Method for functionalising polyolefins via the introduction of an oxime function

Abstract

The invention relates to a method for functionalising at least one polyolefin, comprising the functionalisation of the polyolefin with oxime groups, followed by reaction of the oxime groups introduced.

Description

Description Title of the invention: Method for functionalizing polyolefins via the introduction of an oxime function Technical Field

[0001] The invention relates to a method for functionalizing polyolefins via the introduction of oxime groups. Prior art

[0002] Currently, plastic waste pollution is constantly increasing and has become a major problem. This source of pollution has harmful effects on rivers, seas and oceans, as well as on marine animals.

[0003] About a third of all plastics produced are polyolefins. These plastic wastes are generally made from polymers designed to be strong, both mechanically and chemically. This makes them difficult to recycle and recover.

[0004] Today, plastic waste is often landfilled, incinerated, or mechanically recycled. Landfilling carries the risk of dispersing lighter plastics due to wind. Incineration has the disadvantage of releasing toxic products, including greenhouse gases. For example, HCl is released when PVC burns. It is therefore necessary to find alternatives for recycling plastic waste in a closed loop or to "upcycle" it, i.e., to recover it into smaller molecules with added value.

[0005] Currently, plastic recycling is mainly mechanical: the polymer is extruded for reuse. The disadvantage associated with such a process is that the polymer degrades with repeated extrusions, which leads in particular to a reduction in its mechanical properties. Therefore, the polymer cannot be reused after a certain number of extrusions. In addition, soiled plastics are very difficult to recycle in this way.

[0006] Another solution that is currently being researched is the chemical or enzymatic degradation of polymers.

[0007] Regarding the enzymatic degradation of polymers, we can notably cite the enzymatic degradation of PET (Nature, vol. 580 (2020), 216-219). This method allows, in 10 hours and thanks to enzymes, to depolymerize at least 90% of PET into monomers which can then be reused to synthesize new PET for example. While this solution seems effective, it is only applicable to PET, and not to polyolefins which only contain hydrocarbon chains that are less reactive than the ester functions of PET.

[0008] Regarding chemical degradation, a widely studied pathway is the introduction of polar groups, and in particular ester groups, via a prior oxidation of the parent polymer introducing carbonyl or hydroxyl functions, followed by a Baeyer-Villiger reaction. However, the preliminary step is not well controlled because it is not selective.

[0009] Another method has been reported by Conk et al. (Science, 377, 1561-1566, 2022), which describes the production of propylene by partial dehydrogenation of polyethylene and tandem ethanolysis-isomerization. This method is particularly interesting since it allows to obtain highly recoverable products. However, this method involves the use of expensive catalysts: iridium or platinum-zinc complex for the dehydrogenation of polyethylene, and second-generation Hoveyda-Grubbs metathesis catalyst and [PdP(t-Bu)3(p-Br)]2 for the isomerization. In addition, heating and high pressure are required.

[0010] The Applicant therefore sought an easy-to-implement alternative method for recycling and recovering polyolefins. The Applicant was particularly interested in the functionalization of these polyolefins with oxime groups, with a view to utilizing the particular reactivity of these functions. oximes to valorize these polyolefins. Indeed, as is explained in particular in the document Rykaczewski et al. (Nature Synthesis, 2022, vol. 1, 24-36), the oxime functions have a reactivity towards transition metals and photocatalysis such that they constitute reagents of choice for the synthesis of nitrogen heterocycles, amino alcohols and amines in particular.

[0011] In order to introduce oxime functions into polyolefins, the Applicant sought a process that was easy to implement and efficient. Advantageously, the process is reproducible. Advantageously, the process can be used with various polyolefins, and in particular different grades of polyethylene, polypropylene, and hydroxypolymethylene.

[0012] The Applicant was particularly interested in the photochemical transformation allowing the introduction of an oxime function on an alkane. This reaction was notably studied for the synthesis of caprolactam which is a precursor of Nylon-6. For example, the Toray process (US 3,090,739) involves the preparation of cyclohexanone oxime by introducing an oxime unit into cyclohexane photochemically using NOCI and HCl under UV (mercury vapor lamp). The cyclohexanone oxime is then transformed into caprolactam under acidic conditions. This process has the disadvantage of using NOCI and HCl which are corrosive. In order to overcome this problem, the use of less corrosive alternative reagents was studied. In particular, it was reported, notably in the document Wysocki et al. (ChemPhotoChem, 2018, 2, 22-26), the photochemical transformation of cyclohexane to cyclohexanone oxime using tert-butyl nitrite (t-BuONO) and UV irradiation.The best yields were obtained using 0.1 equivalents of t-BuONO and 0.8 equivalents of t-BuOH for one equivalent of cyclohexane, and a UV lamp at 365 nm, at a temperature of 50 °C.

[0013] However, no studies have been reported on the introduction of oxime functions into polyolefins.

[0014] Furthermore, the Applicant is not aware of any documents reporting polyolefins functionalized with oxime groups undergoing post- functionalization, hydrolysis, reduction or Beckmann rearrangement for example. Statement of the invention

[0015] Polyolefins have a different reactivity than alkanes, particularly in terms of viscosity, crystallinity, solubility, and accessibility to the reaction site. The Applicant has therefore undertaken research work to determine the operating conditions allowing the introduction of oxime units on different polyolefins. Advantageously, the polyolefins functionalized with oximes thus obtained can then be post-functionalized, undergo hydrolysis or reduction, or a Beckmann rearrangement for example. The method according to the invention then makes it possible to valorize the polyolefins thus functionalized which show properties different from the parent polymers.

[0016] The invention firstly relates to a method for functionalizing polyolefins, and thus enhancing their value. The method according to the invention comprises the following steps: 1) have at least one polyolefin of formula I: with : - RI representing a methyl, ethyl or n-butyl group, - R2 representing H, CH3 or OH, - n representing an integer ranging from 0 to 100000, - m representing an integer ranging from 0 to 100000, and - n + m =# 0, 2) functionalizing at least one polyolefin I with oxime groups, in order to obtain at least one polyolefin functionalized with oxime groups II, 3) reacting the oxime groups present in the at least one functionalized polyolefin with oxime groups II.

[0017] The method according to the invention has the advantage of being simple to implement.

[0018] The method according to the invention also has the advantage of allowing the production of small molecules and polymers of a wide variety (varied chain length and introduced functional groups), depending on the intended use. Indeed, the first step consists of introducing oxime units. This first step has the advantage of generating few by-products, which are easily removed by precipitation and filtration. Then, during a second step, these oxime groups can be hydrolyzed, reduced, post-functionalized or undergo a Beckmann rearrangement. Thus, from a polyolefin, it is possible to obtain a very wide range of molecules and polymers, with a wide variety of functional groups such as amide, amine, carboxylic acid functions, etc.

[0019] The method according to the invention has the advantage of being effective on polyolefins of various structures. In addition, it has been demonstrated that the method according to the invention is effective not only on polyolefins but also on plastic waste containing them.

[0020] The method according to the invention may have one or other of the following characteristics, or a combination of these characteristics: - step 2) comprises the reaction, under irradiation at a wavelength belonging to the range from 300 nm to 456 nm, preferably from 300 to 450 nm, of at least one polyolefin of formula I and at least one nitrosating agent III; - the nitrosating agent III is of formula III-a, III-b or III-c below: with : - R4 and R5 being identical or different and representing independently of one another a group chosen from (C1-C6) alkyl, N[(C1-C6) alkyl]3, CO[(C1-C6) alkyl], SO2Ph, CO-Ph-CF3, - or R4 and R5 together forming a (C5-C10) cycloalkyl group optionally substituted by one or more linear or branched (C1-C6) alkyl groups, or a -SO2-Ph-C(CH3)2- group, or a -CO-Ph-CO- group, - R6 representing a phthalimide group or a linear or branched (C1-C6) alkyl group, - R7 representing an aromatic or heteroaromatic group possibly perfluorinated; - the at least one nitrosating agent is chosen from: - the molar ratio of nitrosating agent(s) III / polyolefin repeating unit(s) I ranges from 0.01 to 2, preferably from 0.1 to 0.5; - the reaction in step 2) is carried out in the presence of t-BuOH; - the molar ratio of nitrosation agent(s) III / t-BuOH ranges from 0.1 to 0.01, preferably 0.1; - the reaction in step 2) is carried out in the absence of photocatalyst; - the reaction in step 2) is carried out in the presence of at least one photocatalyst; - when present, the at least one photocatalyst is chosen from 5,7,12,14-pentacenetetrone IV-1, 9-fluorenone IV-2 and acetophenone IV-3; - the reaction is carried out at a temperature of up to 130°C; - the at least one polyolefin I is chosen from polyethylene and polypropylene optionally hydroxylated in the terminal position, or an ethylene-propylene copolymer optionally hydroxylated in the terminal position; - step 3) comprises the reaction of at least one acid chloride with the groups oximes of polyolefin functionalized with oxime groups II; - step 3) includes a Beckmann rearrangement; - step 3) includes a hydrolysis reaction in an acid medium, subsequent to the Beckmann rearrangement; - step 3) comprises the reduction of the oxime groups of the polyolefin functionalized with oxime groups II; - step 3) comprises a hydrolysis reaction in an acid medium; - step 3) comprises the reaction of at least one isocyanate with the oxime groups of the polyolefin functionalized with oxime groups II; - step 3) comprises a grafting reaction of polymer chains, such as polyethylene glycol or polycaprolactone chains. Brief description of the drawings

[0021] Figure 1 is the spectrum X H NMR of oxime II-5 functionalized HDPE.

[0022] Figure 2 is the HMBC NMR spectrum of oxime II-5 functionalized HDPE.

[0023] Figure 3 is the spectrum X H NMR of the polymer functionalized with oxime groups II-6.

[0024] Figure 4 is the spectrum X H NMR of the polymer functionalized with oxime groups II-7.

[0025] Figure 5 is the spectrum X H NMR of the polymer functionalized with oxime groups II-8.

[0026] Figure 6 is the spectrum X H NMR of the polymer functionalized with oxime groups II-9.

[0027] Figure 7 is the spectrum X H and 19 F NMR of the functionalized polymer VII-1.

[0028] Figure 8 is the spectrum X H and 19 F NMR of the functionalized polymer VII-2.

[0029] Figure 9 is the spectrum X H NMR of the functionalized polymer VIII-1.

[0030] Figure 10 is the spectrum X H NMR of the functionalized polymer IX-1.

[0031] Figure 11 is the spectrum X H NMR after nitrosation reaction on a sample of an HDPE bottle.

[0032] Figure 12 is the spectrum X H NMR after nitrosation reaction on a sample of an LDPE plastic bag.

[0033] Figure 13 is the spectrum X H of the functionalized polymer Xl.

[0034] Figure 14 is the spectrum X H of the functionalized polymer X-2. Description of the embodiments

[0035] The invention relates to a method for functionalizing at least one polyolefin I comprising the following steps:

[0036] !) have at least one polyolefin of formula I:

[0038] with : - RI representing a methyl, ethyl or n-butyl group, - R2 representing H, CH3 or OH, - n representing an integer ranging from 0 to 100000, - m representing an integer ranging from 0 to 100000, and - n + m =# 0.

[0039] 2) functionalizing at least one polyolefin I with oxime groups, in order to obtain at least one polyolefin functionalized with oxime groups II,

[0040] 3) reacting the oxime groups present in the at least one functionalized polyolefin with oxime groups II.

[0041] In the context of the invention, "at least one polyolefin I" means exactly one polyolefin I or a mixture of several polyolefins each of formula I. In the following and unless otherwise specified, reference is made to "the polyolefin" instead of "the at least one polyolefin" for reasons of simplicity, but it is understood that one or more polyolefins I may be used within the scope of the invention.

[0042] In the context of the invention, the term "functionalizing a polymer" means introducing at least one chemical function into the polymer, either into the polymer chain (i.e. the function interrupts the polymer chain), or as a substituent on the polymer chain. The chemical functions may, for example, be amine, hydroxylamine, amide, etc. functions, as will be detailed later.

[0043] In the context of the invention, “functionalizing a polyolefin with oxime groups”, “introducing oxime groups onto a polyolefin” and “nitrosylating a polyolefin” are synonymous, and designate the introduction of an oxime group (=N-OH) onto the polyolefin, onto the main chain and / or onto the branched chain(s) if they are present.

[0044] In the context of the invention, the term "polyolefin functionalized with oxime groups" or "nitrosylated polyolefin" means a polyolefin comprising at least one oxime group or substituent. When the polyolefin functionalized with oxime groups comprises several oxime groups or substituents, these groups or substituents can be distributed regularly or statistically on said polyolefin functionalized by oxime groups. According to a particular embodiment, the distribution of the oxime groups can be oriented thanks to the prior introduction of functional groups which make it possible to orient the selectivity during the reaction of introduction of the oxime groups.

[0045] By "oxime group" we mean an =N-OH group.

[0046] According to a preferred embodiment, the polyolefin of formula I is such that RI represents CH3, R2 represents H, CH3 or OH, n represents an integer ranging from 0 to 100000, and m represents an integer ranging from 0 to 100000, it being understood that ne and m are not both equal to 0. In other words, according to this embodiment, the polyolefin I is either a homopolymer of ethylene or propylene, optionally hydroxylated in the terminal position, or a copolymer of ethylene and / or propylene, optionally hydroxylated in the terminal position.

[0047] According to a first embodiment, polyolefin I is a homopolymer. In other words, according to this embodiment, polyolefin I is either polyethylene (i.e. n=0 and m=#0), or polypropylene or polybutylene or polyhexylene optionally hydroxylated in the terminal position (i.e. m=0 and n=#0, and RI represents Me, Et or Bu respectively).

[0048] According to this first embodiment, the polyethylene may be low density polyethylene or high density polyethylene.

[0049] In the context of the invention, "low density polyethylene" or LDPE is produced by free radical polymerization, at high pressures (typically 500 atm to 3000 atm) and high temperatures (typically 200 °C to 300 °C) (see Aggarwal et al., Chem. Rev. 1957, 57, 4, 665-742, and Jubinville et al., Sustain. Mater. Technol. 25, 2020, e00188). This type of polymerization generates numerous branches, both long and short. These are due to inter- and intramolecular chain transfers, respectively, during polymerization. The density of LDPE ranges from 0.915 to 0.933 g.cm 3 .

[0050] Within the scope of the invention, the density of the different polymers can be determined according to ISO 1183-3: 1999.

[0051] In the context of the invention, "high-density polyethylene" or HDPE can be synthesized at lower pressure (typically from 1 atm to 300 atm), for example in the presence of a Ziegler-Natta metal catalyst (see Aggarwal et al., Chem. Rev. 1957, 57, 4, 665-742, and Jubinville et al., Sustain. Mater. Technol. 25, 2020, e00188). This process allows the production of a linear polyethylene that contains little or no branching. The density of HDPE ranges from 0.93 to 0.97 g.cm 3 .

[0052] High-density polyethylene (HDPE) and low-density polyethylene (LDPE) differ in their degree of branching and their crystallinity. High-density polyethylene is more crystalline than low-density polyethylene.

[0053] According to this first embodiment, the polypropylene is preferably an isotactic polypropylene, that is to say that the distribution of the RI substituents is uniform along the main chain of the polymer.

[0054] According to a second embodiment, polyolefin I is a copolymer. In other words, the polyolefin is such that n=#0 and m=#0. The copolymer may be a block or random copolymer.

[0055] Preferably according to this embodiment, the polyolefin is either an optionally hydroxylated copolymer of ethylene and propylene, or a linear low density polyethylene (LLDPE).

[0056] For the purposes of the invention, a "linear low density polyethylene" or LLDPE is a copolymer of ethylene with an olefin selected from propylene, butylene, pentylene, hexylene and octylene. Such a polymer can be obtained by the Ziegler-Natta route (see Aggarwal et al., Chem. Rev. 1957, 57, 4, 665-742, and Jubinville et al., Sustain. Mater. Technol. 25, 2020, e00188). The density of LLDPE ranges from 0.92 to 0.94 g.cm 3 .

[0057] According to an advantageous embodiment of the invention, the crystallinity rate (mass or volume) of polyolefin I ranges from 40% to 95%, preferably from 40% to 80%. The crystallinity rate is a measure of the proportion of crystalline material in the sample studied. In the context of the invention, the crystallinity rate can be determined, for example, by differential scanning calorimetry (DSC), by the ratio between the enthalpy of fusion measured for the sample considered and the enthalpy of fusion of the 100% crystalline sample.

[0058] According to an advantageous embodiment of the invention, the melting temperature of polyolefin I ranges from 120°C to 140°C. In the context of the invention, the melting temperature of polyolefin I can be measured by thermogravimetric analysis (TGA) or by differential scanning calorimetry (DSC). In the context of the invention, the melting temperature corresponds to the temperature measured at the maximum of the peak of the thermal phenomenon corresponding to melting.

[0059] The second step of the method according to the invention consists of introducing at least one oxime function onto the polyolefin I to obtain a polyolefin functionalized with oxime groups II. These oxime functions can be distributed regularly or statistically on the polymer chain.

[0060] Several methods can be envisaged for introducing oxime functions onto polyolefin I (step 2). Below, a preferred method is described and called "method of the invention" but it is understood that another method could be used without departing from the scope of the invention. The method according to the invention makes it possible to easily introduce oxime functions and has the advantage of generating few by-products, which can be easily removed by precipitation and filtration or any other purification method. The method according to the invention makes it possible to obtain polyolefins functionalized with oxime functions II with a molar percentage of incorporation of oxime functions in polyolefin I ranging from 0.5 to 10%. The molar percentage of incorporation of oxime functions is the molar percentage of oxime functions per repeating unit of polyolefin I, as detailed below. It can be determined by X H NMR.

[0061] Preferably, step 2) of the method according to the invention (or "process according to the invention") comprises the reaction, under irradiation at a wavelength belonging to the range from 300 nm to 460 nm, preferably from 300 to 456 nm, preferably from 300 to 450 nm, of the polyolefin I and at least one nitrosation agent III.

[0062] The method according to the invention is carried out under UV or near-visible irradiation, preferably under UV irradiation. According to a preferred embodiment, the reaction is carried out under irradiation at a wavelength ranging from 350 nm to 430 nm, and preferably at a wavelength ranging from 365 nm to 405 nm. Advantageously, the method is carried out at a wavelength corresponding to an absorption line of the nitrosating agent. According to a first particular embodiment of the invention, the reaction is carried out at a wavelength ranging from 365 nm to 370 nm. According to a second particular embodiment of the invention, the reaction is carried out at 405 nm. Preferably, the reaction is carried out at a wavelength of 365 nm. According to another preferred embodiment of the invention, the reaction is carried out at a wavelength of 427 nm.

[0063] Several devices (typically lamps) are known to those skilled in the art and are commercially available for carrying out reactions at these wavelengths. The number and arrangement of these devices around the reactor may vary, according to techniques common to those skilled in the art. Thus, a single device may be used, or several devices arranged (typically two or three) around the reactor, or even a series of devices distributed around the entire perimeter of the reactor.

[0064] The nitrosating agent III that can be used is of the formula:

[0066] with R3 representing a group comprising an N, O or S atom linked to the NO group.

[0067] In other words, the nitrosating agent is a compound that allows the release of the NO* radical under the reaction conditions.

[0068] Advantageously, the nitrosating agent III is of the following formula III-a, III-b or III-c:

[0070] with R4 and R5 being the same or different and independently representing a group selected from (Cl-C6)alkyl, N[(Cl-C6)alkyl]3, CO[(C1-C6)alkyl], SO2Ph, CO-Ph-CF3, or R4 and R5 together forming a (C5-C10) cycloalkyl group optionally substituted by one or more linear or branched (C1-C6) alkyl groups, or a -SO2-Ph-C(CH3)2- group, or a -CO-Ph-CO- group; preferably R4 and R5 being the same or different and independently representing a group selected from (Cl-C6)alkyl, N(CH3)3, CO[(Cl-C6)alkyl], SO2Ph, CO-Ph-CF3, or R4 and R5 together forming a group (C5-C6) cycloalkyl optionally substituted by one or more linear or branched (Cl-C6) alkyl groups, or a -SO2-Ph-C(CH3)2- group, or a -CO-Ph-CO- group,

[0072] with R6 representing a phthalimide group or a linear or branched (Cl-C6)alkyl group, preferably R6 representing a linear or branched (Cl-C6)alkyl group,

[0074] with R7 representing an optionally perfluorinated aromatic or heteroaromatic group, preferably R7 representing a perfluorinated aromatic or heteroaromatic group, more preferably R7 representing a perfluorinated heteroaromatic group.

[0075] Preferably, the at least one nitrosating agent III is chosen from:

[0085] According to a preferred embodiment, only one nitrosating agent is used.

[0086] According to a preferred embodiment, the nitrosating agent III is tert-butylnitrite III-9.

[0087] Preferably, the molar ratio of nitrosating agent III / repeating unit(s) of polyolefin(s) I ranges from 0.01 to 2, preferably 0.1 to 0.5.

[0088] The term "repeating unit" or "repeating unit" of a polymer refers to the smallest constituent unit whose repetition describes the polymer. In the case of a copolymer, it is made up of several distinct repeating units.

[0089] In the context of the invention, the number of moles of repeating units of a polymer is estimated using the method detailed in the document Fazekas et al., Science 375, 545-550 (2022): the number of moles of repeating units of a polymer (homopolymer or copolymer) is calculated by the ratio between the mass of polymer involved and the molar mass of the repeating unit (if homopolymer) or of the repeating units (if copolymer). For the particular case of polyolefins functionalized with oxime groups II, it is considered, for the determination of the number of moles of repeating units, that all the repeating units are functionalized with oxime groups: the number of moles of repeating units of a polyolefin functionalized with oxime groups II is then equal to the ratio between the mass of polyolefin functionalized with oxime groups II and the molar mass of the repeating units including an oxime group.

[0090] According to a preferred embodiment of the invention, the process according to the invention is carried out in the presence of t-BuOH. According to this embodiment, the molar ratio of nitrosation agent(s) III / t-BuOH advantageously ranges from 0.1 to 0.01, and preferably is 0.1. According to this embodiment, the molar ratio of t-BuOH / polyolefin(s) I advantageously ranges from 10 to 1, and preferably is 1.

[0091] Advantageously, the process according to the invention is carried out in at least one solvent allowing the solubilization of at least one polyolefin I, preferably a solvent. The solvent is advantageously chosen from chlorinated solvents such as than chlorobenzene (PhCI), dichlorobenzene (PhCL), trichlorobenzene (PhCI3) and tetrachloroethane (CH2CH2CI4).

[0092] According to a first embodiment, the functionalization reaction of the at least one polyolefin with oxime groups (step 2) of the method according to the invention) is carried out in the absence of catalyst, and in particular in the absence of photocatalyst.

[0093] According to a second embodiment, the functionalization reaction of the at least one polyolefin with oxime groups (step 2) of the method according to the invention) is carried out in the presence of at least one photocatalyst IV, and preferably in the presence of a photocatalyst. According to this embodiment, the molar ratio of photocatalyst(s) IV / nitrosation agent III preferably ranges from 0.2 to 1, and preferably is 1. According to this embodiment, the molar ratio of photocatalyst(s) IV / polyolefin I preferably ranges from 0.02 to 0.1, and preferably is 0.1.

[0094] Examples of photocatalysts that can be used include: 5,7,12,14-pentacenetetrone IV-1, 9-fluorenone IV-2 and acetophenone IV-3:

[0098] According to a particularly preferred embodiment, the photocatalyst is 5,7,12,14-pentacenetetrone IV- 1.

[0099] Advantageously, the reaction allowing the introduction of the oxime groups is carried out at a temperature of up to 130°C, preferably from 100°C to 130°C, and more preferably from 110°C to 130°C.

[0100] Advantageously, the reaction allowing the introduction of the oxime groups is carried out at atmospheric pressure.

[0101] Preferably, the reaction allowing the introduction of the oxime groups is carried out in the absence of O2, typically under an atmosphere of N2 or Ar.

[0102] Advantageously, the reaction is carried out under anhydrous conditions.

[0103] More specifically, the method according to the invention (i.e. step 2) of the method according to the invention) comprises the following steps:

[0104] i) have at least one polyolefin I as defined above, and optionally a photocatalyst as defined above,

[0105] (ii) have at least one nitrosating agent III as defined above,

[0106] iii) adding to the at least one polyolefin I at least one nitrosating agent III, optionally at least one solvent, optionally t-BuOH, and optionally a photocatalyst,

[0107] iv) optionally heating the reaction mixture to a temperature of up to 130°C,

[0108] v) irradiating the reaction mixture at a wavelength as defined previously, in order to obtain a polyolefin functionalized with oxime groups II.

[0109] The contents used and the nature of each of the reagents are as detailed above.

[0110] The process according to the invention may further comprise a step vi), subsequent to step v), of purification of the polyolefin functionalized with oxime groups II. This purification step may for example be carried out by precipitation of the polyolefin functionalized with oxime groups II. The precipitation may be followed by centrifugation(s) and / or filtration(s).

[0111] According to a first embodiment, steps 2) and 3) of the method according to the invention are carried out sequentially: the polyolefin functionalized with oxime II groups obtained in step 2) is isolated (after a possible purification step) then used in step 3).

[0112] According to a second embodiment, steps 2) and 3) of the method according to the invention are carried out successively in the same reactor: the polyolefin functionalized with oxime II groups obtained in step 2) is not isolated (therefore no purification step) and is used in step 3) by adding the reagents to the reaction mixture to carry out the reaction of step 3).

[0113] Advantageously, during step 3), all the oxime groups in the polyolefin functionalized with oxime II groups present react. However, it is conceivable to react only a part of them (for example by introducing deficient reagents), or even to react a part of the oxime groups in a first reaction and a second part (or more) in a second reaction (or more), without departing from the scope of the invention.

[0114] Various reactions can be considered during step 3): reduction, Beckmann rearrangement, hydrolysis, addition of isocyanate or acid chloride, etc.

[0115] According to a first embodiment, step 3) comprises, or even consists of, a reaction of an acid chloride with the oxime groups of the polyolefin functionalized with oxime groups II. Preferably, this reaction is carried out in a basic medium, for example in the presence of triethylamine, N, N- diisopropylethylamine or 1,4-diazabicyclo[2.2.2.]octane. Preferably, this reaction is carried out at a temperature allowing the solubilization of the polyolefin functionalized with oxime groups II, i.e. a temperature generally ranging from 20°C to 70°C, preferably from 40°C to 60°C.

[0116] According to this embodiment, this step advantageously comprises a step of bringing the polyolefin functionalized with oxime groups II into contact with an acid chloride of the following formula V:

[0118] With R8 representing a (Cl-C6)alkyl group, a (Cl-C6)alkylene group, an aromatic group optionally substituted by one or more (Cl-C6)alkyl or (Cl-C6)perfluoroalkyl groups.

[0119] Preferably, R8 represents Ph, p-CF3-Ph, a vinyl group (CH=CH2).

[0120] Preferably, the molar ratio of polyolefin repeat units functionalized with oxime groups II / acid chloride V is from 1 / 0.9 to 1 / 1.3, preferably from 1 / 1 to 1 / 1.2, and more preferably is 1 / 1.1.

[0121] Advantageously, during this reaction, the polyolefin functionalized with oxime groups II is dissolved in at least one solvent, optionally with heating to facilitate the solubilization of the polyolefin functionalized with oxime groups II. Then the acid chloride V and the base are added.

[0122] According to a second embodiment, step 3) comprises, or even consists of, a Beckmann rearrangement reaction. The Beckmann rearrangement is known to enable an oxime group to be transformed into an amide group. This reaction thus makes it possible to obtain a polyolefin functionalized with amide groups. According to this embodiment, the amide functions are incorporated into the polymer chain, i.e. the polymer chain is interrupted by amide functions.

[0123] This Beckmann rearrangement reaction is advantageously carried out in an acidic medium. This Beckmann rearrangement reaction, and the operating conditions that can be used, are well known to those skilled in the art (see for example New J. Chem., 2020, 44, 18530-18572) and will not be detailed here.

[0124] It is then possible to carry out a hydrolysis reaction of the amide functions. The amide functions are then transformed into carboxylic acid functions (COOH). The hydrolysis reaction of the amide functions is usually carried out in an acidic medium. This reaction thus makes it possible to obtain carboxylic acids of variable chain length.

[0125] According to a third embodiment, step 3) comprises, or even consists of, a reduction reaction of the oxime groups into hydroxylamine groups. This reaction then makes it possible to obtain a polyolefin functionalized with hydroxylamine groups.

[0126] Reducing agents and operating conditions that can be used to reduce oxime groups to hydroxylamine groups are known in the state of the art. An example of a reducing agent is NaBH3CN.

[0127] According to a fourth embodiment, step 3) comprises, or even consists of, a reduction reaction of the oxime groups into amine groups. This reaction then makes it possible to obtain a polyolefin functionalized with amine groups.

[0128] Reducing agents and operating conditions that can be used to reduce oxime groups to amine groups are known in the state of the art. An example of a reducing agent is LiAIH4.

[0129] According to a fifth embodiment, step 3) comprises, or even consists of, a hydrolysis reaction, in order to convert the oxime groups to =0.

[0130] Usually, the hydrolysis reaction is carried out by adding water, possibly mixed with a water-miscible solvent such as acetone or formaldehyde or 2,2,2-trifluoroacetophenone for example, in an acidic or basic medium.

[0131] According to a sixth embodiment, step 3) comprises, or even consists of, a reaction of an isocyanate with the oxime groups of the polyolefin functionalized with oxime groups II. Preferably, this reaction is carried out by heating the reaction mixture to a temperature allowing the solubilization of the polyolefin functionalized with oxime groups II, that is to say for example at a temperature ranging from 50°C to 110°C.

[0132] According to this embodiment, this step advantageously comprises a step of bringing the polyolefin functionalized with oxime groups II into contact with an isocyanate of formula VI:

[0134] with R9 and RIO being the same or different and independently representing (C1-C6) alkyl, (C6-C10) aryl, or an isocyanate NCO group; or R9 and RIO together represent a (C5-C8) cycloalkyl group.

[0135] Preferably, the molar ratio of polyolefin functionalized with oxime II groups / isocyanate VI ranges from 1 / 0.8 to 1 / 1.2, preferably from 1 / 0.9 to 1 / 1.1, and more preferably is 1 / 1.

[0136] Alternatively, step 3) includes, or even consists of, a grafting reaction of polymer chains, such as PEG (polyethylene glycol) or PCL (polycaprolactone) chains.

[0137] According to a seventh embodiment, step 3) comprises, or even consists of, a grafting reaction of PEG (polyethylene glycol) chains. According to this embodiment, this step advantageously comprises a step of bringing the polyolefin functionalized with oxime groups II into contact with at least one polyethylene glycol derivative comprising at least one reactive function capable of reacting under the reaction conditions with at least one oxime function of the polyolefin functionalized with oxime groups II. In the context of the invention, a polyethylene glycol “derivative” is a polyethylene glycol on which one or more substituents or functions have been introduced. In the context of the invention, the reactive function of the polyethylene glycol derivative is not a hydroxyl function (OH) present on the polyethylene glycol, but another function capable of reacting under the reaction conditions with at least one oxime function of the polyolefin functionalized with oxime groups II. According to a preferred embodiment, this step comprises bringing the polyolefin functionalized with oxime groups II into contact with a polyethylene glycol derivative comprising at least one reactive function capable of reacting under the reaction conditions with at least one oxime function of the polyolefin functionalized with oxime groups II.Such a polyethylene glycol derivative comprising at least one reactive function may, for example, be a polyethylene glycol acid chloride or a polyethylene glycol comprising at least one carboxylic acid function. Advantageously, the reactive function(s) of the polyethylene glycol derivative are terminal, i.e. at the end of the chain.

[0138] Preferably, this reaction is carried out in the presence of a solvent. Preferably, this reaction is carried out by heating the reaction mixture to a temperature allowing the solubilization of the polyolefin functionalized with oxime groups II, i.e. for example at a temperature ranging from 50 °C to 110 °C.

[0139] Advantageously, the polyethylene glycol or its derivative is introduced in excess. According to this embodiment, the molar ratio of reactive functions of the polyethylene glycol derivative / oxime functions of the polyolefin functionalized with oxime groups II ranges from 1.1 / 1 to 10 / 1, and is preferably 10 / 1. In the context of the invention, the number of moles of reactive functions of the polyethylene glycol derivative is determined as detailed in the document Hôvelmann et al., Macromolecules 2017, 50, 4169-4179. In the context of the invention, the number of moles of oxime functions of the polyolefin functionalized with oxime groups II is determined by the following formula:

[0140]

[0141] With :

[0142] - standards ii representing the number of oxime functions in the polyolefin functionalized with oxime groups II,

[0143] - mu representing the mass of polyolefin functionalized with oxime groups II,

[0144] - P representing the percentage of oxime functionalization of the polyolefin functionalized with oxime groups II,

[0145] - M representing the molar mass of the repeating unit(s) without oxime function of the polyolefin functionalized with oxime groups II (28.05 g / mol if CH2CH2).

[0146] According to an eighth embodiment, step 3) comprises, or even consists of, a PCL (polycaprolactone) chain grafting reaction. According to this embodiment, this step advantageously comprises a step of bringing the polyolefin functionalized with oxime groups II into contact with E-caprolactam. This reaction advantageously takes place in the presence of a catalyst capable of catalyzing the ring-opening polymerization of E-caprolactam, such as stannous octanoate for example.

[0147] Preferably, this reaction is carried out in the presence of a solvent. Preferably, this reaction is carried out by heating the reaction mixture, for example at a temperature ranging from 50°C to 190°C, and typically from 100°C to 170°C, or even from 120°C to 150°C.

[0148] These eight embodiments illustrate that the method according to the invention makes it possible to easily obtain polyolefins (or molecules of smaller molecular weight) comprising a wide variety of functional groups. It is also possible to use the known reactivity of oximes to obtain other functional groups without departing from the scope of the invention. Examples

[0149] Example 1: Study of the effect of t-BuONO and t-BuOH content on the oxime function introduction reaction on high-density polyethylene (HDPE), without photocatalyst

[0150] Five functionalization reactions with HDPE oxime groups were carried out according to the procedure described below.

[0152] HDPE 1-1 (1 eq., marketed by Sigma Aldrich under reference 54799, and having a melt index of 2.2 g / 10 min at 190 °C and 2.16 kg) was introduced under argon into a dry Schlenk tube equipped with a magnetic stirrer. The Schlenk tube was then placed under vacuum. Three cycles of vacuuming and purging the Schlenk tube with argon were performed to remove all traces of air. Chlorobenzene (1.9 mL / mmol of HDPE), te / t-butyl nitrite III-9 and tert-butanol were added under argon. The reaction mixture was then heated at 130 °C for 30 minutes to solubilize the HDPE. The reaction mixture was then irradiated using a Kessil type lamp (370 nm) for 22 hours. After this period, the irradiation was stopped and the reaction mixture was cooled to room temperature (20 °C).The homogeneous solution was then added to acetone with stirring to precipitate the polymer and the medium was then transferred into two Falcon tubes to recover the functionalized polymer by centrifugation (three cycles at 5000 rpm for 10 min with an Eppendorf Centrifuge 5804 centrifuge). The recovered polymer was then placed under high vacuum (< 1 mbar) overnight before being characterized.

[0153] The reaction conditions used are detailed in Table 1 below: Tl

[0154] Table 1:

[0155] The HDPEs functionalized with oxime groups II-1 to II-5 obtained all show the presence of ethylenic double bonds (alkenes) and the proportion of which increases with the quantity of f-BuONO involved. This is attributable to a phenomenon of desaturation of a fraction of the ethylene units. With 2 equivalents of te / t-butyl nitrite, the resulting product is identical to that described during the hydrolysis reaction of the oxime functions into carbonyl functions, i.e. a hydrolysis phenomenon is deduced. With 5 equivalents of te / t-butyl nitrite, the percentage of functionalization is difficult to assess by NMR X H due to the presence of residual water. Qualitatively, however, we note the appearance of multiplets between 4.0 and 5.0 ppm, a sign of the presence of double bonds probably formed by desaturation.

[0156] The obtained HDPEs functionalized with oxime groups II-1 to II-5 were analyzed by NMR. The spectrum XH NMR obtained for the oxime II-5 functionalized HDPE is represented in Figure 1 and detailed below:

[0157] x H NMR (600 MHz, C2D2CI4, 110 °C) δ (ppm) 2.46-2.10 (m), 1.73-1.58 (m), 1.50-1.25 (m), 1.01-0.96 (m).

[0158] A 2D NMR analysis of the HMBC type (proton-carbon correlation in 2 J and 3J) of a sample of HDPE functionalized with oxime II-5 as described above confirmed the presence of oxime groups on the polymer chain. Indeed, a correlation can be observed between the carbons present in alpha and alpha' of the oxime function and the carbon of the oxime function at 162 ppm. This type of chemical shift is characteristic of a quaternary carbon carrying an oxime function. The NMR spectrum is reproduced in Figure 2.

[0159] The percentage of incorporation of oxime functions was then determined by integration of the NMR spectrum signals 1H. Peaks between 0.8 and 2.0 ppm (corresponding to the methylene groups) were integrated over a total of 400 protons. The protons present in the alpha and alpha' positions of the incorporated oxime function appear between 2.1 and 2.5 ppm and are used to determine the molar percentage of oxime function per repeating unit. The results obtained are detailed in Table 2 below:

[0161] The oxime II-5 functionalized HDPE was analyzed by infrared:

[0162] IR (pure, ATR, cm 1 ): 3397, 2914, 2847, 1462, 1261, 1086, 803, 729, 718.

[0163] The obtained oxime II-5 functionalized HDPE was characterized by size exclusion chromatography, or gel permeation chromatography (140 °C, 1,3,5-trichlorobenzene). Size exclusion chromatography or gel permeation chromatography (GPC) was obtained using an Agilent PL-GPC120 (high temperature) with refractive index detection, using polystyrene standard solutions in trichlorobenzene (TCB) with BHT at 140 °C, the instrument being equipped with a Plgel guard column and two Plgel 5 pm mixed-c columns. The results obtained were compared with those obtained with HDPE used as a reagent. The results are shown in Table 3 below.

[0164] Table 3:

[0165] Example 2: introduction of oxime groups on hydroxy polymethylene, without photocatalyst

[0166] 1-2-hydroxypolymethylene was prepared according to the protocol described in Baez et al., Ind. Eng. Chem. Res., 2017, 56, 10366-10383. The obtained 1-2-hydroxypolymethylene has a number-average molecular weight Mn equal to 3428 g / mol (determined by NMR) and equal to 3255 g / mol (determined by GPC). The obtained 1-2-hydroxypolymethylene has a mass-average molecular weight Mw of 3366 g / mol (determined by GPC) and a polydispersity index of 1.03. Size exclusion chromatography or gel permeation chromatography (GPC) was obtained using an Agilent PL-GPC120 (high temperature) instrument with refractive index detection, using standard solutions of polystyrene in trichlorobenzene (TCB) with BHT at 140 °C, the instrument being equipped with a Plgel guard column and two Plgel 5 pm mixed-c columns.

[0167] The 1-2-hydroxypolymethylene was then functionalized with oxime groups, according to the protocol detailed below.

[0169] 1-2-hydroxypolymethylene (97 mg, 3.24 mmol, 1 eq.) was introduced into a dry Schlenk tube equipped with a magnetic stirrer under argon. The Schlenk tube was then placed under vacuum. Three cycles of vacuuming and purging the Schlenk tube with argon were performed to remove all traces of air. Chlorobenzene (8 mL), tert-butanol (3.1 mL, 32.4 mmol, 10 eq.), and nitrite of tert-butyl III-9 (0.04 mL, 0.324 mmol, 0.1 eq.) were then added into the Schlenk tube and this reaction mixture was then heated at 130 °C for 30 minutes to solubilize the hydroxy-polymethylene 1-2. The reaction mixture was then irradiated using a Kessil type lamp (370 nm) for 22 hours. After this period, the irradiation was stopped and the reaction mixture was cooled to room temperature (20 °C). The homogeneous solution was then added into acetone with stirring to precipitate the polymer. The mixture was then transferred into two Falcon tubes to recover the resulting polymer by centrifugation (three cycles at 5000 rpm for 10 min with an Eppendorf Centrifuge 5804 centrifuge). The recovered polymer II-6 obtained was placed under high vacuum (< 1 mbar) for 12 h before being characterized (m = 95 mg, 98% conversion).

[0170] The polymer functionalized with oxime groups II-6 was analyzed by X H NMR:

[0171] 1 H NMR (600 MHz, C2D2CI4, 110 °C) δ (ppm) 3.72-3.70 (m), 2.44-2.24 (m), 1.75-1.65 (m), 1.64-1.62 (m), 1.40-1.23 (m), 1.02-0.97 (m).

[0172] The Spectrum X The obtained RMH is shown in Figure 3.

[0173] The percentage of incorporation of oxime functions was then determined by integration of the NMR spectrum signals 1 H. Considering the polymer composition, the peaks between 0.8 and 2.0 ppm were integrated into a total of 400 protons. The protons present in the alpha and alpha' positions of the incorporated oxime function appear between 2.1 and 2.5 ppm and are used to determine the molar percentage of oxime function per repeating unit. Thus, the molar percentage of incorporation of oxime functions was estimated to be 1.2%.

[0174] The obtained hydroxypolymethylene functionalized with oxime groups II-6 was characterized by size exclusion chromatography, or gel permeation chromatography (140 °C, 1,3,5-trichlorobenzene). Size exclusion chromatography or gel permeation chromatography (GPC) was obtained using an Agilent PL-GPC120 (high temperature) with refractive index detection, using standard solutions of polystyrene in trichlorobenzene (TCB) with BHT at 140 °C, the apparatus being equipped with a Plgel guard column and two Plgel 5 pm mixed-c columns. The results obtained were compared with those obtained with hydroxy-polymethylene 1,2 used as reagent. The results are shown in Table 4, and show a small change in molecular weight distribution.

[0175] Table 4: i i

[0176] Example 3: Introduction of oxime groups on low-density polyethylene (LLDPE), without photocatalyst

[0177] Low density polyethylene (LLDPE) 1-3 was functionalized with oxime groups, according to the protocol detailed below.

[0179] LLDPE 1-3 (1 eq., 120 mg, 4.3 mmol, marketed by Sigma Aldrich under the reference 428078, and having a melt index of 1.0 g / 10 min at 190 °C and 2.16 kg) was introduced under argon into a dry Schlenk tube equipped with a magnetic stirrer. The Schlenk tube was then placed under vacuum. Three cycles of vacuuming and purging with argon of the Schlenk tube were carried out to eliminate all traces of air. Under argon, chlorobenzene (8.3 mL), te / t-butanol (4.1 mL, 43 mmol, 10 eq.) and te / t-butyl nitrite III-9 (0.05 mL, 0.43 mmol, 0.1 eq) were then added. The reaction tube was then heated to 130 °C for 30 minutes to solubilize the LLDPE 1-3. The reaction mixture was then irradiated using a Kessil type lamp (370 nm) for 22 hours. After this period, the irradiation was stopped and the reaction mixture was cooled to room temperature. room temperature (20 °C). The homogeneous solution was then added to acetone with stirring to precipitate the polymer and the medium was then transferred into two Falcon tubes to recover the functionalized polymer by centrifugation (three cycles at 5000 rpm for 10 min with an Eppendorf Centrifuge 5804 centrifuge). The collected polymer II-7 is then placed under high vacuum (< 1 mbar) overnight before being characterized (136 mg, quantitative conversion). The excess mass obtained is due to residual traces of chlorobenzene.

[0180] The polymer functionalized with oxime groups II-7 was analyzed by X H NMR:

[0181] 1 H NMR (600 MHz, C2D2CI4, 110 °C) δ (ppm) 2.46-2.24 (m), 1.68-1.60 (m), 1.52-1.26 (m), 0.98-0.95 (m).

[0182] The Spectrum X The obtained RMH is shown in Figure 4.

[0183] The percentage of incorporation of oxime functions was then determined by integration of the NMR spectrum signals 1 H. Peaks between 0.8 and 2.0 ppm (corresponding to methylene units) were integrated over a total of 400 protons. The protons present in the alpha and alpha' positions of the incorporated oxime function appear between 2.1 and 2.5 ppm and are used to determine the molar percentage of oxime function per repeating unit. Thus, the percentage of incorporation of oxime functions was estimated to be 0.35%.

[0184] The obtained II-7 oxime-functionalized polymer was characterized by size exclusion chromatography, or gel permeation chromatography (140 °C, 1,3,5-trichlorobenzene). Size exclusion chromatography or gel permeation chromatography (GPC) was obtained using an Agilent PL-GPC120 (high temperature) with refractive index detection, using standard solutions of polystyrene in trichlorobenzene (TCB) with BHT at 140 °C, the instrument being equipped with a Plgel guard column and two Plgel 5 pm mixed-c columns. The results obtained were compared with those obtained with LLDPE used as a reagent. The results are shown in Table 5.

[0185] Table 5:

[0186] LLDPE functionalized with oxime II-7 groups was analyzed by infrared:

[0187] IR (pure, ATR, cm 1 ): 2914, 2847, 1462, 1370, 719.

[0188] Example 4: introduction of oxime groups on hydroxy polymethylene, with photocatalyst

[0189] 1-2'-hydroxypolymethylene was prepared according to the protocol described in Baez et al., Ind. Eng. Chem. Res., 2017, 56, 10366-10383. The obtained 1-2' hydroxypolymethylene has a number-average molecular weight Mn equal to 5158 g / mol (determined by GPC). The obtained 1-2' hydroxypolymethylene has a mass-average molecular weight Mw of 5580 g / mol (determined by GPC) and a polydispersity index of 1.08. Size exclusion chromatography or gel permeation chromatography (GPC) was obtained using an Agilent PL-GPC120 (high temperature) with refractive index detection, using standard solutions of polystyrene in trichlorobenzene (TCB) with BHT at 140 °C, the apparatus being equipped with a Plgel guard column and two Plgel 5 pm mixed-c columns.

[0190] The 1-2' hydroxypolymethylene was then functionalized with oxime groups, according to the protocol detailed below.

[0191]

[0192] 1-2'-hydroxy-polymethylene (120 mg, 4.3 mmol, 1 eq.) and 5,7,12,14-pentacenetetrone IV-1 (7 mg, 0.0215 mmol, 0.05 mol%) were introduced under argon in a dry Schlenk tube equipped with a magnetic stirrer. The Schlenk tube was then placed under vacuum. Three cycles of vacuuming and purging the Schlenk tube with argon were performed to remove all traces of air. Chlorobenzene (8.3 mL), tert-butanol (4.1 mL, 43 mmol, 10 eq.), and tert-butyl nitrite III-9 (0.05 mL, 0.43 mmol, 0.1 eq.) were then added to the Schlenk tube under argon, and this reaction mixture was then heated at 130 °C for 30 minutes to solubilize the hydroxy-polymethylene 1,2'. The reaction mixture was then irradiated using a Kessil type lamp (427 nm) for 22 hours (4 cm distance between the reaction tube and the irradiation source). After this period, the irradiation was stopped and the reaction mixture was cooled to room temperature (20 °C). The homogeneous solution was then added to an excess of acetone (20 mL) with stirring in order to precipitate the polymer.The mixture was then transferred into two Falcon tubes to recover the resulting polymer by centrifugation (three cycles at 5000 rpm for 10 min with an Eppendorf Centrifuge 5804 centrifuge). The recovered polymer II-8 obtained was placed under high vacuum (< 1 mbar) for 12 h before being characterized (m = 117 mg, 98% conversion).

[0193] The polymer functionalized with oxime groups II-8 was analyzed by X H NMR:

[0194] 1 H NMR (600 MHz, C2D2CI4, 110 °C) ô (ppm) 3.72-3.70 (m), 2.44-2.24 (m), 1.75-1.65 (m), 1.64-1.62 (m), 1.40-1.23 (m), 1.02-0.97 (m).

[0195] The Spectrum X The obtained RMH is shown in Figure 5.

[0196] The polymer functionalized with oxime groups II-8 was also analyzed by IR:

[0197] IR (pure, ATR, cm 1 ) 3376, 2914, 2847, 2360, 2340, 1675, 1668, 1593, 1462, 1268, 1051, 972, 718, 445.

[0198] The percentage of incorporation of oxime functions was then determined by integration of the NMR spectrum signals 1 H. Considering the polymer composition, the peaks between 0.8 and 2.0 ppm were integrated into a total of 400 protons. The protons present in the alpha and alpha' positions of the oxime function incorporated appear between 2.1 and 2.5 ppm and are used to determine the molar percentage of oxime function per repeating unit. Thus, it has been estimated that the molar percentage of incorporation of oxime functions is 0.9%.

[0199] The obtained hydroxypolymethylene functionalized with II-8 oxime groups was characterized by size exclusion chromatography, or gel permeation chromatography (140 °C, 1,3,5-trichlorobenzene). Size exclusion chromatography or gel permeation chromatography (GPC) was obtained using an Agilent PL-GPC120 (high temperature) with refractive index detection, using standard solutions of polystyrene in trichlorobenzene (TCB) with BHT at 140 °C, the instrument being equipped with a Plgel guard column and two Plgel 5 pm mixed-c columns. The results obtained were compared with those obtained with 1,2'-hydroxypolymethylene used as a reagent. The results are shown in Table 6 below.

[0200] Table 6:

[0201] Example 5: Introduction of oxime groups on high-density polyethylene (HDPE), with photocatalyst

[0202] HDPE 1-1 (marketed by Sigma Aldrich under the reference 54799, and having a melt index of 2.2g / 10 min at 190°C and 2.16 kg) was functionalized with oxime groups, according to the protocol detailed below.

[0204] HDPE 1-1 (120 mg, 4.3 mmol, 1 eq.) and a photocatalyst were introduced under argon into a dry Schlenk tube equipped with a magnetic stirrer. The Schlenk tube was then placed under vacuum. Three cycles of vacuuming and purging the Schlenk tube with argon were performed to remove all traces of air. Chlorobenzene (8.3 mL), tert-butanol (4.1 mL, 43 mmol, 10 eq.), and tert-butyl nitrite III-9 (0.05 mL, 0.43 mmol, 0.1 eq.) were then added to the Schlenk tube under argon, and this reaction mixture was then heated at 130 °C for 30 minutes to solubilize HDPE 1-1. The reaction mixture was then irradiated using a Kessil type lamp for 22 hours (4 cm distance between the reaction tube and the irradiation source). After this period, the irradiation was stopped and the reaction mixture was cooled to room temperature (20 °C).The homogeneous solution was then added to an excess of acetone (20 mL) with stirring to precipitate the polymer. The mixture was then transferred into two Falcon tubes to recover the resulting polymer by centrifugation (three cycles at 5000 rpm for 10 min with an Eppendorf Centrifuge 5804 centrifuge). The resulting polymer was then placed under high vacuum (< 1 mbar) for 12 h before being characterized.

[0205] The recovered oxime functionalized polymers II-9 to 11-16 were obtained according to Table 7 below.

[0206] Table 7:

[0207] The polymer functionalized with oxime groups 11-10 was analyzed by X H NMR:

[0208] 1 H NMR (600 MHz, C2D2CI4, 110 °C) ô (ppm) 2.46-2.10 (m), 1.73-1.58 (m), 1.50-1.25 (m), 1.01-0.96 (m).

[0209] The Spectrum X The obtained RMH is shown in Figure 6.

[0210] The polymer functionalized with oxime groups 11-10 was also analyzed by IR:

[0211] IR (pure, ATR, cm 1 ) 2914, 2847, 1715, 1668, 1602, 1462, 1152, 729, 718, 501.

[0212] The oxime-functionalized polymer 11-16 was also analyzed by X H NMR:

[0213] x H NMR (600 MHz, C2D2CI4, 110 °C) ô 2.46-2.24 (m), 1.68-1.61 (m), 1.50-1.39 (m), 1.01-0.99 (m).

[0214] The polymer functionalized with oxime groups 11-16 was also analyzed by IR:

[0215] IR (pure, ATR, cm 1 ) 2914, 2847, 1715, 1668, 1602, 1462, 1152, 729, 718, 501.

[0216] The percentage of incorporation of oxime functions in polymers II-9 to 11-16 was then determined by integration of the NMR spectrum signals 1H. Considering the polymer composition, the peaks between 0.8 and 2.0 ppm were integrated into a total of 400 protons. The protons present in the alpha and alpha' positions of the incorporated oxime function appear between 2.1 and 2.5 ppm and are used to determine the molar percentage of oxime function per repeating unit. The results are detailed in Table 7 above.

[0217] The obtained 11-10 and 11-16 oxime functionalized HDPEs were characterized by size exclusion chromatography, or gel permeation chromatography (140 °C, 1,3,5-trichlorobenzene). Size exclusion chromatography or gel permeation chromatography (GPC) was obtained using an Agilent PL-GPC120 (high temperature) with refractive index detection, using standard solutions of polystyrene in trichlorobenzene (TCB) with BHT at 140 °C, the apparatus being equipped with a Plgel guard column and two Plgel 5 pm mixed-c columns. The results obtained were compared with those obtained with 1,2'-hydroxypolymethylene used as a reagent. The results are shown in Table 8 below.

[0218] Table 8:

[0219] Example 6: Benzoylation of nitrosylated hydroxy-poly methylene II-6

[0220] The benzoylation reaction was carried out according to the procedure described below.

[0221]

[0222] Nitrosylated hydroxy-polymethylene II-6 (21 mg, 0.4 mmol, eq) was introduced into a two-necked, round-bottom flask equipped with a magnetic stirrer and a condenser. The flask was then placed under vacuum to perform 3 vacuum / argon cycles. Under argon, chlorobenzene (2 mL) and dichloromethane (3 mL) were added. The flask was then heated at 100 °C for 30 minutes to dissolve the polymer. 4-Trifluoromethyl benzoyl chloride (0.07 mL, 0.44 mmol, 1.1 eq) and triethylamine (0.07 mL, 0.48 mmol) were then added. The reaction mixture was left stirring overnight, before being cooled to room temperature (20 °C). A saturated solution of NaHCO3 (5 mL) was then added. The homogeneous solution was then added to acetone with stirring to precipitate the polymer and the medium was transferred into two Falcon tubes to recover the resulting polymer by centrifugation (three cycles at 5000 rpm for 10 min with an Eppendorf Centrifuge 5804 centrifuge). The functionalized polymer VII-1 thus recovered is placed under high vacuum (< 1 mbar) overnight before being characterized (23 mg, 109% conversion). The excess mass obtained is due to residual traces of chlorobenzene.

[0223] The functionalized polymer VII-1 was analyzed by NMR. The spectra X H and 1 9 F NMR are represented in Figure 7 and are detailed below:

[0224] xH RMN (600 MHz, C2D2CI4, 110 °C) ô (ppm) 8.24-8.22 (m), 7.83-7.79 (m), 4.47-4.45 (t), 2.58-2.50 (m), 1.92-1.88 (m), 1.79-1.59 (m), 1.57-1.22 (m), 1.02- 0.96 (m).

[0225] 19 F RMN (600 MHz, C2D2CI4, 110 °C) ô (ppm) -62. 48, -62.56 (d, 3F)

[0226] The obtained functionalized polymer VII-1 was characterized by size exclusion chromatography, or gel permeation chromatography (140 °C, 1,3,5-trichlorobenzene). Size exclusion chromatography or gel permeation chromatography (GPC) was obtained using an Agilent PL-GPC120 (high temperature) with refractive index detection, using standard solutions of polystyrene in trichlorobenzene (TCB) with BHT at 140 °C, the instrument being equipped with a Plgel guard column and two Plgel 5 pm mixed-c columns. The results obtained were compared with the oxime functionalized polymer II-6 used as a reagent. The results are shown in Table 9 below.

[0227] Table 9:

[0228] Example 7: Benzoylation of nitrosylated H DPE II-3

[0229] The benzoylation reaction of nitrosylated HDPE II-3 was carried out according to the procedure described below:

[0230]

[0231] Nitrosylated H DPE II-3 (28 mg, 0.49 mmol, 1 eq) was introduced into a two-necked round-bottom flask equipped with a magnetic stirrer and a condenser. The flask was then placed under vacuum. Three vacuum / argon cycles were then performed. Under argon, chlorobenzene (5 mL) and dichloromethane (3 mL) were added. The reaction flask was then heated at 100 °C for 30 min to dissolve the oxime-functionalized polyolefin II-3. 4-Trifluoromethyl benzoyl chloride VI (0.08 mL, 0.54 mmol, 1.1 eq) and triethylamine (0.08 mL, 0.59 mmol, 1.2 eq) were then added. The reaction was stirred overnight. The reaction mixture was then cooled to room temperature and saturated NaHCCh solution (5 mL) was added.The homogeneous solution was then added to acetone with stirring to precipitate the polymer and the mixture was then transferred into two Falcon tubes to recover the functionalized polyolefin by centrifugation (three cycles). The product VII-2 obtained is placed under high vacuum (< 1 mbar), overnight before being characterized (27 mg, 96% conversion).

[0232] The functionalized polymer VII-2 was analyzed by NMR. The spectra X H and 1 9 F NMR are represented in Figure 8 and are detailed below:

[0233] x H NMR (600 MHz, C2D2CI4, 110 °C) ô 8.24-8.22 (m), 7.83-7.81 (m), 2.58-2.43 (m), 1.79-1.65 (m), 1.52-1.26 (m), 1.01-0.96 (m).

[0234] 19 F NMR (600 MHz, C2D2CI4, 110 °C) ô -62. 60 (d, 3F).

[0235] Example 8: Urethaneization of nitrosylated HDPE II-3

[0236] The urethanization reaction of nitrosylated HDPE II-3 was carried out according to the procedure described below.

[0237]

[0238] Nitrosylated HDPE II-3 (20 mg, 0.35 mmol, 1 eq) was introduced into a two-necked round-bottom flask equipped with a magnetic stirrer and a condenser. The flask was then placed under vacuum and then performed three vacuum / argon cycles. Under argon, chlorobenzene (4 mL) and dichloromethane (4 mL) were added. The reaction flask was then heated at 100 °C for 30 minutes to dissolve the polymer. Cyclohexylisocyanate VI-1 (0.05 mL, 0.35 mmol, 1 eq) was added. The reaction mixture was left stirring overnight and then cooled to room temperature (20 °C). The homogeneous solution was then added to acetone with stirring to precipitate the polymer. The medium was then transferred into two Falcon tubes to recover the functionalized polyolefin by centrifugation (three cycles at 5000 rpm for 10 min with an Eppendorf Centrifuge 5804 centrifuge).The recovered polymer VIII-1 was placed under high vacuum (< 1 mbar) overnight before being characterized (25 mg, 125% conversion). The excess mass obtained is due to residual traces of chlorobenzene.

[0239] The functionalized polymer VIII-1 was analyzed by NMR. The spectrum X H NMR is shown in Figure 9 and is detailed below:

[0240] x H NMR (600 MHz, C2D2CI4, 110 °C) ô 4.03 (br), 3.61-3.55 (m), 2.03-2.00 (m), 1.82-1.77 (m), 1.71-1.68 (m), 1.50-1.21 (m), 1.01-1.96 (m).

[0241] Example 9: introduction of oxime functions on HDPE then hydrolysis

[0242] Oxime functions were introduced onto HDPE and then these were hydrolyzed to obtain the corresponding keto-polyethylene. ) t-BuONO. t-BuOH, PhC 370 1 0

[0243]

[0244] HDPE 1-1 (1 eq., marketed by Sigma Aldrich under the reference 54799, and having a melt index of 2.2 g / 10 min at 190 °C and 2.16 kg) was introduced under argon into a dry Schlenk tube equipped with a magnetic stirrer. The Schlenk tube was then placed under vacuum. Three cycles of vacuuming and purging with argon of the Schlenk tube were carried out to eliminate all traces of air. Chlorobenzene (1.9 mL / mmol of HDPE), te / t-butyl nitrite III-9 (x eq.) and te / t-butanol (y eq.) were added under argon. The reaction mixture was then heated at 130 °C for 30 minutes to solubilize the HDPE. The reaction mixture was then irradiated using a Kessil type lamp (370 nm) for 22 hours. After this period, the irradiation was stopped and the reaction mixture was cooled to a temperature of (50 °C).The reaction mixture was then added to acetone (20 mL) with stirring and heated at 50°C for 1 hour. The reaction mixture was then cooled to room temperature to precipitate the polymer and then the reaction mixture was transferred into two Falcon tubes to recover the functionalized polymer by centrifugation (three cycles at 5000 rpm for 10 min with an Eppendorf centrifuge). Centrifuge 5804). The recovered keto-polyethylene IX-1 was then placed under high vacuum (< 1 mbar) overnight before being characterized.

[0245] Keto-polyethylene IX-1 was analyzed by NMR. The spectrum X H NMR is shown in Figure 10 and is detailed below:

[0246] x H NMR (600 MHz, C2D2CI4, 110 °C) ô 2.45-2.40 (m), 1.80-1.60 (m), 1.52-1.26 (m), 0.98-0.95 (m).

[0247] Example 10: Nitrosation reaction on a sample of an HDPE bottle after use

[0248] An HDPE bottle sample (132 mg, 4.71 mmol) was introduced under argon into a dry Schlenk tube equipped with a magnetic stirrer. The Schlenk tube was then placed under vacuum. Three cycles of vacuuming and purging the Schlenk tube with argon were performed to remove all traces of air. Chlorobenzene (8.5 mL), te / t-butanol (4.5 mL, 47.8 mmol), and te / t-butyl nitrite (0.07 mL, 0.471 mmol) were added to the Schlenk tube under argon. The reaction mixture was then heated at 130 °C for 30 minutes to solubilize the sample. The reaction mixture was then irradiated using a Kessil lamp (370 nm) for 22 hours. After this period, the irradiation was stopped and the reaction mixture cooled to room temperature (20 °C). The reaction mixture was then added to acetone with stirring to precipitate the polymer.The mixture was then transferred into two Falcon tubes to recover the functionalized polymer by centrifugation (three cycles at 5000 rpm for 10 min with an Eppendorf Centrifuge 5804 centrifuge). The recovered polymer was then placed under high vacuum (< 1 mbar) for 12 h before being characterized (122 mg, 92% conversion).

[0249] The obtained material was characterized by X H NMR:

[0250] x H NMR (600 MHz, C2D2CI4, 110 °C) ô 2.51-2.37 (m), 2.28-2.04 (m), 1.80-1.60 (m), 1.50-1.25 (m), 1.02-0.95 (m).

[0251] The obtained NMR spectrum is shown in Figure 11.

[0252] The percentage of incorporation of oxime functions was then determined by integration of the signals from the NMR spectrum 1H. Considering the polymer composition, the peaks between 0.8 and 2.0 ppm were integrated into a total of 400 protons. The protons present in alpha and alpha' of the incorporated oxime function which appear between 2.1 and 2.5 ppm are used to determine the molar % of nitrosation per repeating unit. Thus, it was estimated that the molar percentage of incorporation of oxime functions is 0.7% and that the molar ratio of oxime functions: ketone functions is 7:3.

[0253] Example 11: Nitrosation reaction on a sample of LDPE plastic bag

[0254] A sample of LDPE plastic bag (140 mg, 4.3 mmol) was introduced under argon into a dry Schlenk tube equipped with a magnetic stirrer. The Schlenk tube was then placed under vacuum. Three cycles of vacuuming and purging the Schlenk tube with argon were performed to remove all traces of air. Chlorobenzene (8.3 mL), te / t-butanol (4.1 mL, 43 mmol), and te / t-butyl nitrite (0.05 mL, 0.43 mmol) were then added to the Schlenk tube under argon. The reaction mixture was then heated at 130 °C for 30 minutes to solubilize the sample. The reaction mixture was then irradiated using a Kessil lamp (370 nm) for 22 hours. After this period, the irradiation was stopped and the reaction mixture cooled to room temperature (20 °C). The reaction mixture was then added to acetone with stirring to precipitate the polymer.The mixture was then transferred into two Falcon tubes to recover the functionalized polymer by centrifugation (three cycles at 5000 rpm for 10 min with an Eppendorf Centrifuge 5804 centrifuge). The recovered polymer was then placed under high vacuum (< 1 mbar) for 12 h before being characterized (131 mg, 94% conversion).

[0255] The obtained material was characterized by X H NMR:

[0256] x H NMR (600 MHz, C2D2CI4, 110 °C) δ (ppm) 2.58-2.49 (m), 2.45-2.42 (m), 2.28-2.09 (m), 1.83-1.59 (m), 1.49-1.29 (m), 1.00-0.96 (m).

[0257] The obtained NMR spectrum is shown in Figure 12.

[0258] The percentage of incorporation of oxime functions was then determined by integration of the signals from the NMR spectrum 1H. Considering the polymer composition, the peaks between 0.8 and 2.0 ppm were integrated into a total of 400 protons. The protons present in alpha and alpha' of the incorporated oxime function which appear between 2.1 and 2.5 ppm are used to determine the molar % of nitrosation per repeating unit. Thus, it was determined that the molar percentage of incorporation of the oxime functions is 0.65%.

[0259] Example 12: Introduction of PEG chains on the oxime-functionalized polyolefin II-9

[0260] First, α-methoxy-β-acyl polyethylene glycol chloride Xc was previously obtained according to the following procedure.

[0262] 25 g of α-methoxy-ε-hydroxyl polyethylene glycol Xa (12.5 mmol, Mp 2000, sold by TCI under the reference P2186,) was solubilized in 450 mL of distilled water with sodium bromide (2.95 g, 28.75 mmol, 2.3 equivalents) and TEMPO (0.282 g, 1.8 mmol, 0.15 equivalents). The reaction was then heated to 40°C to allow complete solubilization of TEMPO. After the reaction mixture had cooled to room temperature, sodium hypochlorite solution (140 mL, 340 mmol, 27.2 equivalents) was added. The reaction was then stirred for 30 minutes and was then cooled to 0°C using an ice bath. A sodium hydroxide solution was then added (4 M, 140 mL), followed by a sodium bisulfite solution (40%, 150 mL). The solution was then stirred for 30 minutes. The reaction was then acidified to a pH of 2 using a 5 M sodium hydroxide solution. hydrochloric acid. The desired product was then obtained by extraction with dichloromethane (300 mL). The collected organic phases were then washed several times with water. The organic phase was then concentrated under reduced pressure. A white solid was then obtained and dried under high vacuum for 24 hours. A mass of 23.7 g of Xb was obtained (94% yield).

[0263] Xb was characterized by NMR and IR:

[0264] x H NMR (300 MHz, CDCI3) ô (ppm) 4.07 (s, 2H), 3.82-3.79 (m, 2H), 3.57 (m, 180H), 3.30 (m, 3H).

[0265] 13 C NMR (75 MHz, CDCI3) ô (ppm) 171.51, 70.49, 58.95.

[0266] IR (pure, ATR, cm 1 ) 2880, 2859, 2739, 1962, 1737, 1466, 1369, 1340, 1279, 1239, 1146, 1099, 1059, 946, 841, 670, 582, 508.

[0267] In a 50 mL flask equipped with a magnetic stir bar was added α-methoxy-β-carboxylic acid polyethylene glycol Xb (Mp 2000, 346 mg, 0.17 mmol, 1 equivalent). The flask was then placed under vacuum. Three vacuum / argon cycles were then performed. Under argon, dichloromethane (10 mL) was added. The reaction flask was then cooled to 0 °C using an ice bath. Oxalyl chloride (1.5 mL, 17.3 mmol, 100 equivalents) was added using a syringe, followed by the addition of DMF (0.01 mL, 0.017 mmol, 0.1 equivalent). The reaction mixture was then stirred at room temperature for 24 h and then concentrated under reduced pressure. A caramel-colored solid was obtained and dried under high vacuum overnight. A mass of 355 mg of product Xc was obtained (Quantitative conversion).

[0268] Xc was analyzed by NMR and IR:

[0269] xH NMR (300 MHz, CDCI3) ô (ppm) 4.51 (s, 2H), 3.64 (m, 180H), 3.38 (m, 3H).

[0270] 13 C NMR (75 MHz, CDCI3) ô (ppm) 171.68, 70.63, 59.08.

[0271] IR (pure, ATR, cm 1 ) 3395, 2876, 1960, 1726, 1648, 1465, 1359, 1340, 1278, 1240, 1144, 1099, 1059, 946, 841, 526, 507.

[0272] Then, the nitrosylated HDPE II-9 was functionalized with PEG chains, according to the following procedure.

[0273]

[0274] Nitrosylated HDPE (50 mg, 0.01 mmol) and α-methoxy-ε-acyl chloride polyethylene glycol Mp 2000 (200 mg, 0.1 mmol) were introduced into a round-bottom Bicol flask equipped with a magnetic stirrer and a condenser. The flask was then placed under vacuum and three vacuum / argon cycles were performed. Under argon, chlorobenzene (10 mL) was added. The reaction flask was then heated to 100 °C for 30 minutes to dissolve the polyolefin. The reaction medium was then maintained at a temperature of 90 °C. Triethylamine (0.02 mL, 0.12 mmol) was then added. The reaction was allowed to stir for 24 hours. The reaction mixture was then cooled to room temperature and saturated NaHCO3 solution (5 mL) was added.The homogeneous solution was then added to acetone with stirring to precipitate the polymer and the medium was transferred into two Falcon tubes to recover the functionalized polyolefin by centrifugation (three cycles). The resulting polymer Xl was placed under high vacuum (< 1 mbar) overnight before being characterized (44 mg, 88% conversion).

[0275] The functionalized polymer Xl was analyzed by NMR. The spectrum X H NMR is shown in Figure 13 and is detailed below:

[0276] x H NMR (600 MHz, C2D2CI4, 110 °C) ô (ppm) ô 4.16 (m), 3.72 (m), 3.46 (m), 2.46-2.42 (m), 2.27-2.24 (m), 1.68-1.59 (m), 1.50-1.25 (m), 1.02-0.97 (m).

[0277] The functionalized polymer Xl was also analyzed by IR:

[0278] IR (pure, ATR, cm 1 ) 2915, 2847, 1723, 1670, 1476, 1462, 1108, 730, 719.

[0279] The functionalized polymer Xl obtained was characterized by size exclusion chromatography, or gel permeation chromatography (140 °C, 1,3,5- Size exclusion chromatography or gel permeation chromatography (GPC) was performed using an Agilent PL-GPC120 (high temperature) with refractive index detection, using polystyrene standard solutions in trichlorobenzene (TCB) with BHT at 140 °C, the instrument being equipped with a Plgel guard column and two Plgel 5 pm mixed-c columns.

[0280] SEC (1,3,5-trichlorobenzene (TCB, 140 °C) Mn = 15439 g / mol, dispersity (£>) = 4.897.

[0281] Example 13: Introduction of PCL chains on an oxime-functionalized polyolefin

[0282] The oxime 11-16 functionalized HDPE was functionalized with PCL chains.

[0284] This reaction was carried out in a glove box. In a sealed tube equipped with a magnetic stirrer, 11-16-nitrosylated HDPE (1.2 mol%, 50 mg, 0.02 mmol), E-caprolactone (0.22 mL, 2 mmol), stannous octanoate (6 μL, 0.002 mmol), and 10 mL of toluene were introduced. The sealed tube was then closed and heated at 140 °C for 2 days with stirring. The reaction mixture was then cooled to room temperature. The homogeneous solution was then added to acetone (10 mL) with stirring to precipitate the polymer, and the medium was then transferred to two Falcon tubes to recover the post-functionalized polyolefin by centrifugation (three cycles). The collected polymer X-2 was placed under high vacuum (< 1 mbar) for 12h before being characterized (129 mg, 68% conversion of E-caprolactone, 34% yield of PCL chain grafting).

[0285] Polymer X-2 was analyzed by NMR. The spectrum XH is represented in Figure 14 and is detailed below:

[0286] X H NMR (600 MHz, C2D2CI4, 110 °C) ô (ppm) ô 4.17 (m), 3.72 (m), 2.50-2.48 (m), 2.39 (m), 2.26 (m), 1.78-1.72 (m), 1.53-1.48 (m), 1.50-1.25 (m), 1.02-0.97 (m).

[0287] The functionalized polymer X-2 was also analyzed by infrared:

[0288] IR (pure, ATR, cm 1 ) 2915, 2847, 1726, 1462, 1364, 1239, 1167, 1104, 961, 729, 719, 578.

[0289] The obtained functionalized polymer X-2 was characterized by size exclusion chromatography, or gel permeation chromatography (140 °C, 1,3,5-trichlorobenzene). Size exclusion chromatography or gel permeation chromatography (GPC) was obtained using an Agilent PL- GPC120 (high temperature) with refractive index detection, using polystyrene standard solutions in trichlorobenzene (TCB) with BHT at 140 °C, the apparatus being equipped with a Plgel guard column and two Plgel 5 pm mixed-c columns.

[0290] SEC (1,3,5-trichlorobenzene (TCB, 140 °C) Mn = 11996 g / mol, dispersity (£>) = 8.345.

Claims

Claims

1. Method for functionalizing at least one polyolefin (I), comprising the following steps: 1) have at least one polyolefin of formula (I): with : - RI representing a methyl, ethyl or n-butyl group, - R2 representing H, CH3 or OH, - n representing an integer ranging from 0 to 100000, - m representing an integer ranging from 0 to 100000, and - n + m =# 0, 2) functionalizing the at least one polyolefin (I) with oxime groups, in order to obtain at least one polyolefin functionalized with oxime groups (II), 3) reacting the oxime groups present in the at least one functionalized polyolefin with oxime groups (II).

2. The method of claim 1, wherein the step 2) comprises the reaction, under irradiation at a wavelength belonging to the range from 300 nm to 456 nm, preferably from 300 nm to 450 nm, of at least one polyolefin of formula (I) and at least one nitrosating agent (III).

3. A method according to claim 2, wherein the nitrosating agent (III) is of formula (III-a), (III-b) or (III-c) below: with : - R4 and R5 being identical or different and independently representing one from the other a group selected from (Cl-C6)alkyl, N[(Cl-C6)alkyl]3, CO[(Cl-C6)alkyl], SO2Ph, CO-Ph-CF3, - or R4 and R5 together forming a (C5-C10) cycloalkyl group optionally substituted by one or more linear or branched (C1-C6) alkyl groups, or a -SO2-Ph-C(CH3)2- group, or a -CO-Ph-CO- group, - R6 representing a phthalimide group or a linear or branched (Cl-C6)alkyl group, - R7 representing an aromatic or heteroaromatic group possibly perfluorinated.

4. Method according to claim 2 or 3 according to which the at least one nitrosating agent is chosen from: 4),

5. Method according to any one of claims 2 to 4 according to which the molar ratio of nitrosating agent(s) (III) / polyolefin repeating unit(s) (I) ranges from 0.01 to 2, preferably from 0.1 to 0.

5.

6. A method according to any one of claims 2 to 5, wherein the reaction in step 2) is carried out in the presence of t-BuOH.

7. Method according to the preceding claim, according to which the molar ratio nitrosation agent(s) (III) / t-BuOH ranges from 0.1 to 0.01, preferably is 0.

1.

8. A method according to any one of claims 2 to 7, wherein the reaction in step 2) is carried out in the absence of photocatalyst.

9. Method according to any one of claims 2 to 7, according to which the reaction in step 2) is carried out in the presence of at least one photocatalyst (IV).

10. Method according to the preceding claim, according to which the at least one photocatalyst is chosen from 5,7,12,14-pentacenetetrone (IV-1), 9-fluorenone (IV-2) and acetophenone (IV-3).

11. A method according to any one of claims 2 to 10, wherein the reaction is carried out at a temperature of up to 130°C.

12. Method according to any one of the preceding claims, according to which the at least one polyolefin (I) is chosen from polyethylene and polypropylene optionally hydroxylated in the terminal position, or an ethylene-propylene copolymer optionally hydroxylated in the terminal position.

13. A method according to any preceding claim, wherein step 3) comprises reacting at least one acid chloride with the oxime groups of the oxime-functionalized polyolefin (II).

14. A method according to any one of claims 1 to 12, wherein step 3) comprises a Beckmann rearrangement.

15. Method according to the preceding claim, according to which step 3) comprises a hydrolysis reaction in an acid medium, subsequent to the Beckmann rearrangement.

16. A method according to any one of claims 1 to 12, wherein step 3) comprises reducing the oxime groups of the polyolefin functionalized with oxime groups (II).

17. Method according to any one of claims 1 to 12, according to which step 3) comprises a hydrolysis reaction in an acid medium.

18. Method according to any one of claims 1 to 12, according to which step 3) comprises the reaction of at least one isocyanate with the oxime groups of the polyolefin functionalized with oxime groups (II).

19. Method according to any one of claims 1 to 12, according to which step 3) comprises a grafting reaction of polymer chains, such as polyethylene glycol or polycaprolactone chains.

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