USEFUL MATERIAL FOR THE DETECTION OF CHEMICAL COMPOUNDS

Abstract

The invention relates to a material comprising a layer C1 resulting from the freezing and subsequent sublimation of a foam formed by the dispersion of gas bubbles in a foaming aqueous solution A1, the foaming aqueous solution A1 comprising at least one detection indicator, at least one surfactant, and optionally, at least one gelling agent. The invention also relates to a method for preparing the material as described above. It also relates to the use of said material for detecting the presence of at least one chemical compound. Applications: colorimetric and / or fluorescence detection of chemical compounds, toxic warfare agents, or toxic industrial chemicals.

Description

Title of the invention: MATERIAL USEFUL FOR THE DETECTION OF CHEMICAL COMPOUNDS technical field

[0001] The invention relates to the field of chemical compound detection.

[0002] More specifically, the invention relates to a material for detecting at least one chemical compound.

[0003] It also relates to a process for preparing this material.

[0004] The invention also relates to the use of this material to detect the presence of at least one chemical compound likely to be present in a medium.

[0005] The present invention can be applied to the detection of toxic compounds, such as toxic warfare compounds or toxic industrial chemical compounds (known by the abbreviation TICs). Prior art

[0006] It is known that certain organophosphate compounds exhibit proven toxicity to the human body. Indeed, these compounds can be involved in the mechanism of inhibition of serine proteases and, in particular, of acetylcholinesterase, which is involved in synaptic junctions and whose dysregulation of activity can prevent muscle relaxation and thus cause death by asphyxiation.

[0007] These compounds are notably used in the formulation of certain insecticides, pesticides or even chemical warfare agents (such as organophosphate compounds of the G series or the V series).

[0008] Furthermore, toxic compounds can spread rapidly in the environment in the event of CBRN-E risks (for "nuclear, radiological, biological, chemical and explosive risks resulting in particular from industrial accidents, criminal acts (such as the use of toxic weapons) or natural or environmental disasters.

[0009] However, due to the high lethality of these compounds and their proliferation, it is important to have systems or devices available to detect them.

[0010] Some detection devices used to date are based on technologies involving physical measurement methods, such as ion mobility spectroscopy, flame photometry, IR and Raman spectroscopies, with the difficulties that these systems require complex and expensive equipment which is not necessarily suitable for all intervention environments in terms of mass and size, in addition to the expertise of the operator to be taken into account.

[0011] In view of what exists, the inventors have set themselves the objective of proposing a new material, useful for the detection of at least one chemical compound, which material must allow the detection and, where appropriate, the discrimination, of the chemical compound(s) and must meet criteria of sensitivity, speed, portability, reliability. Description of the invention

[0012] Thus, the invention relates, firstly, to a material useful for detecting at least one chemical compound. The material of the invention comprises a layer Cl resulting from the freezing and then sublimation of a foam formed by a dispersion of gas bubbles in a foaming aqueous solution Al, the foaming aqueous solution Al comprising at least one detection indicator, at least one surfactant and, optionally, at least one gelling agent.

[0013] According to the invention, the material is a "macroporous material", that is to say a material comprising macropores, the diameter of which is greater than 50 nm (according to the definition of IUP AC).

[0014] In the preceding and following, it is specified that "foam" means a biphasic system comprising a gaseous phase (i.e. the dispersion of gas bubbles) and a liquid phase (i.e. the foaming aqueous solution).

[0015] Furthermore, a "detection indicator" is understood to be a chemical substance capable of undergoing a transformation upon contact with at least one chemical compound to be detected, this transformation being indicative of the presence of that chemical compound. This transformation is manifested by a color change when the detection indicator is a colored indicator (also called a colorimetric detection indicator). More specifically, when the detection indicator is a colored indicator, it classically corresponds to a chemical substance that takes on at least one characteristic color in the presence of a chemical compound; in other words, a chemical substance that exhibits at least two colored states: one colored state existing when the chemical substance is not in the presence of the chemical compound to be detected, and at least one other colored state when the chemical substance is in the presence of the chemical compound(s) to be detected.The detection indicator can also be a fluorescent indicator (or fluorophore), in which case the transformation is manifested by a change in fluorescence emission intensity, a shift in fluorescence emission wavelength, or a change in the shape of the emission spectrum when this indicator is excited by an excitation source at a given wavelength and when it is in the presence of the chemical compound to be detected.

[0016] Furthermore, in the foregoing and following, "sublimation" means any process by which a substance passes from a solid state to a gaseous state without passing through a liquid state. In other words, sublimation allows the foam thus frozen to dehydrate.

[0017] In this regard, freezing and sublimation can be achieved by freeze-drying.

[0018] According to one embodiment of the invention, the material can consist of the Cl layer.

[0019] As mentioned above, the material can be used for the detection of a single chemical compound or for the detection of several (i.e., at least two) distinct chemical compounds.

[0020] When the material is used for the detection of a single chemical compound, then the foaming aqueous solution Al advantageously comprises one or more detection indicators enabling the detection of that chemical compound.

[0021] When the material is used for the detection of several distinct chemical compounds, then the foaming aqueous solution Al can comprise a single detection indicator allowing the detection of all the chemical compounds.

[0022] However, when the material is used for the detection of several distinct chemical compounds, it is preferred that the material also comprise a layer C2 resulting from the freezing and subsequent sublimation of a foam formed by the dispersion of gas bubbles in a foaming aqueous solution A2, the foaming aqueous solution A2 comprising at least one detection indicator, at least one surfactant, and optionally, at least one gelling agent. In this case, the Cl and C2 layers together form a stack (in other words, the material comprises a stack of at least two Cl and C2 layers), and the foaming aqueous solutions A1 and A2 comprise at least one different detection indicator.

[0023] According to a variant of the invention, the material can be made up of the stacking of at least two Cl and C2 layers.

[0024] More specifically, when the material is used for the detection of several distinct chemical compounds, this material advantageously comprises as many layers as there are chemical compounds to be detected, it being understood that the foams from which the layers are obtained advantageously comprise at least one different detection indicator, each detection indicator enabling the detection of a given chemical compound.

[0025] Depending on the chemical compounds to be detected, the detection indicator(s) can be chosen from colored indicators and / or fluorescent indicators.

[0026] It goes without saying that, when the detection indicator(s) are colored indicators, they are chosen so that they exhibit at least one color change in the presence of the chemical compound(s) to be detected. and are chosen, preferably, from those which are colorless and those which have an initial color - i.e. before any exposure to one or more chemical compounds - of light color, for example, in shades of pale yellow.

[0027] Furthermore, in the case where the material comprises (or is made up of) the stacking of at least two Cl and C2 layers and the detection indicators are colored indicators, then these indicators are advantageously chosen so that they exhibit at least one colorimetric change contrasted with each other, so as to be able to discriminate the chemical compounds.

[0028] The colour indicators can be chosen from anthraquinone compounds, azo compounds, triarylmethane compounds, xanthenic compounds, indigo compounds, metal complexes, compounds comprising at least one stilbene group, coumarin compounds, compounds comprising at least one cyanine group, compounds comprising at least one phthalocyanine group, compounds comprising at least one porphyrin group and compounds comprising at least one hydrazone group.

[0029] By way of examples of anthraquinone compounds, mention may be made of 1,4-dihydroxyanthraquinone, 1-aminoanthraquinone, carminic acid, 1,5-diaminoanthraquinone, 1,2-diaminoanthraquinone, l,4-diamino-5-nitroanthraquinone, 1,4,5,8-tetraaminoanthraquinone (also called "Disperse Blue 1" in English), l-methylamino-4-(2-hydroxyethyl)aminoanthraquinone (also called "Disperse Blue 3" in English), l-amino-2-methylanthraquinone (also called "Disperse Orange 77" in English) and 1,4-7"A-(p-tolylamino)anthraquinone (also called "Solvent Green 3" in English).

[0030] By way of examples of azo compounds, mention may be made of 10-(2',4'-dinitrophenylazo)-9-phenanthrol, disodium 6-hydroxy-5-[(2-methoxy-5-methyl-4-sulfophenyl)azo]-2-naphthalenesulfonate (also called "Allura Red AC"), 4-dimethylaminoazobenzene (also called "Methyl Yellow"), 4-(2-carboxyphenylazo)-A,A-dipropylaniline (also called "Propyl Red"), 3-(diethylamino)-7-{(E)-[4-(dimethylamino)phenyl]diazenyl}-5-phenylphenazin-5-ium chloride (also called "Janus Green B"), A,A-dimethyl-4,4'-azodianiline, A-ethyl- l-((4-phenyldiazenyl)phenyl)diazenyl)naphthalene-2-amine (also known as "Sudan Red 7B" in English), amaranth, 4-[[3-[(2,4-diaminophenyl)diazenyl]phenyl]diazenyl]benzene-l,3-diamine dihydrochloride (also known as "Bismarck Brown Y"), disodium 4-hydroxy-3-[(4-sulfo-l-naphthalenyl)azo]-1-naphthalenesulfonate (also known as "Chromotrope FB"),benzidinediazo-bis-l-naphthylamine-4-sulfonic acid (also known as "Congo Red"), 2,2'-[4-(4-aminophenylazo)phenylimino]diethanol (also known as "Disperse Black 9" in English), 2,2'-[[4-[(4-nitrophenyl)azo]phenyl]imino]bisethanol (also, called "Disperse Red 19" in English), (4Z)-4-[(l-hydroxynaphthalene-2-yl-hydrazinylidene]-7-nitro-3-oxo Y-naphthalene-l-sulfonate sodium (also called "Eriochrome Black T"), 4'-(4-(diethylamino)phenylazo)acetophenone, 4-[(E)-(4-nitrophenyl)diazenyl]-A-phenylaniline (also called "Disperse Orange 1" in English), methyl orange (also called "Methyl Orange"), 4-(4-nitrophenylazo)aniline (also called "Disperse Orange 3" in English), 4-[4-(phenylazo)-l-naphthylazo]phenol (also called "Disperse Orange 13" in English), the 3-[A-ethyl-4-(4-nitrophenylazo)phenylamino]propionitrile (also known as "Disperse Orange 25" in English), 4-amino-5-hydroxy-3-(4-nitrophenylazo)-6-(phenylazo)naphthalene-2,7-sodium disulfonate (also known as "Blue Black Naphthol"), (2,2-dimethyl-1,3-dihydroperimidine-6-yl)-(4-phenylazo-1-naphthyl)diazene (also known as "Sudan Black B" in English),6-hydroxy-5-[(4-sulfonatophenyl)azo]naphthalene-2-sulfonate disodium (also known as "Sunset Yellow FCF"), tartrazine, Evans blue, 4-[4-(phenylazo)phenylazo]-o-cresol (also known as "Disperse Yellow 7") and 4'-nitro-4-dimethylaminoazobenzene.

[0031] Examples of triarylmethane compounds may include bromocresol green, diammonium aniline blue salt, bromophenol blue, m-cresol violet, cresol red, gentian violet (also called "Crystal Violet" in English), chlorophenol red, sodium salt of (4-(α-(p-(diethylamino)phenyl)-2,4-disulfobenzylidene)-2,5-cyclohexadien-l-ylidene)diethylammonium hydroxide (also called "Patent blue V sodium salt" in English), methyl blue, rosolic acid, pyrocatechol violet, brilliant green BS, pararosaniline base, fuchsin, thymol blue and 4-(dimethylamino)-α-[4-(dimethylamino)phenyl]-α-phenylbenzenemethanol.

[0032] By way of examples of xanthenic compounds, mention may be made of [9-(2-carboxyphenyl)-6-diethylamino-3-xanthenylidene]-diethylammonium chloride (also called "Rhodamine 610"), rhodamine 6G possibly in the form of perchlorate salt, rhodamine B, hydrated sulforhodamine 101, fluoresceinamine (in particular isomer I) and rhodamine 110 chloride.

[0033] Indigo may be mentioned as an example of indigoic compounds.

[0034] Trisodium 5-nitroso-6-oxidonaphthalene-2-sulfonate complexed with iron(III) (also called "Naphthol Green B" in English) may be mentioned as an example of metal complexes.

[0035] As examples of compounds comprising at least one stilbene group, mention may be made of the dye known under the English terminology "Fluorescent Brightener 28" or of the compounds described in French application FR 2113676, such as 2,4-Z?A[p-(dimethylamino)styryl)quinoline.

[0036] Examples of coumarin compounds may include 7-amino-4-(trifluoromethyl)coumarin, 7-amino-4-methylcoumarin, 3-(2-N-methylbenzimidazolyl)-7-AGV-diethylaminocoumarin (also called "Coumarin 30" in English), 2,3,6,7-tetrahydro-10-(3-pyridyl)-1H,5H,1llH-[1]benzopyrano[6,7,8-11]quinolizine-11-one (also called "Coumarin 510" in English), 3-(2-Benzothiazolyl)-7-(diethylamino)coumarin (also called "Coumarin 6" in English).

[0037] As examples of compounds comprising at least one cyanine group, mention may be made of indocyanine green, 5,5'-dichloro-11-diphenylamino-3,3'-diethyl-10,12-ethylenethiamine-140 perchlorate, (2E)-1,1,3-trimethyl-2-[5-(1,1,3-trimethylbenzo[e]indole iodide (also called "IR176 iodide").

[0038] By way of examples of compounds comprising at least one phthalocyanine group, mention may be made of iron(III) phthalocyanine chloride, iron(III) phthalocyanine-4,4',4”,4'”-tetrasulfonic acid and cobalt(II) 1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexadecafluoro-29H,31H-phthalocyanine, compounds comprising a monosodium oxygen salt hydrate.

[0039] By way of examples of compounds comprising at least one hydrazone group, mention may be made of conjugated hydrazones, such as those described in French application FR-A-2113669 (such as 4-nitrobenzaldehyde(2,4-dinitrophenyl) hydrazone) or of non-conjugated hydrazones, such as those described in French application (not yet published) FR 2303301.

[0040] It should be noted that some of these colored indicators may intrinsically exhibit the properties of a fluorophore.

[0041] In addition to these colored indicators exhibiting the properties of a fluorophore, fluorescent indicators can be chosen from fluorescent oxides, fluorescent silicates, fluorescent halosilicates, fluorescent phosphates, fluorescent halophosphates, fluorescent borates, fluorescent aluminates and gallates, fluorescent molybdates and tungstates, fluorescent halides and oxyhalides, fluorescent sulfates and sulfites.

[0042] A large number of fluorescent oxides can be mentioned in CaO:Bi3+; CaO:Cd2+ ; CaO:Eu3+ ; CaO:Eu3+,Na+ ; CaO:Mn2+ ; CaO:Pb2+ ; CaO:Sb3+ ; CaO:Sm3+ ; CaO:Tb3+ ; CaO:Ti+ ; CaO:Zn2+ ; ZnO:Al3+,Ga3+ ; ZnO:S ; ZnO:Se; ThO2:Pr3+ ; ThO2:Tb3+ ; Y2O3:Bi3+ ; Y2O3:Er3+ ; Y2O3:Eu3+ ; Y2O3:Ho3+ ; Y2O3:Tb3+ ; La2O3:Bi3+ ; La2O3:Eu3+ ; La2O3:Pb LiInO2:Eu3+ LiInO2:Sm3+ LiLaO2:Eu3+ NaYO2:Eu3+ CaTiO3:Pr3+ CaGeO3:Mn2+ Mg2TiO4 :Mn4+ Zn2GeO4:Mn2+ YV04 :Eu3+ LaVO4:Eu3+ YAsO4:Eu3+ LaAsO4:Eu3+ Ca5(VO4)3Cl Mg8Ge20nF2:Mn4+ CaY2ZrO6:Eu3+ and Mg3SiO3F4:Ti4+.

[0043] By way of examples of fluorescent silicates, mention may be made of the following silicates selected from CaSiO3:Ce3+ ; CaSiO3:Eu2+ ; CaSiO3:Pb2+ ; CaSiO3:Ti4+ ; CaSiO3:Pb2+,Mn 2+ ; Be2SiO4:Mn2+ ; Mg2SiO4:Mn2+ ; Zn2SiO4:Mn2+,P ; Zn2SiO4:Mn2+,As5+ ; Zn2SiO4:Ti 4+ ; (Zn,Be)2SiO4:Mn2+ ; SrSiO4:Eu2+ ; SrBaSiO4:Eu2+ ; Ba2SiO4:Eu2+ ; Ba2SiO4:Ce3+,Li +,Mn2+ ; Ba2SiO5:Eu2+ ; Ba2SiO5:Pb2+ ; Y2O5:Ce3+; CaMgSiO6:Eu2+; CaMgSiO6:Eu2+,Mn+2; Ca2MgSiO7:Eu2+; Ca2MgSiO7:Eu2+,Mn+2; Sr2MgSiO7:Eu2+; Ba2MgSiO7:Eu2+; BaMgSiO7:Eu2+; BaSrSiO7:Eu2+; Ba2Li2SiO7:Eu2+; Ba2Li2SiO7:Sn2+; Ba2Li2SiO7:Sn2+,Mn2+; MgSrBa2SiO7:Eu2+ ; MgBa2Si2O8:Eu2+,Mn2+; Sr3MgSi2O8:Eu2+; Ca5B2SiOi0:Eu 3+; Ca3Al2SiO3O12:Eu2+; LiCeBa4Si4O14:Mn2+ and LiCeSrBa3Si4O14:Mn2+.

[0044] As examples of fluorescent halosilicates, mention may be made of halosilicates chosen from LaSiO3Cl:Ce3+ ; LaSiO3Cl:Ce3+,Tb3+ ; Ca3SiO4Cl2:Pb2+ ; Ca3 SiO4C12:Eu2+ ; Ba5SiO4Cl6:Eu2+ and Sr5Si4OiOCl6:Eu2+.

[0045] A large number of examples of fluorescent phosphates may mention the phosphates chosen by YPO4:Ce3+; YPO4:Ce3+,Tb3+ ; YPO4:Eu3+ ; YPO4:Mn2+,Th4+ ; YPO4:V5+ ; LaPO4:Ce3+ ; LaPO4:Eu3+ ; CaP2O6:Mn2+ ; Sr2P2O7:Sn2+ ; Ca2P2O7:Ce3+ ; Ca2P2O7:Eu2+,Mn2+ ; Ca2P2O7:Eu2+ ; Li2CaP2O7:Ce3+,Mn2+ ; MgCaP2O7:Mn2+ ; BaTiP2O7 ; MgSrP2O7:Eu2+ ; MgBaP2O7:Eu2+ ; MgBaP2O7:Eu2+,Mn2+; Ca3(PO4)2:Ce3+; CaB2P2O9:Eu2+; Ca3(PO4)2:Sn2+; Ca3(PO4)2:Sn2+; Ca3(PO4)2:Pb2+; Ca3(PO4)2:Ti+; Ca3(PO4)2:Ce3+; Ca3(PO4)2:Eu2+; Ca3(PO4)2:Eu2+; Ca3(PO4)2:Eu2+,Mn2+; Sr3(PO4)2:Sn2+,Mn2+; Sr3(PO4)2:Sn2+; Sr3(PO4)2:Eu2+; Ba3(PO4)2:Eu2+; Na3Ce(PO4)2:Tb3+; (Ca,Sr)3(PO4)2:Sn2+,Mn2+ ; ZnMg2(PO4)2:Mn2+ ; Zn3(PO4)2:Mn2+ (Zn,Mg)3(PO4)2:Mn2+ Mg3Ca3(PO4)4:Eu2+ MgSr5(PO4)4:Sn2+ MgBa2(PO4)2:Sn2+ CaSr2(PO4)2:Bi3+ et Sr2P2O7:Eu2+.

[0046] By way of examples of fluorescent halophosphates, mention may be made of halophosphates chosen from among Ca5(PO4)3F:Mn2+ ; Ca5(PO4)3F:Sb3+ ; Ca5(PO4)3F:Sn2+ ; Ca5(PO4)3Cl:Eu2+ ; Ca5(PO4)3Cl:Mn2+ ; Ca5(PO4)3Cl:Sb3+ ; Ca5(PO4)3Cl:Sn2+ ; Sr5(PO4)3 C1:Eu2+ ; Sr5(PO4)3Cl:Mn2+ ; Sr5(PO4)3Cl:Sb3+ ; Sr5(PO4)3F:Mn2+ ; Sr5(PO4)3F:Sb3+ ; Sr5 (PO4)3F:Sb3+,Mn2+ ; Sr5(PO4)3Cl:Eu2+,Pr3+ ; Sr5(PO4)3F:Sn2+ ; Ba5(PO4)3Cl:Eu2+ and Ca2Ba 3(PO4)3C1:Eu2+.

[0047] By way of examples of fluorescent borates, mention may be made of borates selected from among YBO3:Ce3+; YBO3:Eu3+; LaBO3:Eu3+; SrO3B2O3:Pb2+; SrO3B2O3:Pb2+,Mn2+; SrO3B2O3:Eu2+,C1; SrO3B2O3:Sm2+; B2O4:Mn2+; MgYO4:Eu3+; CaB2O4:Mn2+; CaB2O4:Pb2+; CaYBO4:Bi3+; CaYBO4:Eu3+; CaLaBO4:Eu3+; ZnB2O4:Mn2+; Ca2B2O5:Mn2+; LaAIB2O6:Eu3+; CaLaB3O7:Ce3+,Mn2+; SrB4O7:Eu2+(F,Cl,Br); SrB4O7:Pb2+; SrB4O7:Pb2+,Mn2+; Cd2B6OH:Mn2+; YAl3B4O12:Ce3+; YAl3B4O12:Bi3+; YA13B4O12:Eu3+ ; YAl3B4O12:Eu3+,Cr3+ ; YAl3B4O12:Th4+,Ce3+,Mn2+ ; YAl3B4O12:Ce3+,Tb3+ LaAl3B4O12 :Eu3+; BaB80i3:Eu2+ SrB80i3:Sm2+ Ca2B5O9Cl:Eu2+ Ca2B5O9Cl:Pb2+ Ca2B5O9Br:Eu2+ Sr2B5O9Cl:Eu2+ CaYBO8O37:Eu3+ La2BO65:Pb2+ YAI3B40i2:Ce3+,Mn2+.

[0048] There are many examples of aluminates and fluorescent gallates, it may be mentioned that aluminates and gallates are chosen by LiAIO2:Fe3+; LiAIO2:Mn2+ ; YAIO3:Ce3+ ; YAIO3:Eu3+ ; YAIO3:Sm3+ ; YAIO3:Tb3+ ; LaAIO3:Eu3+ ; LaAIO3:Sm3+ ; MgAI2O4:Mn2+ ; MgGa2O4:Mn2+ ; CaAI2O4:Mn2+ CaAI2O4:Eu2+ ZnAI2O4:Mn2+ ZnGa2O4:Mn2+ CaGa2O4:Mn2+ CaGa4O7:Mn2+ SrAI2O4:Eu2+ BaAI2O4:Eu2+ CaAI4O7:Pb2+,Mn2+ LiAI5O8:Fe3+ LiAI5O8:Mn2+ Y4AI2O9:Eu3+ YsAl5Oi2:Ce3+ KAInOi7:Ti+ KGanOi7:Mn2+ BaMgAlioOi7:C63+ Y3Al5Oi2:Eu3+ BaMgAlwOi7:Eu2+ ; BaMgAlwOi7:Eu2+,Mn2+ ; Cao.5Bao.5Ali2Oi9:Ce3+,Mn2+ ; SrAli20i9:Eu2+,Mn2+ SrGai2Oi9:Mn2+ et SrAli2Oi9:Ce3+,Mn2+.

[0049] By way of examples of fluorescent molybdates and tungstates, reference may be made to molybdates and tungstates selected from CaMoO4:Sm3+,Eu3+,Tb3+ ; SrMoO4:Eu,Tb ; SrMoO4:Sm3+,Dy3+,Eu3+,Tb3+ ; MgWO4:Eu3+,Tb3+ ; CaWO4:Eu3+,Tb3+; Ca3WO6:Eu3+,Tb3+; Sr3WO6:Eu3+,Tb3+; Ba3WO6:Eu3+ and La2W3Oi2:Eu3+.

[0050] By way of examples of fluorescent halides and oxyhalides, mention may be made of the following halides and oxyhalides selected from MgF2:Mn2+; CaF2:Ce3+; CaF2:Eu2+; CaF2:Mn2+; CaF2:Ce3+,Mn2+; CaF2:Ce3+,Tb3+; CaCl2:Eu2+ in SiO2; CaCl2:Eu2+,Mn2+ in SiO2; Sr(Cl,Br,l)2:Eu2+ in SiO2; ZnF2:Mn2+; Ba#Sr1-#F2:Eu2+; YF3:Mn2+; YF3:Mn2+,Th4+; KMgF3:Eu2+; KMgF3:Mn2+; LiAlF4:Mn2+; K2SiF6:Mn4+; YOBr:Eu3+ ; YOCI:Ce3+; YOCI:Eu3+ ; YOF:Eu3+ ; YOF:Tb3+; LaOF:Eu3+ ; LaOCI:Bi3+ and LaOCI:Eu3+.

[0051] As examples of fluorescent sulfates and sulfites, mention may be made of selected sulfates and sulfites including MgS04:Eu2+; MgS04:Pb2+ ; CaSO4:Eu2+,Mn2+ ; CaS04:Pb2+ ; CaSO4:Bi ; CaS04:Ce3+ ; CaSO4:Ce3+,Mn2+ ; CaS04:Eu2+ ; SrSO4:Bi ; SrS04:Ce3+ ; SrSO4:Eu2+,Mn2+ ; SrS04:Eu2+ ; BaS04:Ce3+ ; BaS04:Eu2+ ; MgBa(SO4)2:Eu2+ ; Mg2Ca(SO4)3:Eu2+ ; Mg2Ca(SO4)3:Eu2+,Mn2+ ; Mg2Sr(SO4)3:Eu2+ ; ZnS:Ag+,CF ; ZnS:Au,In ; ZnS:Cu,Sn ; ZnS:Cu+,AI3+ ; ZnS:Eu2+ ; ZnS:Sn,Ag ; ZnS:Sn2+,Li+ ; ZnSe:Cu+,CF ; CdS:Ag+,CF ; CdSfln; ZnS-CdS:Cu,I; ZnS-CdS ; ZnS-CdS:Ag,Br,Ni ; ZnS-CdS:Ag+,CF ; ZnS-CdS:Cu,Br ; ZnS-ZnTe:Mn ; MgS:Eu2+ ; CaS:Bi3+; CaS:Bi3+,Na+ ; CaS:Ce3+ ; CaS:Cu+,Na+ ; CaS:Eu2+ ; CaS:Mn2+ ; CaS:La3+ ; CaS:Pb2+,CF ; CaS:Pb2+ ; CaS:Pb2+,Mn2+ ; CaSPr^Pb^CF ; CaS:Sb3+,Na+ ; CaS:Sm3+ ; CaS:Sn2+ ; CaS:Sn2+,F- ; CaS:Tb3+; CaS:Tb3+,CF; CaS:Y3+ ; CaS:Yb2+; CaS:Yb2+,CF; SrS:Ce3+; SrS:Cu+,Na+; SrS:Eu2+; SrS:Mn2+; BaS:Au,K+; CaGa2S4:Ce3+ ; CaGa2S4:Eu2+ ; CaGa2S4:Mn2+; CaGa2S4:Pb2+; ZnGa2S4:Eu2+; ZnBa2S3:Mn; SrAI2S4:Eu2+; SrGa2S4:Pb2+; BaAI2S4:Eu2+; SrGa2S4:Ce2+ ; SrGa2S4:Eu2+ ; BaGa2S4:Ce3+; BaGa2S4:Eu2+; Y2O2S:Eu3+ ; Y2O2S:Tb3+ and Gd2O2S:Tb3+.

[0052] Fluorescent indicators can also be in the form of an organo-lanthanide complex comprising a ligand chosen from, preferably, polyaminocarboxylates, [3-diketonates, pyridine-tetrazolate tridentates and carboxylic acids.

[0053] According to the invention, the coloured indicator(s) and / or the fluorescent indicator(s) can be encapsulated in solid particles in a (co)polymer, crosslinked or not, it being understood that these solid particles comprise (or encapsulate) only one coloured indicator or only one fluorescent indicator, when the foaming aqueous solution Al and - when the material also comprises the layer C2 - the foaming aqueous solution A2 each comprise several coloured indicators and / or several fluorescent indicators.

[0054] Encapsulation makes it possible in particular to limit, or even avoid, the migration of detection indicators in foaming aqueous solutions and, consequently, to limit, or even avoid, any interaction between them.

[0055] It is specified that by "(co)polymer" we mean both a homopolymer which is derived from a single monomer and which is therefore formed of a single repeating motif, and a copolymer which is derived from several (that is to say, two or more of two) different monomers and which is therefore formed of several different repeating motifs.

[0056] Such particles can be obtained by (co)polymerization of one or more monomers - this (co)polymerization can then be a (co)polymerization in bulk, in solution, in suspension, in dispersion or in emulsion, induced by heat or UV, in the presence or not of a polymerization initiator - or by solubilization / precipitation of one or more (co)polymers in a suitable solvent.

[0057] In the case where the solid particles are in a crosslinked (co)polymer, then this crosslinking can result from: - of a functionalization of the monomer(s) prior to (co)polymerization, in which case the (co)polymerization is accompanied by cross-linking; - functionalization of the monomer(s) after (co)polymerization, in which case (co)polymerization and crosslinking are carried out in two steps; or - in the case of a copolymer, a copolymerization of one or more monofunctional monomers and one or more multifunctional monomers.

[0058] Crosslinking makes it possible to limit as much as possible the migration of the detection indicator(s) in foaming aqueous solutions.

[0059] Preferably, the (co)polymer is obtained from the (co)polymerization of at least one monomer chosen from among the acrylate monomers such as, for example, methacrylate methyl, trimethylolpropane triacrylate, dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate.

[0060] Preferably, the (co)polymer is a poly(methyl methacrylate) (or PMMA) crosslinked by trimethylolpropane triacrylate (or TMPTA).

[0061] Said solid particles are, preferably, microparticles, that is to say, they have an average size in number between 0.1 pm and 100 pm and, even better, between 5 pm and 50 pm.

[0062] This average size can be determined by measurements in optical microscopy, for example using an optical microscope such as that marketed by Fisher Scientific, under the reference Fisherbrand™ AX-500.

[0063] In this regard, it is specified that "size" means the largest of the three dimensions of the microparticles.

[0064] When the detection indicator(s) are encapsulated in solid particles, then the foaming aqueous solution Al can comprise a total of 0.5% to 10% by mass and, preferably, 2% to 5% by mass of these solid particles, relative to the total mass of foaming aqueous solution.

[0065] Similarly, when the material further comprises the C2 layer and the detection indicator(s) are encapsulated in solid particles, then the foaming aqueous solution A2 can comprise a total of 0.5% to 10% by mass and, preferably, 2% to 5% by mass of these solid particles, relative to the total mass of foaming aqueous solution.

[0066] According to the invention, the aqueous foaming solution Al and - when the material further comprises the layer C2 - the aqueous foaming solution A2, each comprise at least one surfactant, preferably of 0.05% to 1.5% by mass and, optionally, at least one gelling agent, preferably of 0.00% to 0.8% by mass relative to the total mass of aqueous foaming solution.

[0067] In the preceding and following, it is specified that "surfactants" means organic foaming surfactants, that is to say, surfactants comprising a lipophilic (nonpolar) part and a hydrophilic (polar) part and having a hydrophilic / lipophilic balance (or HLB for "Hydrophilic-Lipophilic Balance" in English) between 3 and 8. The HLB value of such a surfactant can easily be obtained by the method as described by JT Davies (in "A quantitative kinetic theory of emulsion type I. Physical Chemistry of the emulsifying agent", Gas / Liquid and Liquid / Liquid Interfaces, Proceedings of 2nd International Congress Surface Activity 1957, 426-438, hereinafter reference [1]) and from the HLB tables for different chemical groups, available to those skilled in the art.

[0068] The surfactant(s) may be chosen from non-ionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants and surfactants of bolaform or gemini type structure, preferably non-ionic surfactants, anionic surfactants and cationic surfactants and, even better, non-ionic surfactants.

[0069] Nonionic (or neutral) surfactants are compounds whose surface-active properties, particularly hydrophilic properties, are provided by uncharged functional groups such as an alcohol, an ether, an ester, or an amide, and may contain heteroatoms such as nitrogen or oxygen. Due to the limited hydrophilic contribution of these functional groups, nonionic surfactants are most often polyfunctional.

[0070] In the context of the present invention, the nonionic surfactants may in particular be selected from alkyl alkoxylates, fatty alcohol alkoxylates, fatty amine alkoxylates, fatty acid alkoxylates, oxoalcohol alkoxylates, alkylphenol alkoxylates, alkyl ethoxylates, fatty alcohol ethoxylates, fatty amine ethoxylates, fatty acid ethoxylates, oxoalcohol ethoxylates, alkylphenol ethoxylates such as octylphenol and nonylphenol ethoxylates, alcohols, α-diols, polyethoxylated and polypropoxylated alkylphenols having a carbon chain, for example, C8-C[8] and comprising from 2 to 50 groups of ethylene oxides or propylene oxides, complex polymers of polyethylene and polypropylene oxides, copolymers of ethylene and propylene oxides, block copolymers of polyethylene and polypropylene oxides such as triblock copolymers POEPOP-POE,ethylene and propylene oxide condensates on fatty alcohols, polyethoxylated fatty amides preferably having 2 to 30 moles of ethylene oxide, polyethoxylated ethers preferably having 2 to 30 moles of ethylene oxide, monoesters (monolaurate, monomyristate, monostearate, monopalmitate, monooleate, etc.) and polyesters of fatty acids and glycerol, polyglycerol fatty amides comprising, on average, 1 to 5 and, more particularly, 1.5 to 4 glycerol groups, oxyethylenated sorbitan fatty acid esters preferably comprising 2 to 30 moles of ethylene oxide, monoesters (monolaurate, monomyristate, monostearate, monopalmitate, monooleate, etc.) and polyesters of fatty acids and sorbitan, polyoxyethylene sorbitan monoesters, sucrose fatty acid esters, polyethylene glycol fatty acid esters, alkyl polyglucosides, IV-alkylglucamine derivatives and amine oxides such as alkylamine oxides,for example, in C10-C14 and oxides of iV-acylaminopropylmorpholine, polyols and in particular glucose alkylates such as glucose hexanoate, surfactants derived from glucoside (laurate, of sorbitol) and polyols such as glycerol alcohol ethers, alkanolamides and their mixtures.

[0071] In particular, non-ionic surfactants may be chosen from those described in international application WO-A-2004 / 008463 (hereinafter reference [2]), and in particular from those belonging to the families of alkylpolyglucosides or alkylpolyetherglucosides, derived from glucose and biodegradable, such as those marketed by BASF under the trade names Glucopon™ (Glucopon™ 215 for example) or by SEPPIC under the trade names Oramix™ (Oramix™ CG-110 for example).

[0072] Anionic surfactants, on the other hand, are surfactants whose hydrophilic part is negatively charged. They can be chosen from sulfuric acid esters, phosphoric acid esters, alkyl or aryl sulfonates, alkyl or aryl sulfates, alkyl or aryl phosphates, alkyl or aryl sulfosuccinates and alkyl and aryl sarcosinates associated with a counter ion such as an ammonium ion, a quaternary ammonium such as tetraethylammonium or tetrabutylammonium and cations such as Na+, Li+, Ca2+, Mg2+, Zn2+ and K+.

[0073] More specifically, the anionic surfactants may be selected from tetraethylammonium paratoluenesulfonate, sodium dodecyl sulfate (or SDS), sodium laurylsarcosinate (or sarcosyl), sodium palmitate, sodium stearate, sodium myristate, sodium di(2-ethylhexyl) sulfosuccinate, methylbenzene sulfonate and ethylbenzene sulfonate.

[0074] Cationic surfactants, for their part, typically have at least one hydrocarbon chain and a polar head, and their hydrophilic part is positively charged. They can be chosen from quaternary ammonium compounds comprising at least one C4-C22 aliphatic chain associated with an anionic counter-ion chosen in particular from boron derivatives such as tetrafluoroborate and halide ions such as F, Br, I or Cl.

[0075] More particularly, the cationic surfactants can be selected from tetrabutylammonium chloride, tetradecylammonium chloride, tetradecyltrimethylammonium bromide (TTAB), alkylpyridinium halides bearing an aliphatic chain and alkylammonium halides.

[0076] Furthermore, the gelling agent(s) are advantageously biodegradable and pseudo-plastic agents. Preferably, they are chosen from water-soluble polymers, hydrocolloids, heteropolysaccharides such as trisaccharide branched-chain polyglucosidic polymers, cellulosic derivatives and polysaccharides such as polysaccharides comprising glucose as the sole monomer.

[0077] More particularly, the gelling agent(s) usable within the framework of the present invention may be chosen from xanthan gum, guar gum, agar-agar, carrageenan, sodium alginate, caseinate, gelatin, pectin, starch, cellulose, sodium carboxymethylcellulose, 2-hydroxyethylcellulose (HEC) and chitosan, preference being given to xanthan gum and sodium carboxymethylcellulose.

[0078] The aqueous foaming solution Al and - when the material also includes the layer C2 - the aqueous foaming solution A2, may for example include at least one of the detection indicators mentioned above (and more particularly, those selected from Disperse Black 9, bromocresol green, 4-nitrobenzaldehyde(2,4-dinitrophenyl) hydrazone, SrMoO4:Eu,Tb and mixtures thereof), an alkyl polyglucoside, xanthan gum and, optionally, sodium carboxymethylcellulose.

[0079] Furthermore, it should be noted that the foaming aqueous solutions Al and A2 can be neutral, acidic, or basic depending on the detection indicator(s) they contain and the pH conditions required for the proper functioning of said indicator(s). A person skilled in the art will be able to determine the most suitable pH for these solutions.

[0080] According to the invention, where the material comprises a stack of at least two Cl and C2 layers, these layers are advantageously separated from each other by at least one buffer layer to limit, or even prevent, the Cl and C2 layers from mixing, which could cause a color change at the interface between these two layers. The buffer layer(s) thus stabilize the Cl and C2 layers and improve the detection of the presence of the chemical compound(s) to be identified.

[0081] For example, the Cl and C2 layers can be separated from each other by a buffer layer C3 which results from the freezing and then sublimation of a foam formed by a dispersion of gas bubbles in a foaming aqueous solution A3, the foaming aqueous solution A3 comprising at least one surfactant, optionally at least one gelling agent and / or solid particles in a (co)polymer, but being free of a detection indicator.

[0082] In this case, it is preferred that the composition of the aqueous foaming solution A3 differ from the composition of the aqueous foaming solution Al and / or from the composition of the aqueous foaming solution A2 only by the absence of a detection indicator.

[0083] In other words, the aqueous foaming solution A3 may comprise the same surfactant(s) and the same gelling agent(s) (when present in the aqueous foaming solutions A1 and / or A2) in the same proportions as in the aqueous foaming solutions A1 and / or A2. Similarly, when, in the foaming aqueous solutions Al and / or A2, the detection indicator(s) are encapsulated in solid particles, then the foaming aqueous solution A3 may comprise solid particles of the same nature and in the same proportions but being free of detection indicator.

[0084] The Cl and C2 layers can also be separated from each other by at least two layers C3' and C3”, the C3' layer being in contact with the Cl layer and the C3” layer being in contact with the C2 layer. The C3' layer results from the freezing and then sublimation of a foam formed by a dispersion of gas bubbles in a foaming aqueous solution A3' and the C3” layer results from the freezing and then sublimation of a foam formed by a dispersion of gas bubbles in a foaming aqueous solution A3”, each of the foaming aqueous solutions A3' and A3” comprising at least one surfactant, optionally at least one gelling agent and / or solid particles in a (co)polymer, but being free of a detection indicator.

[0085] In this case, it is preferred that the composition of the aqueous foaming solution A3' differs from the composition of the aqueous foaming solution Al only by the absence of a detection indicator, while the composition of the aqueous foaming solution A3” differs from the composition of the aqueous foaming solution A2 only by the absence of a detection indicator.

[0086] Thus, the buffer layers C3, C3' and C3” have, respectively, the same pH, the same density and the same viscosity as the Cl and / or C2 layers, which allows the superposition of these different layers without them mixing with each other and without causing a change of color at the interface of each of these layers.

[0087] The material as described above thus allows the detection of the presence of at least one chemical compound, preferably in the form of a gas (i.e. vapors), a liquid or an aerosol (i.e. a dispersion of liquid or solid particles in a gas such as air).

[0088] This or these chemical compounds may be organic compounds and, more particularly, toxic compounds such as toxic warfare compounds or TICs compounds.

[0089] More specifically, toxic warfare compounds can be selected from among G series organophosphate compounds (such as Soman, Sarin or Tabun), V series organophosphate compounds (such as compound VX), other organophosphate compounds, vesicant compounds (such as mustard gas and lewisite) and arsenic compounds.

[0090] The TICs compounds, for their part, can be chosen from chlorine, ammonia, carbon disulfide, hydrogen cyanide, nitric acid, sulfuric acid and / or formaldehyde.

[0091] The material as described above allows for easy and rapid reading of color change, fluorescence intensity and / or fluorescence emission wavelength shift, in particular by the porous structure of the material which allows chemical compounds, and more particularly when in the form of a gas, to spread rapidly in this material and thus react rapidly with the detection indicator(s).

[0092] This principle is illustrated in the attached [Fig. 1], which represents (part (a)) a material (1) comprising a stack of two layers (2; 4) which include a different detection indicator, separated from each other by a buffer layer (3). Part (b) of this figure illustrates this material (1) after exposure to a chemical compound and shows that the layer (2), which includes a detection indicator capable of detecting the chemical compound, has changed color, unlike the other layer (4) and the buffer layer (3), which have not changed color.

[0093] By virtue of the foams from which the Cl, C2 layers and the buffer layer(s) are obtained, it is possible to obtain a material comprising a stack of at least two distinct layers, without these layers mixing. Furthermore, these foams make it possible to obtain a material that is not or only slightly friable, i.e., resistant.

[0094] The invention also relates to a method for preparing the material as described above and comprising a Cl layer, the method comprising at least the following steps: a) preparation of the mousse; b) depositing the foam obtained at the end of step a) onto a substrate and then freezing the foam; c) sublimation of the foam obtained at the end of step b); and d) possible removal of the substrate; whereby the material is obtained.

[0095] It also relates to a method for preparing the material as described above and comprising a stacking of at least two layers Cl and C2. This preparation method comprises at least the following steps: a) preparation of the foams; b) Formation of the stacking of Cl and C2 layers by: i) successive deposits on a substrate of the mosses obtained at the end of step a); ii) freezing of the foams, the freezing being carried out between the deposition of the foams and / or after the successive depositions of the foams; c) sublimation of the stack obtained at the end of step b); and d) possible removal of the substrate; whereby the material is obtained.

[0096] It goes without saying that, during step a), as many foams as there are desired layers in the stacking of the material, are prepared.

[0097] Furthermore, whether in the process of preparing the material comprising the Cl layer or comprising the stacking of at least two Cl and C2 layers, the foam(s) are typically prepared in step a) by mixing the ingredients intended to be part of the composition of their foaming aqueous solution (i.e. water, detection indicator(s), surfactant(s) and, possibly, gelling agent(s), as described above) and then are generated by any foam generation device described in the prior art and known to those skilled in the art.More specifically, this refers to devices ensuring gas-liquid mixing, in particular by mechanical agitation, by bubbling, by static mixer including or not containing beads, by microbead tube foam generator, by devices such as those described in international application WO-A-02 / 043847 (hereinafter reference [3]) or by any other device, in particular nozzle or venturi systems allowing large flow rates (generally between 1 and 1,000 m3 / h).

[0098] Step a) of the process of preparing the material comprising the Cl layer or comprising the stacking of at least two Cl and C2 layers, may include the possible encapsulation of one or more colored indicators and / or fluorescent indicators in solid particles in a (co)polymer, as described above, it being understood that each solid particle comprises only one colored indicator or only one fluorescent indicator when the foaming aqueous solutions comprise several colored indicators and / or several fluorescent indicators.

[0099] Step a) may also include the possible formation of solid particles in a (co)polymer, not including a detection indicator.

[0100] It goes without saying that, in the case where the material comprises the stacking of at least two layers Cl and C2, the foams from which these layers are obtained are deposited successively, during step b), so as to obtain the desired stacking.

[0101] For example, the stacking can be a stacking of the Cl and C2 layers, or of the Cl layer, the C3 buffer layer then the C2 layer, or of the Cl layer, the C3' buffer layer, the C3” buffer layer then the C2 layer.

[0102] The substrate on which the foam(s) are deposited can be a container, allowing the mechanical strength of the material to be improved.

[0103] The container can be any type of conventional container, such as a flask, bottle, test tube, beaker, etc. It can also be a tube, such as a flexible tube closed at least at one end. The container thus allows the material to be given the desired geometry.

[0104] The container is chosen so as not to interfere with the detection of the presence of the chemical compound(s). The container is preferably transparent and may be made of plastic (such as polypropylene, polyethylene, polystyrene, acrylonitrile butadiene styrene, polymethyl methacrylate, polyethylene terephthalate, polyamide 6, polyethylene oxide, polycarbonate, etc.), glass, quartz, or sapphire. In particular, when at least one fluorescent indicator is present in the material, the container is advantageously made of quartz.

[0105] Moreover, freezing is preferably carried out at a temperature between -200 °C and -10 °C and, even better, between -20 °C and -15 °C and, preferably, for a period ranging from a few minutes to several hours, for example from 1 hour to 24 hours.

[0106] According to the invention, freezing can be carried out either with a freezer or with a cryogenic fluid such as liquid nitrogen.

[0107] Next, the sublimation step is carried out under vacuum, for example at a pressure between 0.04 mbar (i.e. 4 Pa) and 0.2 mbar (i.e. 20 Pa) and is carried out, preferably, for several hours to several days, for example, for 2 days.

[0108] According to the invention, the freezing and sublimation steps can be carried out by lyophilization.

[0109] The material thus obtained advantageously has a density between 0.005 g.cm3 and 0.03 g.cm3. This density can be conventionally determined by measuring the volume of the entire layer or layers formed and then weighing the material obtained after sublimation.

[0110] The invention also relates to a material comprising a Cl layer or to a material comprising a stack of at least two Cl and C2 layers, which can be obtained by the processes as described above.

[0111] The invention also relates to the use of the material as described above to detect the presence of at least one chemical compound present in a medium.

[0112] According to the invention, the use of the material advantageously includes bringing the material of the invention into contact with the medium which may include the chemical compound(s), the medium being preferably in the form of a gas (such as air), a liquid or an aerosol.

[0113] The chemical compound(s) that may be detected may be organic compounds and, more particularly, toxic compounds such as toxic warfare compounds and / or TICs.

[0114] More specifically, toxic warfare compounds can be selected from among the G-series organophosphate compounds (such as Soman, Sarin or Tabun), the V-series organophosphate compounds (such as compound VX), other organophosphorus compounds, vesicant compounds (such as yperite and lewisite) and arsenic compounds.

[0115] The TICs compounds, for their part, can be chosen from chlorine, ammonia, carbon disulfide, hydrogen cyanide, nitric acid, sulfuric acid or formaldehyde.

[0116] Once contact has been made and, possibly, after a waiting period, the presence of the chemical compound(s) can be deduced based on the response of the material, for example, by a change of color, when the detection indicator(s) are colored indicators and / or by a change in fluorescence emission intensity and / or by a shift in fluorescence emission wavelength when the detection indicator(s) are fluorescent indicators.

[0117] In this regard, when the detection indicator(s) are coloured indicators, the operator may rely on a colourimetric scale associated with the material of the invention, which will define, for all chemical compounds likely to be detected by the material, the corresponding colour change, this colourimetric scale being able to be determined by prior tests, for each of the materials and chemical compounds intended to be detected by these materials.

[0118] Furthermore, when the detection indicator(s) are fluorescent indicators, the operator may rely on the fluorescence emission spectra associated with the material of the invention, which will define, for all chemical compounds likely to be detected by the material, the change in fluorescence emission intensity, the corresponding fluorescence emission wavelength shift or the change in the shape of the emission spectrum, these spectra being able to be determined by prior tests, for each of the materials and chemical compounds intended to be detected by these materials.

[0119] The deduction can be made with the naked eye or via opto-electronic means such as a fluorimeter.

[0120] Other features and advantages of the invention will become apparent from the following supplementary description.

[0121] It goes without saying that this additional description is given only as an illustration of the object of the invention and should in no case be interpreted as a limitation of this object. Brief description of the figures

[0122] [Fig. 1], already commented on, illustrates the general principle of detection according to the invention.

[0123] [Fig.2] and [Fig.3] represent, respectively, the fluorescence emission spectra of two layers, included in a material of the invention, before and after exposure to a chemical compound; in these figures, the x-axis corresponds to the emission wavelengths, expressed in nm and denoted X, while the y-axis corresponds to the intensity of fluorescence emitted, expressed in arbitrary units (au) and denoted I.

[0124] Detailed description of particular embodiments

[0125] 1. Preparation of copolymer solid particles

[0126] 1.1 _ Encapsulation of Disperse Black 9 in solid particles of P MMA / TMPTA

[0127] The encapsulation of Disperse Black 9 in PMMA / TMPTA particles (i.e., poly(methyl methacrylate) crosslinked with trimethylolpropane triacrylate) is carried out according to the following protocol: 1°) 5 mg of previously ground Disperse Black 9 and 50 mg of Irgacure™ 819 photoinitiator (supplied by BASF with commercial reference 56415892) are suspended in 20 mL of cyclohexane and then passed through ultrasound; 2°) the suspension thus obtained is placed under magnetic stirring in a UV tank (supplied by Hônle, under the reference UVA-cubelOO; 365 nm; ~4 mW / cm2); 3°) still under stirring, a solution comprising 0.2 mL of MMA and 0.8 mL of TMPTA is introduced into the suspension using a syringe; 4°) the suspension obtained at the end of point 3°) is irradiated under UV for 4 minutes; it then changes from a transparent appearance to a milky appearance; 5°) Cyclohexane is then added to eliminate the residual photoinitiator; 6°) the suspension is then centrifuged at 10,000 rpm for 5 minutes, then the cyclohexane is removed and replaced with ethanol; 7°) the suspension is centrifuged again at 10,000 rpm for 5 minutes to remove, this time, the residual unencapsulated Disperse Black 9; and finally, 8°) the particles thus obtained in the suspension are recovered by filtration on a pleated filter, rinsed with water and dried at room temperature.

[0128] L2 _ Encapsulation of 4-nitrobenzaldehyde(2,4-dinitrophenyl) hydrazone _ and bromocresol green in solid particles of P MMA / TMPTA

[0129] The same protocol as that described in point 1.1 above is implemented, using respectively 4-nitrobenzaldehyde(2,4-dinitrophenyl) hydrazone and bromocresol green, instead of Disperse Black 9.

[0130] L 3 _ Preparation of solid particles of P MMA / TMPTA not comprising a colour indicator

[0131] PMMA / TMPTA particles free of colour indicator are obtained by implementing the same steps as those described in point 1.1 above, without however using a colour indicator during step 1°).

[0132] 2. Preparation of mousses Ml to M7

[0133] Five foams M1 to M5 are prepared from aqueous foaming solutions according to the compositions indicated in the following Table I and according to the following steps: 1) mixing, under magnetic stirring and at room temperature, of water, Glucopon™ (marketed by BASF, under the commercial reference Glucopon™215 UP) and Xanthan gum (marketed by Sigma-Aldrich, under the commercial reference G1253); 2) if necessary, add 1 mol / L phosphoric acid until the desired pH is reached; 3) Addition of the detection indicator(s), 4) Mixing the solution with a spatula until a foam forms.

[0134] [Table 1] Table I Deionized (g) Glucopon™ (g) Xanthan Gum kl HiPOi Detection Indicator M1 4.5 0.0456 0.0137 - Encapsulated Disperse Black 9: 0.170 g M2 4.5 0.0456 0.0137 - Encapsulated 4-n-tribenzaldehyde 2,4-dinitrope nylhydrazone: 0.170 g M3 4.5 0.0456 0.0137 pH = 4 Encapsulated Bromocresol Green: 0.170 g M4 LS 0.0152 0.0046 - Encapsulated Disperse Black 9: 0.0567 g; SrMoO^; Eu,Tb: 0.1 g

[0135] Two other foams M6 and M7 comprising sodium carboxymethylcellulose (more simply noted CMC) are prepared from foams corresponding respectively to foams M1 and M3 but which have been prepared in such a way as to obtain 6 g.

[0136] To do this, 0.385 g of a CMC solution (8 wt%; Mw ~ 90,000 g / mol marketed by Sigma-Aldrich under reference 419273) are added to 6 g of each of the foams corresponding to foams M1 and M3. The mixtures obtained are then stirred with a spatula until a foam is obtained.

[0137] 3. Preparation of MT 1 and MT 3 foams, free of indicators of detection

[0138] Two foams MT1 and MT3 are prepared, respectively, in the same way (with the same compounds and in the same proportions) as foams M1 and M3, except that the encapsulated color indicators are replaced by the solid PMMA / TMPTA particles free of detection indicators obtained in point 1.3 above.

[0139] 4. Preparation and use of materials according to the invention

[0140] 4.1 _ Example 1

[0141] The Ml foam is deposited, to a thickness of about 1 cm, inside a transparent plastic bottle, then is soaked in liquid nitrogen for 1 minute.

[0142] The same operations are carried out first with M2 and then with M3 (so as to obtain an M1-M2-M3 stack) and the whole then undergoes sublimation, under vacuum, for 2 days.

[0143] A paper containing diphenylchlorophosphate (more simply denoted DPCP), simulating a toxic compound, is introduced into the bottle containing the stack M1-M2-M3. This paper is glued to the bottle stopper so that it is not in direct contact with the stack.

[0144] After 6 hours of exposure of the stack to DPCP vapors, it is observed that the layer obtained from M1 changes from a pale yellow color to a violet color, while the two other layers obtained from M2 and M3 do not change color. Thus, the layer obtained from M1 allows the detection of DPCP.

[0145] 4.2 _ Example 2

[0146] The M4 foam is deposited, to a thickness of approximately 1 cm, inside a transparent plastic bottle, and then immersed in liquid nitrogen for 1 minute. Next, the M5 foam is deposited on top of the previously frozen M4 foam layer, and the whole assembly is again immersed in liquid nitrogen for 1 minute.

[0147] The assembly then undergoes sublimation, under vacuum, for 2 days.

[0148] The material is then demolded from the bottle and a sample of the layer obtained from the M4 foam is exposed to a drop of DPCP, while a sample of the layer obtained from the M5 foam is exposed to a drop of ammonia (NH40H).

[0149] A color change from pale yellow to violet is then observed for the layer obtained from M4 and a color change from pale yellow to blue for the layer obtained from M5. Thus, the layer obtained from M4 allows the detection of DPCP while the layer obtained from M5 allows the detection of NH4OH.

[0150] Furthermore, Figures 2 and 3 show the fluorescence emission spectra of each of these layers before and after exposure to DPCP or NH40H.

[0151] Fig. 2 represents the fluorescence emission spectrum of the layer obtained from M4, with excitation at a wavelength of 310 nm. The spectrum shows that, before exposure to DPCP, an intensity peak of 54761 au is observed at 543.3 nm and an intensity peak of 65535 au is observed at 614.4 nm, whereas, after exposure to DPCP, an intensity peak of 14029 au is observed at 534.3 nm and an intensity peak of 212634 au is observed at 614.4 nm.

[0152] Fig. 3 represents the fluorescence emission spectrum of the layer obtained from M4, with excitation at a wavelength of 310 nm. The spectrum shows that, before exposure to NH4OH, an intensity peak of 59644 au is observed at 543.3 nm and an intensity peak of 61352 au is observed at 614.4 nm, whereas, after exposure to NH40H, an intensity peak of 40622 au is observed at 543.3 nm and an intensity peak of 33399 au is observed at 614.4 nm.

[0153] These figures confirm that the layer obtained from M4 allows the detection of DPCP while the layer obtained from M5 allows the detection of NH40H.

[0154] 4.3 _ Example 3

[0155] The Ml foam is deposited inside a transparent plastic bottle, to a thickness of approximately 1 cm.

[0156] The MT3 and then M3 foams are deposited to obtain an M1-Mt3-M3 stack. The assembly is then placed in a freezer at -20 °C overnight before undergoing sublimation under vacuum for 1 day.

[0157] The material is first exposed to DPCP vapors. As a result, only the layer obtained from Ml changes color (from pale yellow to violet).

[0158] The material is then exposed to ammonia vapors. This time, a color change is observed in the layer obtained from M3 (from pale yellow to blue) while the layer obtained from M1 retains its violet color.

[0159] No color change is observed for the MT3 buffer layer.

[0160] This example shows that the material of the invention allows the detection as well as the discrimination of different chemical compounds.

[0161] Moreover, thanks to the presence of the buffer layer obtained from MT3, no interaction or interference between the two layers M1 and M3 is observed.

[0162] It is also noted that the material obtained in this example is more resistant (shows no cracks) compared to the materials obtained in previous examples, which is due in particular to the freezing step carried out using a freezer.

[0163] 4.4 _ Example 4

[0164] The M6 ​​foam is deposited in a flexible, transparent plastic tube, previously closed at one end, to a thickness of approximately 1 cm. Foams MT1, MT3, and M7 are then successively deposited on the M6 ​​layer to obtain the stack M6-MT1-MT3-M7. The MT1 and MT2 foams are approximately 0.5 cm thick, while the M7 layer is approximately 1 cm thick.

[0165] The second end of the tube is then closed.

[0166] The tube is placed in a freezer overnight, before undergoing sublimation under vacuum for 1 day.

[0167] The material obtained exhibits improved mechanical strength compared to those obtained in previous examples, notably due to the presence of CMC in the M6 ​​and M7 foams.

[0168] Both ends of the tube are then opened and the material is exposed to DPCP vapors. Again, only the layer obtained from M6 changes color (from pale yellow to violet).

[0169] The material is then exposed to ammonia vapors and as a result the layer obtained from M7 changes from pale yellow to blue, while the layer obtained from M6 retains its violet color.

[0170] No color change is observed for the buffer layers obtained from MT1 and MT3.

[0171] Furthermore, since the MT1 buffer layer has the same pH as the M6 ​​layer, no interaction—and therefore no color change—is observed at the interface of these two layers. The same is true for the MT3 and M7 layers.

[0172] 5. Counterexample: material not obtained from foams

[0173] An SI solution is prepared by mixing 0.16 g of a CMC solution (8 wt%, Mw ~ 90,000 g / mol) with 3 g of deionized water.

[0174] Next, four solutions are prepared from this SI solution: - a first solution is obtained by mixing 1 g of SI, previously acidified to a pH of 4 by phosphoric acid at 1 mol / L, with 0.038 g of encapsulated bromocresol green; - a second solution is obtained by mixing 0.5 g of SI, previously acidified to a pH of 4 by phosphoric acid at 1 mol / L, with 0.019 g of PMMA / TMPTA particles obtained in point 1.3 above; - a third solution is obtained by mixing 0.5 g of SI with 0.019 g of PMMA / TMPTA particles obtained in point 1.3 above; then - a fourth solution is obtained by mixing 1 g of SI with 0.038 g of encapsulated Disperse Black 9.

[0175] The four solutions thus obtained are deposited one on top of the other, in the order described above, in a flexible transparent plastic tube previously closed at one of its ends.

[0176] It is observed that the solutions mix with each other and that a stacking of them is therefore impossible to obtain.

[0177] This counterexample therefore shows the importance of the foams from which the layers of the stacking of the material are obtained. References cited

[0178] [1] “A quantitative kinetic theory of emulsion type I. Physical Chemistry of the emulsifying agent”, Gas / Liquid and Liquid / Liquid Interfaces, Proceedings of 2nd International Congress Surface Activity 1957, 426-438 [2] WO-A-2004 / 008463 [3] WO-A-02 / 043847

Claims

Demands

1. Material comprising a layer Cl resulting from the freezing and then sublimation of a foam formed by a dispersion of gas bubbles in a foaming aqueous solution Al, the foaming aqueous solution Al comprising at least one detection indicator, at least one surfactant and, optionally, at least one gelling agent.

2. Material according to claim 1, further comprising a layer C2 which results from the freezing and then sublimation of a foam formed by a dispersion of gas bubbles in a foaming aqueous solution A2, the foaming aqueous solution A2 comprising at least one detection indicator, at least one surfactant and, optionally, at least one gelling agent, in which: - the layers Cl and C2 together form a stack; and - the foaming aqueous solution Al and the foaming aqueous solution A2 comprise at least one different detection indicator.

3. Material according to claim 1 or 2, wherein the detection indicator(s) are selected from colored indicators and fluorescent indicators.

4. Material according to claim 3 dependent on claim 1, wherein the coloured indicator(s) and / or the fluorescent indicator(s) are encapsulated in solid particles in a (co)polymer, each solid particle comprising only one coloured indicator or only one fluorescent indicator when the foaming aqueous solution Al comprises several coloured indicators and / or several fluorescent indicators.

5. Material according to claim 4, wherein the foaming aqueous solution Al comprises in total from 0.5% to 10% by mass and preferably from 2% to 5% by mass of solid particles encapsulating a detection indicator, relative to the total mass of foaming aqueous solution.

6. Material according to claim 3 dependent on claim 2, wherein the colored indicator(s) and / or the fluorescent indicator(s) are encapsulated in solid particles of a (co)polymer, each solid particle comprising only one colored indicator or only one fluorescent indicator when the A2 foaming aqueous solution comprises several colored indicators and / or several fluorescent indicators.

7. Material according to claim 6, wherein the foaming aqueous solution A2 comprises in total from 0.5% to 10% by mass and preferably from 2% to 5% by mass of solid particles encapsulating a detection indicator, relative to the total mass of foaming aqueous solution.

8. Material according to any one of claims 4 to 7, wherein the (co)polymer is obtained from the (co)polymerization of at least one monomer selected from acrylate monomers such as methyl methacrylate, trimethylolpropane triacrylate, dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate.

9. Material according to claim 8, wherein the (co)polymer is a poly(methyl methacrylate) crosslinked with trimethylolpropane triacrylate.

10. Material according to claim 1, wherein the aqueous foaming solution Al comprises from 0.05% to 1.5% by mass of surfactant(s) and from 0.00% to 0.8% by mass of gelling agent(s), relative to the total mass of aqueous foaming solution.

11. Material according to claim 2, wherein the foaming aqueous solution A2 comprises from 0.05% to 1.5% by mass of surfactant(s) and from 0.00% to 0.8% by mass of gelling agent(s), relative to the total mass of foaming aqueous solution.

12. Material according to claim 2, wherein the Cl and C2 layers are separated from each other by a buffer layer C3 which results from the freezing and then sublimation of a foam formed by a dispersion of gas bubbles in a foaming aqueous solution A3, the foaming aqueous solution A3 comprising at least one surfactant, optionally at least one gelling agent and / or solid particles in a (co)polymer, but being free of a detection indicator.

13. Material according to claim 12, wherein the composition of the aqueous foaming solution A3 differs from the composition of the aqueous foaming solution Al and / or from the composition of the aqueous foaming solution A2 only by the absence of a detection indicator.

14. Material according to claim 2, wherein the Cl and C2 layers are separated from each other by at least two C3' layers and C3”, layer C3' being in contact with layer Cl and layer C3” being in contact with layer C2, layer C3' resulting from the freezing and then sublimation of a foam formed by a dispersion of gas bubbles in a foaming aqueous solution A3' and layer C3'' resulting from the freezing and then sublimation of a foam formed by a dispersion of gas bubbles in a foaming aqueous solution A3”, each of the foaming aqueous solutions A3' and A3” comprising at least one surfactant, optionally at least one gelling agent and / or solid particles in a (co)polymer, but being free of detection indicator.

15. Material according to claim 14, wherein the composition of the aqueous foaming solution A3' differs from the composition of the aqueous foaming solution Al only by the absence of a detection indicator while the composition of the aqueous foaming solution A3” differs from the composition of the aqueous foaming solution A2 only by the absence of a detection indicator.

16. A method for preparing the material according to claim 1, comprising at least the following steps: a) preparation of the foam; b) deposition of the foam obtained at the end of step a) onto a substrate and then freezing of the foam; c) sublimation of the foam obtained at the end of step b); and d) optional removal of the substrate; thereby obtaining the material.

17. A method for preparing the material according to claim 2, comprising at least the following steps: a) preparation of the foams; b) formation of the stack of Cl and C2 layers by: i) successive depositions on a substrate of the foams obtained at the end of step a); ii) freezing of the foams, the freezing being carried out between the deposition of the foams and / or after the successive depositions of the foams; c) sublimation of the stack obtained at the end of step b); and d) possible removal of the substrate; thereby obtaining the material.

18. A method according to claim 16 or 17, wherein freezing is carried out at a temperature between -200 °C and -10 °C and preferably between -20 °C and -15 °C.

19. Use of the material according to any one of claims 1 to 15 to detect the presence of at least one chemical compound in a medium.

20. Use according to claim 19, wherein the chemical compound(s) are toxic warfare compounds and / or toxic industrial chemical compounds.

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