Method for preparing and purifying a polymer comprising disulfide bridges

Abstract

The present invention relates to a process for preparing and purifying a polymer comprising disulfide bridges.

Description

[0001] Description

[0002] Title: Process for the preparation and purification of a polymer comprising disulfide bridges

[0003] Technical field of the invention

[0004] The present invention relates to the preparation and purification of polymers comprising disulfide bridges. More particularly, the present invention relates to the preparation and purification of poly(1,8-dimercapto-3,6-dioxaoctane).

[0005] Technological background of the invention

[0006] The next generation of lithium-ion secondary batteries aims to use a solid electrolyte instead of a liquid electrolyte. This allows for higher energy density and improved safety compared to traditional lithium-ion batteries. All-solid-state batteries are also more resistant to thermal runaway, a major concern with traditional lithium-ion batteries. They have the potential to enable further miniaturization and integration of electronic devices, as well as improve the range and safety of electric vehicles. However, the commercialization of solid-state batteries is still in its early stages, and technical challenges remain before they can be widely adopted.

[0007] Solid polymer electrolytes have been investigated as alternative electrolytes for Li-ion batteries due to their good mechanical strength, high ionic conductivity, and safety advantages. They consist of a polymer matrix containing conductive salts of Li ions. The polymers form a flexible and stable membrane that can separate the cathode and anode of the battery, while allowing the Li-ions to move freely through the electrolyte. This can improve battery performance and stability, but some challenges remain, such as a low Li-ion transfer number and a limited operating temperature range.

[0008] One of the most widely used polymers is polyethylene oxide (PEO). Due to its crystalline nature (melting point between 60 and 70 °C), PEO has low ionic conductivity at room temperature. Therefore, it is primarily used at high temperatures to increase conductivity (in molten form). Operating temperatures are significantly impacted and limited to high-temperature applications. However, an all-solid-state battery may be necessary in countries with low winter temperatures, requiring conductivity even below 0 °C. Consequently, there is still a need to develop new all-solid-state batteries incorporating novel polymers. Sulfur-containing polymers or those containing disulfide bonds are being considered. Nevertheless, the preparation of these types of polymers can be complex.For the intended applications, it is important to control the molecular weight of the polymers while limiting the presence of impurities. The present invention makes it possible to solve, at least in part, the problems identified above by providing a process for preparing a polymer suitable for use in novel all-solid-state battery applications.

[0009] Summary of the invention

[0010] According to a first aspect, the present invention relates to a process for preparing a PI polymer comprising at least one disulfide bond, said process comprising: a) A polymerization step, preferably in aqueous medium, by adding a solution of a peroxide to a dispersion, preferably aqueous, comprising at least one compound of formula (I) HS-R-SH and a base for forming said PI polymer comprising at least one segment — (SRS)-(SRS)- with R being, independently for each unit -(SRS)-, a hydrocarbon substituent having a molecular mass less than 1000 g / mol.

[0011] According to a preferred embodiment, said PI polymer has a weight average molecular mass Mw, expressed in kg / mol, between: ((2226 + 1951754*C1)*O, 00055) < Mw < ((2226 + 1951754*C1)*O, 00145); Cl being the concentration of said peroxide solution, expressed in % by weight.

[0012] According to a preferred embodiment, step a) is carried out at a temperature between 10°C and 50°C.

[0013] According to a preferred embodiment, said process includes a step b) of purifying said PI polymer obtained in step a) comprising a step of removing said base used in step a) or a step of filtering said PI polymer or a combination of both.

[0014] According to a preferred embodiment, the step of removing the base used in step a) is carried out by heat-treating the PI polymer at a temperature of 20°C to 100°C and a pressure of 0.01 bar to 1 bar, prior to and / or after the filtration of the PI polymer. According to a preferred embodiment, the filtration step of the PI polymer is carried out using a filtration device comprising a membrane made of at least one fluorinated polymer or a polyolefin.

[0015] According to a preferred embodiment, said membrane comprises pores of a size from 1 nm to 100 nm, advantageously from 1 nm to 75 nm, preferably from 2 nm to 50 nm, more preferably from 3 nm to 25 nm, in particular from 3 nm to 10 nm.

[0016] According to a preferred embodiment, said base used in step a) has a saturated vapor pressure greater than lkPa at 20°C.

[0017] According to a preferred embodiment, said peroxide used in step a) is selected from the group consisting of organic peroxides, percarbonates, perborates, persulfates, perphosphates and hydroperoxides.

[0018] According to a preferred embodiment, said compound of formula (I) is HS-R-SH in which R is a hydrocarbon comprising at least one ether, ester or carbonyl functional group.

[0019] According to a preferred embodiment, R is of the formula -[R 1 -X-] n -[Y] m - in which

[0020] R 1 is, independently for each unit n, selected from the group consisting of Ci-Cio alkyl, C3-C10 cycloalkyl, Cg-Cu aryl;

[0021] X is O, C(O), C(O)O, OC(O); n is an integer from 1 to 20;

[0022] Y is, independently for each unit m, selected from the group consisting of C1-C10 alkyl, C3-C10 cycloalkyl, Cg-Cu aryl; m is an integer from 0 to 20.

[0023] According to a preferred embodiment, R has the formula -R 2 -GOLD 3 -GOLD 4 - in which R 2 , R 3 and R 4 , are independently of each other, selected from the group consisting of C1-C10 alkyl, C3-C10 cycloalkyl, Cg-Ci2 aryl.

[0024] According to a preferred embodiment, said compound of formula (I) is l,8-dimercapto-3,6-dioxaoctane and in that said polymer PI is poly(l,8-dimercapto-3,6-dioxaoctane).

[0025] According to a preferred embodiment, said base is selected from the group consisting of LiOH, NaOH, KOH, CsOH, RbOH, Mg(OH)2, Ca(OH)2, NH3 x (C n H2n +i)3-x with n being an integer from 1 to 10 and x an integer from 0 to 3, N,N-Diisopropylethylamine, morpholine, pyridine, pyrrolidine, Piperidine, piperazine, 4-Methylmorpholine, 1,8-Diazabicyclo(5.4.0)undec-7-ene, 6-(Dibutylamino)-1,8-diazabicyclo[5.4.0]undec-7-ene, 1,8-Diazabicyclo[5.4.0]undec-7-ene bonded to polystyrene, 1,5,7-Triazabicyclo[4.4.0]dec-5-ene, 7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1,1,3,3-Tetramethylguanidine, 2-tert-Butyl-l,l,3,3-tetramethylguanidine, 1,5,7-Triazabicyclo[4.4.0]dec-5-ene linked to polystyrene, 1,4-Diazabicyclo[2.2.2]octane, Quinuclidine, l,5-Diazabicyclo(4.3.0)non-5-ene, 2,6-Di-tert-butylpyridine, 2,8,9-Trimethyl-2,5,8,9-tetraza-l-phosphabicyclo[3.3.3]undecane, Cyclodiphosphazane, Lithium diisopropylamide, sodium diisopropylamide, potassium diisopropylamide, magnesium diisopropylamide, calcium diisopropylamide, rubidium diisopropylamide, lithium bis(trimethylsilyl)amide, sodium bis(trimethylsilyl)amide, potassium bis(trimethylsilyl)amide, magnesium bis(trimethylsilyl)amide, calcium bis(trimethylsilyl)amide, rubidium bis(trimethylsilyl)amide, lithium tetramethylpiperidide, sodium tetramethylpiperidide, potassium tetramethylpiperidide, magnesium tetramethylpiperidide, calcium tetramethylpiperidide, rubidium tetramethylpiperidide, [18-crown-6]-KHF2, KHF2, N,N'-diisopropylimidazonium, bifluorure, tetrabutylammonium, N(C. n H2n+i)4 + OH _ avec n étant un entier de 1 à 10.

[0026] According to another aspect, the present invention provides a composition comprising at least 99.5% by mole of said PI polymer as defined according to the present invention; said PI polymer having a weight-average molecular mass Mw greater than 10000 g / mol, preferably greater than 15000 g / mol, in particular greater than 20000 g / mol.

[0027] According to a preferred embodiment, said composition comprises: from 1 ppb to 100 ppm by mole of sodium; less than 10 ppm by mole of a metal selected from the group consisting of iron, aluminum, copper and magnesium; based on said total composition.

[0028] According to a preferred embodiment, said composition comprises less than 0.5% by mole of said base as defined in the present invention on the basis of the total composition.

[0029] According to a preferred embodiment, said composition comprises less than 0.1% by mole of water on the basis of the total composition.

[0030] According to another aspect, the present invention provides a film comprising the composition according to the present invention.

[0031] According to another aspect, the present invention provides an electrochemical device comprising said film according to the present invention.

[0032] According to another aspect, the present invention provides poly(1,8-dimercapto-3,6-dioxaoctane) having a weight-average molecular mass Mw greater than 10,000 g / mol, and comprising less than 0.1% by weight of water. Brief description of the figures

[0033] Figure 1 represents the cyclic voltammetry of a film prepared with a polymer according to an embodiment of the present invention.

[0034] Detailed description of the invention

[0035] The present invention provides a method for preparing a disulfide polymer. The invention allows for the preparation of this type of polymer by effectively controlling the resulting molecular mass. Controlling the polymer's molecular mass is very useful for the intended applications. By controlling it, different conductivity properties can be obtained for a film containing the polymer.

[0036] Process of

[0037] The said process for preparing the PI polymer comprises a) a polymerization step, preferably in aqueous medium, by adding a solution of a peroxide to a dispersion, preferably aqueous, comprising at least one compound of formula (I) HS-R-SH and a base for forming said PI polymer comprising at least one segment — (SRS)-(SRS)- with R being, independently for each unit -(SRS)-, a hydrocarbon substituent having a molecular mass of less than 1000 g / mol.

[0038] Step a)

[0039] Step a) is preferably carried out in such a way as to control the temperature of the reaction medium. The reaction between the peroxide and the compound of formula (I) in the presence of said base is exothermic. The temperature of the reaction medium is preferably controlled to maintain efficient polymerization. Preferably, step a) is carried out at a temperature between 10°C and 50°C, advantageously between 15°C and 45°C, preferably between 15°C and 40°C, and in particular between 15°C and 35°C. For example, the rate of addition of said peroxide solution is thus adapted to maintain the temperature between 10°C and 50°C, advantageously between 15°C and 45°C, preferably between 15°C and 40°C, and in particular between 15°C and 35°C.

[0040] This step (a) can be carried out under an inert or non-inert atmosphere. Thus, this step (a) can be carried out under an atmosphere of air, oxygen, or nitrogen.

[0041] This step (a) is preferably carried out at a pressure of 0.8 bar to 3 bar, advantageously from 1 bar to 3 bar, in particular at atmospheric pressure. Compound of formula (I)

[0042] The compound of formula (I) HS-R-SH is such that R is, independently for each unit - (SRS)-, a hydrocarbon substituent having a molecular mass less than 1000 g / mol. Advantageously, R has a molecular mass less than 950 g / mol, preferably less than 900 g / mol, more preferably less than 850 g / mol, particularly less than 800 g / mol, more particularly less than 750 g / mol, preferably less than 700 g / mol, advantageously preferred less than 650 g / mol, preferably preferred less than 600 g / mol, more preferably preferred less than 550 g / mol, particularly preferred less than 500 g / mol. Preferably, R is a hydrocarbon comprising at least one ether, ester, or carbonyl functional group. An ether functional group has the formula A 1 -OA 2 An ester functional group has the formula A 1 -C(O)OA 2or A 1 -OC(O)-A 2 A carbonyl functional group has the formula A 1 -C(O)-A 2 Substituents A 1 and A 2 are preferably hydrocarbons comprising from 1 to 30 carbon atoms, in particular from 1 to 25 carbon atoms, more particularly from 1 to 20 carbon atoms.

[0043] In said compound of formula (I), R can be of formula -[R 1 -X-] n -[Y] m - in which

[0044] R 1 is, independently for each unit n, selected from the group consisting of C1-C20 alkyl, C3-C20 cycloalkyl, C6-C20 aryl;

[0045] X is O, C(O), C(O)O, OC(O); n is an integer from 1 to 20, advantageously n is an integer from 1 to 15, preferably n is an integer from 1 to 12, more preferably n is an integer from 1 to 10, in particular n is an integer from 1 to 8, more particularly n is an integer from 1 to 5;

[0046] Y is, independently for each unit m, selected from the group consisting of C1-C20 alkyl, C3-C10 cycloalkyl, Cg-Ci2 aryl; m is an integer from 0 to 20, advantageously m is an integer from 1 to 15, preferably m is an integer from 1 to 12, more preferably m is an integer from 1 to 10, in particular m is an integer from 1 to 8, more particularly m is an integer from 1 to 5.

[0047] Advantageously, R can be of the formula -[R'-X-Jn-Mm- in which

[0048] R 1 is, independently for each unit n, selected from the group consisting of C1-C15 alkyl, C3-C15 cycloalkyl, Cg-Cis aryl;

[0049] X is O, C(O), C(O)O, OC(O); n is an integer from 1 to 15, preferably n is an integer from 1 to 12, more preferably n is an integer from 1 to 10, in particular n is an integer from 1 to 8, more particularly n is an integer from 1 to 5;

[0050] Y is, independently for each unit m, selected from the group consisting of C1-C15 alkyl, C3-C15 cycloalkyl, Cg-Cis aryl; m is an integer from 0 to 15, preferably m is an integer from 1 to 12, more preferably m is an integer from 1 to 10, in particular m is an integer from 1 to 8, more particularly m is an integer from 1 to 5.

[0051] Preferably, R can be of the formula -[R 1 -X-] n -[Y] m - in which

[0052] R 1 is, independently for each unit n, selected from the group consisting of C1-C12 alkyl, C3-C12 cycloalkyl, Cg-Ci2 aryl;

[0053] X is O, C(O), C(O)O, OC(O); n is an integer from 1 to 12, more preferably n is an integer from 1 to 10, in particular n is an integer from 1 to 8, more particularly n is an integer from 1 to 5;

[0054] Y is, independently for each unit m, selected from the group consisting of C1-C12 alkyl, C3-C12 cycloalkyl, Cg-Ci2 aryl; m is an integer from 0 to 12, more preferably m is an integer from 1 to 10, in particular m is an integer from 1 to 8, more particularly m is an integer from 1 to 5.

[0055] More preferably, R can be of the formula -[R 1 -X-] n -[Y] m - in which

[0056] R 1 is, independently for each unit n, selected from the group consisting of C1-C10 alkyl, C3-C10 cycloalkyl, Cg-Ci2 aryl;

[0057] X is O, C(O), C(O)O, OC(O); n is an integer from 1 to 10, in particular n is an integer from 1 to 8, more particularly n is an integer from 1 to 5;

[0058] Y is, independently for each unit m, selected from the group consisting of C1-C10 alkyl, C3-C10 cycloalkyl, Cg-Ci2 aryl; m is an integer from 0 to 10.

[0059] In particular, R can be of the formula -[R 1 -X-] n -[Y] m - in which

[0060] R 1 is, independently for each unit n, selected from the group consisting of Ci-Cg alkyl, C3-C8 cycloalkyl, Cg-Cio aryl;

[0061] X is O, C(O), C(O)O, OC(O); n is an integer from 1 to 8, more particularly n is an integer from 1 to 5; Y is, independently for each unit m, selected from the group consisting of Ci-Cg alkyl, Cg-Cg cycloalkyl, Cg-Cio aryl; m is an integer from 0 to 8, more particularly m is an integer from 1 to 5.

[0062] More specifically, R can be of the formula -[R 1 -X-] n -[Y] m - in which

[0063] R 1 is, independently for each unit n, selected from the group consisting of Ci-C5alkyl, C3-C5 cycloalkyl, Cg-Cg aryl;

[0064] X is O, C(O), C(O)O, OC(O); n is an integer from 1 to 5;

[0065] Y is, independently for each unit m, selected from the group consisting of C1-C5 alkyl, C3-C5 cycloalkyl, Cg-Cg aryl; m is an integer from 0 to 5, more particularly m is an integer from 1 to 5.

[0066] Preferably, R can be of the formula -[R 1 -X-] n -[Y] m - in which

[0067] R 1 is, independently for each unit n, selected from the group consisting of C1-C5 alkyl, Cg-Cg aryl;

[0068] X is O, C(O), C(O)O, OC(O); n is an integer from 1 to 5;

[0069] Y is, independently for each unit m, selected from the group consisting of C1-C5 alkyl, Cg-Cg aryl; m is an integer from 1 to 5.

[0070] R can be of the formula -R 2 -GOLD 3 -GOLD 4 - in which R 2 , R 3 and R 4, are independently of each other, selected from the group consisting of C1-C20 alkyl, C3-C20 cycloalkyl, Cg-C2o aryl.

[0071] Advantageously, R has the formula -R 2 -GOLD 3 -GOLD 4 - in which R 2 , R 3 and R 4 , are independently of each other, selected from the group consisting of C1-C15 alkyl, C3-C15 cycloalkyl, Cg-Ci5aryl.

[0072] Preferably, R has the formula -R 2 -GOLD 3 -GOLD 4 - in which R 2 , R 3 and R 4 , are independently of each other, selected from the group consisting of C1-C12 alkyl, C3-C12 cycloalkyl, C6-Ci2 aryl.

[0073] More preferably, R has the formula -R 2 -GOLD 3 -GOLD 4 - in which R 2 , R 3 and R 4These are independently selected from the group consisting of C1-C10 alkyl, C3-C10 cycloalkyl, and Cg-Ci2 aryl compounds. In particular, R has the formula -R 2 -GOLD 3 -GOLD 4 - in which R 2 , R 3 and R 4 , are independently of each other, selected from the group consisting of Ci-Cg alkyl, Cs-Cg cycloalkyl, Cg-Cio aryl.

[0074] More specifically, R has the formula -R 2 -GOLD 3 -GOLD 4 - in which R 2 , R 3 and R 4 , are independently of each other, selected from the group consisting of Ci-C5alkyl, C3-C5cycloalkyl, Cg-Cg aryl.

[0075] Preferably, R has the formula -R 2 -GOLD 3 -GOLD 4 - in which R 2 , R 3 and R 4, are independently of each other, selected from the group consisting of C1-C5 alkyl, Cg-Cg aryl.

[0076] In an advantageously preferred manner, said compound of formula (I) has the formula HS-R 2 -GOLD 3 -GOLD 4 -SH in which R 2 , R 3 and R 4 are selected from the group consisting of C1-C5 alkyl, Cg-Cg aryl.

[0077] In a preferential manner, said compound of formula (I) has the formula HS-R 2 - GOLD 3 -GOLD 4 -SH in which R 2 , R 3 and R 4 are selected from the group consisting of C1-C3 alkyl.

[0078] In a more preferably preferred manner, said compound of formula (I) has the formula HS-R 2 -GOLD 3 -GOLD 4 -SH in which R 2 , R 3 and R 4are selected from the group consisting of CH2CH2 and CH(CH3)CH2.

[0079] In particular, said compound of formula (I) is l,8-dimercapto-3,6-dioxaoctane. In this case, said polymer PI is poly(l,8-dimercapto-3,6-dioxaoctane).

[0080] Peroxide

[0081] The said peroxide is preferably selected from among organic peroxides, percarbonates, perborates, persulfates, perphosphates, and hydroperoxides. For example, among the perborates, one might cite sodium perborate, potassium perborate, or lithium perborate. For example, among the percarbonates, one might cite sodium percarbonate, potassium percarbonate, or lithium percarbonate.For example, among the organic peroxides and hydroperoxides, we can mention H2O2; bis-acylperoxides of formula (Rf-C(0)-0)2 with Rf being Ci-C10 (per)haloalkyl, C1-C10 (per)fluoropolyoxyalkylene in particular bis-trichloroacetyl peroxide and bis-dichlorofluoroacetyl peroxide; dialkylperoxides of formula (RH-O)2 with RH being C1-C10 alkyl, in particular diterbutylperoxide (DTBP); dialkylperoxydicarbonates in which the alkyl group has from 1 to 8 carbon atoms such as di-n-propyl-peroxydicarbonate or diisopropylperoxydicarbonate; alkyl peroxyesters such as tert-amylperoxypivalate or tert-butylperoxyisobutirate. Examples of persulfates and perphosphates include sodium or potassium persulfate; sodium or potassium perphosphate.

[0082] In particular, the peroxide is H₂O₂. Indeed, the use of hydrogen peroxide offers the added advantage of avoiding the presence of organic impurities or additional processing steps such as precipitation or extractions in the presence of organic solvents, which are energy-intensive. These types of impurities can affect performance in certain electronic applications. The use of hydrogen peroxide also avoids the presence of potentially toxic or flammable organic solvents.

[0083] The concentration Cl of said peroxide solution may be between 0.01% and 70% by weight, advantageously between 0.1% and 65%, preferably between 0.5% and 60%, more preferably between 0.75% and 55% by weight.

[0084] Base

[0085] The said base can be selected from the group consisting of LiOH, NaOH, KOH, CsOH, RbOH, Mg(OH)2, Ca(OH)2, NH3 x (Cn H2n+i)3-x with n being an integer from 1 to 10 and x an integer from 0 to 3, morpholine, pyridine, pyrrolidine, piperidine, piperazine, 4-Methylmorpholine, N,N-Diisopropylethylamine, 1,8-Diazabicyclo(5.4.0)undec-7-ene, 6-(Dibutylamino)-1,8-diazabicyclo[5.4.0]undec-7-ene, 1,8-Diazabicyclo[5.4.0]undec-7-ene bonded to polystyrene, 1,5,7-Triazabicyclo[4.4.0]dec-5-ene, 7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1, 1,3,3-

[0086] Tetramethylguanidine, 2-tert-Butyl-l,l,3,3-tetramethylguanidine, 1,5,7-

[0087] Triazabicyclo[4.4.0]dec-5-ene lié à du polystyrène, 1,4-Diazabicyclo[2.2.2]octane, Quinuclidine, l,5-Diazabicyclo(4.3.0)non-5-ene, 2,6-Di-tert-butylpyridine, 2,8,9-Trimethyl-2,5,8,9-tetraza-l- phosphabicyclo[3.3.3]undecane, Cyclodiphosphazane, Lithium diisopropylamide, sodium diisopropylamide, potassium diisopropylamide, magnesium diisopropylamide, calcium diisopropylamide, rubidium diisopropylamide, lithium bis(trimethylsilyl)amide, sodium bis(trimethylsilyl)amide, potassium bis(trimethylsilyl)amide, magnesium bis(trimethylsilyl)amide, calcium bis(trimethylsilyl)amide, rubidium bis(trimethylsilyl)amide, lithium tetramethylpiperidide, sodium tetramethylpiperidide, potassium tetramethylpiperidide, magnesium tetramethylpiperidide, calcium tetramethylpiperidide, rubidium tetramethylpiperidide, [18-crown-6]-KHF2, KHF2, N,N'-diisopropylimidazonium, bifluorure, tetrabutylammonium, N(C n H2n+i)4 + OH _with n being an integer from 1 to 10. Preferably, said base may be selected from the group consisting of LiOH, NaOH, KOH, CsOH, RbOH, Mg(OH)2, Ca(OH)2, NH3 x (C n H2n+i)3-x with n being an integer from 1 to 8 and x an integer from 0 to 2, morpholine, pyridine, pyrrolidine, Piperidine, piperazine, 4-Methylmorpholine, N,N-Diisopropylethylamine, l,8-Diazabicyclo(5.4.0)undec-7-ene and 6-(Dibutylamino)-l,8-diazabicyclo[5.4.0]undec-7-ene.

[0088] In particular, said base can be selected from the group consisting of LiOH, NaOH, KOH, CsOH, RbOH, Mg(OH)2, Ca(OH)2, NH3 x (C n H2n+i)3-x with n being an integer from 1 to 5 and x an integer from 0 to 1, morpholine, pyridine, pyrrolidine, Piperidine, piperazine, 4-Methylmorpholine, N,N-Diisopropylethylamine, l,8-Diazabicyclo(5.4.0)undec-7-ene and 6-(Dibutylamino)-l,8-diazabicyclo[5.4.0]undec-7-ene.

[0089] More specifically, the said base is selected from among the bases mentioned above having a saturated vapor pressure greater than 1kPa at 20°C, advantageously greater than 2kPa at 20°C, preferably greater than 3kPa at 20°C, more preferably greater than 4kPa at 20°C, in particular greater than 5kPa at 20°C.

[0090] Step b)

[0091] The process according to the present invention may also include a step b) of purifying said PI polymer obtained in step a). Said step b) includes a step of removing said base used in step a) or a step of filtering said PI polymer or a combination of both.

[0092] The removal step of the base used in step a) is preferably carried out by heat treatment of the PI polymer at a temperature of 20°C to 150°C and a pressure of 0.01 bara to 1 bara, prior to and / or after the filtration of the PI polymer. The temperature may be from 20°C to 140°C, advantageously from 20°C to 130°C, preferably from 20°C to 120°C, more preferably from 20°C to 110°C, in particular from 20°C to 100°C, more particularly from 20°C to 90°C, preferably from 20°C to 80°C.

[0093] The filtration step of the PI polymer can be carried out using a filtration device comprising a membrane made of at least one fluorinated polymer or a polyolefin. The fluorinated polymer may comprise monomeric units derived from a monomer selected from the group consisting of vinyl fluoride; vinylidene fluoride (VDF); trifluoroethylene (VF3); chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (TFE); hexafluoropropylene (HFP); perfluoro(alkyl vinyl) ethers such as perfluoro(methyl vinyl) ether (PMVE), perfluoro(ethyl vinyl) ether (PEVE) and perfluoro(propyl vinyl) ether (PPVE); perfluoro(1,3-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD); the product of the formula CF2=CFOCF2CF(CF3)OCF2CF2X in which X is SO2F, CO2H, CH2OH, CH2OCN or CH2OPC>3H; the product of the formula CF2=CFOCF2CF2SO2F; the product of the formula F(CF2)nCH2OCF=CF2 in which n is 1, 2, 3, 4 or 5; the product of the formula R 1CH2OCF=CF2 in which R 1 is hydrogen or F(CF2)m and m is 1, 2, 3 or 4; the product of formula R 2 OCF=CH2 in which R 2 is F(CF2)p and p is 1, 2, 3 or 4; perfluorobutylethylene (PFBE); trifluoropropene, tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene and 2-trifluoromethyl-

[0094] 3.3.3-Trifluoro-l-propene or a mixture thereof. Examples of trifluoropropenes include

[0095] 3,3,3-trifluoropropene. Examples of tetrafluoropropene include 2,3,3,3-tetrafluoropropene and 1,3,3,3-tetrafluoropropene. Examples of pentafluoropropene include...

[0096] 1,1,3,3,3-pentafluoropropene or 1,2,3,3,3-pentafluoropropene. Chlorofluoroethylene may refer to either 1-chloro-1-fluoroethylene or 1-chloro-2-fluoroethylene. The 1-chloro-1-fluoroethylene isomer is preferred. Chlorotrifluoropropene is preferably 1-chloro-

[0097] 3,3,3-Trifluoropropene or 2-chloro-3,3,3-trifluoropropene. Advantageously, said fluorinated polymer may comprise monomeric units derived from a monomer selected from the group consisting of vinyl fluoride, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, 1,2-difluoroethylene, tetrafluoroethylene, and hexafluoropropylene. Preferably, said fluorinated polymer may comprise monomeric units derived from a monomer selected from the group consisting of vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, and hexafluoropropylene. In particular, said fluorinated polymer may be a homopolymer of tetrafluoroethylene, a homopolymer of vinylidene fluoride, or a copolymer comprising monomeric units derived from tetrafluoroethylene or vinylidene fluoride.

[0098] The said polyolefin can be polyethylene, polypropylene, polymethylpropene, polybutene, polypentene, polymethylpentene, polymethylbutene, polyhexene, polymethylpentene and polyethylbutene.

[0099] Preferably, said membrane comprises pores of a size from 1 nm to 100 nm, advantageously from 1 nm to 75 nm, preferably from 2 nm to 50 nm, more preferably from 3 nm to 25 nm, in particular from 3 nm to 10 nm.

[0100] In particular, said membrane may be made of a tetrafluoroethylene homopolymer, a vinylidene fluoride homopolymer, or a copolymer comprising monomeric units of tetrafluoroethylene or vinylidene fluoride, and may include pores with a size of 1 nm to 100 nm, advantageously from 1 nm to 75 nm, preferably from 2 nm to 50 nm, more preferably from 3 nm to 25 nm, and in particular from 3 nm to 10 nm. The pore size is preferably determined according to standard 4003:1977.

[0101] PI Polymer

[0102] The present invention enables the preparation of said PI polymer. said PI polymer comprises at least one segment -(SRS)-(SRS)- with R being, independently for each unit -(SRS)-, a hydrocarbon substituent having a molecular mass less than 1000 g / mol.Advantageously said substituent R has a molecular mass less than 950 g / mol, preferably said substituent R has a molecular mass less than 900 g / mol, more preferably said substituent R has a molecular mass less than 850 g / mol, in particular said substituent R has a molecular mass less than 800 g / mol, more particularly said substituent R has a molecular mass less than 750 g / mol, preferably said substituent R has a molecular mass less than 700 g / mol, advantageously preferred said substituent R has a molecular mass less than 650 g / mol, preferably preferred said substituent R has a molecular mass less than 600 g / mol, more preferably preferred said substituent R has a molecular mass less than 550 g / mol, particularly preferred said substituent R has a molecular mass less than 500 g / mol.

[0103] Preferably, in said polymer Pl, R is a hydrocarbon comprising at least one ether, ester, or carbonyl functional group. An ether functional group has the formula A 1 -OA 2 An ester functional group has the formula A 1 -C(O)OA 2 or A 1 -OC(O)-A 2 A carbonyl functional group has the formula A 1 -C(O)-A 2 Substituents A 1 and A 2 are preferably hydrocarbons comprising from 1 to 30 carbon atoms, in particular from 1 to 25 carbon atoms, more particularly from 1 to 20 carbon atoms.

[0104] In said polymer Pl, R can have the formula -[R 1 -X-] n -[Y] m - in which

[0105] R 1 is, independently for each unit n, selected from the group consisting of C1-C20 alkyl, C3-C20 cycloalkyl, C6-C20 aryl;

[0106] X is O, C(O), C(O)O, OC(O); n is an integer from 1 to 20, advantageously n is an integer from 1 to 15, preferably n is an integer from 1 to 12, more preferably n is an integer from 1 to 10, in particular n is an integer from 1 to 8, more particularly n is an integer from 1 to 5; Y is, independently for each unit m, selected from the group consisting of C1-C20 alkyl, C3-C10 cycloalkyl, Cg-Cu aryl; m is an integer from 0 to 20, advantageously m is an integer from 1 to 15, preferably m is an integer from 1 to 12, more preferably m is an integer from 1 to 10, in particular m is an integer from 1 to 8, more particularly m is an integer from 1 to 5.

[0107] Advantageously, in said polymer Pl, R can be of the formula -[R 1 -X-] n -[Y] m - in which R 1 is, independently for each unit n, selected from the group consisting of C1-C15 alkyl, C3-C15 cycloalkyl, Cg-Cis aryl;

[0108] X is O, C(O), C(O)O, OC(O); n is an integer from 1 to 15, preferably n is an integer from 1 to 12, more preferably n is an integer from 1 to 10, in particular n is an integer from 1 to 8, more particularly n is an integer from 1 to 5;

[0109] Y is, independently for each unit m, selected from the group consisting of C1-C15 alkyl, C3-C15 cycloalkyl, Cg-Cis aryl; m is an integer from 0 to 15, preferably m is an integer from 1 to 12, more preferably m is an integer from 1 to 10, in particular m is an integer from 1 to 8, more particularly m is an integer from 1 to 5.

[0110] Preferably, in said polymer Pl, R can be of the formula -[R 1 -X-] n -[Y] m - in which

[0111] R 1 is, independently for each unit n, selected from the group consisting of C1-C12 alkyl, C3-C12 cycloalkyl, Cg-Ci2 aryl;

[0112] X is O, C(O), C(O)O, OC(O); n is an integer from 1 to 12, more preferably n is an integer from 1 to 10, in particular n is an integer from 1 to 8, more particularly n is an integer from 1 to 5;

[0113] Y is, independently for each unit m, selected from the group consisting of C1-C12 alkyl, C3-C12 cycloalkyl, Cg-Ci2 aryl; m is an integer from 0 to 12, more preferably m is an integer from 1 to 10, in particular m is an integer from 1 to 8, more particularly m is an integer from 1 to 5.

[0114] More preferably, in said polymer Pl, R can be of the formula -[R 1 -X-] n -[Y] m - in which

[0115] R 1 is, independently for each unit n, selected from the group consisting of C1-C10 alkyl, C3-C10 cycloalkyl, Cg-Ci2 aryl;

[0116] X is O, C(O), C(O)O, OC(O); n is an integer from 1 to 10, in particular n is an integer from 1 to 8, more particularly n is an integer from 1 to 5;

[0117] Y is, independently for each unit m, selected from the group consisting of Ci-Cio alkyl, C3-C10 cycloalkyl, Cg-Ci2 aryl; m is an integer from 0 to 10.

[0118] In particular, in said polymer Pl, R can have the formula -[R 1 -X-] n -[Y] m - in which

[0119] R 1 is, independently for each unit n, selected from the group consisting of Ci-Cg alkyl, C3-C8 cycloalkyl, Cg-Cio aryl;

[0120] X is O, C(O), C(O)O, OC(O); n is an integer from 1 to 8, more particularly n is an integer from 1 to 5;

[0121] Y is, independently for each unit m, selected from the group consisting of Ci-Cg alkyl, Cg-Cg cycloalkyl, Cg-Cio aryl; m is an integer from 0 to 8, more particularly m is an integer from 1 to 5.

[0122] More specifically, in said polymer Pl, R can have the formula -[R 1 -X-] n -[Y] m - in which

[0123] R 1 is, independently for each unit n, selected from the group consisting of C1-C5 alkyl, C3-C5 cycloalkyl, Cg-Cg aryl;

[0124] X is O, C(O), C(O)O, OC(O); n is an integer from 1 to 5;

[0125] Y is, independently for each unit m, selected from the group consisting of C1-C5 alkyl, C3-C5 cycloalkyl, Cg-Cg aryl; m is an integer from 0 to 5, more particularly m is an integer from 1 to 5.

[0126] Preferably, in said polymer Pl, R can have the formula -[R 1 -X-] n -[Y] m- in which

[0127] R 1 is, independently for each unit n, selected from the group consisting of C1-C5 alkyl, Cg-Cg aryl;

[0128] X is O, C(O), C(O)O, OC(O); n is an integer from 1 to 5;

[0129] Y is, independently for each unit m, selected from the group consisting of C1-C5 alkyl, Cg-Cg aryl; m is an integer from 1 to 5. In a preferred embodiment, in said polymer Pl, R has the formula -R 2 -GOLD 3 -GOLD 4 - in which R 2 , R 3 and R 4 , are independently of each other, selected from the group consisting of C1-C20 alkyl, C3-C20 cycloalkyl, C6-C20 aryl.

[0130] Advantageously, in said polymer Pl, R has the formula -R 2 -GOLD 3 -GOLD 4 - in which R 2 , R 3 and R 4, are independently of each other, selected from the group consisting of Ci-C15 alkyl, C3-C15 cycloalkyl, Cg-Cis aryl.

[0131] Preferably, in said polymer Pl, R has the formula -R 2 -GOLD 3 -GOLD 4 - in which R 2 , R 3 and R 4 , are independently of each other, selected from the group consisting of C1-C12 alkyl, C3-C12 cycloalkyl, Cg-Ci2 aryl.

[0132] More preferably, in said polymer Pl, R has the formula -R 2 -GOLD 3 -GOLD 4 - in which R 2 , R 3 and R 4 , are independently of each other, selected from the group consisting of C1-C10 alkyl, C3-C10 cycloalkyl, Cg-Ci2 aryl.

[0133] In particular, in said polymer Pl, R has the formula -R 2 -GOLD 3 -GOLD 4 - in which R 2 , R 3 and R 4, are independently of each other, selected from the group consisting of Ci-Cg alkyl, C3-C8 cycloalkyl, Cg-Cio aryl.

[0134] More specifically, in said polymer Pl, R has the formula -R 2 -GOLD 3 -GOLD 4 - in which R 2 , R 3 and R 4 , are independently of each other, selected from the group consisting of C1-C5 alkyl, C3-C5 cycloalkyl, Cg-Cg aryl.

[0135] Preferably, in said polymer Pl, R has the formula -R 2 -GOLD 3 -GOLD 4 - in which R 2 , R 3 and R 4 , are independently of each other, selected from the group consisting of C1-C5 alkyl, Cg-Cg aryl.

[0136] In an advantageously preferred manner, said PI polymer comprises, advantageously is constituted, repeating units of formula -(-SR 2 -GOLD 3 -GOLD 4 -SSR2 -GOLD 3 -GOLD 4 -S-)- in which R 2 , R 3 and R 4 are selected from the group consisting of C1-C5 alkyl, Cg-Cg aryl.

[0137] In a preferred manner, said PI polymer comprises, advantageously is constituted, repeating units of formula -(-SR 2 -GOLD 3 -GOLD 4 -SSR 2 -GOLD 3 -GOLD 4 -S-)- in which R 2 , R 3 and R 4 are selected from the group consisting of C1-C3 alkyl.

[0138] In a more preferred manner, said PI polymer comprises, advantageously is constituted, repeating units of formula -(-SR 2 -GOLD 3 -GOLD 4 -SSR 2 -GOLD 3 -GOLD 4 -S-)- in which R 2 , R 3 and R 4 are selected from the group consisting of CH2CH2 and CH(CH3)CH2.

[0139] In a particularly preferred manner, said polymer PI is poly(1,8-dimercapto-3,6-dioxaoctane). This polymer PI may have a molar mass greater than 10,000 g / mol. Advantageously, said polymer PI may have a molar mass greater than 15,000 g / mol. Preferably, said polymer PI may have a molar mass greater than 20,000 g / mol. More preferably, said polymer PI may have a molar mass greater than 25,000 g / mol. In particular, said polymer PI may have a molar mass greater than 30,000 g / mol.

[0140] The PI polymer can be linear or cyclic. The ring can be formed via a reaction between two sulfur atoms resulting in the formation of a ring through a disulfide bond.

[0141] Composition

[0142] The present invention provides a composition comprising at least 99.5% by mole of said PI polymer according to the present invention.

[0143] The composition may contain traces of metals. For example, it may contain from 1 ppb to 100 ppm sodium. It may also contain from 1 ppb to 50 ppm silver and / or zinc.

[0144] The said composition may also include less than 10 ppm by mole of a metal selected from the group consisting of iron, aluminum, copper and magnesium on the basis of the said total composition.

[0145] The said composition may also include less than 10 ppm by mole of a metal selected from the group consisting of calcium, potassium, phosphorus or silicon on the basis of the said total composition.

[0146] Preferably, said composition comprises less than 0.5% by mole of said base on the basis of the total composition. The molar content of said base in the composition may be less than 0.45%, advantageously less than 0.40%, preferably less than 0.35%, more preferably less than 0.30%, in particular less than 0.25%, more particularly less than 0.20%, preferably less than 0.15%, advantageously preferred less than 0.1%, preferably preferred less than 0.05%, more preferably preferred less than 0.01%, particularly preferred less than 0.005%.

[0147] Preferably, the composition comprises less than 0.1% by mole of water on the basis of the total composition. The molar content of water in the composition may be less than 0.09%, advantageously less than 0.08%, preferably less than 0.07%, more preferably less than 0.06%, in particular less than 0.05%, more particularly less than 0.04%, preferably less than 0.03%, advantageously preferred less than 0.02%, preferably preferred less than 0.01%, more preferably preferred less than 0.005%, particularly preferred less than 0.001%, more particularly preferred less than 0.0001%.The molar content of water in the composition may be less than 90 ppm, advantageously less than 80 ppm, preferably less than 70 ppm, more preferably less than 60 ppm, in particular less than 50 ppm, more particularly less than 40 ppm, preferably less than 30 ppm, advantageously preferred less than 20 ppm, preferably preferred less than 10 ppm.

[0148] The molar content of said base and water in the composition can be determined by NMR 1 H.

[0149] Use

[0150] The composition can be used in many applications.

[0151] The present invention provides, in particular, a film comprising the composition according to the present invention. The present invention also provides an electrochemical device comprising said film according to the present invention.

[0152] Examples

[0153] Measurement of average molecular mass by weight

[0154] The weight-average molecular weight was measured on a Waters Alliance 2695-15 instrument with two detectors: a Waters 2414 RI and a Waters 2487 Dual UV 254 nm, equipped with two PL gel 10 µm Mixed-B 300 x 7.5 mm columns. The flow rate was 1 mL / min, the eluent was BHT-stabilized THF, and the sample concentration was 1 g / L dissolved at room temperature for at least 4 hours. The injection volume was 5 µL. Calibration was performed with Easivial PS-H standards from 580 to 6545000 g / mol.

[0155] Examples a-f: Preparation of poly(l,8-dimercapto-3,6-dioxaoctane)

[0156] In a container, 15 mL of 1,8-dimercapto-3,6-dioxaoctane (0.09 mol) was mixed with 25 mL of triethylamine (0.19 mol, 2.2 eq). After 5 min of mixing, 25 mL of water was added, resulting in a dispersion. 25 mL of hydrogen peroxide solution (35 wt% in water) was then added to the mixture via 5 mL injections to maintain controllable exothermicity. The temperature was raised from 16 °C to 35 °C, and after 3 hours of mixing, a white polymer formed alongside a clear water phase, and the bath temperature dropped to room temperature, indicating the completion of the reaction. The polymer was then isolated by decantation from the liquid phase. The weight-average molecular weight (Mw) was 850 kg / mol.

[0157] The example above is reproduced with hydrogen peroxide solutions having concentrations of 1%, 3%, 5%, 10%, and 30%, respectively. Table 1 below details the average molecular mass by weight obtained.

[0158] [Table 1]

[0159] Cl refers to the concentration of the peroxide solution introduced into the reaction medium.

[0160] As demonstrated by the examples above, the concentration of the peroxide solution used allows for effective control of the average molecular mass by weight.

[0161] Example 2: Purification of poly(1,8-dimercapto-3,6-dioxaoctane)

[0162] The polymer obtained in Example 1 was dried in a ventilated oven at 50 °C for 6 hours under vacuum (25 mbar), resulting in a white polymer film. Residual triethylamine and water were quantified by NMR: Triethylamine: 0 mol% (undetectable), Water: 0 mol% (undetectable). The polymer was dissolved in 10% anhydrous THF. After dissolution, the polymer was precipitated in methanol, and the solution was filtered and then dried under vacuum at 40 °C. The recovered polymer was again dissolved in a 5% anhydrous THF solution. The solution was filtered through a PTFE membrane filter with a pore size of 3 nm to 10 nm to remove metallic impurities. The polymer was again dried in a ventilated oven at 30 °C. The resulting polymer had a metal content of less than 40 ppm.

[0163] Comparative example 3

[0164] The polymer obtained in Example 1 was heated in a ventilated oven at 80 °C for 12 hours, resulting in a white product. Residual triethylamine and water were quantified by NMR: Triethylamine: 0.9 mol%, Water: 13.8 mol%. A film was prepared from the polymers obtained in Example 2 according to the invention and in Comparative Example 3, respectively. This film was deposited on a lithium metal anode. The anode on which a film made of the polymer from Comparative Example 3 was deposited degraded rapidly, unlike the anode on which a film made of the polymer from Example 2 according to the invention was deposited. Cyclic voltammetry was performed on the purified polymer according to Example 2 and in Comparative Example 3. The cyclic voltammetry was carried out between 2 and 5 V at 0.1 mV / s. Figure 1 represents the cyclic voltammetry with the polymer according to example 2.The film prepared with the polymer according to Example 2 is more electrochemically stable than the film prepared with the polymer according to comparative Example 3, which degrades rapidly. The electrochemical stability of the polymer according to Example 2 is sufficient for use in Li-ion batteries, including with high-voltage positive active materials (such as nickel-rich NMC).

Claims

1. Demands 1. Process for preparing a PI polymer comprising at least one disulfide bond, said process comprising: a) A polymerization step, preferably in aqueous medium, by adding a solution of a peroxide to a dispersion, preferably aqueous, comprising at least one compound of formula (I) HS-R-SH and a base for forming said PI polymer comprising at least one segment — (SRS)-(SRS)- with R being, independently for each unit -(SRS)-, a hydrocarbon substituent having a molecular mass less than 1000 g / mol.

2. A process for preparing a PI polymer according to the preceding claim, characterized in that said PI polymer has a weight average molecular mass Mw, expressed in kg / mol, between: ((2226 + 1951754*C1)*O, 00055) < Mw < ((2226 + 1951754*C1)*O, 00145); Cl being the concentration of said peroxide solution, expressed in % by weight.

3. A process for preparing a PI polymer according to any one of the preceding claims characterized in that step a) is carried out at a temperature between 10°C and 50°C.

4. A process for preparing a PI polymer according to any one of the preceding claims characterized in that it comprises a step b) of purifying said PI polymer obtained in step a) comprising a step of removing said base used in step a) or a step of filtering said PI polymer or a combination of both.

5. A process for preparing a PI polymer according to the preceding claim, characterized in that said step of removing said base used in step a) is carried out by heat treating said PI polymer at a temperature of 20°C to 100°C and a pressure of 0.01 bara to 1 bara, prior to and / or after said filtration of said PI polymer.

6. A process for preparing a PI polymer according to the preceding claim, characterized in that said filtration step of said PI polymer is carried out using a filtration device comprising a membrane made of at least one fluorinated polymer or a polyolefin.

7. A process for preparing a PI polymer according to the preceding claim characterized in that said membrane comprises pores of a size from 1 nm to 100 nm, advantageously from 1 nm to 75 nm, preferably from 2 nm to 50 nm, more preferably from 3 nm to 25 nm, in particular from 3 nm to 10 nm.

8. A process for preparing a PI polymer according to any one of the preceding claims characterized in that said base used in step a) has a saturated vapor pressure greater than lkPa at 20°C.

9. A process for preparing a PI polymer according to any one of the preceding claims characterized in that said peroxide used in step a) is selected from the group consisting of organic peroxides, percarbonates, perborates, persulfates, perphosphates and hydroperoxides.

10. A process for preparing a PI polymer according to any one of the preceding claims characterized in that said compound of formula (I) is HS-R-SH in which R is a hydrocarbon comprising at least one ether, ester or carbonyl functional group.

11. A process for preparing a PI polymer according to any one of the preceding claims, characterized in that R has the formula -[R 1 -X-] n -[Y] m - in which R 1 is, independently for each unit n, selected from the group consisting of Ci-Cio alkyl, C3-C10 cycloalkyl, Cg-Ci2 aryl; X is O, C(O), C(O)O, OC(O); n is an integer from 1 to 20; Y is, independently for each unit m, selected from the group consisting of C1-C10 alkyl, C3-C10 cycloalkyl, Cg-Ci2 aryl; m is an integer from 0 to 20.

12. A process for preparing a PI polymer according to any one of the preceding claims, characterized in that R has the formula -R 2 -GOLD 3 -GOLD 4 - in which R 2 , R 3 and R 4 , are independently of each other, selected from the group consisting of Ci-Cio alkyl, C3-C10 cycloalkyl, Cg-Ci2aryl.

13. A process for preparing a PI polymer according to any one of the preceding claims characterized in that said compound of formula (I) is 1,8-dimercapto-3,6-dioxaoctane and in that said PI polymer is poly(1,8-dimercapto-3,6-dioxaoctane).

14. A process for preparing a PI polymer according to any one of the preceding claims, characterized in that said base is selected from the group consisting of LiOH, NaOH, KOH, CsOH, RbOH, Mg(OH)2, Ca(OH)2, NH3 x (CnH2n +i)3-x with n being an integer from 1 to 10 and x an integer from 0 to 3, N,N-Diisopropylethylamine, morpholine, pyridine, pyrrolidine, Piperidine, piperazine, 4-Methylmorpholine, 1,8-Diazabicyclo(5.4.0)undec-7-ene, 6-(Dibutylamino)-1,8-diazabicyclo[5.4.0]undec-7-ene, 1,8-Diazabicyclo[5.4.0]undec-7-ene bonded to polystyrene, 1,5,7-Triazabicyclo[4.4.0]dec-5-ene, 7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1,1,3,3-Tetramethylguanidine, 2- tert-Butyl-l,l,3,3-tetramethylguanidine, l,5,7-Triazabicyclo[4.4.0]dec-5-ene linked to polystyrene, 1,4-Diazabicyclo[2.2.2]octane, Quinuclidine, l,5-Diazabicyclo(4.3.0)non-5-ene, 2,6-Di-tert-butylpyridine, 2,8,9-Trimethyl-2,5,8,9-tetraza-l-phosphabicyclo[3.3.3]undecane, Cyclodiphosphazane, Lithium diisopropylamide, sodium diisopropylamide, potassium diisopropylamide, magnesium diisopropylamide, calcium diisopropylamide, rubidium diisopropylamide, lithium bis(trimethylsilyl)amide, sodium bis(trimethylsilyl)amide, potassium bis(trimethylsilyl)amide, magnesium bis(trimethylsilyl)amide, calcium bis(trimethylsilyl)amide, rubidium bis(trimethylsilyl)amide, lithium tetramethylpiperidide, sodium tetramethylpiperidide, potassium tetramethylpiperidide, magnesium tetramethylpiperidide, calcium tetramethylpiperidide, rubidium tetramethylpiperidide, [18-crown-6]-KHF2, KHF2, N,N'- diisopropylimidazonium, bifluorure, tetrabutylammonium, N(C. n H2n+i)4 + OH _ avec n étant un entier de 1 à 10.

15. Composition comprising at least 99.5% by mole of said PI polymer as defined according to any one of claims 1, 9 to 12; said PI polymer having a weight-average molecular mass Mw greater than 10000 g / mol, preferably greater than 15000 g / mol, in particular greater than 20000 g / mol.

16. Composition according to the preceding claim characterized in that it comprises: from 1 ppb to 100 ppm in mole of sodium; less than 10 ppm in mole of a metal selected from the group consisting of iron, aluminum, copper and magnesium; based on said total composition.

17. Composition according to any one of the preceding claims 15 or 16 characterized in that it comprises less than 0.5% by mole of said base as defined in claim 14 on the basis of the total composition.

18. Composition according to any one of the preceding claims 15 to 17 characterized in that it comprises less than 0.1% by mole of water on the basis of the total composition.

19. Film comprising the composition according to any one of claims 15 to 18.

20. Electrochemical device comprising said film according to the preceding claim.

21. Poly(1,8-dimercapto-3,6-dioxaoctane) having a weight average molecular mass Mw greater than 10000 g / mol, and comprising less than 0.1% by weight of water.

Images