Ring-opening polymerization process

Abstract

The invention relates to a process for preparing linear organopolysiloxanes (OL) by ring-opening polymerization from cyclic organopolysiloxanes (OC), using a basic catalyst (B). More specifically, the process of the present invention makes it possible to obtain linear organopolysiloxanes (OL) of controlled molar mass with a very low cyclic content. The invention also relates to the composition (S1) used in the process of the present invention.

Description

Title of the invention: Ring-opening polymerization process technical field

[0001] The invention relates to a process for preparing linear organopolysiloxanes OL by a ring-opening polymerization reaction in the presence of cyclic organopolysiloxanes OC, a basic catalyst B and a chain blocker C. More specifically, the process of the present invention makes it possible to obtain linear organopolysiloxanes OL of controlled molar mass with a very low residual cyclic organopolysiloxane content. Previous technique

[0002] A major challenge for the silicone industry in the coming years is to industrially synthesize organopolysiloxanes with a very low or even zero residual cyclic content.

[0003] To date, the industrial synthesis of organopolysiloxanes by polycondensation or ring-opening polymerization results in the formation of cyclic organopolysiloxanes such as octamethyltetrasiloxane (D4) and decamethylcyclopentasiloxane (D5), or other undesired cyclic organopolysiloxanes. In conventional industrial processes, this content of undesired products can reach between 10 and 15% relative to the total mass of linear organopolysiloxane obtained during the synthesis, which corresponds to thermodynamic equilibrium. Typically, this high content of cyclic products necessitates energy-intensive process steps, such as a devolatilization step at high temperature and / or reduced pressure, to separate these byproducts from the linear organopolysiloxane obtained.

[0004] Thus, in the interest of economic and energy efficiency, there is a need to develop new solutions to eliminate or at least limit these long and costly separation steps.

[0005] Furthermore, cyclic silicones or organopolysiloxanes such as octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) are and will be subject to restrictions on their use. In addition to the fact that these cyclic compounds present environmental risks due to their non-biodegradability, they are also suspected of being endocrine disruptors and potentially carcinogenic.

[0006] In this regard, in 2018 European regulations limited the content of D4 and D5 to 0.1% by mass in rinse-off cosmetic products. Coming soon, This regulation will be adopted for other cosmetic products as well as in other areas of silicone application. For example, in the electronics sector, restrictions tend to limit the content of cyclic organopolysiloxanes to a value below 100 ppm.

[0007] Consequently, there is a need to develop processes for producing silicone products that are free of, or at least have a low content of, cyclic silicones. In particular, there is an advantage to providing a ring-opening polymerizable composition (S) that enables such a process. There is also an advantage to being able to reliably control the molar mass of the products formed. This capability expands the potential uses and applications of such polymers.

[0008] In the prior art, US patent application 2012142956A1 teaches a process for preparing linear organopolysiloxanes (OLs) in the presence of a quaternary amine such as tetramethylammonium hydroxide or choline. On the one hand, the examples in US patent application 2012142956 disclose that tests in the presence of choline and its derivatives do not yield satisfactory yields of linear organopolysiloxanes (OLs). On the other hand, regarding tests with tetramethylammonium hydroxide, there is a need to find an alternative to this catalyst and its derivatives, which are toxic to humans and the environment.

[0009] More recently, a patent application such as WO2018051792 discloses a process for preparing linear organopolysiloxanes (OLs) in the presence of guanidine derivatives as a basic catalyst. However, unlike the catalysts of the present invention, most guanidine derivatives require synthesis, unlike commercially available choline. Furthermore, the process disclosed in patent application WO2018051792 requires the presence of chlorosilane, which is known to be a highly toxic compound.

[0010] Furthermore, the present invention makes it possible to achieve the multiple objectives listed below and those which will become apparent upon reading the description of the invention that follows. Summary of the invention

[0011] An objective of the present application is therefore to propose a process for the preparation of linear organopolysiloxanes OL by a ring-opening polymerization reaction of cyclic organopolysiloxanes OC allowing control of the molar mass of the final product with a yield of linear organopolysiloxanes greater than 95%, preferably greater than 98%.

[0012] Another objective of the present application is to be able to control the nature of the chemical functions of the linear organopolysiloxane OL obtained.

[0013] Another objective of the present application is to provide a poly- composition merizable by opening cycle S allowing the implementation of this process.

[0014] Another objective of the present application is to propose a low-toxicity S-ring opening polymerizable composition compatible with industrialization of the process.

[0015] Another objective of the present application is to propose a process that is satisfactory from an industrial point of view and that falls within the framework of environmentally friendly chemistry.

[0016] Other objectives will become apparent upon reading the description of the invention which follows.

[0017] Surprisingly, the Applicant has developed a ring-opening polymerizable composition S that meets these requirements. Thus, the present invention relates to a process for preparing linear organopolysiloxanes OL by a ring-opening polymerization reaction, said process comprising the following steps: a) Implement a ring-opening polymerizable composition S comprising: i) at least one cyclic organopolysiloxane OC having three siloxane motifs, ii) at least one basic catalyst B of formula (I): [Chem 1] in which: -Ri, identical or different, represents an alkyl chain of 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms. -R2 represents a hydrogen atom or a -C(=O)-R3 radical with R3 representing an alkyl group of 1 to 12 carbon atoms; - X represents an anion chosen from the group comprising: carboxylates and their derivatives, carbonates and their derivatives, hydroxyl, siloxanolates, silanolates, -n is a natural number between 1 and 6, and iii) at least one C chain blocker. b) Optionally, add later a chain blocker C identical or different from that of step a) or an acid A with the ring-opening polymerizable composition S mentioned in the previous step, c) Obtain the linear organopolysiloxane OL.

[0018] In this case, the basic catalyst B and the chain blocker C make it possible during the process of the present invention to control the molar mass of the final product while allowing the nature of the terminal chemical functions to be varied. Description of the implementation methods

[0019] Silicones, otherwise known as organopolysiloxanes, are polymeric materials comprising silicon and oxygen atoms alternating with various silicon-bound organic radicals.

[0020] In the context of the present invention, silicone, silicone products, silicone polymers, or organopolysiloxanes are defined as polymers comprising a siloxane (Si-O-Si) backbone having silicon and oxygen atoms alternating with various silicon-bonded organic radicals. These silicone polymers may be liquid or solid, depending on the molar mass and the degree of polymerization.

[0021] For the purposes of the present invention, the term "reaction mixture" means all the reactive chemical species present in the ring-opening polymerizable composition S mentioned above. By way of example, this includes the catalyst(s) B, the cyclic organopolysiloxane(s) OC, and the chain blocker(s) C.

[0022] All viscosities referred to in this presentation correspond to a dynamic viscosity quantity at 25°C called “Newtonian”, that is to say the dynamic viscosity which is measured, in a manner known per se, with a Brookfield viscometer at a shear rate gradient sufficiently low so that the measured viscosity is independent of the rate gradient.

[0023] For the purposes of the present invention, the cyclic organopolysiloxane OC is represented by the following formula (II): [Chem 2] in which, R identical or different is a radical representing an alkyl group of 1 to 6 carbon atoms, an alkenyl group of 2 to 6 carbon atoms, or an aryl group of 6 to 18 carbon atoms; and n represents a natural number between 1 and 2.

[0024] Preferably, the cyclic organopolysiloxane OC is represented by formula (III): [Chem 3] RR \ .0, / R----If"" '"If----R 0^ Formula III If " RR in which, R, identical or different, is a radical representing an alkyl group of 1 to 6 carbon atoms, an alkenyl group of 2 to 6 carbon atoms, or an aryl group of 6 to 18 carbon atoms.

[0025] Examples include commercially available cyclic organopolysiloxanes (OC) such as hexamethylcyclotrisiloxane (CAS 541-05-9), 2-ethenyl-2',4,4',6,6'-pentamethylcyclotrisiloxane (CAS 18395-32-9), 2,4,6-triethenyl-2,4,6-trimethylcyclotrisiloxane (CAS 3901-77-7), hexaphenylcyclotrisiloxane (CAS 512-63-0), 1,3,5-Trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane (CAS 2374-14-3), 2,2,4-Trimethyl-4,6,6-triphenyl-1,3,5,2,4,6-trioxatrisilinane (CAS 546-45-2), 1,3,5-Trimethyl-1,3,5-triphenylcyclotrisiloxane (CAS 546-45-2);2 4 6-trimethylcyclotrisiloxane (CAS 13269-39-1), 3,5-trivinyl-l,3,5-trimethylcyclotrisiloxane (CAS 3901-77-7), 2-Ethenyl-2,4,4,6,6-pentamethylcyclotrisiloxane (CAS 18395-32-9), 2,4,6,8-Tetramethylcyclotetrasiloxane (CAS 2370-88-9), 2,4,6,8-Tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (CAS 2554-06-5), 2,4,6,8-Tetramethyl-2,4,6,8-tetraphenylcyclotetrasiloxane (CAS 77-63-4), octaphenylcyclotetrasiloxane (CAS 546-56-5). ;

[0026] Advantageously, the cyclic organopolysiloxane OC is hexamethylcyclotrisiloxane (CAS 541-05-9).

[0027] According to one embodiment of the invention, the process of the present invention uses at least two cyclic organopolysiloxanes OC having 3 siloxane motifs such as for example the association of hexamethylcyclotrisiloxane (CAS 541-05-9) and 2,4,6-triethenyl-2,4,6-trimethylcyclotrisiloxane (CAS 3901-77-7).

[0028] The introduction of these reagents into the reaction mixture is carried out simultaneously or sequentially. For example, hexamethylcyclotrisiloxane can be added first, followed by 2,4,6-triethenyl-2,4,6-trimethylcyclotrisiloxane, or vice versa. This method is suitable for various cyclic organopolysiloxanes (OC) having three siloxane moieties.

[0029] In the context of this application, the basic catalyst B is represented by formula (IV): [Chem 4] / ■„ X'? / i R1 v ® kk kk .'.N""' R; P k § '' J FûotIHV R3 in which: Ri, whether identical or different, represents an alkyl chain of 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms. R2 represents a hydrogen atom or a -C(=O)-R3 radical with R3 representing an alkyl group of 1 to 12 carbon atoms; X represents an anion chosen from the group including: carboxylates and their derivatives, carbonates and their derivatives, hydroxyl, siloxanolates, silanolates and n is a natural number between 1 and 6.

[0030] Examples of carboxylate anions include salicylate, oxalate, malonate, glyconate, maleate or citrate.

[0031] Regarding Fanion carbonate, we can mention bicarbonate or carbonate.

[0032] For the purposes of the present invention, siloxanolate means anionic compounds the following siloxanols of formula (V): [Chem 5] in which, R1, whether identical or different, represents: -a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, -an alkenyl group comprising 2 to 6 carbon atoms, -an aryl group in C6-Ci8, -a hydroxyl group, or R2, whether identical or different, represents: -an alkenyl group comprising 2 to 6 carbon atoms, preferably vinyl, -a hydroxyl group (OH), -a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 5 carbon atoms, q is an integer between 1 and 20, preferably between 1 and 10, more preferably tiellement between 1 and 5, and with the condition that at least one radical R2 is a hydroxyl group (OH).

[0033] Preferably, siloxanolate refers to anionic compounds of formula (V) in which: R1, whether identical or different, represents: -a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, -an alkenyl group comprising 2 to 6 carbon atoms, -a cycloalkyl group of 5 to 10 carbon atoms, possibly substituted by an O, N, S heteroatom or a halide, -an aryl group in C6-Ci8, -a hydroxyl group, or R2 identical to each other represent: - a hydroxyl group (OH), q is an integer between 1 and 20, preferably between 1 and 10, more preferably between 1 and 5.

[0034] In the context of the present invention, silanolate means the anion associated with trimethylsilanol (CAS 1066-40-6) or triethylsilanol (CAS 597-52-4) compounds.

[0035] We can also mention in particular the anions associated with silanols represented by formula (VI): [Chem 6] R HQ—to--R | Formula VI R in which: R is the same or different and represents: -an alkyl group of 1 to 12 carbon atoms, -a cycloalkyl group of 5 to 8 carbon atoms, -an alkenyl group of 2 to 12 carbon atoms, -a benzyl group or a phenyl group, said radical R is possibly substituted by an alkyl chain, alkenyl of 2 to 6 carbon atoms, a cycloalkyl group, an aryl group or a heteroatom such as oxygen, sulfur or nitrogen.

[0036] Preferably, a person skilled in the art may use the compounds trimethylsilanol (CAS 1066-40-6) or triethylsilanol (CAS 597-52-4).

[0037] Preferably, the basic catalyst B is represented by formula (VII): [Chem 7] X" Formula VII R, in which: Ri identical or different represents an alkyl chain of 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms; X represents an anion chosen from the group including: carboxylates and their derivatives, carbonates and their derivatives, hydroxyl, siloxanolates, silanolates, and n is a natural number between 1 and 6.

[0038] Preferably, the basic catalyst B is represented by formula (VII) above in which: Ri represents an alkyl chain of 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms; X represents an anion chosen from the group including: hydroxyl or silanolate and n is a natural number between 1 and 6.

[0039] According to a specific embodiment of the invention, the basic catalysts B are represented above by formula (VII) in which: Ri represents an alkyl chain of 1 or 2 carbon atoms; X represents a trimethylsilanolate or triethylsilanolate anion and n is equal to 1.

[0040] In particular, basic catalysts B may be chosen from: choline hydroxide (CAS 123-41-1), choline silanolate, choline lactate (CAS 99150-55-7), triethylcholine hydroxide (CAS 3651-90-9), (2-hydroxyethyl)tripropylammonium hydroxide (CAS 96311-53-4), (2-hydroxyethyl)tributylammonium hydroxide, triethylcholine silanolate, choline bicarbonate (CAS 78-73-9), or choline salicylate (CAS 2016-36-6).

[0041] The molar quantity of basic catalyst B used in the process of the invention is from 150 ppm to 4000 ppm relative to that of the reaction mixture, preferably from 250 to 2500 ppm, more preferably from 250 ppm to 1500 ppm relative to that of the reaction mixture.

[0042] According to one embodiment of the invention, the catalyst B is solubilized in a solvent chosen from alcohols or water.

[0043] According to one embodiment of the invention, the alcohol is selected from: methanol (CAS 67-56-1), ethanol (CAS 64-17-5), propanol (CAS 71-23-8), isopropanol (CAS 67-63-0), butanol (CAS 71-36-3), allylic alcohol (CAS 107-18-6), benzyl alcohol (CAS 100-51-6), 3-buten-l-ol (627-27-0), long alkyl chain alcohols such as undecanol (CAS 112-42-5) or dodecanol (CAS 27342-88-7).

[0044] Preferably, catalyst B is solubilized in methanol or water.

[0045] For the purposes of the present invention, the chain blocker C is selected from H2O, alcohols and their derivatives, or silanols and their derivatives.

[0046] In the context of this application, the chain blocker C is selected from H2O or compounds of formula (VIII): [Chem 8] R hü—y--r | Formula VIII R in which: Y represents a carbon atom or a silicon atom; R is the same or different and represents: -an alkyl group of 1 to 12 carbon atoms, -a cycloalkyl group of 5 to 8 carbon atoms, -an alkenyl group of 2 to 12 carbon atoms containing 1 to 6 unsaturated carbon-carbon bonds -an aryl group of 6 to 18 carbon atoms, preferably phenyl, -a benzyl group -a siloxyl group having at least 5 motifs, preferably at least 10 motifs of the formula R1cSiO(4_c) / 2 in which R1, identical or different, represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl; an aryl group comprising from 6 to 10 carbon atoms, preferably phenyl; and c = 0, 1 or 2 and; said radical R may or may not be substituted by an alkyl chain of 1 to 12 carbon atoms, an alkenyl chain of 2 to 6 carbon atoms, a cycloalkyl group of 5 to 8 carbon atoms, an aryl group of 6 to 18 carbon atoms or a heteroatom such as oxygen, sulfur or nitrogen.

[0047] In the context of this application, the chain blocker C is selected from H2O or compounds of formula (VIII): [Y represents a carbon atom or a silicon atom; R is the same or different and represents: -an alkyl group of 1 to 12 carbon atoms, -a cycloalkyl group of 5 to 8 carbon atoms, -an alkenyl group of 2 to 12 carbon atoms, -an aryl group of 6 to 18 carbon atoms, preferably phenyl, -a benzyl group -a siloxyl group having at least 5 motifs, preferably at least 10 motifs of formula R1cSiO(4_c) / 2 in which R1, identical or different, represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl; an aryl group comprising from 6 to 10 carbon atoms, preferably phenyl; and c = 0, 1 or 2.

[0048] In one embodiment of the present invention, the chain blocker C is an alcohol or a silanol having a pKa of 10 to 16, preferably a pKa of 12 to 16, preferably a pKa of 14 to 16.

[0049] According to one embodiment of the invention, the chain blocker C is H2O.

[0050] According to another embodiment of the invention, the chain blocker C is a compound of formula (IX): [Chem 9] R MO--Y--R | Fomndé IX R in which: Y represents a carbon atom, R is the same or different and represents: -an alkyl group of 1 to 12 carbon atoms, -a cycloalkyl group of 5 to 8 carbon atoms, -an alkenyl group of 2 to 12 carbon atoms, -a benzyl or phenyl group, said radical R may or may not be substituted by an alkyl chain of 1 to 12 carbon atoms, an alkenyl chain of 2 to 6 carbon atoms, a cycloalkyl group of 5 to 8 carbon atoms, an aryl group of 6 to 18 carbon atoms or a heteroatom such as oxygen, sulfur or nitrogen.

[0051] According to one embodiment, the chain blocker C is an alcohol selected from the primary or secondary alcohols. Preferably, the chain blocker C is an alcohol chosen from among the primary alcohols.

[0052] According to one embodiment, the chain blocker C is an alcohol selected from saturated or unsaturated polyols having 2 to 6 hydroxyl groups. By way of example, the following polyols may be cited: glycerol, pentaerythritol, sorbitol or 1,4-butanediol.

[0053] According to one embodiment, the chain blocker C is an alcohol having a pKa of 10 to 16, preferably a pKa of 12 to 16, preferably a pKa of 14 to 16.

[0054] According to one embodiment, the chain blocker C is an alcohol selected from: methanol (CAS 67-56-1), ethanol (CAS 64-17-5), propanol (CAS 71-23-8), isopropanol (CAS 67-63-0), butanol (CAS 71-36-3), allylic alcohol (CAS 107-18-6), benzyl alcohol (CAS 100-51-6), 3-buten-l-ol (627-27-0), long alkyl chain alcohols such as undecanol (CAS 112-42-5) or dodecanol (CAS 27342-88-7).

[0055] Preferably, the chain blocker is benzyl alcohol (CAS 100-51-6), butanol (CAS 71-36-3) or 3-buten-l-ol (627-27-0).

[0056] Alternatively, within the scope of this application, the chain blocker C has at least one terminal silanol function.

[0057] Preferably, the C chain blocker having a silanol terminal function is tri-methylsilanol (CAS 1066-40-6), triethylsilanol (CAS 597-52-4) or mixtures thereof.

[0058] According to another embodiment of the invention, the chain blocker C has at least one siloxyl motif.

[0059] According to another embodiment, the chain blocker C having a silanol terminal chemical function has at least two siloxyl motifs. Alternatively, the chain blocker C having a silanol terminal function has at least three siloxyl motifs.

[0060] The term silanol terminal function refers to a chemical function at the end of a chain formed by the chemical bond between a silicon atom and a hydroxyl group.

[0061] According to one embodiment of the invention, the chain blocker C is represented by the formula (X): [Chem 10] R1 R in which, R1, whether identical or different, represents: -a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, optionally substituted by an O, N, S heteroatom or a halide, -an alkenyl group comprising 2 to 6 carbon atoms, -a cycloalkyl group of 5 to 10 carbon atoms, possibly substituted by an O, N, S heteroatom or a halide, -an aryl group in C6-Ci8, or -a hydroxyl group, R2, whether identical or different, represents: -an alkenyl group comprising 2 to 6 carbon atoms, preferably vinyl, -a hydroxyl group (OH), or -a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 5 carbon atoms, optionally substituted by at least one O, N, S heteroatom or a halide such as a fluorine atom, for example 1 to 10 fluorine atoms, for example (Ci-C5)alkyl-CF3, the alkyl being linear or branched; q is an integer between 0 and 20, preferably between 0 and 10, more preferably between 0 and 5, and with the condition that at least one R2 radical is a hydroxyl group (OH).

[0062] According to one embodiment of the invention, the chain blocker C is represented by the formula (X) above: in which, R1, whether identical or different, represents: -a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, optionally substituted by an O, N, S heteroatom or a halide, -an alkenyl group comprising 2 to 6 carbon atoms, -a cycloalkyl group of 5 to 10 carbon atoms, possibly substituted by an O, N, S heteroatom or a halide, -an aryl group in C6-Ci8, or -a hydroxyl group, R2 identical to each other represent: -a hydroxyl group (OH), q is an integer between 0 and 20, preferably between 0 and 10, more preferably between 0 and 5.

[0063] In another embodiment, the chain blocker C is represented by the formula (X) above, in which: R1, identical, represents CH3 R2, whether identical or different, represents: -an alkenyl group comprising 2 to 6 carbon atoms, preferably vinyl, -a hydroxyl group (OH), -a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, or -an aryl group in C6-Ci8, possibly substituted; q is an integer between 0 and 20, preferably between 0 and 10, more preferably between 0 and 5, and with the condition that at least one radical R2 is a hydroxyl group (OH).

[0064] In another embodiment, the chain blocker C is represented by the formula (X) above, in which: R1, identical, represents CH3 R2 identical, represent: -a hydroxyl group (OH), and q is an integer between 0 and 20, preferably between 0 and 10, more preferably between 0 and 5.

[0065] The chain blocker C can be in a solvent. This is particularly advantageous for solubilizing it in the reaction mixture. The solvent can, in particular, be a nonpolar solvent such as an alkane-type organic solvent or an aromatic hydrocarbon. Preferably, the solvent is chosen from pentane, n-hexane, n-heptane, n-decane, n-dodecane, isododecane, EXXSOL D60, xylene, toluene, and mixtures thereof.

[0066] Alternatively, the C chain blocker can be in a polar solvent such as THF, Me-THF or CH2C12.

[0067] These chain blockers enable the functionalization of the linear organopolysiloxane OL during the polymerization reaction. Thus, it is possible to obtain linear organopolysiloxanes OL having, for example, identical or different terminal chemical functions.

[0068] According to one embodiment, the process of the invention is characterized in that in step a) of said process the molar ratio of chain blocker C with respect to the basic catalyst B engaged is from 0.01 to 600, preferably from 0.8 to 300, preferably from 1.5 to 300, preferably from 4 to 200 and even more preferably from 8 to 100.

[0069] According to one embodiment, the process of the invention is characterized in that during step a) the molar ratio of cyclic organopolysiloxane OC with respect to the chain blocker C engaged is from 1 to 20,000, preferably from 2 to 5,000, preferably from 2 to 1,400, preferably from 4 to 700, even more preferably from 4 to 300 and even more preferably from 10 to 150.

[0070] According to one embodiment of the invention, linear organopolysiloxane OL is a compound of formula (XI): [Chem 11] in which, R, identical or different, represents: -an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, -an aryl group comprising 6 to 10 carbon atoms, preferably phenyl, R1, identical or different, represents: -an alkyl group comprising 1 to 5 carbon atoms -an alkenyl group comprising 2 to 6 carbon atoms, preferably vinyl, -a hydroxyl group (OH), or -an aryl group at C6-Ci8, preferably phenyl, R2, whether identical or different, represents: -an alkenyl group comprising 2 to 6 carbon atoms, preferably vinyl, -a hydroxyl group (OH), - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 5 carbon atoms, optionally substituted by at least one O, N, S heteroatom or a halide such as a fluorine atom, for example 1 to 10 fluorine atoms, for example (Ci-C5)alkyl-CF3, the alkyl being linear or branched, - a C5-C10 cycloalkyl group, optionally substituted, -an aryl group in C6-C^ possibly substituted, or a group (O-R3) with R3 representing: an alkyl group comprising 1 to 15 carbon atoms, preferably 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, preferably OCH3 or OC2H5, an alkenyl group comprising 2 to 15 carbon atoms, preferably 2 to 10 carbon atoms, a C6-Ci8 aryl group or alkylaryl group such as a benzyl group q is an integer between 0 and 50, preferably between 0 and 20, more preferably between 0 and 10; preferably q = 0 n2 represents an integer between 10 and 25,000, preferably between 10 and 5,000, preferably between 10 and 1,500, preferably between 50 and 1,000, more preferably between 100 and 500; m2 represents an integer between 0 and 100, preferably between 0 and 50, more preferably between 0 and 30, preferably m2=0.

[0071] According to a preferred embodiment of the invention, linear organopolysiloxane OL is a compound of formula (XI): in which, R identical or different, represents CH3 or phenyl, preferably CH3; R1, whether identical or different, represents: -an alkyl group comprising 1 to 5 carbon atoms -an alkenyl group comprising 2 to 6 carbon atoms, preferably vinyl, -an aryl group at C6-Ci8, preferably phenyl, R2, whether identical or different, represents: -an alkyl group comprising 1 to 6 carbon atoms -an alkenyl group comprising 2 to 6 carbon atoms, preferably vinyl, -a hydroxyl group (OH), -an aryl group in C6-Ci8, -a group (O-R3) with R3 representing: an alkyl group comprising 1 to 10 carbon atoms, an alkenyl group comprising 2 to 10 carbon atoms, or a benzyl group q is an integer between 0 and 50, preferably between 0 and 20, more preferably between 0 and 10, preferably q = 0; n2 represents an integer between 10 and 1500, preferably between 10 and 1000, preferably between 50 and 1000, more preferably between 100 and 500; m2 represents an integer between 0 and 500, preferably between 0 and 100, more preferably between 0 and 50.

[0072] According to a particularly preferred embodiment of the invention, the linear organopolysiloxane OL of the invention is a compound of formula (XI) in which, R, whether the same or different, represents CH3 or phenyl, preferably CH3. R1, identical or different, represents CH3, phenyl or vinyl; R2, whether identical or different, represents: -an alkenyl group comprising 2 to 6 carbon atoms, preferably vinyl, -a hydroxyl group (OH), -a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, -an aryl group at C6-Ci8, possibly substituted, or -a group (O-R3) with R3 representing: an alkyl group comprising 1 to 10 carbon atoms, an alkenyl group comprising from 2 to 10 carbon atoms, or a benzyl group q is equal to 0; n2 represents an integer between 10 and 1500, preferably between 10 and 1000, preferably between 50 and 1000, more preferably between 100 and 500; m2 represents an integer between 0 and 500, preferably between 0 and 100, more preferably between 0 and 50

[0073] According to one embodiment of the invention, the linear organopolysiloxane OL of the invention, as represented above by formula (XI), is a compound for which R2 is identical. In other words, the linear organopolysiloxane OL is homotele-chelic.

[0074] As a reminder, a linear homotelecholic organopolysiloxane (OL) is defined as a linear organopolysiloxane having identical terminal chemical functions.

[0075] Similarly, according to one embodiment of the invention, the linear organopolysiloxane OL of the invention, as represented above by formula (XI), is a compound for which R2 is different. In other words, the linear organopolysiloxane OL is heterotele-chelic.

[0076] As a reminder, a linear organopolysiloxane OL heterotelecholic is understood to be a linear organopolysiloxane having different terminal chemical functions.

[0077] In the context of the present invention, the mass average molar mass and the number average molar mass, denoted respectively Mw and Mn, of the various linear organopolysiloxanes OL can be determined by size exclusion chromatography (SEC) in the presence of polystyrene standards in a solvent such as toluene at 35 °C.

[0078] According to one embodiment of the process of the invention, the linear organopolysiloxane OL of the invention is characterized in that its degree of polymerization is between 5 and 28,000, preferably between 5 and 7,000, preferably between 5 and 4,000, preferably between 15 and 2,000, more preferably between 20 and 1,000 and even more preferably between 20 and 400.

[0079] According to one embodiment of the process of the invention, the linear organopolysiloxane OL of the invention is characterized in that its mass average molar mass Mw can be between 500 and 2,000,000 g / mol, preferably between 500 and 500,000 g / mol, preferably between 500 and 300,000 g / mol, preferably between 1,000 and 150,000 g / mol, more preferably between 1,000 and 100,000 g / mol, even more preferably between 5,000 and 40,000 g / mol.

[0080] According to one embodiment of the process of the invention, the linear organopolysiloxane OL of the invention is characterized in that its number-average molar mass Mn is between 500 and 2,000,000 g / mol, preferably between 500 and 500,000 g / mol, preferably between 500 and 300,000 g / mol, preferably between 1 000 and 150,000 g / mol, more preferably between 1,000 and 100,000 g / mol, even more preferably between 5,000 and 40,000 g / mol.

[0081] According to one embodiment of the process of the invention, the linear organopolysiloxane OL of the invention is characterized in that its dynamic viscosity is between 100 and 1,000,000 mPa.s at 25°C, preferably between 1,000 and 500,000 mPa.s at 25°C, preferably between 1,000 and 100,000, and even more preferably between 10,000 and 80,000 mPa.s at 25°C.

[0082] In the context of this application, the mass percentage or weight percentage of D4 in the products obtained according to the process of the present invention can be measured via quantitative 29Si NMR spectra. Alternatively, the mass percentage or weight percentage of D4 in the products obtained according to the process of the present invention could be measured via chromatograms obtained from size exclusion chromatography (SEC) analysis.

[0083] Hereafter the product resulting from the reaction is the sum of the linear organopolysiloxane OL and the cyclic organopolysiloxane OC at the end of the process of the present invention.

[0084] In one embodiment, the process according to the invention is characterized in that the content of cyclic organopolysiloxanes OC is less than 2%, preferably less than or equal to 1%, preferably less than or equal to 0.5% relative to the total mass of product from the reaction.

[0085] In one embodiment, the process according to the invention is characterized in that the content of octamethylcyclotetrasiloxane (D4) is less than 2%, preferably less than or equal to 1%, preferably less than or equal to 0.5% relative to the total mass of product from the reaction.

[0086] Preferably, the process of the invention is carried out without any solvent other than the amount necessary to solubilize and / or dissolve the catalyst B in the reaction medium.

[0087] This embodiment is particularly advantageous because it eliminates the need for solvent, its treatment or recycling once used, while still obtaining satisfactory results when carrying out the process of the present invention.

[0088] However, in an alternative embodiment, the process of the invention is carried out in a nonpolar solvent. The solvent may, in particular, be an organic solvent of the alkane or aromatic hydrocarbon type.

[0089] Preferably, the solvent is chosen from n-hexane, n-heptane, n-decane, n-dodecane, isododecane, EXXSOL D60, xylene, toluene and mixtures thereof.

[0090] Alternatively, the process of the invention is carried out in a polar solvent. The solvent may in particular be an organic solvent such as THF or Me-THF.

[0091] In one embodiment, the process of the invention is characterized in that the mass ratio of cyclic organopolysiloxane OC to the mass of solvent involved is from 0.5 to 50, preferably from 1.5 to 15, preferably from 3 to 10 to the mass of solvent involved.

[0092] Advantageously, and preferably, the reaction is carried out at a temperature between 25°C and 150°C, preferably between 35°C and 100°C, more preferably between 35°C and 80°C.

[0093] According to the process of the invention, the duration of the reaction is between 1 minute and 48h, preferably between 1 minute and 18h, more preferably between 1 minute and 8h, even more preferably between 1 minute and 2h, and even more preferably between 1 minute and 1h.

[0094] A person skilled in the art will be able to adapt these parameters according to the nature of the reactors and the species used.

[0095] The process defined according to the present invention may further include a step b), by the subsequent addition of a chain blocker C identical or different from that of step a) or of an acid A with a ring-opening polymerizable composition S.

[0096] Step b) of the process of the present invention allows for flexibility in controlling the nature of the terminal chemical functions as well as in controlling the molar masses of the OL product.

[0097] Indeed, it is possible to obtain a linear organopolysiloxane OL homotele-chelic or heterotele-chelic depending on the nature of step b) of said process.

[0098] As a reminder, a linear homotelecholic organopolysiloxane (OL) is understood to be a linear organopolysiloxane having identical terminal chemical functions.

[0099] Linear organopolysiloxane OL heterotelecholic means a linear organopolysiloxane having different terminal chemical functions.

[0100] According to one embodiment of the invention, the process further comprises a step b) defined by the subsequent addition of a chain blocker C identical to that introduced during step a) of said process.

[0101] This embodiment makes it possible to obtain a homotelecholic linear organopolysiloxane OL while controlling the molar mass of the product thus obtained.

[0102] According to one embodiment of the invention, the process further comprises a step b) defined by the subsequent addition of a chain blocker C different from that introduced during step a) of said process.

[0103] This embodiment allows control of both the molar mass and the nature of the terminal chemical functions of the OL product. A linear heterotelechelic organopolysiloxane OL is thus obtained.

[0104] According to one embodiment of the invention, the process of the invention is characterized in that the molar ratio of chain blocker C to basic catalyst B committed during step b) is between 1 and 200, preferably between 1 and 100, preferably between 20 and 100.

[0105] According to one embodiment of the invention, the process of the invention is characterized in that the molar ratio of cyclic organopolysiloxane OC with respect to the chain blocker C engaged during step b) is from 1 to 100, preferably from 5 to 80, preferably from 10 to 50.

[0106] Alternatively, step b) of the process of the present invention includes a step of further adding acid A to the ring-opening polymerizable composition S.

[0107] This step b) makes it possible to neutralize the basic catalyst B and to stop the polymerization reaction carried out according to the process of the present invention.

[0108] This embodiment also allows control over the nature of the terminal chemical functions of the OL product. This yields a linear heterotelechelic organopolysiloxane OL.

[0109] According to one embodiment of the process of the invention, the acid A introduced during step b) of said process is selected from acids such as organic acids, Lewis acids, functionalized organohalosilanes, ion-exchange resins or mineral acids

[0110] Regarding organic acids, we can mention in particular derivatives of carboxylic acid such as propionic acid, glycolic acid, valeric acid, butyric acid, caproic acid, caprylic acid, capric acid, octanoic acid, lauric acid, myristic acid, stearic acid, palmitic acid, oleic acid, undecylenic acid, or other derivatives of carboxylic acids.

[0111] Preferably, acid A is chosen from the group of carboxylic acid derivatives or mineral polyacids.

[0112] For the purposes of the present invention, a "mineral polyacid" is a compound formed of hydrogen and one or more other elements (excluding carbon), which has the ability to release several protons in aqueous solution, unlike monoacids which can only release one. Examples include phosphoric acid, sulfuric acid, and the hydronium ion.

[0113] According to one embodiment of the invention, acid A is phosphoric acid.

[0114] According to one embodiment of the invention, acid A has a pKa ranging from 1 to 13, preferably from 1.5 to 10, preferably from 2 to 8.

[0115] It appears evident that a person skilled in the art will be able to adapt the nature and quantity of acid A introduced to meet the requirements of the process of the present invention.

[0116] According to a particular embodiment, step b) of the process of the present invention includes a step of adding a chain blocker C identical or different from that of step a) and an acid A with a ring-opening polymerizable composition S.

[0117] According to one embodiment of the process of the invention, step b) is carried out from 2 to 45 minutes after step a) of said process, preferably from 2 to 30 minutes, preferably from 2 to 15 minutes after step a) of said process.

[0118] During step c) of the process of the present invention, the linear organopolysiloxane OL is obtained.

[0119] This step c) may further include one or more filtration, evaporation, distillation steps allowing the linear organopolysiloxane OL to be obtained.

[0120] A person skilled in the art will be able to adapt the implementation of these treatment steps and their operating conditions to meet the requirements of the process of the present invention.

[0121] This application also relates to the linear organopolysiloxane OL obtained according to the various embodiments of the process of the present invention described above. It also relates to a silicone composition comprising the organopolysiloxane OL obtained according to the various embodiments of the process of the present invention described above.

[0122] The present application also relates to a composition SI comprising: i) at least one cyclic organopolysiloxane OC having three siloxane motifs, ii) at least one basic catalyst B of formula (XII): [Chem 12] y X jnt \ v r2 K | Formula XII in which: -Ri, identical or different, represents an alkyl chain of 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms. -R2 represents a hydrogen atom or a -C(=O)-R3 radical with R3 representing an alkyl group of 1 to 12 carbon atoms; - X represents an anion chosen from the group including: carboxylates and their derivatives, carbonates and their derivatives, hydroxyl, siloxanolates, silanolates, and n is a natural number between 1 and 6, iii) at least one C chain blocker.

[0123] According to one embodiment of the invention, the present application also relates to the SI composition comprising: i) at least one cyclic organopolysiloxane OC having three siloxane motifs, ii) at least one basic catalyst B of formula (XIII): [Chem 13] Formula XIII in which: -Ri identical or different represents an alkyl chain of 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms; -X represents an anion chosen from the group including: carboxylates and their derivatives, carbonates and their derivatives, hydroxyl, siloxanolates, silanolates, and n is a natural number between 1 and 6.

[0124] This application also relates to the use of organopolysiloxanes OL obtained according to the process of the present invention as an ingredient that can be directly used in various silicone formulations useful in fields such as cosmetics, household cleaning products, automotive, energy.

[0125] Finally, the present application relates to basic catalysts B represented by formula (XIV): [Chem 14] FL in which: -Ri identical or different represents an alkyl chain of 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms; -X represents a siloxanolate or silanolate anion and n is a natural number between 1 and 6.

[0126] Preferably, the basic catalysts B represented by formula (XIV) above: in which: -Ri identical or different represents an alkyl chain of 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms; -X represents a silanolate anion and n is a natural number between 1 and 6.

[0127] The basic catalysts B represented by formula (XIV) above: in which: -Ri identical or different represents an alkyl chain of 1 or 2 carbon atoms; -X represents a trimethylsilanolate or triethylsilanolate anion and n is equal to 1. Examples

[0128] Cyclic organopolysiloxanes used in the examples:

[0129] Cyclic organopolysiloxane OCi: hexamethylcyclotrisiloxane (CAS 541-05-9)

[0130] Cyclic organopolysiloxane OC2: 2,4,6-triethenyl-2,4,6-trimethylcyclotrisiloxane (CAS 3901-77-7)

[0131] Basic B catalysts implemented in the examples:

[0132] Commercial Bi:choline hydroxide (CAS 123-41-1) catalyst diluted in water or methanol [Chem 15] Ol-f x. 4) Catalyst B2: choline trimethylsilanolate (13%) diluted in 1,3-buten-l-ol (CAS 627-27-0), synthesized within the framework of the invention. [Chem 16] xr, -CM xx rr Catalyst B3: triethylcholine trimethylsilanolate (13%) diluted in 1,3-buten-l-ol (CAS 627-27-0), synthesized within the framework of the invention. [Chem 17] y 'oh Catalyst B4: choline bicarbonate (CAS 78-73-9) [Chem 18]

[0133]

[0134]

[0135] Catalyst Bs: choline salicylate (CAS 2016-36-6) [Chem 19] 'N Bcompi Catalyst: Triazabicyclodecene CAS (5807-14-7) [Chem 20] f'z 'N' '"4 'H'H Catalyst Bcomp2: KOSiMe3 (CAS 10519-96-7) diluted in 1,3-buten-l-ol (CAS 627-27-0), (13% wt) Bcomp3 Catalyst: KOSime3 (CAS 10519-96-7) Catalyst Bcomp4: choline chloride (CAS 67-48-1) [Chem 21] Cl"

[0136] BcompS Catalyst: Tetramethylammonium hydroxide (CAS 75-59-2) Chain blockers implemented in the examples: Ccompi chain blocker: divinyltetramethyldisiloxane (CAS 2627-95-4). Chain blocker Cx: benzyl alcohol (CAS 100-51-6) Chain blocker C2: 1-3-buten-l-ol (CAS 627-27-0) C3 chain blocker: triethylsilanol (CAS 597-52-4) C4 chain blocker: trimethylsilanol (CAS 1066-40-6) Chain blocker Cs: H2O C6 chain blocker: n-butanol (CAS 71-36-3)

[0137] In the context of the examples described below, the residual mass percentages of cyclic organopolysiloxanes OC (D3 or D4, D5 and D6) and the mass percentages of linear organopolysiloxane OL obtained according to the process of the present invention are measured by size exclusion chromatography (SEC) in the presence of polystyrene standards in a solvent such as toluene at 35°C.

[0138] Similarly, the number-average molar mass denoted Mn of the different linear organopolysiloxanes OL according to the present invention is determined by the same size exclusion chromatography (SEC) method. Example 1: Synthesis of catalysts B2 and B3:

[0139] In a 100mL flask, weigh a solution of cholinium chloride or ethyl cholinium chloride (1.2 eq solubilized in 15% wt. 3-buten-l-ol alcohol) and a solution of potassium silanolate (1.0 eq solubilized in 25% wt. 3-buten-l-ol alcohol).

[0140] The cloudy reaction medium obtained is mixed under magnetic stirring for 2 hours at room temperature. After filtration, catalysts B2 or B3 are obtained as a clear 13 wt% solution in 3-buten-l-ol alcohol.

[0141] Example 2: General protocol of the polymerization process defined according to the invention

[0142] In a 500 mL reactor under an inert atmosphere (argon), a cyclic organopolysiloxane OC, a basic catalyst B, and a chain blocker C are introduced. The reaction mixture is placed at 70°C with stirring for a duration of 1 h. A sample is taken and analyzed by ¹H NMR and ²⁹Si NMR.

[0143] Example 3: Screening of the different basic catalysts B to implement the process of the invention:

[0144] In this example, the reaction mixture consists of the cyclic organopolysiloxane OCi (10 g), a basic catalyst B (5 to 9 mg), and a chain blocker (with an OC / C ratio of 15 or 21). For this entire example, the chain blocker C is 1,3-butenyl-ol (CAS 627-27-0) (C2). The reaction mixture is heated to 70°C with stirring. A sample is taken and analyzed by ¹H NMR and ²⁹Si NMR.

[0145] The nature of catalyst B, the reaction time, the molar quantity of catalyst B, and the various products obtained at the end of the ring-opening polymerization reaction are shown in Table 1 below. [Table 1] Catalyst B Molar quantity of catalyst B (ppm) Reaction time (min) Mass percentage of residual D3 (%) Mass percentage of residual D4, D5 and D6 (%) Mass percentage of product OL (%) Mn of product OL (g / mol) Catalyst I^compl 1200 (43 pmol) 30 15 0.8 84.2 3 600 Catalyst I$comp2 980 (47 pmol) 30 10 2.2 87.8 5 600 Catalyst I$comp3 1400 (70 pmol) 30 8 2.2 89.8 6 000 Catalyst I$comp4 1400 (65 pmol) 300 99.1 0.9 - - Catalyst Bi 800 (38.7 pmol) 20 0.7 1.3 98 4 900 Catalyst b2 980 (47.4 pmol) 20 0.2 1.5 98.3 4 300

[0146] Further tests were repeated with an OC / C molar ratio of 15. [Table 2] Catalyst B Molar quantity of catalyst B (ppm) Reaction time (min) Mass percentage of residual D3 (%) Mass percentage of residual D4, D5 and D6 (%) Mass percentage of product OL (%) Mn of product OL (g / mol) Catalyst I$comp5 536 ppm (26 pmol) 30 0.9 0.4 98.7 4903 Catalyst Bi 850 ppm (41.6 pmol) 10 0.3 0.7 99 4466 Catalyst b3 780 ppm (38 pmol) 10 1.8 0.5 97.7 3679 Catalyst b4 2070 ppm (100 pmol) 30 1.5 0.5 98 4130 Catalyst Bs 1190 ppm (57.5 pmol) 20 1.8 0.5 97.7 4303

[0147] Regarding the calculation of the molar ppm of catalyst B, they were obtained according to the The following calculations: [Math] ppm molar of B = x 106

[0148] The tables above show that the basic catalysts B of the process of the present invention allow to carry out a ring opening polymerization where the conversion is maximum in 10 to 30 minutes with a small amount of by-products, in this case the residual cyclic compounds.

[0149] In the following examples, all of these secondary products will be referred to as residual OCs. It should be noted that the only satisfactory comparative catalyst (Bcomp5) is toxic and ecotoxic, unlike those of the present invention.

[0150] Example 3: Influence of the nature of the chain blocker C on the process of the invention:

[0151] The protocol of Example 2 is implemented with the cyclic organopolysiloxane OCi (250 g), the basic catalyst Bi (950 pmol), and the chain blocker C (52.7 mmol). The reaction mixture is placed at 70°C under stirring for 1 h. The molar ratio OCi / C is 21.

[0152] The table below mentions the nature of the chain blocker, the molar mass of the linear organopolysiloxane OL obtained and the mass percentage of residual cyclic organopolysiloxane OC from the process of the present invention. [Tables 3] Test number Chain blocker C Mn of product OL (g / mol) Mass percentage of residual OC (D3 to D6) (%) 1 Ccompl 18,300 2.8 2 Ci 12,100 0.9 3 c2 10,300 1.2 4 c3 10,600 1.0 5 c4 10,500 0.8

[0153] Test 1 shows that a conventional chain blocker such as Ccompi does not allow for the regulation of the molar mass of the product obtained. Furthermore, it is observed that the percentage of cyclic by-products (residual cyclic organopolysiloxanes OC) is higher than that obtained under the conditions of the claimed process.

[0154] Indeed, the presence of chain blockers C in tests 2 to 5, claimed according to the process of the invention, makes it possible to obtain a very low level of cyclic by-products (< 1%). Furthermore, these chain blockers make it possible to regulate the molar mass of the product obtained OL and to control the nature of the terminal chemical functions. Thus, the results shown in the table above demonstrate that the The method of the invention is versatile and can be used with different C chain blockers defined according to the present invention.

[0155] Example 4: Influence of the quantity of chain blocker C on the process of the invention:

[0156] In this example, the protocol of Example 2 is implemented with the cyclic organopolysiloxane OCi (250g), the basic catalyst Bx (950 pmol) and the chain blocker C4 (quantities defined in the table below). The reaction mixture is placed at 70°C under stirring for 1h.

[0157] The table below shows the molar ratio of OCi to the moles of C, as well as the molecular mass of the product obtained OL and the mass percentage of residual cyclic organopolysiloxane OC from the process of the present invention. [Tables4] Test number | Molar ratio OCi / C | Molar quantity of chain blocker C (mmol) | Mn of product OL (g / mol) | Mass percentage of residual OC (D3 to D6) (%) | 1 | 21 | 52.7 | 10,500 | 0.8 | 2 | 87 | 12.5 | 15,100 | 1.3 | 3,179 | 6.24 | 27,200 | 1.6

[0158] The amount of chain blocker C introduced into the reaction mixture allows control of the molecular mass of the linear product obtained OL.

[0159] Example 5: Obtaining homotelechelic or heterotelechelic organopolysiloxanes

[0160] In this example, the protocol of Example 2 is implemented with the cyclic organopolysiloxane OCi (250 g), the basic catalyst Bi (950 pmol), and the chain blocker C4 (52.7 mmol). The reaction mixture is placed at 70°C under stirring for a period ranging from a few minutes to 1 hour. Then, a sample is taken and analyzed by ¹H NMR and ²⁹Si NMR. In this example, the initial molar ratio OCi / C is identical for each assay and is equal to 21. Trial number Subsequent addition of a C4 chain blocker during optional step b) of the process Subsequent addition of acid (H3PO4) during optional step b) of the process Mn of product OL (g / mol) Mass percentage of residual OC (%) 1 No No 10,500 0.8 2 63.5 mmol No 6,400 1.2 3 No 0.77 mmol 4 800 1.2

[0161] In the tests mentioned in the table above, different steps of the process of the present invention are implemented.

[0162] First, test 1 implements only step a) of the process of the present invention. This test makes it possible to obtain a homotele-chelic linear organopolysiloxane OL.

[0163] As a reminder, a linear homotelecholic organopolysiloxane (OL) is defined as a linear organopolysiloxane having identical terminal chemical functions.

[0164] Test 2 implements step a) of the process of the present invention and the optional step b) of said process. In this example, step b) consists of a subsequent addition of the same C4 chain blocker. For Test 2, this subsequent addition of the C4 chain blocker occurs after a few minutes of reaction (8 to 15 minutes). This yields a homotelechyl linear organopolysiloxane OL. This embodiment (Test 2) allows control of the molar mass of the OL product.

[0165] Finally, test 3 implements step a) of the process of the invention followed by step b) of said process. For this test, step b) consists of the addition of an acid (H3PO4) which makes it possible to obtain a linear heterotelechelic organopolysiloxane OL.

[0166] Thus, these different strategies detailed in the table above, depending on the nature of the reaction inhibition (addition of a second chain blocker or addition of acid to the reaction medium), influence the nature of the terminal chemical functions of the linear organopolysiloxane OL obtained. The various 1H NMR and 29Si NMR spectra of the linear organopolysiloxanes OL thus obtained in tests 1 to 3 confirm these results.

[0167] Example 6: Obtaining short a.co-hydroxypolydimethylsiloxane in solvent medium:

[0168] In this example, the protocol of example 2 is implemented with the cyclic organopolysiloxane OCi (250g), the basic catalyst Bi (950 pmol) and the chain blocker C5 (52.7 mmol)

[0169] In order to obtain α,co-hydroxypolydimethylsiloxane oils with a low number molar mass (Mn), the chain blocker C is mixed with a solvent such as Me-THF (80 mL) and the reaction mixture is heated to 45°C. A sample is taken and analyzed by β-H NMR and 29Si NMR.

[0170] Under these operating conditions, a linear organopolysiloxane OL is obtained, having two hydroxyl functions at the end of the chain, with a molar mass in number Mn of 6900 g / mol and a mass percentage in residual cyclic organopolysiloxane OC of 1.2%.

[0171] This test confirms the flexibility of the process of the present invention and the possibility of obtaining low molar mass α,co-hydroxypolydimethylsiloxane oils in number Mn. Example 7: Block copolymers:

[0172] Characterization of the V and D triads of the copolymers by NMR:

[0173] Microstructure analysis by 29Si NMR is an extremely efficient method for determining the structure and microstructures of linear organopolysiloxanes (OLs). This allows for the differentiation of D and V units, respectively derived from homopolymerization of the introduced cyclic organopolysiloxanes OCi and OC2.

[0174] Thus, the distribution of V units in the silicon chain is determined according to the distribution of the VVV, DW (or WD), and DVD triads. These triads are clearly identified by 29Si NMR thanks to the presence of triplets characteristic of the VVV, DW (or WD), and DVD motifs. As a reminder, for the purposes of this application, the VVV, DW (or WD), and DVD triads are defined as the following motifs:

[0175] VVV Triad: [Chem 22] DW (or WD) Triad: [Chem 23] Triad DVD: [Chem 24] The triads DDD, DDV and VDV will be declined in a similar manner.

[0176] In the context of this example, the statistical product is understood to be a linear organopolysiloxane OL obtained according to the process of the invention having a random distribution of vinylized units (V).

[0177] On the other hand, in the context of the present invention, block copolymers are called block copolymers the linear organopolysiloxane OL obtained according to the process of the invention having a non-random distribution of vinylized units (V).

[0178] In the context of this example, the process of the present invention is implemented in six different embodiments:

[0179] In a pillbox under an inert atmosphere (argon), a cyclic organopolysiloxane OC, a basic catalyst B (800 ppm), and a chain blocker C are introduced. The reaction mixture is placed at 70°C with stirring for a duration of 1 h. A sample is taken and analyzed by ¹H NMR and ²⁹Si NMR.

[0180] In the various tests A, B and C mentioned below, the cyclic organopolysiloxanes introduced are OCi (5g, 70 mol%) and OC2 (2.5g, 30 mol%). The basic catalyst Bx is in solution in methanol and the chain blocker is C4.

[0181] Test A: is carried out with the cyclic organopolysiloxanes OCiet and OC2 introduced simultaneously. Test B is carried out with the cyclic organopolysiloxane OCi, then the cyclic organopolysiloxane OC2 is introduced about ten minutes after the start of the reaction. Test C: is carried out with the cyclic organopolysiloxane OC2 then OCi is introduced about ten minutes after the start of the reaction.

[0182] In the context of the various tests D, E and F mentioned below, the cyclic organopolysiloxanes introduced are OCi (5g, 80 mol%) and OC2 (1.7g, 20 mol%). The basic catalyst Bx is in aqueous solution and the chain blocker is C6.

[0183] Test D: is carried out with the cyclic organopolysiloxanes OCi and OC2 introduced simultaneously. Test E: is carried out with the cyclic organopolysiloxane OCi, then the cyclic organopolysiloxane OC2 is introduced about ten minutes after the start of the reaction. Test F: is carried out with the cyclic organopolysiloxane OC2 then the cyclic organopolysiloxane OCi is introduced about ten minutes after the start of the reaction. [Tableauxô] Experimental integration of triads by NMR measurement. C4 chain blocker. C6 chain blocker. Trial A. Trial B. Trial C. Trial D. Trial E. Trial F. Triads V VVV 59.30% 63.50% 79.60% 53.00% 60.50% 71.70% WD 29.60% 30.50% 12.60% 31.70% 32.90% 17.10% DVD 11.10% 6.00% 7.80% 15.30% 6.60% 11.20%. Triads D DDD 79.30% 78.70% 90.90% 83.10% 84.60% 91.40% DDV 18.10% 16.90% 7.80% 15.30% 12.00% 7.80% VDV 2.60% 4.40% 1.30% 1.60% 3.40% 0.9%

[0184] Thus, the experimental data measured under the conditions mentioned above demonstrate the tendency to form block copolymers under these specific experimental conditions. Therefore, in addition to controlling the nature of the terminal chemical functions discussed in the preceding examples, the process of the present invention allows control of the structure of the linear organopolysiloxane OL obtained.

[0185] Characterization of the end units of the chains for tests A, B and C:

[0186] The microstructure by 29Si NMR mentioned above also made it possible to identify the end units of the chains during tests A, B and C. In other words, this made it possible to evaluate a possible influence of the order of addition of the cyclic organopolysiloxanes OC on the nature of the end units of the chains.

[0187] In the table below, the acronym HO-D designates the following unit: [Chem 25] .......... gj The acronym (Me)3SiO-D designates the following unit: [Chem 26] {MefeSiQ—SI^aa Similarly, the acronym HO-V designates the following unit: [Chem 27] Finally, the acronym (Me)3SiO-V designates the following unit: [Chem 28]

[0188] The results obtained are shown in the table below. [Tables?] Tests Nature of units present at the end of chains HO-D (Me)3SiO-D HO-V (Me)3SiO-VA 0 35% 0 65% B 0 100.00% 0 0.00% C 0 0.00% 0 100.00%

[0189] Thus, with the C4 chain blocker, depending on the implementation of the process of the invention (Test A, B, or C), a different distribution of the unit present at the ends of the chains is observed. Indeed, the table above shows that the order of addition of the cyclic organopolysiloxane OC strongly influences the nature of the "terminal" unit. Furthermore, the C4 chain blocker allows for complete control over the nature of the units present at the ends of the chains.

Claims

Claims

1. Process for the preparation of linear organopolysiloxanes OL by a ring-opening polymerization reaction, said process comprising the following steps: a) Implementing a ring-opening polymerizable composition S comprising: i) at least one cyclic organopolysiloxane OC having three siloxane units, ii) at least one basic catalyst B of formula (I): [Chem 29] ,N A'-'-" R; R: ' ri î î r mmik- i R, in which: -Ri, identical or different, represents an alkyl chain of 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms, -R2 represents a hydrogen atom or a radical -C(=O)-R3 with R3 which represents an alkyl group of 1 to 12 carbon atoms;- X represents an anion chosen from the group comprising: carboxylates and their derivatives, carbonates and their derivatives, hydroxyl, siloxanolates, silanolates, -n is a natural number between 1 and 6, and iii) at least one chain blocker C; b) Optionally, subsequently adding a chain blocker C identical or different to that of step a) or an acid A to the composition polymerizable by ring opening S, c) Obtaining the linear organopolysiloxane OL.;

2. A method according to any one of the preceding claims wherein the cyclic organopolysiloxane OC is represented by the formula (II): [Chem 30] RR \ / R--sr" Si---R 0K ..0 Fmmdê II 's> / X RR in which, R, identical or different, is a radical representing an alkyl group of 1 to 6 carbon atoms, an alkenyl group of 2 to 6 carbon atoms, or an aryl group of 6 to 18 carbon atoms.

3. A process according to any preceding claim, wherein the basic catalyst B is represented by formula (III): [Chem 31] / \ ® 1---3 x° M JT \ Ri

4.

5. in which: - Ri represents an alkyl chain of 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms; - X represents an anion chosen from the group comprising: carboxylates and their derivatives: carbonates and their derivatives, hydroxyl, siloxanolates, silanolates, and n is a natural number between 1 and 6. Process according to any one of the preceding claims, in which the molar quantity of basic catalyst B relative to that of the reaction mixture is from 150 ppm to 4000 ppm, preferably from 250 to 2500 ppm, more preferably from 250 ppm to 1500 ppm relative to that of the reaction mixture. A method according to any one of the preceding claims, wherein the chain blocker C is selected from H2O or compounds of formula (VIII): [Chem 32] R HO--y—R [Formula VIII 13 in which: Y represents a carbon atom or a silicon atom; R is identical or different and represents: - an alkyl group of 1 to 12 carbon atoms, - a cycloalkyl group of 5 to 8 carbon atoms, - an alkenyl group of 2 to 12 carbon atoms comprising 1 to 6 unsaturated carbon-carbon bonds, - an aryl group of 6 to 18 carbon atoms, preferably phenyl, - a benzyl group - a siloxyl group having at least 5 units, preferably at least 10 units of formula R1cSiO(4_c) / 2 in which R1, identical or different, represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl; an aryl group comprising from 6 to 10 carbon atoms, preferably phenyl; and c = 0, 1 or 2 and;said radical R may be substituted or not by an alkyl chain of 1 to 12 carbon atoms, alkenyl of 2 to 6 carbon atoms, a cycloalkyl group of 5 to 8 carbon atoms, an aryl group of 6 to 18 carbon atoms or a heteroatom such as oxygen, sulfur or nitrogen.;

6. A method according to any one of the preceding claims, wherein the chain blocker C is an alcohol or a silanol having a pKa of 10 to 16, preferably a pKa of 12 to 16, more preferably a pKa of 14 to 16.

7. Process according to any one of the preceding claims, in which, in step a), the molar ratio of chain blocker C relative to the basic catalyst B used is from 0.01 to 600, preferably from 0.8 to 300, preferentially from 1.5 to 300, preferentially from 4 to 200 and even more preferentially from 8 to 100.

8. Method according to any one of the preceding claims, in which, in step a), the molar ratio of cyclic organopolysiloxane OC relative to the chain blocker C employed is from 1 to 20,000, preferably from 2 to 5,000, preferentially from 2 to 1,400, preferentially from 4 to 700, even more preferentially from 4 to 300 and even more preferentially from 10 to 150.

9. A method according to any preceding claim, in which, during step b) the molar ratio of cyclic organopolysiloxane OC relative to the chain blocker C used during this step is from 1 to 100, preferably from 10 to 80, preferentially from 10 to 50.

10. A method according to any one of the preceding claims, wherein the degree of polymerization of the linear organopolysiloxane OL is between 5 and 28,000, preferably between 5 and 7,000, preferably between 5 and 4,000, preferably between 15 and 2,000, more preferably between 20 and 1,000 and even more preferably between 20 and 400.

11. Silicone composition comprising the organopolysiloxane OL obtained according to any one of claims 1 to 10.

12. Use of the linear organopolysiloxanes OL obtained according to one of claims 1 to 10 as a compound which can be directly used in various silicone formulations useful in fields such as cosmetics, household cleaning products, automobiles, energy.

13. Composition SI comprising: i) at least one cyclic organopolysiloxane OC having three siloxane units, ii) at least one basic catalyst B of formula (XII): [Chem 33] O f i. R. J Fütiiside XI l in which: -Ri, identical or different, represents an alkyl chain of 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms, -R2 represents a hydrogen atom or a radical -C(=O)-R3 with R3 representing an alkyl group of 1 to 12 carbon atoms; - X represents an anion chosen from the group comprising carboxylates and their derivatives, carbonates and their derivatives, hydroxyl, siloxanolates, silanolates, and n is a natural number between 1 and 6, and iii) at least one chain blocker C.

14. Catalysts B represented by formula (XIV): [Chem 34] / \ 'N' X''-'"'" ^ ■: s FwHni4e XIV Ri in which: -Ri, identical or different, represents an alkyl chain of 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms; -X represents a siloxanolate or silanolate anion and n is a natural number between 1 and 6.