AROMATIC EUTECTIC MIXTURES AND THEIR USE AS LIQUID SCINTILLATORS

Abstract

This disclosure concerns aromatic and polyaromatic eutectic mixtures and their use as liquid scintillators. The mixtures may include compounds including di-tert-butyl-benzenes, biphenyls and terphenyls, polycyclic aromatic hydrocarbons selected from naphthalenes, acenaphthenes, anthracenes and pyrenes, fluorenes and carbazoles, 2,5-Diphenyloxazoles, and compounds of formula (I).

Claims

1. A composition comprising two or more compounds chosen from: Di-tert-butyl-benzenes; Biphenyls and terphenyls, optionally substituted by two groups independently selected from the linear or branched C.sub.1 to C.sub.6 alkyls; Polycyclic aromatic hydrocarbons selected from naphthalenes, acenaphthenes, anthracenes and pyrenes, which are optionally substituted by two groups independently selected from linear or branched C.sub.1 to C.sub.6 alkyls; Fluorenes and carbazoles, which are optionally substituted by two or four groups independently selected from linear or branched C.sub.1 to C.sub.6 alkyls; 2,5-Diphenyloxazoles, optionally substituted by two groups independently selected from linear or branched C.sub.1 to C.sub.6 alkyls; and Compounds of formula (I): ##STR00018## wherein: i is equal to 0 or 1; R.sub.a, R.sub.b, R.sub.c and R.sub.d are independently selected from H and phenyl, at least two of R.sub.a, R.sub.b, R.sub.c and R.sub.d being phenyl; and the compounds of formula (I) being optionally substituted by two groups chosen independently from linear or branched C.sub.1 to C.sub.6 alkyls; the composition not consisting of biphenyl and naphthalene.

2. The composition according to claim 1, which is eutectic.

3. The composition according to claim 1, wherein the at least two compounds are chosen from the following compounds: ##STR00019## wherein R.sub.1 and R.sub.2 are chosen independently of each other, R.sub.1 being selected from H and linear or branched C.sub.1 to C.sub.6 alkyls, and R.sub.2 being selected from H and linear or branched C.sub.1 to C.sub.6 alkyls.

4. The composition according to claim 1, which is binary, tertiary, quaternary or quinary.

5. The composition according to claim 1, which is: binary, and the two compounds of the composition are present therein in an amount of 20 to 80 mol %; tertiary, and the three compounds of the composition are present therein in an amount of 10 to 55 mol %; quaternary, and the four compounds of the composition are present therein in an amount of 5 to 45 mol %; or quinary, and the five compounds of the composition are present therein in an amount of 5 to 45 mol %.

6. The composition according to claim 1, further comprising at least one wavelength-shifter compound.

7. A method of use of a composition for liquid scintillation, the composition comprising at least two compounds selected from: Di-tert-butyl-benzenes; Biphenyls and terphenyls, optionally substituted by two groups independently selected from the linear or branched C.sub.1 to C.sub.6 alkyls; Polycyclic aromatic hydrocarbons selected from naphthalenes, acenaphthenes, anthracenes and pyrenes, which are optionally substituted by two groups independently selected from linear or branched C.sub.1 to C.sub.6 alkyls; Fluorenes and carbazoles, which are optionally substituted by at least two groups independently selected from linear or branched C.sub.1 to C.sub.6 alkyls; 2,5-Diphenyloxazoles, optionally substituted by two groups independently selected from linear or branched C.sub.1 to C.sub.6 alkyls; and Compounds of formula (I): ##STR00020## wherein: i is equal to 0 or 1; R.sub.a, R.sub.b, R.sub.c and R.sub.d are independently selected from H and phenyl, at least two of R.sub.a, R.sub.b, R.sub.c and R.sub.d being phenyl; and the compounds of formula (I) being optionally substituted by two groups independently selected from linear or branched C.sub.1 to C.sub.6 alkyls.

8. The method of use according to claim 7 of the composition as a liquid scintillator.

9. The method of use according to claim 7, wherein the composition further comprises at least one wavelength-shifter compound.

10. The method of use according to claim 7, wherein the composition is solvent-free of a solvent, the solvent being a compound different from any of the compounds defined in claim 7, or mixtures thereof.

11. The composition of claim 1, wherein the compounds of formula (I) are optionally substituted on the phenyl groups by two groups chosen independently from linear or branched C.sub.1 to C.sub.6 alkyls.

12. The composition of claim 5, wherein: when the composition is binary, the two compounds of the composition are present therein in an amount of 40 to 60 mol %; when the composition is tertiary, the three compounds of the composition are present therein in an amount of 25 to 40 mol %; when the composition is quaternary, the four compounds of the composition are present therein in an amount of 22 to 40 mol % for three of the four compounds, and in an amount of 6 to 34 mol % for the fourth of the four compounds.

13. The method of use of claim 7, wherein the compounds of formula (I) are optionally substituted on the phenyl groups by two groups independently selected from linear or branched C1 to C6 alkyls.

Description

DESCRIPTION OF THE DRAWINGS

[0060] The foregoing aspects and many of the attendant advantages of the claimed subject matter will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

[0061] FIG. 1 shows the pulse area spectra of the eutectics T.sub.A, Q.sub.A, Q.sub.B and Q.sub.C from Example 1 under irradiation with a .sup.137Cs source (Example 2).

[0062] FIG. 2 shows the pulse area spectra of the eutectics T.sub.A, Q.sub.A, Q.sub.B and Q.sub.C with POPOP from Example 1 under irradiation with a .sup.137Cs source (Example 2).

[0063] FIG. 3 is a comparison, according to example 3, of the area spectrum between a commercial reference liquid scintillator not used in the disclosure (BC501A) and two scintillating liquid eutectics T.sub.A and Q.sub.A from Example 1, in the presence of POPOP (T.sub.A+POPOP and Q.sub.A+POPOP from Example 2).

DETAILED DESCRIPTION

[0064] As understood here, the value ranges in the form of x-y or from x to y or between x and y include the x and y bounds as well as 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 refer to the integers 1, 2, 3, 4 and 5. The preferred embodiments include each individual integer in the value range, as well as any sub-combination of those integers. For example, the preferred values for 1-5 may comprise the integers 1, 2, 3, 4, 5, 1-2, 1-3, 1-4, 1-5, 2-3, 2-4, 2-5, etc.

[0065] As used herein, the term alkyl designates a linear or branched chain alkyl group having the number of carbon atoms indicated before the 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 C.sub.1 to C.sub.4 alkyl designates an alkyl radical containing from 1 to 4 carbon atoms.

[0066] By the composition does not consist of biphenyl and naphthalene is meant in particular that the composition is not a mixture consisting of unsubstituted biphenyl and unsubstituted naphthalene. In particular, the composition not consisting of biphenyl, optionally substituted with two groups independently selected from linear or branched C.sub.1 to C.sub.6 alkyl, and naphthalene, optionally substituted with two groups independently selected from linear or branched C.sub.1 to C.sub.6 alkyl.

[0067] The compositions of the disclosure are eutectics. By eutectic we mean in particular a mixture of two or more substances which has a lower melting temperature than that of each of the individual substances.

[0068] The di-tert-butyl-benzene is in particular 1,4-di-tert-butyl-benzene.

[0069] The biphenyls and terphenyls are in particular biphenyl and para-terphenyl.

[0070] The optionally substituted biphenyls are in particular of the following formula:

##STR00004## [0071] wherein R.sub.1 is selected from H and linear or branched C.sub.1 to C.sub.6 alkyl.

[0072] The optionally substituted terphenyls are in particular of the following formula:

##STR00005## [0073] wherein R.sub.1 is selected from H and linear or branched C.sub.1 to C.sub.6 alkyl.

[0074] The naphthalenes are optionally of one of the following formulae:

##STR00006## [0075] wherein R.sub.1 is selected from H and linear or branched C.sub.1 to C.sub.6 alkyl.

[0076] The acenaphthene in particular is unsubstituted.

[0077] The optionally substituted anthracenes are in particular of the following formula:

##STR00007## [0078] wherein R.sub.1 is selected from H and linear or branched C.sub.1 to C.sub.6 alkyl, and R.sub.2 is selected from H and linear or branched C.sub.1 to C.sub.6 alkyl.

[0079] The optional pyrenes are in particular of the following formula:

##STR00008## [0080] wherein R.sub.1 is selected from H and linear or branched C.sub.1 to C.sub.6 alkyl.

[0081] The 2,5-diphenyloxazoles optionally are in particular of the following formula:

##STR00009## [0082] wherein R.sub.1 is selected from H and linear or branched C.sub.1 to C.sub.6 alkyl.

[0083] The optionally substituted fluorenes are in particular of the following formula:

##STR00010## [0084] wherein R.sub.1 is selected from H and linear or branched C.sub.1 to C.sub.6 alkyl, and R.sub.2 is selected from H and linear or branched C.sub.1 to C.sub.6 alkyl.

[0085] The optionally substituted carbazoles are in particular of the following formula:

##STR00011## [0086] wherein R.sub.1 is selected from H and linear or branched C.sub.1 to C.sub.6 alkyl, and R.sub.2 is selected from H and linear or branched C.sub.1 to C.sub.6 alkyl.

[0087] The compounds of formula (I) are in particular chosen from 1,2-diphenylethenes, 1,1,2,2-tetraphenylethenes, 1,2-diphenylbutadienes, 1,1,4,4-tetraphenylbutadienes, optionally substituted, in particular on the phenyl groups, by two groups chosen independently from linear or branched C.sub.1 to C.sub.6 alkyls.

[0088] The 1,1,2,2-diphenylethenes are optionally of the following formula:

##STR00012## [0089] wherein R.sub.1 is selected from H and linear or branched C.sub.1 to C.sub.6 alkyl.

[0090] The 1,1,2,2-tetraphenylethenes are optionally of the following formula:

##STR00013## [0091] wherein R.sub.1 is selected from H and linear or branched C.sub.1 to C.sub.6 alkyl.

[0092] The 1,2-diphenylbutadienes optionally have the following formula:

##STR00014## [0093] wherein R.sub.1 is selected from H and linear or branched C.sub.1 to C.sub.6 alkyl.

[0094] The optional 1,1,4,4-tetraphenylbutadienes are in particular of the following formula:

##STR00015## [0095] wherein R.sub.1 is selected from H and linear or branched C.sub.1 to C.sub.6 alkyl.

[0096] The composition according to the disclosure can be a composition in which the at least two compounds are of the same formula as defined above, differing only in the meaning of the R.sub.1 and/or R.sub.2 group.

[0097] According to a particular embodiment, the composition according to the disclosure consists of at least two compounds as defined above.

[0098] The composition, in particular the eutectic, according to the disclosure can be binary (two-component), tertiary (three-component), quaternary (four-component), quinary (five-component) and so on.

[0099] According to one embodiment, the composition of the disclosure is tertiary, quaternary or quinary. This is likely to enable compositions with a lower melting temperature, for example much lower than ambient temperature, to be obtained if desired.

[0100] According to a particular embodiment, the composition consists of, consists essentially of, or comprises: [0101] a biphenyl, optionally substituted by two groups independently selected from linear or branched C.sub.1 to C.sub.6 alkyls, in particular biphenyl; and [0102] a 2,5-diphenyloxazole, optionally substituted with two groups independently selected from linear or branched C.sub.1 to C.sub.6 alkyls, in particular 2,5-diphenyloxazole.

[0103] According to a particular embodiment, the composition consists of, consists essentially of, or comprises: [0104] a biphenyl, optionally substituted by two groups independently selected from linear or branched C.sub.1 to C.sub.6 alkyl, in particular biphenyl; [0105] a 2,5-diphenyloxazole, optionally substituted by two groups independently selected from linear or branched C.sub.1 to C.sub.6 alkyls, in particular 2,5-diphenyloxazole; and [0106] a carbazole, optionally substituted with two groups independently selected from linear or branched C.sub.1 to C.sub.6 alkyls, in particular 9-ethylcarbazole.

[0107] According to a particular embodiment, the composition consists of, consists essentially of, or comprises: [0108] a biphenyl, optionally substituted by two groups independently selected from linear or branched C.sub.1 to C.sub.6 alkyl, in particular biphenyl; [0109] a 2,5-diphenyloxazole, optionally substituted by two groups independently selected from linear or branched C.sub.1 to C.sub.6 alkyls, in particular 2,5-diphenyloxazole; [0110] a carbazole, optionally substituted by two groups independently selected from linear or branched C.sub.1 to C.sub.6 alkyls, in particular 9-ethylcarbazole; and [0111] a diterbutylbenzene, in particular 1,4-Diterbutylbenzene, a second biphenyl, optionally substituted with two groups independently selected from C.sub.1 to C.sub.6 different from the first, in particular diterbutylbiphenyl, and/or a fluorene, in particular diterbutylfluorene.

[0112] The composition of the disclosure may additionally comprise at least one wavelength-shifter compound.

[0113] According to a particular embodiment, the at least one wavelength-shifter compound is chosen from the following compounds, and mixtures thereof: POPOP, 9-10 DPA, Bis-MSB, Coumarine-6.

[0114] These compounds have the following formula:

##STR00016##

[0115] According to a particular embodiment, the at least one wavelength-shifter compound is present in the composition in an amount of 0.01% to 0.3% by weight relative to the total weight of the composition, in particular 0.03% to 0.1% by weight.

[0116] According to another aspect, the disclosure also relates to a composition consisting of, consists essentially of, or comprising at least two compounds chosen from: [0117] Di-tert-butyl-benzenes; [0118] Biphenyls and terphenyls, optionally substituted by two groups independently selected from the linear or branched C.sub.1 to C.sub.6 alkyls; [0119] Polycyclic aromatic hydrocarbons selected from naphthalenes, acenaphthenes, anthracenes and pyrenes, which are optionally substituted by two groups independently selected from linear or branched C.sub.1 to C.sub.6 alkyls; [0120] Fluorenes and carbazoles, which are optionally substituted by two or four groups independently selected from linear or branched C.sub.1 to C.sub.6 alkyls; [0121] 2,5-Diphenyloxazoles, optionally substituted by two groups independently selected from linear or branched C.sub.1 to C.sub.6 alkyls; [0122] The compounds of formula (I):

##STR00017## [0123] wherein: [0124] i is equal to 0 or 1; [0125] R.sub.a, R.sub.b, R.sub.c and R.sub.d are independently selected from H and phenyl, at least two of R.sub.a, R.sub.b, R.sub.c and R.sub.d being phenyl; [0126] the compounds of formula (I) being optionally substituted, in particular on the phenyl groups, by two groups chosen independently from linear or branched C.sub.1 to C.sub.6 alkyls; [0127] and in addition at least one wavelength-shifter compound.

[0128] The composition of the disclosure may also additionally comprise at least one secondary fluorophore (or wavelength-shifter).

[0129] These secondary fluorophores are well known to those skilled in the art.

[0130] According to a particular embodiment, the at least one secondary fluorophore is chosen from POPOP, BisMSB, 9-10 DPA and Coumarin 6.

[0131] According to a particular embodiment, the at least one secondary fluorophore is present in the composition at a level of 0.01 to 0.3% by mass.

[0132] According to another aspect, the disclosure also relates to the use of a composition as described above for liquid scintillation, in particular as a liquid scintillator.

[0133] All the embodiments previously defined in relation to the composition of the disclosure also apply here, alone or in combination.

[0134] According to a particular embodiment, the composition does not consist of biphenyl and naphthalene. In fact, their binary eutectic may not have a low enough melting point depending on the intended use.

EXAMPLES

Example 1: Preparation of Compositions According to the Disclosure

[0135] The binary mixtures B.sub.A, ternary mixtures T.sub.A, and quaternary mixtures Q.sub.AQ.sub.B and Q.sub.C were prepared and characterized as follows.

[0136] The melting temperature of the mixtures was determined by Differential Scanning Calorimetry (DSC).

TABLE-US-00001 Molecule Molar proportion T.sub.melt ( C.) Biphenyl 44% 69 Diphenyleoxazole (PPO) 56% 70 Eutectic T.sub.eutectic ( C.) B.sub.A 39 Molecule Molar proportion T.sub.melt Biphenyl 35.0% 69 9-ethylcarbazole 37.5% 70 Diphenyleoxazole (PPO) 27.5% 70 Eutectic T.sub.eutectic ( C.) T.sub.A 19 Molecule Molar proportion T.sub.melt Biphenyl 31.6% 69 9-ethylcarbazole 33.7% 70 Diphenyleoxazole (PPO) 24.8% 70 Diterbutylbenzene (DTBB) 9.9% 77 Eutectic T.sub.eutectic ( C.) Q.sub.A 16 Molecule Molar proportion T.sub.melt Biphenyl 32.5% 69 9-ethylcarbazole 34.7% 70 Diphenyleoxazole (PPO) 25.6% 70 Diterbutybiphenyl (DTBP) 7.3% 127 Eutectic T.sub.eutectic ( C.) Q.sub.B 16 Molecule Molar proportion T.sub.melt Biphenyl 32.6% 69 9-ethylcarbazole 34.8% 70 Diphenyleoxazole (PPO) 25.6% 70 Diterbutylfluorene (DTBF) 7.0% 123 Eutectic T.sub.eutectic ( C.) Q.sub.C 15

Example 2: Use of Compositions According to the Disclosure as Liquid Scintillators

[0137] The mixtures in Example 1 were used as liquid scintillators. The mixtures T.sub.A, QA, Q.sub.B, and Q.sub.C were in particular exposed as follows: [0138] The area spectra shown in this example (FIG. 1) were produced 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 face is then brought into contact with a photomultiplier connected to standard scintillation measurement electronics.

[0139] FIG. 1 shows that the mixtures studied are all used successfully as liquid scintillators.

[0140] Mixtures of T.sub.A+POPOP, QA+POPOP, Q.sub.B+POPOP, et Q.sub.C+POPOP have also been successfully studied (FIG. 2).

Example 3: Comparison of the Compositions According to the Disclosure as Liquid Scintillators with a Commercial Reference not Used in the Disclosure

[0141] The mixtures T.sub.A+POPOP et Q.sub.A+POPOP of example 2 were compared as liquid scintillators with a commercial reference not included in the disclosure (BC501A). The mixtures T.sub.A, Q.sub.A, Q.sub.B, and Q.sub.C were in particular exposed as follows: [0142] The area spectra were carried out as before.

[0143] FIG. 3 shows that the compositions of the disclosure are at least equivalent, if not more effective, than the commercial scintillator.

[0144] In the detailed description herein, references to one embodiment, an embodiment, an example embodiment, one or more embodiments, some embodiments, etc., indicate that the embodiment or embodiments described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment or embodiments. In addition, when a particular feature, structure, or characteristic is described in connection with an embodiment or embodiments, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments. Thus, it will be appreciated that embodiments of the present disclosure may employ any combination of features described herein. All such combinations or sub-combinations of features are within the scope of the present disclosure.

[0145] Throughout this specification, terms of art may be used. These terms are to take on their ordinary meaning in the art from which they come, unless specifically defined herein or the context of their use would clearly suggest otherwise.

[0146] The principles, representative embodiments, and modes of operation of the present disclosure have been described in the foregoing description. However, aspects of the present disclosure which are intended to be protected are not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. It will be appreciated that variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present disclosure. Accordingly, it is expressly intended that all such variations, changes, and equivalents fall within the spirit and scope of the present disclosure, as claimed.