Actinide complexing copolymer capable of forming a hydrogel useful for actinide decontamination of surfaces, hydrogel obtained from such a copolymer and uses of said copolymer and hydrogel

Abstract

The invention relates to a copolymer which has a dual capability: that of complexing actinides, and in particular uranium (VI), and that of forming a hydrogel in the presence of water. It also relates to a hydrogel obtained from such a copolymer. It further relates to the uses of said copolymer and of said hydrogel for the actinide decontamination of surfaces. Applications: treatment of a known or suspected external body contamination of a person with one or more actinides; decontamination of surfaces other than skin, such as textile surfaces, wooden surfaces, surfaces made of thermoplastic or thermoset materials, surfaces made of cement or concrete, ceramic surfaces, metal surfaces, etc., and in particular surfaces of nuclear facilities, for example in the context of operations for cleaning up and / or dismantling such facilities.

Description

[0001] Description

[0002] Title: Actinide-complexing copolymer capable of forming a hydrogel useful for the decontamination of actinide surfaces, hydrogel obtained from such a copolymer and uses of said copolymer and hydrogel

[0003] Technical field

[0004] The invention relates to the field of decontamination of actinide surfaces, i.e. uranium, plutonium, neptunium, americium and / or curium. More specifically, it relates to a copolymer which has a dual capacity: that of complexing actinides and, in particular, uranium(VI) and that of forming a hydrogel in the presence of water.

[0005] It also relates to a hydrogel obtained from such a copolymer.

[0006] It also relates to the uses of said copolymer and said hydrogel for the decontamination of actinide surfaces.

[0007] The invention is of particular interest in the treatment of external bodily contamination, proven or suspected, of a person by one or more actinides and, as such, finds application in all cases where people are contaminated or potentially contaminated by one or more actinides, whether in the context of a nuclear accident, a military operation or even a professional activity likely to accidentally expose them to contamination by actinides. However, it can also be used to decontaminate surfaces other than skin, of a porous or non-porous nature, such as textile surfaces, wooden surfaces, surfaces made of thermoplastic or thermoset materials, cement or concrete surfaces, ceramic surfaces, metal surfaces, etc., and, in particular, the surfaces of nuclear installations, for example in the context of clean-up and / or dismantling operations of such installations.

[0008] State of the prior art

[0009] External contamination of a person by a radioactive substance is defined as: - a deposit of the radioactive substance on the skin, hair and / or clothing in the case of external contamination, and / or

[0010] - incorporation of the radioactive substance into the body by inhalation, ingestion and / or skin injury in the case of internal contamination.

[0011] Unlike what happens in the case of irradiation by ionizing radiation where it is sufficient to isolate the person from the source of radiation for the effect of the irradiation to cease, an individual contaminated by a radioactive substance remains in permanent contact with this substance as long as it has not been eliminated from his body. The main effect of contamination is that of the irradiation induced by the radioactive substance. However, a certain number of radioelements such as actinides (uranium, plutonium, neptunium, ...) present, in addition to their radiotoxicity, a chemical toxicity which can, in certain cases, prevail if the radioactivity emitted by the radioelements is low, which is the case, for example, of uranium-238 or thorium-232.

[0012] Therefore, to stop the irradiation and limit the spread of contamination, the radioactive substance must be eliminated from the body as quickly as possible or, at the very least, reduced within the body.

[0013] In the case of external actinide contamination, the main decontamination method consists of rinsing the body or contaminated skin areas with lukewarm water, with the addition of a neutral or acidic, non-aggressive soap, which can be combined with an actinide chelator to minimize the processes of actinide fixation and skin penetration. The reference chelator is diethylenetriamine pentaacetic acid (or DTPA), which is typically used in the form of its trisodium monocalcium salt, more simply called Ca-DTPA.

[0014] The effectiveness of DTPA has been proven for the water-soluble forms (nitrates or chlorides) of actinides (III) and (IV) including plutonium and americium, but it has been shown to be low for their water-insoluble forms (oxides for example), their complexes with organic compounds as well as for uranium and neptunium. In addition, whatever the actinide chelator used, the effectiveness of decontamination by rinsing the body or contaminated skin areas using aqueous solutions is naturally limited by the runoff of these solutions.

[0015] Moreover, this method of decontamination faces a major constraint, which is that of having water free of any contamination to carry out this rinsing. However, as the Fukushima nuclear disaster in 2011 showed, such decontamination is not feasible at the site of a nuclear accident because the water available at this site is itself contaminated.

[0016] Statement of the invention

[0017] The invention aims precisely to provide a copolymer which is both capable of very effectively complexing actinides and of forming a hydrogel on contact with water, the hydrogel thus formed making it possible, when used for external body decontamination purposes, on the one hand, to control the residence time of the complexing copolymer on the skin and hair and, on the other hand, to carry out this decontamination under limiting conditions in water and, more particularly, without rinsing.

[0018] The invention therefore relates, firstly, to a copolymer which comprises at least:

[0019] - a first type of repeating units of general formula (I) below: [Chem 1] in which:

[0020] Ri represents a hydrogen atom or a -CH3 group, and

[0021] R represents a saturated, linear, branched or cyclic hydrocarbon group, comprising from 1 to 50 carbon atoms and one or more heteroatoms, this heteroatom or one of these heteroatoms being a nitrogen or oxygen atom which is located at a of the carbonyl group to which R is attached; and - a second type of repeating units of general formula (II) below:

[0022] [Chem 2] in which:

[0023] R2 represents a hydrogen atom or a -CH3 group,

[0024] X represents -O- or -NH-, m is an integer from 3 to 10, and

[0025] R' represents a group of formula (Q) below:

[0026] [Chem 3] Or :

[0027] R3 represents a hydrogen atom, a -CH3 group or a -CH2CH3 group,

[0028] Y represents a nitrogen atom or a carbon atom, if Y represents a nitrogen atom, then n is equal to 1, p is equal to 0 (and, therefore, R4 is absent) and R5 represents a group -P(0)(0Rs)2, if Y represents a carbon atom, then n is equal to 0, p is equal to 1, and

[0029] * either R4 represents a hydrogen atom, in which case R5 represents a hydrogen atom or a -P(0)(0Rs)2 group,

[0030] * either R4 represents an -OH group, in which case R5 represents a -P(O)(0Rs)2 group.

[0031] Thus, according to the invention, the copolymer comprises at least two types of repeating units: - units of general formula (I) above, which make it possible to give it the hydrophilicity necessary for the formation of a hydrogel in contact with water, and

[0032] - motifs of general formula (II) above, which allow it to be given the capacity to complex actinides due to the presence in these motifs of the R' group which comprises one or two phosphonic acid or phosphonate functions.

[0033] In accordance with the invention, the copolymer advantageously also has a third type of repeating units making it possible to give it a thermosensitivity of the LCST (Lower Critical Solution Temperature) type in aqueous solution, such as to facilitate the formation of a hydrogel, in particular when the copolymer is at a temperature above the LCST.

[0034] This third type of repeating unit corresponds to the general formula (III) below: [Chem 4] in which:

[0035] Re represents a hydrogen atom or a -CH3 group,

[0036] Z represents -O- or -NH-, and

[0037] R" represents a saturated, linear, branched or cyclic hydrocarbon group, comprising from 1 to 50 carbon atoms and, optionally, one or more heteroatoms.

[0038] In the foregoing and the following, the term "saturated, linear, branched or cyclic hydrocarbon group comprising from 1 to 50 carbon atoms and one or more heteroatoms, this heteroatom or one of these heteroatoms being a nitrogen or oxygen atom which is located at a of the carbonyl group to which R is attached" means any hydrocarbon group:

[0039] - which comprises at least one carbon atom but at most 50 carbon atoms,

[0040] - which is free from any unsaturation (i.e. any double or triple bond), - whose chain (i.e. when this group contains 2 or more carbon atoms) may be linear, include one or more branches or form a cycle, and

[0041] - which comprises either a single heteroatom, in which case this heteroatom is a nitrogen or oxygen atom which is linked to the carbon atom of the -C=O group, or several heteroatoms, in which case one of these heteroatoms is a nitrogen or oxygen atom which is linked to the carbon atom of the -C=O group to which R is attached, the other heteroatom(s) not necessarily being nitrogen or oxygen atoms and being able to be carried by one or more carbon atoms of the group (instead of a hydrogen atom) or to form a bridge in the group as long as this group comprises a plurality of carbon atoms.

[0042] The term “saturated, linear, branched or cyclic hydrocarbon group comprising from 1 to 50 carbon atoms and, optionally, one or more heteroatoms” means a group as defined above except that the presence of one or more heteroatoms in this group is only optional and is not subject to any condition as to the nature of this (these) heteroatom(s) or its (their) position in the group.

[0043] Finally, "heteroatom" means an atom other than carbon or hydrogen, such as, for example, an atom of nitrogen, oxygen, sulfur, fluorine, chlorine, phosphorus, boron or silicon, with nitrogen and oxygen atoms being preferred.

[0044] Advantageously, the repeating units of general formula (III) are different from the repeating units of general formula (I).

[0045] According to the invention, in the general formula (I), R may be a C1 to C50, preferably C2 to C20, acyclic saturated hydrocarbon group comprising one or more heteroatoms, typically nitrogen and / or oxygen, such as a dialkylamine group (for example, dimethylamine or diethylamine), poly(ethylene glycol), etc. However, it is preferred that R is a saturated heterocycle, preferably a 5- or 6-membered heterocycle comprising 1 or 2 heteroatoms chosen from oxygen and nitrogen atoms. Thus, R may in particular be a pyrrolidinyl, piperidinyl, tetrahydrofuryl, tetrahydropyranyl or morpholinyl group, with particular preference being given to a morpholinyl group. Thus, the repeating units of general formula (I) may in particular correspond to one of the particular formulas (la) and (lb) below:

[0046] [Chem 5] In the group of formula (Q) of general formula (II), it is preferred that Rs represents a group -P(O)(OR3)2.

[0047] Furthermore, it is preferred that Y is a carbon atom, in which case, as previously mentioned, n is 0 (meaning that the -P(O)(OR3)2 group and Rs are both directly bonded to this carbon atom), p is 1 and R4 represents a hydrogen atom or an -OH group, with preference given to an -OH group.

[0048] In other words, we prefer that R' corresponds to the formula:

[0049] [Chem 6] in which R3 is as previously defined.

[0050] Thus, each of the units of formula (II) preferably carries a bis(phosphonic acid) complexing group (if R3 represents a hydrogen atom) or a bisphosphonate group (if R3 represents a -CH3 or -CH2CH3 group), with preference being given to a bis(phosphonic acid) group. Furthermore, in the general formula (II), it is preferred that X is -NH- and that m is equal to 3.

[0051] Thus, the repeating units of general formula (II) may in particular correspond to one of the particular formulas (ll-a) and (ll-b) below: in which the group of atoms -X-(CH2)mR' corresponds to alendronic acid. According to the invention, in general formula (III), it is preferred that Z is -NH- and that R" is an alkyl group comprising from 1 to 20 and, better still, from 3 to 10 carbon atoms, advantageously branched, for example an isopropyl group.

[0052] Thus, the repeating units of general formula (III) may in particular correspond to one of the particular formulas (lll-a) and (lll-b) below:

[0053] [Chem 8] In a preferred embodiment of the invention, the copolymer comprises repeating units of particular formula (Ia) together with repeating units of particular formula (Ia).

[0054] Advantageously, this copolymer further comprises repeating units of particular formula (III-a).

[0055] According to the invention, the copolymer may comprise from 2 repeating units to

[0056] 1,000 repeating units of general formula (I) and 2 repeating units to 1,000 repeating units of general formula (II).

[0057] When the copolymer further comprises repeating units of general formula (III), then these may be 2 to 1,000 in number.

[0058] The copolymer as previously defined can be synthesized from the following monomers:

[0059] - for repeating units of general formula (I), a first monomer of general formula (IV) below:

[0060] [Chem 9] in which Ri and R have the same meaning as before;

[0061] - for repeating units of general formula (II), a second monomer of general formula (V) below:

[0062] [Chem 10] in which R2 and X have the same meaning as above and W represents a carboxylic acid group or an activated acid group, for example acid chloride or / V- succinimidyl; and

[0063] - for the repeating units of general formula (III) if, of course, these are present in the copolymer, a third monomer of general formula (VI) below:

[0064] [Chem 11] in which Re, Z and R" have the same meaning as before.

[0065] In accordance with the invention, the copolymerization of these monomers may in particular be of the radical type and, in particular, of the controlled radical type, for example of the type controlled by reversible addition-fragmentation chain transfer (or RAFT), by atom transfer (or ATRP) or even by nitroxides (or NMP).

[0066] Furthermore, the architecture of the copolymer can be statistical, block or a combination of both.

[0067] Thus, the synthesis of the copolymer can notably include:

[0068] - a controlled radical copolymerization of the monomers of general formulas (IV) and (V) and, where appropriate, of the monomer of general formula (VI), followed by a post-copolymerization reaction aimed at introducing, for example by click chemistry, the phosphonic acid or phosphonate group(s) onto all or part of the repeating units resulting from the copolymerization of the monomer of general formula (V), this introduction possibly comprising a substitution of all or part of the group of atoms -XW; or

[0069] - a controlled radical polymerization of the monomer of general formula (VI) to obtain a homopolymer consisting of a chain of repeating units of general formula (III), followed by a statistical copolymerization, by controlled radical route of the monomers of formulas (IV) and (V) using the homopolymer previously obtained as macro-initiator, then a post-copolymerization reaction aimed at introducing, for example by click chemistry, the phosphonic acid or phosphonate group(s) onto all or part of the repeating units resulting from the copolymerization of the monomer of general formula (V), this introduction possibly comprising a substitution of all or part of the group of atoms -XW.

[0070] So, for example, the copolymer can have the formula: A-(B / C') s state in which:

[0071] - A represents a block consisting of a sequence of repeating patterns of particular formula (lll-a), and

[0072] - (B / C') stat represents a block consisting of a statistical sequence of repetitive patterns of particular formulas (la) and (ll-a).

[0073] The copolymer as just described having, among other things, the property of forming a hydrogel when it is brought into contact with water, without losing its actinide complexing properties, the invention also relates to a hydrogel which is obtained from at least one copolymer as defined above.

[0074] According to the invention, the copolymer advantageously represents at least 5% and, preferably, from 10% to 30% by mass of the mass of the hydrogel.

[0075] In addition to its ability to complex actinides, such a hydrogel has many advantages such as being easily transportable, for example in bags or tubes, being easily applicable to a surface whatever its nature and being able to be easily removed from this surface by wiping or peeling, in particular due to its consistency which is made harder after complexation of one or more actinides, and therefore without requiring water.

[0076] Furthermore, when applied to healthy or damaged skin, contaminated by actinides, this hydrogel has the additional advantage of being unable to cross the skin barrier and, therefore, to cause additional internal contamination.

[0077] Also, the invention also relates to the use of a copolymer as described above or of a hydrogel comprising at least this copolymer for decontaminating a surface of at least one actinide.

[0078] In particular, the subject of the invention is the use of a hydrogel comprising at least one copolymer as described above for treating external bodily contamination, proven or suspected, of a person by one or more actinides. Typically, this treatment comprises bringing the hydrogel into contact with the skin, healthy or damaged, and, optionally, the hair of the person, then, after allowing the hydrogel to act, removing this hydrogel from the areas with which it has been brought into contact. Other characteristics and advantages of the invention will emerge from the additional description which follows and which refers to the appended figures.

[0079] It goes without saying, however, that this additional description is given only as an illustration of the subject of the invention and must in no case be interpreted as a limitation of this subject.

[0080] Brief description of the figures

[0081] [Fig. 1] illustrates the proton NMR spectrum of a copolymer of the invention, of the poly( / V-isopropylacrylamide)-b / oc-poly(4-acryloylmorpholine-stat-alendronate acrylamide) type.

[0082] [Fig. 2] illustrates the phosphorus 31 NMR spectrum of this same copolymer.

[0083] [Fig. 3] illustrates the sorption kinetics of uranium(VI) as obtained for a first copolymer of the invention, of the poly( / V-isopropylacrylamide)-b / oc-poly(4-acryloylmorpholine-stat-alendronate acrylamide) type, in the context of a sorption test of uranium(VI) in an aqueous medium at pH 5.5, as well as that obtained for a copolymer of the poly( / V-isopropylacrylamide)-b / oc-poly(4-acryloylmorpholine) type serving as a reference under the same conditions; in this figure, the abscissa axis corresponds to the time, noted t and expressed in hours, while the ordinate axis corresponds to the sorption capacity at time t, noted Q tand expressed in mmol of uranium(IV) per gram of copolymer.

[0084] [Fig. 4] illustrates the sorption kinetics of uranium(VI) as obtained for a second copolymer of the invention, also of the poly( / V-isopropylacrylamide)- b / oc-poly(4-acryloylmorpholine-stat-alendronate acrylamide) type in the context of a sorption test of uranium(VI) in an aqueous medium at pH 5.5; in this figure, the abscissa axis corresponds to the time, noted t and expressed in hours, while the ordinate axis corresponds to the sorption capacity at time t, noted Q t and expressed in mmol of uranium(IV) per gram of copolymer.

[0085] [Fig. 5] illustrates the sorption isotherm of uranium(VI) as obtained for a first copolymer of the invention, of the poly( / V-isopropylacrylamide)-b / oc-poly(4-acryloylmorpholine-stat-alendronate acrylamide) type, in the context of a sorption test of uranium(VI) in an aqueous medium at pH 5.5; in this figure, the abscissa axis corresponds to the concentration of uranium(VI) at equilibrium, noted [U] e and expressed in mg / L; the left y-axis corresponds to the equilibrium sorption capacity, noted Q e and expressed in mmol / g, while the right-hand y-axis corresponds to the extraction yield of uranium(VI), noted Ru and expressed in %; moreover, in this figure, the values ​​of Q e are represented as black squares while Ru values ​​are represented as black circles.

[0086] [Fig. 6] is a figure similar to [Fig. 5] but relating to a second copolymer of the invention, also of the poly( / V-isopropylacrylamide)-b / oc-poly(4-acryloylmorpholine-stat-alendronate acrylamide) type.

[0087] [Fig. 7] is a figure similar to [Fig. 5] and [Fig. 6] but relating to a copolymer of the poly( / V-isopropylacrylamide)-b / oc-poly(4-acryloylmorpholine) type serving as reference.

[0088] Detailed description of specific embodiments

[0089] I - Synthesis of copolymers of the invention:

[0090] Two copolymers of the invention of the poly( / V-isopropylacrylamide)-b / oc-poly(4-acryloylmorpholine-stat-alendronate acrylamide) type, of schematic formula: A-(B / C') s state in which:

[0091] - A represents a block consisting of a sequence of repeating units of particular formula (III-a) above, providing thermosensitivity, and

[0092] - (B / C') stat represents a block consisting of a statistical sequence of repeating units of particular formulas (la) and (ll-a) above, the repeating units of particular formula (la) providing hydrophilicity and the repeating units of particular formula (ll-a) providing, by their bis(phosphonic acid) function, the capacity to complex actinides, were prepared by first synthesizing two copolymers of poly( / V- isopropylacrylamide)-b / oc-poly(4-acryloylmorpholine-stat- / V-acryloxysuccinimide) type, of schematic formula: A-(B / C) s state in which:

[0093] * A has the same meaning as before, * (B / C) stat represents a block consisting of a statistical sequence of repeating patterns of particular formula (la) above and of the formula below:

[0094] [Chem 12] and then reacting each of these copolymers with alendronic acid in order to introduce the bis(phosphonic acid) functions onto the repeating units of particular formula (ll-b).

[0095] 1.1 - Synthesis of the two copolymers of formula A-(B / C) s state:

[0096] The two copolymers of formula A-(B / C) s tat were synthesized using as monomers:

[0097] - / V-isopropylacrylamide, or NiPAAm, which corresponds to a monomer of formula (VI) in which Re is a hydrogen atom, Z is -NH- and R'' is an isopropyl group,

[0098] - 4-acryloylmorpholine, or NAM, which corresponds to a monomer of formula (IV) in which Ri is a hydrogen atom and R is a morpholinyl group, and

[0099] - / V-acryloxysuccinimide, or NAS, which corresponds to a monomer of formula (V) in which R2 is a hydrogen atom, X is -O- and W is a / V-succinimidyl group.

[0100] These two copolymers differ in a different proportion of units resulting from the polymerization of the NAS monomer (10% versus 25%) and are therefore hereinafter designated PNIPAAm-bP(NAM-st-NAS)10% and PNIPAAm-bP(NAM-st-NAS)25% respectively.

[0101] Their synthesis was carried out in two steps by radical polymerization controlled by reversible addition-fragmentation chain transfer, or RAFT polymerization.

[0102] In a first step, polymerization of the NiPAAm monomer was carried out using 2-cyano-2-propyl dodecyl trithiocarbonate (or CPDTC) as transfer agent and azobisisobutyronitrile (or AIBN) as initiator in molar concentration ratios [CPDTC] / [AIBN] / [NIPAAm] of 1 / 0.2 / 100. The polymerization was carried out in solution in dioxane (2 mol / L) at 70 °C for either 120 minutes or 150 minutes.

[0103] The 120-minute polymerization led to the production of a first poly( / V-isopropylacrylamide), or PNiPAAm, with a molar mass in number M n = 9,300 g / mol and dispersity D = 1.08 (as determined by size exclusion chromatography (SEC) using DMF as eluent and poly(methyl methacrylate), or PMMA, as standard) while the 150-minute polymerization led to the production of a second PNiPAAm, of number molar mass M n = 11,400 g / mol and dispersity D = 1.14 (also as determined by CES).

[0104] In a second step, the two PNiPAAm thus obtained were used as transfer macroagents for the statistical copolymerization of the NAM and NAS monomers under the conditions presented in Table 1 below:

[0105] [Table 1]

[0106] The copolymers PNIPAAm-bP(NAM-st-NAS)10% and PNIPAAm-bP(NAM-st-NAS)25% resulting from this copolymerization were characterized by proton NMR and CES. Their main characteristics are presented in Table 2 below. Also presented in this table are the characteristics of a diblock copolymer of the poly( / V-isopropylacrylamide)-b / oc-poly(4-acryloylmorpholine) type, hereinafter referred to as PNiPAAm-b-PNAM, the synthesis of which was carried out to serve as a reference.

[0107] [Table 2] a conversion rate determined by 1H NMR;

[0108] I.2 - Obtaining copolymers of formula A / (B / C')stat:

[0109] The copolymers PNiPAAm-bP(NAM-co-NAS)10% and PNiPAAm-bP(NAM-co-NAS)25% were reacted with alendronic acid to introduce the complexing bis(phosphonic acid) functions of the actinides.

[0110] The reaction was carried out in aqueous medium by adjusting the pH between 8 and 9 with sodium hydroxide solution. After 48 hours of reaction, the pH was lowered to 7 by adding hydrochloric acid. The resulting copolymers were purified by dialysis against water for 72 hours. The solutions were then lyophilized to yield pure copolymers.

[0111] These copolymers, which will be referred to hereinafter as PNIPAAm-bP(NAM-st-AleAm)10% and PNIPAAm-bP(NAM-st-AleAm)25% respectively, were characterized by proton NMR and phosphorus-31 NMR, which showed a quantitative substitution of the / V-hydroxysuccinimidyl group by alendronic acid. It should be noted that these copolymers could not be characterized by CES due to the retention of bis(phosphonic acid) functions by the CES stationary phase.

[0112] As an example, the proton and phosphorus-31 NMR spectra of PNIPAAm-b-P(NAM-st-AleAm)25% are shown in Figures 1 and 2 respectively.

[0113] II - Capacities of the copolymers of the invention to complex uranium (VI) in solution:

[0114] II.1 - Sorption kinetics:

[0115] Tests aimed at studying the sorption kinetics of the copolymers PNiPAAm-b-P(NAM-st-AleAm)io% and PNiPAAm-bP(NAM-st-AleAm)25% were carried out in aqueous solution at pH 5.5 (which corresponds to the pH of human skin) in the presence of uranyl nitrate, UChfNChh.

[0116] To do this, solutions comprising 50 mg of one of the copolymers in 10 mL of water, acidified to present a pH of 5.5, were placed in dialysis membranes with a retention threshold equal to 10 kD. Then, the dialysis membranes were introduced into flasks containing 100 mL of a uranyl nitrate solution of pH 5.5, comprising either 0.32 mmol / L of UC (fNOg)? in the case of the PNiPAAm-bP(NAM-st-AleAm)10% copolymer or 0.68 mmol / L of UOz (fNOg)? in the case of the PNiPAAm-bP(NAM-st-AleAm)25% copolymer (the molar ratio [U] / AleAm complexing site being in both cases equal to 1.5).

[0117] Samples were taken from the vials at regular intervals over a 72-hour period. Uranium in these samples was measured by inductively coupled plasma atomic emission spectrometry (ICP-OES) and the sorption capacity at time t, denoted Q tand expressed in mmol of U(VI) per gram of copolymer was determined by applying the following formula:

[0118] [Math 1] in which:

[0119] [U]ini corresponds to the initial concentration of uranium (in mmol / mL);

[0120] [U] t corresponds to the concentration of uranium at time t (in mmol / mL); m corresponds to the mass of copolymer (in g), and

[0121] V corresponds to the volume of the uranyl nitrate solution (in mL).

[0122] For comparison purposes, tests were also carried out under the same conditions with the reference PNiPAAm-b-PNAM copolymer, using a 32 mmol / L uranyl nitrate solution.

[0123] The results of these tests are illustrated in Figures 3 and 4, Figure 3 corresponding to the sorption kinetics of the copolymers PNiPAAm-bP(NAM-st-AleAm)io% and PNiPAAm-b-PNAM while Figure 4 corresponds to the sorption kinetics of the copolymer PNiPAAm-bP(NAM-st-AleAm)25%.

[0124] As these figures show, the equilibrium sorption capacities, denoted Q e , of the PNiPAAm-bP(NAM-st-AleAm)10% and PNiPAAm-bP(NAM-st-AleAm)25% copolymers are respectively equal to 0.67 mmol / g and 1.24 mmol / g - which corresponds to U(VI) extraction yields of 83% and 96% respectively - while that of the PNiPAAm-b-PNAM copolymer is considerably lower since it is only 0.12 mmol / g, i.e. a U(VI) extraction yield of 18%. As expected, the highest equilibrium sorption capacity was obtained with the copolymer of the invention having the largest amount of bis(phosphonic acid) functions.

[0125] 11.2 - Maximum sorption capacities:

[0126] The maximum sorption capacities of the PNiPAAm-bP(NAM-st-AleAm)10% and PNiPAAm-bP(NAM-st-AleAm)25% copolymers as well as that of the reference PNiPAAm-b-PNAM copolymer were also determined by carrying out tests similar to those described in point II.1 above, except that the uranyl nitrate concentration of the solutions in which the dialysis membranes were immersed was varied.

[0127] The results of these tests are illustrated in Figures 5, 6 and 7, Figure 5 corresponding to the sorption isotherm obtained for the PNiPAAm-bP(NAM-st-AleAm)10% copolymer, Figure 6 corresponding to the sorption isotherm obtained for the PNiPAAm-b-P(NAM-st-AleAm)25% copolymer and Figure 7, given for comparison, corresponding to the isotherm obtained for the reference PNiPAAm-b-PNAM copolymer.

[0128] As shown in these figures, the sorption capacities of the three copolymers increased with increasing initial uranyl nitrate concentration until reaching a plateau, noted Qmax, estimated at 1.33 mmol / g for the PNiPAAm-b-P(NAM-st-AleAm)io% copolymer, 3.2 mmol / g for the PNiPAAm-bP(NAM-st-AleAm)25% copolymer and only 0.12 mmol / g for the reference PNiPAAm-b-PNAM copolymer.

[0129] As expected, the maximum sorption capacity is also obtained with the copolymer of the invention having the greatest quantity of bis(phosphonic acid) functions.

[0130] Ill - Capacity of the copolymers of the invention to form hydrogels:

[0131] The ability of PNiPAAm-bP(NAM-st-AleAm)10% and PNiPAAm-bP(NAM-st-AleAm)25% copolymers to form hydrogels in aqueous media was verified by introducing these hydrogels into water at mass concentrations of 10%, 20% and 30% respectively. Two water temperatures were tested, namely 25 °C and 37 °C to evaluate the influence of the thermosensitive PNIPAAm block on the occurrence of hydrogelation. For comparison purposes, tests were also carried out under the same conditions with the reference PNiPAAm-b-PNAM copolymer.

[0132] These tests showed that:

[0133] - for a mass concentration of 30%, the three copolymers formed a hydrogel, at both temperatures,

[0134] - for a mass concentration of 20%, only the copolymers of the invention formed a hydrogel but only at a temperature of 37°C, while

[0135] - for a mass concentration of 10%, no copolymer formed a hydrogel, regardless of the temperature.

[0136] IV - Capacity of the hydrogels of the invention to decontaminate a uranium(VI) surface:

[0137] Tests were carried out to assess the capacity of hydrogels of the invention to decontaminate a uranium(VI) surface.

[0138] For reasons of safety of the experimenters, these tests were carried out not with uranium(VI) but with neodymium(III) which is an excellent simulant of uranium(VI).

[0139] They consisted of depositing an aqueous solution comprising 100 mmol / L of neodymium nitrate hexahydrate on hydrophilic nitrocellulose membranes Mil li pore™, removing the water from this solution by evaporation, then covering each membrane with a layer of a hydrogel comprising 30% by mass of one of the copolymers PNiPAAm-b-P(NAM-st-AleAm)io% and PNiPAAm-bP(NAM-st-AleAm)25%.

[0140] The hydrogel layers were left on the membranes for 10 minutes and then easily removed from these membranes with a spatula and the neodymium present in the recovered hydrogels was measured by ICP-OES.

[0141] For comparison purposes, tests were also carried out under the same conditions with a hydrogel comprising 30% by mass of the reference PNiPAAm-b-PNAM copolymer.

[0142] These tests showed that the hydrogels of the invention made it possible to recover more than 80% by mass of the neodymium that had been initially deposited on the membranes, whereas the hydrogel based on the reference PNiPAAm-b-PNAM copolymer made it possible to recover less than 40% by mass of this neodymium. Furthermore, the hydrogels of the invention became harder after complexing the neodymium. They were therefore easier to remove from the membrane on which they had been deposited.

Claims

Claims 1. Copolymer comprising at least: - a first type of repeating patterns of general formula (I) below: in which: Ri represents a hydrogen atom or a -CH3 group, and R represents a saturated, linear, branched or cyclic hydrocarbon group, comprising from 1 to 50 carbon atoms and one or more heteroatoms, this heteroatom or one of these heteroatoms being a nitrogen or oxygen atom which is located at a of the carbonyl group to which R is attached; and - a second type of repeating patterns of general formula (II) below: [Chem 2] in which: R2 represents a hydrogen atom or a -CH3 group, X represents -O- or -NH-, m is an integer from 3 to 10, and R' represents a group of formula (Q) below: [Chem 3] Or : R3 represents a hydrogen atom, a -CH3 group or a -CH2CH3 group, Y represents a nitrogen atom or a carbon atom, if Y represents a nitrogen atom, then n is equal to 1, p is equal to 0 (and, therefore, R4 is absent) and R5 represents a group -P(O)(OR3)2, if Y represents a carbon atom, then n is equal to 0, p is equal to 1, and * either R4 represents a hydrogen atom, in which case R5 represents a hydrogen atom or a -P(O)(OR3)2 group, * either R4 represents a -OH group, in which case R5 represents a -P(O)(OR3h group and - a third type of repeating patterns of general formula (III) below: [Chem 4] in which: Re represents a hydrogen atom or a -CH3 group, Z represents -O- or -NH-, and R" represents a saturated, linear, branched or cyclic hydrocarbon group, comprising from 1 to 50 carbon atoms and, optionally, one or more heteroatoms; and in which R is a heterocycle, preferably 5 or 6-membered and comprising one or more heteroatoms chosen from oxygen and nitrogen atoms and, more preferably, a morpholinyl group.

2. Copolymer according to claim 1, in which the repeating units of general formula (I) correspond to one of the particular formulas (Ia) and (Ib) below: [Chem 5] (lb).

3. Copolymer according to any one of claims 1 to 2, in which Rs represents a group -P(O)(OR3)2.

4. Copolymer according to any one of claims 1 to 3, in which R' corresponds to the following formula: [Chem 6] 5. Copolymer according to any one of claims 1 to 4, in which R3 represents a hydrogen atom.

6. Copolymer according to any one of claims 1 to 5, in which the repeating units of general formula (II) correspond to one of the particular formulas (II-a) and (II-b) below:

7. Copolymer according to claim 1, in which Z represents -NH- and R" represents an alkyl group comprising from 1 to 20 carbon atoms, preferably from 3 to 10 carbon atoms, advantageously branched.

8. Copolymer according to any one of claims 1 to 7, in which the repeating units of general formula (III) correspond to one of the particular formulas (III-a) and (lll-b) below: [Chem 8] 9. Copolymer according to any one of claims 1 to 8, comprising repeating units of particular formula (la) below together with repeating units of particular formula (ll-a) below: [Chem 9] 10. Copolymer according to claim 9, further comprising repeating units of particular formula (II la) below:

11. Copolymer according to claim 10, corresponding to the formula: A-(B / C') s state in which: - A represents a block consisting of a sequence of repeating formula patterns particular (lll-a), and - (B / C') stat represents a block consisting of a statistical sequence of repeating units of particular formulas (la) and (ll-a).

12. Hydrogel obtained from at least one copolymer according to any one of claims 1 to 11.

13. Hydrogel according to claim 12, in which the copolymer represents at least 5% and preferably 10% to 30% by mass of the mass of the hydrogel.

14. Use of a copolymer according to any one of claims 1 to 11 or of a hydrogel according to claim 12 or 13 for the decontamination of an actinide surface.

15. Use of a hydrogel according to claim 12 or 13, in the treatment of actual or suspected contamination of a person by at least one actinide.

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