles (FIG. 3).

III. UV aging and light fastness tests.

III.1. UV resistance with irradiation at 365 nm.

A solution containing 1 g of polyvinyl acetate (PVA) at 10% by weight and

0.1 g of nanoparticles according to the invention was prepared. After stirring in the bath ultrasound for 15 min, this solution was deposited as a film on a glass slide.

The UV aging of this film was verified by subjecting the glass slide to irradiation under a UV lamp irradiating at 365 nm for 5 days.

At the end of this aging test, a good resistance to UV has been observed and proven, as shown in Figures 4A and 4B.

III.2. Light hold in the suntest.

A glass slide prepared as described in III.1. was subjected to an aging test in a Suntest chamber of ATLAS after drying at room temperature.

The aging conditions are as follows: irradiance at 765 W / m ² ; Xenon arc lamp equipped with a "glass window" filter cutting UV below 310 nm, exposure spectrum from 300 to 800 nm, exposure time of 24 hours.

At the end of this aging test, it appears that the sample has not aged (Figure 5). This demonstrates the ability of the nanoparticles of titanium oxide according to the invention to stand against aging imposed by the sun.

REFERENCES

[1] Cheng et al., 2010, "Preparation and properties of a phthalocyanine-sensitized Ti0 ₂ nanotube array for dye-sensitized solar cells", Semicond. Sci. Technol., Vol. 25, 125014.

[2] Giribaru et al., 2009, "Unsymmetrical extended π-conjugated zinc phthalocyanine for sensitization of nanocrystalline TiO ₂ films", J. Chem. Sci., Vol. 121, pp. 75-82.

[3] Machado et al., 2008, "Characterization and evaluation of the efficacy of Ti0 ₂ / Zinc phthalocyanine na nocomposites as photocatalysts for wastewater treatment using solar irradiation", International Journal of Photoenergy, vol. 2008, 12 pages. [4] Li and Xin, 2010, "Photogenerated carrier transfer mechanism and photocatalysis properties of Ti0 ₂ sensitized by Zn (II) phthalocyanine", J. Cent. South Univ. Technol., Vol. 17, pp. 218-222.

[5] Jang et al., 2009, "Synthesis and characterization of Cu-phthalocyanine hybrid TiO ₂ sol", J. Porphyrins Phthalocyanines, vol. 13, pp. 780-786.

[6] Lopez et al., 2010, "Study of the stabilization of zinc phathalocyanine in sol-gel Ti0 ₂ for photodynamic therapy applications," Nanomedecine: Nanotechnology, Biology and Medicine, vol. 6, pages 777-785.

[7] Di et al., 2006, "Electrological behavior of copper phthalocyanine-doped mesoporous TiO ₂ suspensions", Journal of Colloid and I nterface Science, vol. 294, pp. 499-503. [8] CN Patent Application 1,594,330 in the name of University of Tia njin, published March 16, 2005. [9] Patent Application JP 08 134373 in the name of Matsushita Electric Ind. Co. Ltd., published May 28, 1996

Claims

1) A process for preparing a titanium oxide particle having a titanium oxide network and incorporating at least one phthalocyanine derivative, said particle being prepared from at least one titanium phthalocyanine derivative via a reverse microemulsion.

2) Process according to claim 1, characterized in that said titanium phthalocyanine derivative is a compound of formula (I):

(I)

in which

R ₅ and R ₆ , which are identical or different, are chosen from the group consisting of -Cl, -F, -OH and -OR 'with R' representing a linear or branched alkyl of 1 to 12 carbon atoms, and especially from 1 to 6 carbon atoms, optionally substituted.

3) Process according to claim 1 or 2, characterized in that said titanium phthalocyanine derivative is a compound of formula (II):

in which

the groups R ₇ to R 22, which are identical or different, are chosen from the group consisting of hydrogen; a carboxylate; an aldehyde; an ester; an ether; a hydroxyl; a halogen; aryl such as phenyl, benzyl or naphthyl; alkyl, linear or branched, of 1 to 12 carbon atoms and in particular of 1 to 6 carbon atoms, optionally substituted such as methyl, ethyl, propyl or hydroxypropyl; an amine; a friend of ; a sulfonyl; a sulfoxide and a thiol.

the groups R ₅ and R ₆ are as defined in claim 2.

4) Process according to claim 1 or 2, characterized in that said titanium phtaiocyanine derivative is a compound of formula (III) of the naphthalocyanine type:

(III)

in which

the groups R ₂ 3 to R ₄₆ , which are identical or different, are chosen from the group consisting of hydrogen; a carboxylate; an aldehyde; an ester; an ether; a hydroxyl; a halogen; aryl such as phenyl, benzyl or naphthyl; alkyl, linear or branched, of 1 to 12 carbon atoms and in particular of 1 to 6 carbon atoms, optionally substituted such as methyl, ethyl, propyl or hydroxypropyl; an amine; a friend of ; a sulfonyl; a sulfoxide and a thiol.

the groups R ₅ and R ₆ are as defined in claim 2.

5) Method according to any one of claims 1 to 4, characterized in that said method comprises the following successive steps:

c) adding to the microemulsion (M _b ) obtained in step (b) a solvent for destabilizing said microemulsion, d) recovering titanium oxide particles incorporating at least one phthalocyanine derivative precipitated in step (c).

6) Process according to claim 5, characterized in that said step (a) consists of preparing a first solution (Mi) in which a titanium phthalocyanine derivative (s) is subsequently incorporated.

7) Process according to claim 5 or 6, characterized in that said microemulsion (M ^ of the water-in-oil type is obtained by mixing together:

at least one surfactant,

- optionally at least one co-surfactant and

at least one non-polar or slightly polar solvent.

8) Process according to any one of claims 5 to 7, characterized in that a polar solvent is added to the microemulsion (M _a ) after incorporation of said (or said) derivative (s) of titanium phthalocyanine in the solution (M i).

9) Process according to any one of claims 5 to 8, characterized in that said compound for hydrolyzing said (or said) derivative (s) titanium phthalocyanine is selected from the group consisting of ammonia, potassium hydroxide (KOH), lithium hydroxide (LiOH) and sodium hydroxide (NaOH).

10) Microemulsion (M _c ) of water-in-oil type capable of being implemented in the context of a process as defined in any one of the preceding claims, comprising:

at least one surfactant,

- optionally at least one co-surfactant,

at least one non-polar or slightly polar solvent,

at least one polar solvent,

at least one titanium phthalocyanine derivative, and at least one compound capable of hydrolyzing a titanium phthalocyanine derivative.

11) Microemulsion according to claim 10, characterized in that it comprises:

at least one surfactant in an amount of between 1 and 30%, in particular between 5 and 25% and, in particular, between 10 and 20%;

- optionally at least one co-surfactant in an amount of between 1 and 30%, especially between 5 and 25% and, in particular, between 10 and 20%;

at least one titanium phthalocyanine derivative in a concentration of between 50 μM and 50 mM, in particular between 100 μM and 10 mM, and in particular between 500 μM and 5 mM; and

12) Particle of titanium oxide comprising at least one phthalocyanine derivative, capable of being prepared by a process as defined in any one of claims 1 to 9, said phthalocyanine derivative being covalently connected to the network of titanium oxide of said particle.

13) Particle according to claim 12, characterized in that it is in the form of a nanoplate comprising: a length greater than 100 nm and in particular between 100 and

500 nm;

a thickness of between 2 and 20 nm and in particular between 5 and 10 nm; and

a width of between 20 and 80 nm and in particular between 40 and 60 nm.

14) Particle according to claim 12, characterized in that it is in the form of a chip comprising:

a length greater than 1 μηι and in particular between 1 and 2 μιη;

a thickness of between 2 and 20 nm and in particular between 5 and 10 nm; and

15) Use of a particle according to any one of claims 12 to 14 for UV protection.