Method for producing polymer materials comprising gold

Abstract

The invention relates to a method for the specific production of a polymer material doped by a first metal element, which is gold, and at least one second metal element, the first metal element and the at least one second metal element being identical or different from each other.

Claims

1. A method for preparing a polymeric material doped with a first metal element, which is gold, and at least one second metal element, said first metal element and said at least one second metal element being identical or different from each other, said method comprising: a) a step for copolymerization of at least one first monomer comprising at least one chelating group of said first metal element and of at least one second monomer comprising at least one chelating group, of at least a second metal element, in return for which a polymeric material is obtained comprising recurrent units stemming from the polymerization of said first monomer, which recurrent units comprise at least one chelating group of said first metal element and comprising recurrent units stemming from the polymerization of said second monomer, which recurrent units comprise at least one chelating group of said at least one second metal element, said second monomer selected from the group consisting of: aromatic monomers comprising at least one aromatic ring, which ring comprises at least one ethylenic group, at least one hydroxide group OH, at least one oxime group and the optional salts thereof; and monomers comprising an alicyclic amine group; and said first monomer being a cyclic monomer comprising at least one nitrogen-containing group, wherein the first monomer is a heteroaromatic monomer comprising one or several nitrogen atoms; b) when the first metal element, and said at least one second metal element are identical, a step for putting the material obtained in a) in contact with an aqueous solution comprising gold, in return for which the gold is complexed to the aforementioned chelating groups; and b) when the first metal element and said at least one second metal element are different, a first step for putting the material obtained in a) in contact with an alcoholic solution comprising gold followed by a second step for putting the material in contact with an aqueous solution comprising said at least one second metal element.

2. The method according to claim 1, wherein the first monomer is a vinylimidazole monomer.

3. The method according to claim 1, wherein the first monomer is a monomer of the following formula (I): ##STR00012##

4. The method according to claim 1, wherein the second monomer fits the following formula (II): ##STR00013## wherein: R.sub.1 is an ethylenic group; R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6 represent independently of each other, a hydrogen atom, an OH group, an amine group, a CHO group, an oxime group, a hydrazone group, a carboxylic group COOH, a halogen atom, a trialkylsilane group, and the optional salts thereof, provided that at least one of the groups R.sub.2 to R.sub.6 represents an OH group and at least one of the groups R.sub.2 to R.sub.6 represents an oxime group.

5. The method according to claim 1, wherein the second monomer fits the following formula (III): ##STR00014##

6. The method according to claim 1, wherein the second monomer is a monomer comprising a cyclame group fitting the following formula (IV): ##STR00015## wherein: R.sub.7, R.sub.8 and R.sub.9 represent a styrenic group; and p, q, r, x are integers ranging from 0 to 20, provided that, when x is equal to 0, (r+q) is at least equal to 2, and when x is equal to 1, at least one of p, q, r is different from 0.

7. The method according to claim 6, wherein the second monomer fits the following formula (V): ##STR00016##

8. The method according to claim 1, wherein the copolymerization step is achieved in the presence of one or several comonomers.

9. The method according to claim 8, wherein the comonomer(s) is (are) selected from styrenic monomers and acrylate monomers.

10. The method according to claim 8, wherein the comonomer(s) comprise(s) at least two ethylenic groups.

11. The method according to claim 9, wherein the comonomer(s) fit(s) one of the following formulae (VI) or (VII): ##STR00017## wherein the (6-n) R.sub.10, either identical or different, represent a hydrogen atom, an alkyl group, an aryl group, an O-aryl group, an O-alkyl group, an acyl group, an alkylaryl group or a halogen atom, said alkyl, aryl, alkylaryl, O-aryl, O-alkyl groups being optionally perfluorinated and n is an integer ranging from 1 to 3; ##STR00018## wherein R.sub.11 represents an alkyl group, R.sub.12 represents H or an alkyl group and n is an integer ranging from 1 to 3.

12. The method according to claim 1, wherein the copolymerization step is carried out in the presence of at least one polymerization initiator.

13. The method according to claim 1, wherein the copolymerization step is carried out in the presence of at least one pore-forming solvent, which is a polar or apolar organic solvent selected from the group consisting of ether solvents, dimethylsulfoxide, phthalate solvents, alcoholic solvents, aromatic solvents, ketone solvents and mixtures thereof.

14. The method according to claim 1, wherein step a) is applied: in the presence of a first monomer, which is the monomer of formula (I): ##STR00019## with a second monomer, which is a monomer of formula (III): ##STR00020## and of divinylbenzene; or in the presence of a first monomer, which is a monomer of formula (I): ##STR00021## with a second monomer which is a monomer of formula (V): ##STR00022## and of divinylbenzene.

15. The method according to claim 1, wherein, in step b), the aqueous solution comprising gold is an aqueous solution, in which is solubilized a gold salt or complex.

16. The method according to claim 1, wherein, in step b), the alcoholic solution comprising gold is an alcoholic solution, in which is solubilized a gold salt or complex.

17. The method according to claim 16, wherein the alcoholic solution is an ethanol solution comprising a gold salt HAuCl.sub.4.

18. The method according to claim 16, wherein, in step b), between the first contacting step and the second contacting step, a solvent exchange step is provided, consisting of exchanging the alcoholic solvent used for the first contacting step with water.

19. The method according to claim 1, wherein, in step b), the aqueous solution comprising said at least one second metal element is an aqueous solution, in which is solubilized a salt or complex of said at least one second metal element.

20. The method according to claim 19, wherein the salt of at least one second metal element is a copper salt.

21. The method according to claim 1, further comprising a step for drying the material stemming from step b) or from step b).

22. The method according to claim 21, wherein the drying step is a supercritical drying step.

23. The method according to claim 1, wherein the material obtained at the end of the method is a foam.

24. A polymeric material doped with a first metal element, which is gold, and at least one second metal element, said first metal element and said at least one second metal element being identical or different from each other, obtained by a method as defined according to claim 1.

25. The polymeric material according to claim 24, wherein the second metal element is gold.

26. The polymeric material according to claim 25, which has a gold mass content greater than 30% and a specific gravity of less than 100 g/m.sup.3.

27. The polymeric material according to claim 24, wherein the second metal element is different from gold.

28. The polymeric material according to claim 27, wherein the second metal element is copper.

Description

SHORT DESCRIPTION OF THE UNIQUE FIGURE

(1) The unique FIGURE is a graph illustrating the change in the copper concentration C.sub.Cu (in %) versus the immersion period t (in hours), the curves a), b) and c) being respectively those obtained with the gels 1, 2 and 3.

DETAILED DISCUSSION OF PARTICULAR EMBODIMENTS

Example 1

(2) The present example illustrates the synthesis of various polymeric foams doped with gold.

(3) For this, three steps are applied: a step for synthesizing a complexant monomer of the cyclene type including 4 styrene groups (symbolized hereafter by the acronym TSC) (step a); a step for forming a polymeric gel by polymerization of said monomer in the presence of another complexant monomer (vinylimidazole) (step b); a step for immersing the gel obtained into a solution containing a gold salt followed by drying of the thereby immersed gel (step c).

(4) A paragraph d) is dedicated to the obtained results.

a) Synthesis of the TSC Monomer

(5) This step relates to the preparation of the TSC monomer fitting the following formula:

(6) ##STR00009##

(7) This monomer is prepared from cyclene and from chloromethylstyrene.

(8) To do this, in a two-neck flask surmounted with a condenser and under an argon atmosphere, a solution containing the cyclene (1 g), anhydrous dichloromethane (25 mL) (which allows solubilization of the cyclene), anhydrous acetonitrile (25 mL), triethylamine (8 mL) and chloromethylstyrene (5.7 mL), is stirred and refluxed for 24 hours. The solution is then filtered at room temperature. The residue is washed with acetonitrile (20 mL) and then three times with methanol (50 mL). The solid is recovered and dried in vacuo.

(9) b) Step for Forming the Polymeric Gel

(10) This example illustrates the synthesis of a polymeric gel obtained by polymerization of the TSC monomer, of another complexant monomer (vinylimidazole, symbolized hereafter as VI) and of a cross-linking agent, divinylbenzene (symbolized hereafter DVB).

(11) To do this, in a flask, TSC monomer (0.1386 g), vinylimidazole (0.2772 g), DVB (0.0462 g) and azoisobutyronitrile (AiBN, 0.0462 g) are solubilized with tetrahydrofurane (3 mL). Next, a pore-forming solvent (diethyl phthalate, symbolized hereafter as DEP) (9 mL) is added. The solution is degassed with an inert gas (argon) for 5 minutes. Next, the solution (in an amount of 1 mL in each mold) is injected into cylindrical molds placed under an inert atmosphere. Polymerization is carried out at 60 C. for 24 hours. The gels are removed from the molds in an ethanol solution, which is changed three times.

c) Step for Immersing the Gels Obtained, Followed by Drying

(12) This immersion step is achieved according to different methods: a method according to the invention, in which the immersion is carried out in an aqueous medium; a method non-compliant with the invention, in which the immersion is carried out in an alcoholic medium.

(13) Method According to the Invention

(14) To do this, a gel obtained according to step b) is subject to a solvent exchange, i.e. to an exchange of ethanol with water. More specifically, the ethanol is gradually changed with water by successive putting the gel into contact with the following solutions: an ethanol solution with 100% water, an ethanol/water solution 75/25 (v/v), a 50/50 (v/v) ethanol/water solution, a 25/75 (v/v) ethanol/water solution, and distilled water.

(15) The gel is then immersed for 48 hours in an aqueous solution of a gold salt, HAuCl.sub.4*3H.sub.2O (18 mL; Au=8.9 mg/mL). Next, the gel is washed three times with this aqueous solution. The aqueous solution is then gradually exchanged with ethanol by successive contactings of the gel with the following solutions: water, 25/75 (v/v) ethanol/water solution, 50/50 (v/v) ethanol/water solution, 75/25 (v/v) ethanol/water solution and a 100% ethanol solution.

(16) The gel is then dried by supercritical CO.sub.2 drying, in return for which a foam results.

(17) Method Non-Compliant with the Invention

(18) The gel obtained in step b) is immersed for 48 hours in an ethanol solution of a gold salt, HAuCl.sub.4*3H.sub.2O (18 mL; Au=8.9 mg/mL). Next, the gel is washed three times with this ethanol solution.

(19) The gel is then dried by supercritical CO.sub.2 drying, in return for which a foam results.

d) Results

(20) The foam obtained according to the method compliant with the invention has a specific surface area of 15610 m.sup.2/g and a gold mass content of 39.82.0.

(21) The obtained foam according to the method non-compliant with the invention has a specific surface area of 1122 m.sup.2/g and a gold mass content of 32.11.3.

(22) Thus, the inventors were surprisingly able to show that the application of the step for immersion in an aqueous medium contributes to increasing the gold content in the final material.

(23) Without being bound by theory, the authors were able to ascribe this technical effect to the capability of the TSC monomer of forming a complex with gold in a more efficient way in an aqueous medium than in a alcoholic medium.

(24) Indeed, by reproducing the example above, with exclusively TSC and DVB (in an amount of a 50/50 mass proportion) and by carrying out the immersion step in an ethanol solution, the obtained material only includes a gold content of 10.30.4.

(25) As a counterpart, by reproducing the example above, with exclusively VI and DVB (in an amount of a 50/50 mass proportion) and by carrying out the immersion step in an ethanol solution, the material obtained only includes a gold content of 25.81.2, a specific surface area of 16015 m.sup.2/g and a specific gravity of 88.53.8 mg/cm.sup.3.

Example 2

(26) The present example illustrates the synthesis of different gold-doped polymeric foams.

(27) To do this, three steps are applied: a step for synthesizing a complexant monomer: 5-iodosalicylaldoxime (symbolized hereafter by the acronym VSO) (step a); a step for forming a polymeric gel by polymerization of said monomer in the presence of another complexant monomer (vinylimidazole) (step b); a step for immersing the obtained gel in a solution containing a gold salt following by drying of the thereby immersed gel (step c).

(28) A paragraph d) is dedicated to the obtained results.

a) Synthesis of 5-iodosalicylaldoxime

(29) This step illustrates the preparation of 5-iodosalicylaldoxime of the following formula:

(30) ##STR00010##

(31) This monomer is made according to the following synthesis scheme:

(32) ##STR00011##
AcOH meaning acetic acid, MeCN meaning acetonitrile, Ph meaning phenyl, and Bu meaning n-butyl.

(33) Thus, the first step consists from salicylaldehyde of making 5-iodosalicylaldehyde.

(34) In a two-neck flask of 500 mL provided with a condenser are placed with stirring 160 mL of glacial acetic acid and 1.4 mL (100 mmol) of salicylaldehyde. A solution of 10 g (1.1 eq., 110 mmol) of iodine monochloride dissolved in a minimum of acetic acid is then added to the mixture. The reaction is maintained with stirring at T=40 C. for 8 days. The solvent is then evaporated and the residue is solubilized with diethyl ether (200 mL). The resulting solution is washed three times with the following solutions:

(35) (i) an aqueous solution saturated with sodium thiosulfate (Na.sub.2S.sub.2O.sub.3, 100 mL);

(36) (ii) a solution saturated with NaCl (100 mL); and

(37) (iii) distilled water (150 mL).

(38) The solvent is then evaporated and the product is recrystallized in a heptane/diethyl ether (50:50) mixture. The crystals are recovered by filtration on a Frit. They are washed with heptane and recrystallized in dichloromethane.

(39) The second step consists of producing 5-iodosalicylaldoxime from the 5-iodosalicylaldehyde prepared beforehand.

(40) To do this, 35 mmol (3.5 eq., 2.40 g) of hydroxylamine hydrochloride (NH.sub.2OH.HCl) are added to a solution of 4 g of K.sub.2CO.sub.3 (35 mmol, 3.5 eq.) and of 5-iodosalicylaldehyde (10 mmol, 2.50 g) in 50 mL of acetonitrile. The mixture is heated to 70 C. with stirring for 24 hours.

(41) At room temperature, the solution is filtered on a Buchner and the solid residue is removed. The filtrate is then evaporated. The residue is taken up in water (250 mL). The pH is adjusted to 4 by adding a solution of hydrochloric acid. The product is extracted with dichloromethane. The organic phase is dried on MgSO.sub.4, filtered and then the solvent is evaporated. The solid is then purified by chromatography on a silica column (eluant: 80/20 heptane/diethyl ether) and then the filtrate is evaporated.

(42) The third step finally consists of producing 5-vinylsalicylaldoxime from the 5-iodosalicylaldoxime prepared beforehand.

(43) To do this, in a Schlenk tube of 300 mL, dried under Grignard conditions and purged with argon are introduced successively, with stirring and in this order, 3.94 g (15 mmol) of 5-iodosalicylaldoxime, 30 mL of anhydrous toluene, 879 mg (5% by moles) of Pd(PPh.sub.3).sub.4 and 6.60 mL of vinyltin CH.sub.2CHSnBu.sub.3 (Bu meaning n-butyl). The mixture is degassed, purged with argon and heated to 70 C. with intense stirring for 48 hours.

(44) At the end of the reaction, the solution is filtered on celite (with the diethyl ether solvent). The solvents of the filtrate are evaporated.

(45) The residue is purified by a chromatographic column (eluants: 400 mL of heptane, 500 mL of a 95:5 heptane/diethyl ether and 90:10 heptane/diethyl ether mixture.

b) Step for Forming the Polymeric Gel

(46) This example illustrates the synthesis of a polymeric gel obtained by polymerization of the VSO monomer, of another complexant monomer (vinylimidazole, symbolized hereafter as VI) and of a cross-linking agent, divinylbenzene (symbolized hereafter as DVB).

(47) To do this, in a flask, VI monomer (0.16065 g), VSO (0.16065 g), DVB (0.1377 g) and azoisobutyronitrile (AiBN, 0.0459 g) and a pore-forming solvent DEP (9 mL) are degassed for 5 minutes with an inert gas (argon). Next, the solution (in an amount of 1 mL in each mold) is injected into cylindrical molds placed under an inert atmosphere. The polymerization is carried out at 80 C. for 24 hours. The gels are removed from the molds in an ethanol solution, which is changed three times.

c) Step for Immersing the Obtained Gels Followed by Drying

(48) This immersion step is carried out according to different methods: a method according to the invention, in which the immersion is carried out in an aqueous medium; a method non-compliant with the invention, in which the immersion is carried out in an alcoholic medium.

(49) Method According to the Invention

(50) To do this, a gel obtained according to step b) is subject to a solvent exchange, i.e. an exchange of the ethanol with water. More specifically, the ethanol is gradually changed with water by successive contactings of the gel with the following solutions: an ethanol solution with 100% water, a 75/25 (v/v) ethanol/water solution, a 50/50 (v/v) ethanol/water solution, a 25/75 (v/v) ethanol/water solution, and distilled water.

(51) The gel is then immersed for 48 hours in an aqueous solution of a gold salt, HAuCl.sub.4*3H.sub.2O (18 mL; Au=8.9 mg/mL). Next, the gel is washed three times with this aqueous solution. The aqueous solution is then gradually exchanged with ethanol by successive contactings of the gel with the following solutions: water, a 25/75 (v/v) ethanol/water solution, a 50/50 (v/v) ethanol/water solution, a 75/25 (v/v) ethanol/water solution and a 100% ethanol solution.

(52) The gel is then dried by supercritical CO.sub.2 drying, in result for which a foam results.

(53) Method Non-Compliant with the Invention

(54) The gel obtained in step b) is immersed for 48 hours in an ethanol solution of a gold salt, HAuCl.sub.4*3H.sub.2O (18 mL; Au=8.9 mg/mL). Next, the gel is washed three times with this ethanol solution.

(55) The gel is then dried by supercritical CO.sub.2 drying, in return for which a foam results.

d) Results

(56) The obtained foam according to the method compliant with the invention has a specific surface area of 21910 m.sup.2/g, a gold mass content of 41.51.7 and a specific gravity of 93.44.3 mg/cm.sup.3.

(57) The foam obtained according to the method non-compliant with the invention has a specific surface area of 27715 m.sup.2/g and a gold mass content of 15.70.6.

(58) Thus, the inventors have surprisingly been able to show that the application of the immersion step in an aqueous medium contributes to substantial increase in the gold content in the final material.

(59) Without being bound by theory, the authors were able to ascribe this technical effect to the capability of the VSO monomer of forming a complex with gold in an aqueous medium and not in an alcoholic medium.

(60) Indeed, by reproducing the example above, with exclusively VSO and DVB (in an amount of a 50/50 mass proportion) and by carrying out the immersion step in an ethanol solution, the obtained material only includes a gold content of 0.50.0, this low content giving the possibility of concluding that this monomer does not allow complexation of gold in such a medium. The low measured gold content in the material may result from a deposition of gold by absorption in the porosity of the material.

(61) As a counterpart, by reproducing the example above, with exclusively VSO and DVB (in an amount of a 50/50 mass proportion) and by carrying out the immersion step in water, the obtained material includes a gold content of 37.00.3, which confirms the exceptional capability of VSO of forming a complex with gold in an aqueous medium. Without being bound by theory, this result may be ascribed to an aurophilicity phenomena, i.e. mutual attraction of gold atoms. As to the specific gravity of the material, it is of 2009 mg/cm.sup.3. Also the conclusion may be drawn that the association of the VSO monomer with the VI monomer gives the possibility of both increasing the gold content but also reducing the specific gravity to below 100 mg/cm.sup.3.

(62) Thus, the method of the invention may give the possibility of maximizing the gold content while controlling the final specific gravity of the material.

(63) As a conclusion, with regard to examples 1 and 2, the gold-doped materials obtained according to the methods of the invention have a mass content around 40% but the specific surface area of the materials differs. Thus, according to the desired properties, the association of at least two complexant monomers according to the methods of the invention give the possibility of both modulating the gold content but also the morphological properties.

Example 3

(64) The present example illustrates the synthesis of a bimetal gold-copper foam according to the methods of the invention.

(65) To do this, a gel obtained in step b) of example 2 is immersed, in a first phase, for 24 hours in an ethanol solution of a gold salt, HAuCl.sub.4*3H.sub.2O (18 mL; Au=3 mg/mL). During this step, the recurrent units stemming from the polymerization of the VI monomer capture gold.

(66) After this step, the gel is washed three times with ethanol and then the resulting gel is subject to a solvent exchange, i.e. to an exchange of ethanol with water. More specifically, the ethanol is gradually changed with water by successive contactings of the gel with the following solutions: an ethanol solution with 100% water, a 75/25 (v/v) ethanol/water solution, a 50/50 (v/v) ethanol/water solution, a 25/75 (v/v) ethanol/water solution, and distilled water.

(67) The gel is then immersed for 24 hours in an aqueous solution of a copper salt CuCl.sub.2 (18 mL; Cu=3 mg/mL). During this step, the recurrent units from the polymerization of the VSO monomer capture copper.

(68) Next, the gel is washed three times with this aqueous solution. The aqueous solution is then gradually exchanged with ethanol by successive contactings of the gel with the following solutions: water, a 25/75 (v/v) ethanol/water solution, a 50/50 (v/v) ethanol/water solution, a 75/25 (v/v) ethanol/water solution and a 100% ethanol solution.

(69) The gel is then dried by supercritical CO.sub.2 drying in return for which a foam results.

(70) The copper is exclusively complexed by the recurrent units stemming from VSO, because the complexation occurs in an aqueous medium, the complexant functions of VSO not being occupied with gold during the first immersion, because this first immersion occurs in an alcoholic medium.

(71) Without being bound by theory, the following results from the following complementary tests: a test conducted with a gel made in an ethanol medium only comprising recurrent units stemming from the polymerization of the VSO monomer (a so called gel 1); a test conducted with a gel exclusively comprising recurrent units stemming from the polymerization of the VI monomer complexed with gold in an ethanol medium (a so called gel 2); and a test conducted with a gel comprising recurrent units stemming from the polymerization of the VI monomer complexed with de gold in an ethanol medium and comprising free recurrent units stemming from the polymerization of the VSO monomer (a so called gel 3).

(72) After gradual exchange of the ethanol with water, the gels are immersed in an aqueous copper solution for a period ranging up to 7 hours. The concentration of the copper solution is measured versus the immersion period of the relevant gel. The results are reported in the single FIGURE which is a graph illustrating the time-dependent change in the copper concentration C.sub.Cu (in %) versus the immersion period t (in hours), the curves a), b) and c) being respectively those obtained with the gels 1, 2 and 3.

(73) The gel 2 does not form a complex with copper. This result confirms that the formation of the gold complex is stable in an aqueous solution at pH=4.

(74) The gel 1 gives the possibility, after 7 hours of immersion, of reducing the copper concentration of the immersion solution by 10%.

(75) The gel 3 gives the possibility, after 7 hours of immersion, of reducing the copper concentration of the immersion solution by 13%. In this gel, the capture of the copper is achieved by means of the VSO monomer. This capture confirms that the complexant functions of the monomer were not occupied by gold atoms stemming from the first immersion step.