AROMATIC EUTECTIC MIXTURES AND THEIR USE AS LIQUID SPARKLER

Abstract

The present invention relates to aromatic and polyaromatic eutectic mixtures and their use as liquid scintillators. (no figure)

Description

Title of the invention: AROMATIC EUTECTIC MIXTURES AND THEIR USE AS LIQUID SPARKLER

[0001] The present invention relates to aromatic and polyaromatic eutectic mixtures and their use as liquid scintillators.

[0002] Based on the transformation of ionizing radiation into light radiation, liquid scintillation is one of the oldest techniques for detecting and measuring radiation.

[0003] This method is currently one of the most frequently used techniques for measuring the activity of pure beta-emitting radionuclides (for which radioactive decay is not accompanied by gamma radiation detectable by other techniques). It is also used for measuring radionuclides that decay by electron capture or alpha emission. In particular, liquid scintillation is of major interest for measuring low-energy beta radiation.

[0004] The measurement of activity by liquid scintillation is based on the transformation of the ionizing radiation emitted during the disintegration of a radioactive atom into detectable and quantifiable light radiation.

[0005] Liquid scintillation typically involves mixing an aliquot of the solution to be measured with a scintillation liquid, generally a liquid solution containing organic scintillators, to detect radiation emitted by a radioactive source. When the ionizing particles interact with the liquid, they excite the scintillator molecules, which, upon de-excitation, emit light (photons). This light is then detected by a photomultiplier tube or a photodetector, allowing the energy and intensity of the radiation to be quantified.

[0006] This scintillating liquid serves to transform the energy of the ionizing radiation emitted by the decay of a radionuclide into quantifiable light pulses. This liquid relies on a major component: an organic solvent.

[0007] The composition of the scintillating liquid must allow on the one hand (1) perfect miscibility between the matrix in which the radionuclide whose activity is to be measured is located and the solvent and, on the other hand, (2) efficient transfer of energy from the ionizing particle to the fluorescent molecules, to allow the emission of light photons detectable by the photomultipliers.

[0008] The solvent, the main component of the scintillating liquid, is generally composed of aromatic molecules. Its function is to absorb the energy of the radiation. ionizing and propagating it to fluorescent molecules. The solvent must be relatively chemically inert.

[0009] Historically, the molecules used were benzene and toluene, then xylene and pseudocumene, which were less toxic.

[0010] However, these solvents are highly flammable and tend to evaporate easily, which complicates their handling and storage and makes them hazardous. Indeed, all these organic solvents have relatively low flash points, typically <100°C. This represents a major risk for applications that use large volumes of these solvents, such as liquid scintillation.

[0011] The glitter liquids marketed since the 1980s use new generation solvents: diisopropylnaphthalene (DIN), phenylxylylethane (PXE) or dodecylbenzene. Less toxic and having a higher flash point, these solvents nevertheless exhibit lower chemical stability.

[0012] Compositions based on alkaline molecules or phosphonium salts have also been developed for liquid scintillation. However, these two families of molecules are known to be less effective for scintillation than commercial compositions.

[0013] Thus, although liquid organic scintillators are valuable tools for radiation detection, the solvents used present significant challenges in terms of safety, stability and performance.

[0014] The invention thus aims to provide compositions that overcome the aforementioned drawbacks.

[0015] An objective of the invention is to provide compositions with low flammability, in particular having flash points > 100 °C, reducing the aforementioned risks, while being able to be used in liquid scintillation.

[0016] Another objective of the invention is to provide such compositions, which are at least equivalent to, or even more effective than, commercial scintillators. SUBJECT OF THE INVENTION

[0017] Thus, according to a first aspect, the invention relates to a composition consisting of or comprising at least two compounds selected from: - Di-tert-butyl-benzenes; - Biphenyls and terphenyls, optionally substituted by two groups chosen independently from linear or branched alkyls at C1 to C6; - Polycyclic aromatic hydrocarbons selected from naphthalenes, acenaphthenes, anthracenes, pyrenes, which are optionally substituted by two groups selected independently from linear or branched alkyls in C1 to C6; Fluorenes and carbazoles, which are optionally substituted by two or four groups chosen independently from linear or branched alkyls in C1 to C6; 2,5-Diphenyloxazoles, optionally substituted by two groups chosen independently from linear or branched alkyls at C1 to C6; Compounds with formula (I):

[0018] in which:

[0019] i is equal to 0 or 1;

[0020] Ra, Rb, Rc and Rd are independently chosen from H and phenyl, at least two of the groups Ra, Rb, Rc and Rd being a phenyl;

[0021] said compounds of formula (I) being optionally substituted, in particular on the phenyl groups, by two groups chosen independently from linear or branched alkyls at C1 to C6;

[0022] said composition not being made up of the biphenyl and naphthalene couple.

[0023] Surprisingly, it has been highlighted by the Inventors that these compounds have a melting point >60°C individually, but which, once within a composition according to the invention, have a lower melting point, or even liquid at room temperature, within a purely aromatic, or even poly-aromatic, eutectic.

[0024] And all these aromatic, or even poly-aromatic, molecules can be used successfully in scintillation.

[0025] According to one embodiment, the composition according to the invention is eutectic.

[0026] According to one embodiment, the at least two compounds are in particular chosen among the following compounds:

[0027] in which Ri and R2 are chosen independently from one compound to another,

[0028] Ri being chosen from H and linear or branched alkyls at C1 to C6, and R2 being chosen from H and linear or branched alkyls from Ci to C6.

[0029] According to one embodiment, the composition of the invention is binary, tertiary, quaternary, quinquenar and so on depending on the number of components.

[0030] According to one embodiment, the composition of the invention is binary, tertiary, quaternary, quinquenaire.

[0031] According to one embodiment, the composition of the invention is: - binary, and the two compounds of said composition are present in it at a level of 20 to 80 mol%, in particular at a level of 40 to 60 mol%; - tertiary, and the three compounds of said composition are present in it at a rate of 10 to 55 mol%, in particular at a rate of 25 to 40 mol%; - quaternary, and the four compounds of said composition are present therein at a level of 5 to 45 mol%, in particular at a level of 22 to 40 mol% for three of them, and at a level of 6 to 34 mol% for the last; or - quinquénaire, and the five compounds of said composition are present in it at a level of 5 to 45% molar.

[0032] According to one embodiment, the composition of the invention consists of or comprises at least two compounds, and in addition at least one wavelength-shifting compound.

[0033] According to another aspect, the invention also relates to the use of a composition for liquid scintillation, said composition being made up of or comprising at least two compounds selected from: - Di-tert-butyl-benzenes; - Biphenyls and terphenyls, optionally substituted by two groups chosen independently from linear or branched alkyls at C1 to C6; - Polycyclic aromatic hydrocarbons selected from naphthalenes, acenaphthenes, anthracenes, pyrenes, which are optionally substituted by two groups selected independently from linear or branched alkyls in C1 to C6; - Fluorenes and carbazoles, which are optionally substituted by at least two groups chosen independently from linear or branched alkyls at C1 to C6; - 2,5-Diphenyloxazoles, optionally substituted by two groups chosen independently from linear or branched alkyls at C1 to C6; - Compounds with formula (I): Ra

[0034] in which:

[0035] i is equal to 0 or 1;

[0036] Ra, Rb, Rc and Rd are independently chosen from H and phenyl, at least two of the groups Ra, Rb, Rc and Rd being a phenyl;

[0037] said compounds of formula (I) being optionally substituted, in particular on the phenyl groups, by two groups chosen independently from linear or branched alkyls at C1 to C6.

[0038] The compositions of the invention are aromatic, or even poly-aromatic, and can be used successfully in scintillation.

[0039] According to one embodiment, the use of the invention is a use of said composition as a liquid scintillator.

[0040] According to one embodiment, said composition consists of or comprises at least two compounds, and in addition at least one wavelength shifter compound.

[0041] According to one embodiment, said composition is solvent-free, the solvent being different from all the compounds defined above and their mixtures. DETAILED DESCRIPTION OF THE INVENTION Definitions

[0042] As understood here, value ranges in the form of "xy" or "from x to y" or "between x and y" include the bounds x and y, the integers between these bounds, and the positive real numbers between these bounds and / or integers. For example, "1-5", or "from 1 to 5", or "between 1 and 5" denotes the integers 1, 2, 3, 4, and 5. Preferred embodiments include each integer taken individually within the value range, as well as any subcombination of these integers. For example, preferred values ​​for "1-5" may include the integers 1, 2, 3, 4, 5, 1-2, 1-3, 1-4, 1-5, 2-3, 2-4, 2-5, etc.

[0043] As used herein, the term "alkyl" refers to a linear or branched alkyl group having the number of carbon atoms indicated before said term, in particular 1 to 4 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, etc. Thus, an expression such as "C1 to C4 alkyl" refers to an alkyl radical containing 1 to 4 carbon atoms.

[0044] By "said composition is not composed of biphenyl and naphthalene", it is understood in particular that said composition is not a mixture consisting of unsubstituted biphenyl and unsubstituted naphthalene. In particular, said composition is not composed of biphenyl, optionally substituted by two groups independently selected from linear or branched alkyl groups at C1 to C6, and naphthalene, optionally substituted by two groups independently selected from linear or branched alkyl groups at C1 to C6.

[0045] The compositions of the invention are eutectics.

[0046] By "eutectic" is meant in particular a mixture of two or more substances which has a melting point lower than that of each of the individual substances.

[0047] Di-tert-butyl-benzene is in particular 1,4-di-tert-butyl-benzene.

[0048] Biphenyls and terphenyls include, in particular, biphenyl or para-terphenyl.

[0049] Optionally substituted biphenyls are in particular of the following formula: has,

[0050] wherein Ri is selected from H and linear or branched alkyls at Ci to C6.

[0051] Optionally substituted terphenyls are in particular of the following formula: R,

[0052] wherein Ri is selected from H and linear or branched alkyls at Ci to C6.

[0053] The naphthalenes optionally include, in particular, one of the following formulas:

[0054] wherein Ri is selected from H and linear or branched alkyls at Ci to C6.

[0055] Acenaphthene is notably unsubstituted.

[0056] The optionally substituted anthracenes are in particular of the following formula: RJ

[0057] wherein Ri is selected from H and linear or branched alkyls at C6 to C6, and R2 is selected from H and linear or branched alkyls at C6 to C6.

[0058] The pyrenes optionally have the following formula: R< J y has,

[0059] wherein Ri is selected from H and linear or branched alkyls at Ci to C6.

[0060] The optional 2,5-diphenyloxazoles are in particular of the following formula: R, , / '”* '\ y=:N '''C kl

[0061] wherein Ri is selected from H and linear or branched alkyls at Ci to C6.

[0062] The optionally substituted fluorenes are in particular of the following formula:

[0063] wherein Ri is selected from H and linear or branched alkyls from C1 to C6, and R2 is chosen from H and linear or branched alkyls from Ci to C6.

[0064] Optionally substituted carbazoles are in particular of the following formula: R;. % / / 'kj-.-Rt / ■...... /

[0065] in which Ri is selected from H and linear or branched alkyls at C6 to Ci, and R2 is selected from H and linear or branched alkyls at C6 to Ci.

[0066] The compounds of formula (I) are in particular selected from 1,2-diphenylethens, 1,1,2,2-tetraphenylethens, 1,2-diphenylbutadiens, 1,1,4,4-tetraphenylbutadiens, optionally substituted, in particular on the phenyl groups, by two groups selected independently from linear or branched alkyls at C1 to C6.

[0067] The optional 1,2-diphenylethens are in particular of the following formula: R: '

[0068] wherein Ri is selected from H and linear or branched alkyls at Ci to C6.

[0069] The optional 1,1,2,2-tetraphenylethens are in particular of the following formula: Ri

[0070] in which Ri is selected from H and linear or branched alkyls at Ci to C6.

[0071] The 1,2-diphenylbutadienes optionally have, in particular, the following formula:

[0072] wherein Ri is selected from H and linear or branched alkyls from C1 to C6.

[0073] The 1,1,4,4-tetraphenylbutadienes optionally have, in particular, the following formula: Ri R, R,

[0074] wherein Ri is selected from H and linear or branched alkyls at Ci to C6.

[0075] The composition according to the invention may be a composition in which the aux at least two compounds have the same formula as defined above, differing only in the meaning of the Ri and / or R2 group.

[0076] According to a particular embodiment, the composition according to the invention consists of at least two compounds as defined above.

[0077] The composition, in particular the eutectic, according to the invention, can be binary (two-component), tertiary (three-component), quaternary (four-component), quinquenarian (five-component), and so on.

[0078] According to one embodiment, the composition of the invention is tertiary, quaternary, or quinquenaire. This is likely to allow the obtaining, if desired, of compositions with a lower melting temperature, for example much lower than ambient temperature.

[0079] According to a particular embodiment, the composition consists of or comprises: - a biphenyl, optionally substituted by two groups chosen independently from linear or branched alkyls from C1 to C6, in particular biphenyl; and - a 2,5-diphenyloxazole, optionally substituted by two groups chosen independently from linear or branched alkyls at C1 to C6, in particular 2,5-diphenyloxazole.

[0080] According to a particular embodiment, the composition consists of or comprises: - a biphenyl, optionally substituted by two groups chosen independently from linear or branched alkyls from C1 to C6, in particular biphenyl; - a 2,5-diphenyloxazole, optionally substituted by two groups chosen independently from linear or branched alkyl groups at C1 to C6, in particular 2,5-diphenyloxazole; and - a carbazole, optionally substituted by two groups chosen independently from linear or branched alkyls from C1 to C6, in particular 9-ethylcarbazole.

[0081] According to a particular embodiment, the composition consists of or comprises: - a biphenyl, optionally substituted by two groups chosen independently from linear or branched alkyls from C1 to C6, in particular biphenyl; - a 2,5-diphenyloxazole, optionally substituted by two groups chosen independently from linear or branched alkyls at C1 to C6, in particular 2,5-diphenyloxazole; - a carbazole, optionally substituted by two groups chosen independently from linear or branched alkyl groups from C1 to C6, in particular 9-ethylcarbazole; and - a diterbutylbenzene, in particular 1,4-Diterbutylbenzene, a second biphenyl, optionally substituted by two groups independently chosen from linear or branched alkyls at C1 to C6, different from the first, in particular diterbutylbiphenyl, and / or a fluorene, in particular diterbutylfluorene.

[0082] The composition of the invention may further comprise at least one wavelength-shifting compound.

[0083]

[0084] According to a particular embodiment, at least one wavelength-shifting compound is chosen from the following compounds, and their mixtures: POPOP, 9-10 DPA, Bis-MSB, Coumarin-6. These compounds have the following formula:

[0085]

[0086]

[0087] According to a particular embodiment, at least one wavelength-shifting compound is present in the composition at a level of 0.01% to 0.3% by mass relative to the total mass of the composition, in particular from 0.03% to 0.1% by mass. According to another aspect, the invention also relates to a composition consisting of or comprising at least two compounds selected from: - Di-tert-butyl-benzenes; - Biphenyls and terphenyls, optionally substituted by two groups chosen independently from linear or branched alkyls at C1 to C6; - Polycyclic aromatic hydrocarbons selected from naphthalenes, acenaphthenes, anthracenes, pyrenes, which are optionally substituted by two groups selected independently from linear or branched alkyls in C1 to C6; - Fluorenes and carbazoles, which are optionally substituted by two or four groups chosen independently from linear or branched alkyls in C1 to C6; - 2,5-Diphenyloxazoles, optionally substituted by two groups chosen independently from linear or branched alkyls at C1 to C6; - Compounds with formula (I): [Chem.l] M- . .¾ „ / \ l -■

[0088] in which:

[0089] i is equal to 0 or 1;

[0090] Ra, Rb, Rc and Rd are independently chosen from H and phenyl, at least two of the groups Ra, Rb, Rc and Rd being a phenyl;

[0091] said compounds of formula (I) being optionally substituted, in particular on the phenyl groups, by two groups chosen independently from linear or branched alkyls at C1 to C6;

[0092] and in addition at least one wavelength-shifting compound.

[0093] The composition of the invention may therefore also include in addition at least one secondary fluorophore (or wavelength shifter).

[0094] These secondary fluorophores are well known to those skilled in the art.

[0095] According to a particular embodiment, at least one secondary fluorophore is selected from POPOP, BisMSB, 9-10 DPA, Coumarin 6.

[0096] According to a particular embodiment, at least one secondary fluorophore is present in the composition at a level of 0.01 to 0.3% by mass.

[0097] According to another aspect, the invention also relates to the use of a composition as described above for liquid scintillation, in particular as a liquid scintillator.

[0098] All embodiments defined previously with regard to the composition of the invention also apply here, alone or in combination.

[0099] According to a particular embodiment, said composition not being composed of biphenyl and naphthalene. Indeed, their binary eutectic may not have a sufficiently low melting point depending on the intended use. FIGURES

[0100] Fig. 1 shows the pulse area spectra of the eutectics TA, QA, Qb and Qc of Example 1 under irradiation with a 137Cs source (Example 2).

[0101] Fig. 2 shows the pulse area spectra of the TA, QA, QB and Qc eutectics with POPOP of Example 1 under irradiation with a 137Cs source (Example 2).

[0102] Fig. 3 is a comparison according to Example 3 of the area spectrum between a commercial reference liquid scintillator outside the invention (BC501A) and two scintillating liquid eutectics TA and QA from Example 1, in the presence of POPOP (TA + POPOP and Qa + POPOP from Example 2). EXAMPLES

[0103] Example 1: Preparation of compositions according to the invention

[0104] The binary mixtures BA, ternary mixtures TA, and quaternary mixtures QA QB and Qc were prepared and characterized as follows.

[0105] The melting temperature of the mixtures was determined by calorimetry Sweeping Differential (DSC). Molecule Molar proportion Melting point (°C) Biphenyl 44% 69 Diphenyloxazole (PPO) 56% 70 Eutectic (°C) Ba 39 Molecule Molar proportion Melting point Biphenyl 35.0% 69 9-Ethylcarbazole 37.5% 70 Diphenyloxazole (PPO) 27.5% 70 Eutectic (°C) Ta 19 Molecule Molar proportion Melting point Biphenyl 31.6% 69 9-Ethylcarbazole 33.7% 70 Diphenyloxazole (PPO) 24.8% 70 Diterbutylbenzene (DTBB) 9.9% 77 Eutectic (°C) Qa 16 Molecule Molar proportion Melting point Biphenyl 32.5% 69 9-Ethylcarbazole 34.7% 70 Diphenyloxazole (PPO) 25.6% 70 Diterbutybiphenyl (DTBP) 7.3% 127 Eutectic Teutectic (°C) Qb 16 Molecule Molar proportion Melting point Biphenyl 32.6% 69 9-ethylcarbazole 34.8% 70 Diphenyloxazole (PPO) 25.6% 70 Diterbutylfluorene (DTBF) 7.0% 123 Eutectic T 1°^ -1- Eutectic \ '-v Qc 15

[0106] Example 2: Use of the compositions according to the invention as liquid scintillators

[0107] The mixtures of Example 1 have been implemented as liquid scintillators. In particular, mixtures TA, QA, QB, and Qc have been demonstrated as follows:

[0108] The area spectra shown in this example ([Fig. 1]) were obtained by placing 10 g of the targeted eutectic mixture in a glass vial. The vial is then coated with a reflective material (PTFE strip) on all but one side. The free side is then brought into contact with a photomultiplier tube connected to standard scintillation measurement electronics.

[0109] Fig. 1 shows that the mixtures studied are all used successfully as liquid scintillators.

[0110] Mixtures TA+POPOP, QA+POPOP, QB+POPOP, and QC+POPOP have also been successfully studied ([Fig.2]).

[0111] Example 3: Comparison of the compositions according to the invention as liquid scintillators with a commercial reference outside the invention

[0112] The TA+POPOP and QA+POPOP mixtures of Example 2 were compared as liquid scintillators with a commercial reference outside the invention (BC501A). The TA, QA, QB, and Qc mixtures were specifically described as follows:

[0113] Area spectra were obtained as before.

[0114] Fig. 3 shows that the compositions of the invention are at least equivalent to, or even more effective than, the commercial scintillator.

Claims

Demands

1. Composition consisting of or comprising at least two compounds selected from: - Di-tert-butylbenzenes; - Biphenyls and terphenyls, optionally substituted by two groups independently selected from linear or branched C1 to C6 alkyls; - Polycyclic aromatic hydrocarbons selected from naphthalenes, acenaphthenes, anthracenes, pyrenes, which are optionally substituted by two groups independently selected from linear or branched C1 to C6 alkyls; - Fluorenes and carbazoles, which are optionally substituted by two or four groups independently selected from linear or branched C1 to C6 alkyls; - 2,5-Diphenyloxazoles, optionally substituted by two groups independently selected from linear or branched C1 to C6 alkyls; - Compounds of formula (I): Ra, Bd, Rb, Rc in which: i is equal to 0 or 1;Ra, Rb, Rc and Rd are independently selected from H and phenyl, at least two of the Ra, Rb, Rc and Rd groups being phenyl; said compounds of formula (I) being optionally substituted, in particular on the phenyl groups, by two groups independently selected from linear or branched alkyls from C1 to C6; said composition not being composed of biphenyl and naphthalene.

2.

3. A composition according to claim 1, which is eutectic. A composition according to claim 1 or 2, wherein the at least two compounds are in particular selected from the following compounds:

4.

5. in which Ri and R2 are chosen independently from one compound to another, Ri being chosen from H and linear or branched alkyls at Ci to C6, and R2 being chosen from H and linear or branched alkyls at Ci to C6. Composition according to any one of the preceding claims, which is binary, tertiary, quaternary, or quinquenar. Composition according to any one of the preceding claims, which is: - binary, and the two compounds of said composition are present in it at a level of 20 to 80 mol%, in particular at a level of 40 to 60 mol%; - tertiary, and the three compounds of said composition are present in it at a rate of 10 to 55 mol%, in particular at a rate of 25 to 40 mol%;

6.

7. - quaternary, and the four compounds of said composition are present therein at a level of 5 to 45 mol%, in particular at a level of 22 to 40 mol% for three of them, and at a level of 6 to 34 mol% for the last; or - quinquénaire, and the five compounds of said composition are present in it at a level of 5 to 45% molar. Composition according to any one of the preceding claims, consisting of or comprising at least two compounds, and in addition at least one wavelength-shifting compound. Use of a composition for liquid scintillation, said composition consisting of or comprising at least two compounds selected from: - Di-tert-butyl-benzenes; - Biphenyls and terphenyls, optionally substituted by two groups chosen independently from linear or branched alkyls at C1 to C6; - Polycyclic aromatic hydrocarbons selected from naphthalenes, acenaphthenes, anthracenes, pyrenes, which are optionally substituted by two groups selected independently from linear or branched alkyls in QC; - Fluorenes and carbazoles, which are optionally substituted by at least two groups chosen independently from linear or branched C1 to C6 alkyls; - 2,5-Diphenyloxazoles, optionally substituted by two groups chosen independently from linear or branched alkyls at C1 to C6; - Compounds with formula (I): in which: i is equal to 0 or 1;

8.

9.

10. Ra, Rb, Rc and Rd are independently chosen from H and phenyl, with at least two of the groups Ra, Rb, Rc and Rd being phenyl; said compounds of formula (I) being optionally substituted, in particular on the phenyl groups, by two groups independently chosen from linear or branched alkyls at C1 to C6. Use according to claim 7 of said composition as a liquid scintillator. Use according to claim 7 or 8, wherein said composition consists of or comprises at least two compounds, and in addition at least one wavelength-shifting compound. Use according to any one of claims 7 to 9, wherein said composition is solvent-free, the solvent being different from all the compounds defined in claim 1 and their mixtures.

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