Low-temperature silicone composition

Abstract

To provide: a process of preparation of a polysiloxane comprising methyl and ethyl groups; a poly(dimethyl-co-diethyl)siloxane; and a composition for preparation of silicone rubber.SOLUTION: A process of preparation of a polysiloxane comprising methyl and ethyl groups comprises steps of a) hydrolysis reaction of silanol precursors, and b) extension of a chain of silanol-terminated siloxane oligomers obtained in the step a) by means of a Lewis acid-induced polycondensation by addition of a triflate salt catalyst and subsequent addition of a perfluoroborane catalyst. The disclosure also relates to: a poly(dimethyl-co-diethyl)siloxane of the formula (IIIa) in the figure; a poly(methylhydro-co-diethyl)siloxane; a composition for preparation of silicone rubber comprising the polymers; a silicone rubber obtainable by curing the composition; and the use of the silicone rubber in the aerospace industry.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a reinforced silicone rubber and a silicone oil composition capable of withstanding the cryogenic temperatures required for aerospace applications. [Background Art]

[0002] Silicone is an organosilicon polymer having a siloxane structure, characterized in that silicon atoms are bonded to an alkyl group such as an ethyl group or a methyl group, a trifluoromethyl group, an aryl group, or another functional group. Silicone rubber compositions derived from poly(dimethylsiloxane), generally known as PDMS, are known to withstand temperatures down to -60°C. However, many space applications such as space exploration missions require silicone materials that can withstand temperatures far below -100°C, have a tensile yield strength (>3 MPa) and an elongation at break exceeding 300%.

[0003] Poly(diethylsiloxane) (PDIES) is the only polymer material with a glass transition temperature of -142°C. However, pure PDIES exhibits some crystallization / melting transitions between -142°C and 0°C, making it unsuitable for such applications. Crystallization of silicones typically involves hardening, embrittlement, and loss of elasticity. This can degrade or fatally impair the mechanical properties of objects in automotive applications such as space rovers. It is known from prior art that adding small amounts of phenyl, biphenyl, or diethyl groups (less than 10 ml) to poly(dimethylsiloxane) prevents cold crystallization of dimethylpolysiloxane copolymers. In fact, most of the space-grade silicones currently on the market (from companies such as Momentive, Elkem, Nusil, Dow Corning, and IOTA) belong to the poly(biphenyl-co-dimethylsiloxane) or poly(methylphenyl-co-dimethylsiloxane) family. Interestingly, when the biphenyl or methylphenyl content in such copolymers exceeds 10 mol%, the glass transition shifts to the higher temperature side, limiting its use at cryogenic temperatures (down to -150°C). For example, RTV 560, RTV 566, and RTV 567 (methylphenyl silicone) sold by Momentive have a glass transition temperature Tg = -115°C, making these materials unsuitable for missions at the lunar south pole. It is important to note that cold crystallization of RTV 566 under 25% strain conditions, followed by prolonged waiting at -80°C (60 hours), increased its modulus from 5 MPa to 240 MPa, which is likely the main cause of mechanical failures and telescope misalignment.

[0004] Currently, there are no commercially available silicones with relatively high tensile strength (i.e., 4 MPa or higher), elongation at break of 100% or more, and low-temperature resistance below -120°C. The only commercially available silicone is sold by Gelest (EDV-2022), which contains 18-22 mol% poly(diethyl)- and 78-82 mol% poly(dimethylsiloxane), with a Tg of -131°C. However, this material has a relatively low molecular weight (10,000-12,000 g / mol) and may contain cyclic siloxane oligomers that make it brittle, making it unsuitable for aerospace applications.

[0005] The classical method of silicone synthesis relies on the hydrolysis of dimethyldichlorosilane, resulting in disilanol H[O-Si(CH3)2] n -OH, hydrochloric acid, and varying amounts of cyclic siloxane are generated. The hydrochloric acid then acts as a catalyst, causing disilanol to condense to form polydimethylsiloxane. From there, the silanol-terminated silicone is polymerized in various ways depending on the desired properties of the final product.

[0006] U.S. Patent No. 4,960,850 describes polycondensation of a polydiorganosiloxane oligomer having a silanol-terminated group in a sealed reaction zone at a temperature of 20°C to 160°C in the presence of a catalytically effective amount of trifluoromethylsulfonic acid, while continuously removing polycondensation water using vacuum, and terminating the polycondensation reaction by adding a catalyst-neutralizing amount of cyclopolydiorganosilazane or polydiorganosilazane having a diorganoaminosilyl-terminated group to the reaction mixture. However, the boiling point of trifluoromethylsulfonic acid is 162°C, and it can be distilled while removing water under high vacuum.

[0007] Silicones with controlled molecular weights are obtained from ring-opening polymerization (ROP) of cyclic siloxanes. This is a highly controlled method and a major method in industry. While the above method is relatively easy for the polymerization of a single cyclosiloxane, it becomes difficult to control when copolymerizing two cyclosiloxanes, such as decamethylcyclosiloxane (D5Me10) and hexaethylcyclosiloxane (D3Et6), to produce a 1:1 poly(dimethyl-co-diethyl)siloxane. The latter is due to the different strains of the monomer molecules and the different ring-opening rates of D3Et6 and D5Me10. Ring-opening requires relatively high reaction temperatures of 95-160°C, appropriate anionic initiators, end-capping agents, additives, and pressure-treated reactors. Silicones usually undergo some degree of back-biting, resulting in the production of various (or fluctuating) amounts of cyclic siloxanes that can be difficult to remove from high-viscosity silicones. Furthermore, hexaethylcyclosiloxane is known to preferentially polymerize itself, forming brittle regions within the crosslinked rubber, which in turn reduces the mechanical properties of the resulting material.

[0008] Another method for synthesizing polysiloxanes from monomeric silane precursors relies on the polycondensation of silane monomers or oligomers in the presence of a perfluoroarylborane catalyst such as B(C6F5)3 (Michael A. Brooks, JB Grande, F. Ganachaud, New Synthetic Strategies for Structured Silicones Using B(C6F5)3. Adv. Polym. Sci. 2011, 235, 161-183). One advantage of this method, known as the Piers-Rubinsztajn reaction, is that it can be carried out at room temperature and produces far fewer cyclic products than ROP (which relies on cyclic monomers) in high-temperature ROP synthesis. However, the main drawback of this method is that while it can be used for the synthesis of small amounts of silicone (mmol), it is practically unusable for the synthesis of kilograms of dimethyl-co-diethyl (1:1) polysiloxane. This is because such reactions are extremely exothermic, producing large amounts of gaseous products (typically more than 100 liters of H2, CH4, or CH3-CH3 per kilogram of silicone). Attempting to scale up this reaction clearly carries a serious risk of explosion. Furthermore, another drawback of using the Piers-Rubinsztajn reaction is the fact that the borane catalyst must be dissolved in a solvent such as toluene, as water causes catalyst degradation (heptane causes catalyst precipitation). While the viscosity of solvent-free silicone synthesis is very straightforward, as the polymer viscosity can always be measured visually or by a viscometer, monitoring the progress of the reaction can be difficult in organic solvents like toluene. Additionally, depending on the structure of the silane precursor (i.e., -OH, -OCH3, or -OCH2CH3), the reaction temperature may need to be increased to polymerize the monomer. For example, the reaction of dimethoxydimethylsilane with diethylsilane's -OCH3 group occurs at 22-23°C, but the conversion of -OCH2CH3 to ethane in the presence of B(C6F5)3 requires 70°C.

[0009] Conventional knowledge has shown that the rate of hydrolysis of silanes depends on their electronic structure, the solvent used, the presence or absence of a catalyst, and the reaction temperature. For example, hydrolysis of dichlorodimethylsilane in water occurs even at near-zero temperatures, but diethoxydimethylsilane is stable at 25°C, and its hydrolysis requires temperatures above 50°C, ultimately necessitating the presence of a suitable acid or base catalyst. [Overview of the project]

[0010] The applicant has discovered that silanol-terminated poly(dimethyl-co-diethyl)siloxane or polymethylethylsiloxane with an average molecular weight Mw of ~1000 (viscosity of 33~36 mPa.s) can be reproducibly produced by hydrolyzing diethyl / dimethyl / ethylmethylchlorosilane at low temperatures (1~7°C). These siloxanes can be easily polymerized to high molecular weight PDIES or PEMS (Mw-50000~100000) with very low glass transition temperatures and no crystallization / melt transition at low temperatures, in the presence of a suitable Lewis acid catalyst. This method does not require high reaction temperatures (above 100°C), minimizes cyclic silicone byproducts (in ppm), and increases viscosity relatively quickly (within minutes). The present invention's method for PDIES / PEMS synthesis solves the problem of forming large amounts of gaseous products (H2, methane, or ethane) as experienced in the Piers-Rubinsztajn reaction, and therefore suppresses the high exothermic and explosive risks mentioned above.

[0011] Furthermore, another challenge to be addressed is the compatibility of crosslinking agents with vinyl-terminated PDIES. Generally, crosslinking phenyl silicones requires phenyl-containing crosslinking agents because using classical methylhydropolysiloxane crosslinking agents (PHMS) or dimethyl-co-methylhydropolysiloxane crosslinking agents results in phase separation and increased foaming. The applicant noticed a similar phenomenon in the case of dimethyl-co-diethylpolysiloxane. Extensive foaming was observed when a vacuum was applied to PDIES / PHMS mixtures in the absence or presence of silica. To solve this crosslinking agent / diethylsiloxane incompatibility problem, the applicant synthesized a novel type of methylhydro-co-diethylsiloxane crosslinking agent with excellent compatibility with PDIES.

[0012] Therefore, the present invention relates to a method for producing a polysiloxane containing a methyl group and an ethyl group, and the method is Step a) Hydrolysis reaction of the silanol precursor; Step b) The chain of the silanol-terminated siloxane oligomer obtained in step a) is extended by Lewis acid-induced polycondensation by adding a triflate salt catalyst, particularly In(III) triflate, followed by a perfluoroborane catalyst, particularly tris(pentafluorophenyl)borane. Includes.

[0013] Advantageously, polysiloxanes containing methyl and ethyl groups are selected from the group consisting of the following: -Poly(dimethyl-CO-diethyl)siloxane or poly(methylhydro-CO-diethyl)siloxane of the following formula (I): [ka] A represents a methyl group or a hydrogen atom. m and n represent the mole percentages of the repeating motifs -O-Si(Me)(A) and -O-Si(Et2), respectively. m = 0.5 to 0.8, n = 0.2 to 0.5, and m + n = 1. p represents the number of repeating motifs required to obtain a weight-average molecular weight in the range of 20,000 g / mol to 150,000 g / mol when A represents a methyl group, and in the range of 300 g / mol to 3,500 g / mol when A represents a hydrogen atom. And, -Poly(ethylmethylsiloxane) of the following formula (II): [ka] q represents the number of repeating motifs.

[0014] More preferably, the silanol precursor in step a) is selected from (R1)2-ethylmethylsilane, a mixture of (R1)2-dimethylsilane and (R1)2-diethylsilane, and a mixture of (R1)2-methylsilane and (R1)2-diethylsilane, where R1 represents a chlorine atom, a (C1-C6) alkoxy group (preferably a methoxy or ethoxy group), an acetoxy group, or an oxime group, more preferably R1 represents a chlorine atom, a methoxy or ethoxy group, and more preferably R1 represents a chlorine atom.

[0015] In the formula of this invention, Me is a methyl group and Et is an ethyl group.

[0016] In this invention, the terms "included between x and y", "within the range of x to y", "= x to y", and "from x to y" mean that x and y, which are the limits of the range, are included.

[0017] In the present invention, the term "(C1-C6) alkoxy group" means any linear or branched saturated alkoxy group having 1 to 6 carbon atoms, specifically the OCH3 (methoxy) group and the OCH2CH3 (ethoxy) group.

[0018] Therefore, the method of the present invention is for producing a polysiloxane containing a methyl group and an ethyl group, preferably a poly(dimethyl-co-diethyl)siloxane or poly(methylhydro-co-diethyl)siloxane of the following formula (I):

Chemical

[0019] Advantageously, m=0.5 to 0.7, n=0.3 to 0.5, and m+n=1; more advantageously, m=0.5 to 0.6, n=0.4 to 0.5, and m+n=1; even more advantageously, m=n=0.5.

[0020] Specifically, the poly(dimethyl-co-diethyl)siloxane in the present invention has the following formula Ia:

Chemical

[0021] The poly(dimethyl-co-diethyl)siloxane of formula Ia in the present invention advantageously has a weight average molecular weight in the range of 20000 g / mol to 150000 g / mol measured by viscometry method specifically conforming to ASTM E3116-18 standard dated January 25, 2018, more advantageously between 30000 g / mol and 100000 g / mol, even more advantageously between 40000 g / mol and 80000 g / mol, particularly between 45000 g / mol and 60000 g / mol.

[0022] Specifically, the poly(methylhydro-co-diethyl)siloxane in the present invention has the following formula Ib: [ka] Here, m, n, and p are as defined above.

[0023] The poly(methylhydro-co-diethyl)siloxane of formula Ib in the present invention is, more preferably, specifically, a weight-average molecular weight in the range of 300 g / mol to 3500 g / mol, using a viscometric method in accordance with the ASTM E3116-18 standard of January 25, 2018; more preferably, between 500 g / mol and 3000 g / mol; and even more preferably between 1000 g / mol and 2000 g / mol.

[0024] The method of the present invention is also advantageous for producing poly(ethylmethylsiloxane) of the following formula (II): [ka] Here, q represents the number of repeating motifs.

[0025] Advantageously, the poly(ethylmethylsiloxane) in the present invention specifically has a weight-average molecular weight in the range of 1,000 g / mol to 2,000,000 g / mol, measured using a viscosity measurement method in accordance with the ASTM E3116-18 standard of January 25, 2018.

[0026] Step a) in the method of the present invention consists of a hydrolysis reaction of a silanol precursor.

[0027] Advantageously, the silanol precursor is selected from (R1)2-ethylmethylsilane, a mixture of (R1)2-dimethylsilane and (R1)2-diethylsilane, and a mixture of (R1)2-methylsilane and (R1)2-diethylsilane, where R1 represents a chlorine atom, a (C1-C6) alkoxy (preferably a methoxy or ethoxy group), an acetoxy group, or an oxime group, more preferably R1 represents a chlorine atom, a methoxy group, or an ethoxy group, and more preferably R1 represents a chlorine atom.

[0028] Therefore, advantageously, the silanol precursor is a chlorinated or ethoxylated silanol precursor, specifically a chlorinated silanol precursor. More advantageously, they are selected from dichloroethylmethylsilane, diethoxyethylmethylsilane, a mixture of dichlorodimethylsilane and dichlorodiethylsilane, a mixture of dichloromethylsilane and dichlorodiethylsilane, a mixture of diethoxydimethylsilane and diethoxydiethylsilane, and a mixture of diethoxymethylsilane and diethoxydiethylsilane, and more advantageously, they are selected from dichloroethylmethylsilane, a mixture of dichlorodimethylsilane and dichlorodiethylsilane, and a mixture of dichloromethylsilane and dichlorodiethylsilane.

[0029] The product obtained after step a) is an oligomer of siloxane containing methyl and ethyl groups, specifically an oligomer of (dimethyl-co-diethyl)siloxane, (methylhydro-co-diethyl)siloxane, or ethylmethylsiloxane. These oligomers have a weight-average molecular weight between 500 g / mol and 3000 g / mol, specifically measured by a viscometric method in accordance with the ASTM E3116-18 standard of January 25, 2018, and more preferably between 1000 and 3000 g / mol when A is methyl.

[0030] The possible reaction schemes (schemes 1 and 2) for step a) are as follows: [ka] [ka] Here, A, m, and n are as defined above, and R1 represents a chlorine atom, a C1-C6 alkoxy group (specifically a methoxy group or an ethoxy group), an acetoxy group, or an oxime group, more preferably R1 represents a chlorine atom, a methoxy group, or an ethoxy group, and more preferably R1 represents a chlorine atom.

[0031] In a favorable embodiment, step a) is carried out at a temperature of 0°C to 40°C, and more favorably at a temperature of 5°C to 35°C.

[0032] In a favorable embodiment, the reaction is initially carried out at a temperature of 0°C to 7°C, preferably 5°C to 7°C, followed by an increase in temperature to 30-40°C, preferably 30-35°C.

[0033] More favorably, the reaction is carried out with stirring, and even more favorably, by adding the silanol precursor to water, specifically by dropwise addition, and more favorably, by adding at a rate of 1 drop / second to 5 drops / second, specifically at a rate of 3 drops / second.

[0034] In a favorable embodiment, step a) lasts for 1 to 2 hours.

[0035] In a favorable embodiment, the molar concentration of water (w) is higher than the molar concentrations of both silanol precursors (a+b): w > a+b

[0036] In further embodiments, the oligomer obtained in step a) is preferably separated by heptane extraction from the aqueous phase containing HR1, specifically HCl, obtained after carrying out step a), before being used in step b) of the method according to the present invention.

[0037] Step b) in the method of the present invention consists of extending the chain of the silanol-terminated siloxane oligomer obtained in step a), preferably a poly(dimethyl-co-diethyl)siloxane oligomer, poly(methylhydro-co-diethyl)siloxane oligomer, or ethylmethylsiloxane oligomer, by Lewis acid-induced polycondensation by adding a triflate salt catalyst followed by a perfluoroborane catalyst. Preferably, the polymer obtained after step b) is a polymer of formula I or II as detailed above.

[0038] Advantageously, the triflate salt catalyst is selected from In(III) triflate, Bi(III) triflate, Al(III) triflate, and mixtures thereof, and more advantageously, the triflate salt catalyst is In(III) triflate.

[0039] Advantageously, the perfluoroborane catalyst is tris(pentafluorophenyl)borane.

[0040] The reaction schemes (schemes 3 and 4) for step b) using In(III) triflate and perfluoroborane catalysts are as follows: [ka] Here, A, m, n, and p are as defined above. [ka] Here, q is as defined above.

[0041] The polymer of formula (I) is an alternating copolymer.

[0042] The polymer of formula (II) is a homopolymer.

[0043] Advantageously, process (b) is carried out at room temperature (20-25°C).

[0044] In a favorable embodiment: - First, a triflate salt catalyst, specifically In(III) triflate, is added while stirring (step b1), and then the reaction is allowed to proceed, preferably by leaving it undisturbed for at least 1 to 12 hours. -Then, a perfluoroborane catalyst, specifically tris(pentafluorophenyl)borane, is added while stirring (step b2), and the reaction is then allowed to proceed, preferably by leaving it undisturbed for at least 1 to 12 hours.

[0045] Advantageously, step (b) is carried out in bulk without the use of a solvent.

[0046] In advantageous embodiments, the triflate salt catalyst, specifically In(III) triflate, is present in an amount of 0.1 mg to 1 mg per gram of oligomer.

[0047] In another advantageous embodiment, the perfluoroborane catalyst, specifically tris(pentafluorophenyl)borane, is present in an amount of 0.1 mg to 1 mg per gram of oligomer.

[0048] In certain embodiments, step b) is carried out under an inert atmosphere, preferably under nitrogen.

[0049] The method of the present invention may further include step c1), in which a vinyl end group is added to the polymer obtained in step b) by reaction with vinyldimethylmethoxysilane or vinyl-1,1,3,3-tetramethyldisiloxane at a temperature of 20 to 60°C in solvent-free In(III) triflate, or in toluene as a solvent, or in the presence of a solvent-free Lewis acid catalyst such as B(C6F5)3, and advantageously step c1) is a polymer having the following formula (III): [ka] A, m, n, and p are defined in equation I, R2 = -Si(CH3)2CH = CH2: or - A polymer having the following formula (IV) [ka] q is defined as in equation II, and R2 = -Si(CH3)2CH = CH2: This is to obtain.

[0050] The polymer of formula (III) is an alternating copolymer.

[0051] The polymer of formula (IV) is a homopolymer.

[0052] Therefore, the polymer obtained in step c1) is Poly(dimethyl-co-diethyl)siloxane having the following formula (IIIa): [ka] R2, m, n, and p are as defined in Equation III. Or, Poly(methylhydro-co-diethyl)siloxane having the following formula (IIIb): [ka] R2, m, n, and p are as defined in Equation III. It is possible.

[0053] The polymers of formulas (IIIa) and (IIIb) are alternating copolymers.

[0054] Advantageously, the poly(dimethyl-co-diethyl)siloxane of formula (IIIa) has a glass transition temperature (Tg) measured by DSC in accordance with the ASTM E1356 standard of May 15, 2014, in the range of -130°C to -142°C, specifically in the range of -135°C to -141°C, and more specifically in the range of -139°C.

[0055] The polysiloxane of formula (IIIa) is more preferably, specifically, having a weight-average molecular weight in the range of 20,000 g / mol to 150,000 g / mol, measured by a viscosity measurement method in accordance with the ASTM E3116-18 standard of January 25, 2018; even more preferably, between 30,000 g / mol and 100,000 g / mol; even more preferably between 40,000 g / mol and 80,000 g / mol; and particularly between 45,000 g / mol and 50,000 g / mol.

[0056] Advantageously, the poly(methylhydro-co-diethyl)siloxane of formula (IIIb) has a glass transition temperature (Tg) measured by DSC in accordance with the ASTM E1356 standard of May 15, 2014, in the range of -130°C to -146°C.

[0057] The polysiloxane of formula (IIIb) is more preferably, specifically, having a weight-average molecular weight in the range of 300 g / mol to 3500 g / mol, measured by a viscosity measurement method in accordance with the ASTM E3116-18 standard of January 25, 2018, more preferably between 500 g / mol and 3000 g / mol, and even more preferably between 1000 g / mol and 2000 g / mol.

[0058] Advantageously, the poly(ethylmethylsiloxane)siloxane of formula (IV) has a glass transition temperature (Tg) measured by DSC in accordance with the ASTM E1356 standard of May 15, 2014, in the range of -130°C to -142°C.

[0059] The polysiloxane of formula (IV) is more preferably, specifically, has a weight-average molecular weight in the range of 20,000 g / mol to 200,000 g / mol, as measured by the viscometric method in accordance with the ASTM E3116-18 standard of January 25, 2018, and more preferably, in the range of 20,000 g / mol to 150,000 g / mol.

[0060] The reaction schemes (schemes 5 and 6) for step c1) are as follows: [ka] Here, R2, A, m, n, and p are as defined above. [ka] Here, R2 and q are as defined above.

[0061] In certain embodiments, the Lewis acid catalyst is a triflate salt, preferably selected from In(III) triflate, Bi(III) triflate, Al(III) triflate, and mixtures thereof, more preferably In(III) triflate; step c1) is carried out without the use of a solvent, more preferably at a temperature between 50°C and 70°C; and even more preferably, the catalyst is present in an amount of 0.1 mg to 2 mg per gram of polymer.

[0062] In another specific embodiment, the Lewis acid catalyst is a perfluoroborane catalyst such as B(C6F5)3, and step c1) is carried out without a solvent or with toluene as the solvent, more preferably at room temperature (20-25°C), and even more preferably the catalyst is present in an amount of 0.1 mg to 1 mg per gram of polymer.

[0063] Furthermore, in certain embodiments, the Lewis acid catalyst is a mixture of a triflate salt and perfluoroborane, preferably a mixture of In(III) triflate and B(C6F5)3, step c1) is carried out without the use of a solvent, more preferably at room temperature (20-25°C), and even more preferably the catalyst is present in an amount of 0.1 mg to 1 mg per gram of polymer.

[0064] Furthermore, in certain embodiments, when step c1) is carried out, the catalyst used in step b) is not removed, and perfluoroborane, specifically B(C6F5)3, is further added. Advantageously, step c1) is carried out without a solvent, and more advantageously, at room temperature.

[0065] The method of the present invention may include step c2), in which a trialkylsilyl terminal group is added to the polymer obtained in step b) by reaction with a trialkylsilane, specifically trimethylsilane or triethylsilane, more specifically triethylsilane, in the presence of a Lewis acid catalyst such as B(C6F5)3 in toluene as a solvent, wherein step c2) is advantageously a polymer having the following formula (V): [ka] A, m, n, and p are defined in equation I, Each R3 is independently a saturated, linear, or branched C1-C6 alkyl group, preferably an ethyl group: or - A polymer having the following formula (VI) [ka] q is defined as in equation II, Each R3 is independently saturated, linear, or branched C1-C6 alkyl group: This is to obtain.

[0066] In the present invention, the term "(C1-C6) alkyl group" means any linear or branched saturated alkyl group having 1 to 6 carbon atoms, specifically the CH3 (methyl) group and the CH2CH3 (ethyl) group.

[0067] The polymer of formula (V) is a silicone oil and is an alternating copolymer. The polymer of formula (VI) is a silicone oil and is a homopolymer.

[0068] Advantageously, the poly(dimethyl-co-diethyl)siloxane of formula (IVa) has a glass transition temperature (Tg) measured by DSC in accordance with the ASTM E1356 standard of May 15, 2014, in the range of -130°C to -145°C, specifically in the range of -135°C to -142°C, and more specifically in the range of -136°C.

[0069] More favorably, the siloxanes described above have a weight-average molecular weight in the range of 40,000 g / mol to 65,000 g / mol, and even more favorably, between 45,000 g / mol and 55,000 g / mol, using a viscosity measurement method in accordance with the ASTM E3116-18 standard of January 25, 2018.

[0070] Advantageously, the poly(ethylmethyl)siloxane of formula (VI) has a glass transition temperature (Tg) measured by DSC in accordance with the ASTM E1356 standard of May 15, 2014, in the range of -130°C to -142°C.

[0071] More advantageously, the siloxanes described above have a weight-average molecular weight in the range of 20,000 g / mol to 150,000 g / mol, measured using a viscosity measurement method compliant with the ASTM E3116-18 standard of January 25, 2018.

[0072] The reaction schemes (schemes 7 and 8) for step c2) are as follows: [ka] Here, R3, A, m, n, and p are as defined above. [ka] Here, R3 and q are as defined above.

[0073] In another specific embodiment, the Lewis acid catalyst is a perfluoroborane catalyst such as B(C6F5)3, and step c2) is carried out without a solvent or with toluene as the solvent, more preferably at room temperature (20-25°C), and even more preferably, the catalyst is present in an amount of 0.1 mg to 1 mg per gram of polymer.

[0074] In another specific embodiment, the method of the present invention further includes step d) after step c1) or c), which is advantageously used to remove the catalyst used in steps b) and c1), or step c), with aluminum oxide.

[0075] Advantageously, the method of the present invention is for producing 50 / 50 poly(dimethyl-co-diethyl)siloxane or 50 / 50 poly(methylhydro-co-diethyl)siloxane.

[0076] The present invention also relates to the poly(dimethyl-co-diethyl)siloxane of formula (IIIa) described above, which is preferably obtained by the method of the present invention and more preferably has the following: - The weight-average molecular weight, measured using a viscosity measurement method in accordance with the ASTM E3116-18 standard of January 25, 2018, is in the range of 20,000 g / mol to 150,000 g / mol, more preferably between 30,000 g / mol and 100,000 g / mol, even more preferably between 40,000 g / mol and 80,000 g / mol, particularly between 45,000 g / mol and 50,000 g / mol, and / or - The glass transition temperature, as measured by DSC in accordance with the ASTM E1356 standard of May 15, 2014, is in the range of -130°C to -142°C, specifically in the range of -135°C to -141°C, and more specifically in the range of -139°C.

[0077] The polymer of formula (IIIa) is an alternating copolymer.

[0078] The present invention also relates to the poly(methylhydro-co-diethyl)siloxane of formula (IIIb) described above, which is preferably obtained by the method of the present invention and more preferably has the following: - The weight-average molecular weight, measured using a viscosity measurement method in accordance with the ASTM E3116-18 standard of January 25, 2018, is in the range of 300 g / mol to 3500 g / mol, more preferably between 500 g / mol and 3000 g / mol, even more preferably between 1000 g / mol and 2000 g / mol, and / or - The glass transition temperature, as measured by DSC in accordance with the ASTM E1356 standard of May 15, 2014, is within the range of -130°C to -146°C.

[0079] The polymer of formula (IIIb) is an alternating copolymer.

[0080] The present invention also relates to the poly(dimethyl-co-diethyl)siloxane of formula (V) described above, which is preferably obtained by the method of the present invention and more preferably has the following: - The weight-average molecular weight, measured using a viscosity measurement method in accordance with the ASTM E3116-18 standard of January 25, 2018, is in the range of 500 g / mol to 150,000 g / mol, preferably between 1,000 g / mol and 3,000 g / mol, and / or - The glass transition temperature, as measured by DSC in accordance with the ASTM E1356 standard of May 15, 2014, is in the range of -130°C to -145°C, specifically in the range of -135°C to -142°C, and more specifically in the range of -139°C.

[0081] The polymer of formula (V) is an alternating copolymer.

[0082] The polymer of formula (V) is silicone oil.

[0083] The present invention also relates to a composition for the manufacture of silicone rubber, the composition comprising: - (A) 60-94% by weight of vinyl-terminated poly(dimethyl-co-diethyl)siloxane of formula (IIIa) according to the present invention; - (B) Reinforcing filler, preferably 5-35% by weight of calcined silica; - (C)Tg < -130℃, and preferably 1-5% by weight of a crosslinking agent having formula (IIIb) of the present invention; - (D) an appropriate amount of curing catalyst, preferably a Pt(0) catalyst such as platinum(0)-2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane dissolved in methylvinylcyclosiloxane, and - (E) Optionally, a Pt inhibitor such as 1-ethinyl-1-cyclohexanol.

[0084] In this specification, the term "silicone rubber" is understood to mean a material that has the ability to maintain its elasticity in a temperature range of 200 to -140°C.

[0085] The amounts of compound (A) (vinyl-terminated poly(dimethyl-co-diethyl)siloxane of formula (IIIa)) and compound (C) (crosslinking agent) in the composition of the present invention are determined by the ratio of the number of units (R'HSiO2 / 2) to the number of alkenyl groups, and are adjusted considering the relative proportion of alkenyl moieties in compound (A) and the relative proportion of units (R'HSiO2 / 2) in compound (C).

[0086] The essential feature of the silicone rubber composition of the present invention is the ratio of the number of units (R'HSiO2 / 2) in compound (C) introduced into the silicone base composition to the number of diethyl groups in compound (A) introduced into the rubber composition. According to the present invention, this ratio of the number of units (R'HSiO2 / 2) to the number of alkenyl groups is greater than 3. If this ratio is 3 or less, the composition will have insufficient mechanical and adhesive properties for use as a self-adhesive PDIES silicone on metal surfaces such as stainless steel or titanium.

[0087] Conveniently, this ratio is greater than 4 and less than 25.

[0088] The curing catalyst is a hydrosilylation catalyst, specifically a platinum (Pt(0)) catalyst, and more specifically, a catalyst that forms a complex with a divinyltetraalkylsiloxane ligand, preferably 1,3-divinyltetramethylsiloxane, such as platinum(0)-2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane dissolved in methylvinylcyclosiloxane. Such catalysts are described, for example, in reference WO0142258A1. The Karstedt catalyst is particularly suitable. As with conventional hydrosilylation reactions, the amount of catalyst in the composition is catalytic. Catalytic amount means that the amount of platinum is less than 1 molar equivalent relative to the amount of olefin double-bonded unsaturated product present in the composition. In general, it is sufficient to introduce platinum at a concentration of less than 1000 ppm, preferably more than 30 ppm, relative to the total mass of compound (A) and compound (C).

[0089] Reaction design of compound (C) (R'HSiO 2 / 2 Crosslinking of organopolysiloxanes occurs by hydrosilylation of the alkenyl groups of compound (A) and compound (A), thereby producing a crosslinked silicone rubber composition. Crosslinking is usually initiated by raising the silicone rubber composition to a temperature sufficient to cause the hydrosilylation reaction. Crosslinking is generally carried out at a temperature between 15°C and 200°C, for example between 20°C and 150°C, and more preferably between 50°C and 150°C.

[0090] In known methods, crosslinkable silicone compositions generally contain inhibitors. Inhibitors are generally used to control the temperature and time of the hydrosilylation crosslinking reaction, thereby further controlling the crosslinking reaction, particularly its initiation and rate. When crosslinking inhibitors are used, the amount of inhibitor used is preferably 1 to 50,000 ppm, more preferably 20 to 2,000 ppm, and particularly 100 to 1,000 ppm, relative to the total mass of compound (A) and compound (C). Examples of inhibitors include acetylene alcohols, such as 1-ethynyl-1-cyclohexanol, 2-methyl-3-butyne-2-ol, 3,5-dimethyl-1-hexyne-3-ol, 3-methyl-1-dodecine-3-ol, and 2-phenyl-3-butyne-2-ol. Preferably, the silicone rubber composition in the present invention contains an inhibitor.

[0091] The silicone rubber composition of the present invention also has the essential characteristic of containing a reinforcing filler, preferably hydrophobic silica, specifically calcined silica. In known methods, hydrophobic silica is silica in which part of the surface is coated with organic groups such as alkyl groups. The silica may be any reinforcing silica known to those skilled in the art, specifically any precipitated silica or calcined silica. Preferably, the silica is 450m 2 Less than 1g, preferably 80 to 400m 2 / g, particularly preferably 100 to 300m 2 / g, 150 to 250m is advantageous. 2 It has a BET specific surface area within the range of / g. Furthermore, it is possible to use a mixture of multiple silicas, such as Evonik's Aerosil R 8200, Aerosil R 812 S, Aerosil E 9200, or Cabot's Cab-O-Sil TS 530.

[0092] To make silica hydrophobic, it is well known that its surface can be modified. Surface modification of silica can be achieved by known methods, such as reacting silica with a compound having a hydrophobic group, specifically a trialkylsilyl group, or more specifically, a trimethylsilyl group. Surface-modified silica with a trimethylsilyl group is particularly suitable. For example, silica modified with hexamethyldisilazane can be used.

[0093] The hydrophobic silica content is adjusted by those skilled in the art according to its specific surface area and the intended use of the silicone rubber composition. Preferably, the hydrophobic silica content in the silicone rubber composition is 5% or more and 35% or less of the total weight of silica, compound (A), and compound (C). Below 5% of the total weight of silica, compound (A), and compound (C), the reinforcing properties of the composition may be insufficient for certain applications. Above 35% of the total weight of silica, compound (A), and compound (C), the formulation of the silicone rubber may become impossible (for example, when using Wacker's silica HDK H2000, or when using more than 20% by weight of Cab-O-Sil TS 530, Aerosil R 8200, or Aerosil E 9200 to obtain a solid paste).

[0094] The silicone rubber composition according to the present invention can be prepared by compounding hydrophobic silica with compound (A), then adding compound (C) while mixing, and finally adding a catalyst. When an inhibitor is used, the inhibitor is usually added to the mixture of hydrophobic silica and compound (A) before compound (C) is added.

[0095] The present invention also relates to a silicone rubber obtained by curing a composition according to the present invention, wherein the glass transition temperature measured by DSC in accordance with ASTM E1356 of May 15, 2014, is in the range of -130°C to -142°C, preferably in the range of -135°C to -140°C, specifically -138°C, and / or does not have a crystallization / melt transition in the range of -140°C to +250°C as measured by DSC in accordance with ASTM E1356 of May 15, 2014.

[0096] More advantageously, the silicone rubber according to the present invention has a break elongation (measured in September 1988, H2, using INSTRON 34TM-10, France, according to AFNOR NF T 46002 standards) of 100% or more, specifically 200% or more, more specifically 300% or more, for example, 348%.

[0097] Furthermore, the silicone rubber according to the present invention has an elastic modulus of >1 MPa, preferably >3 MPa, as measured by the French INSTRON 34TM-10 in accordance with the AFNOR NF T 46002 standard of September 1988.

[0098] Furthermore, the silicone rubber according to the present invention has a Shore A hardness in the range of 35 to 40, as measured by durometer hardness in accordance with the ASTM D2240 standard of July 23, 2021.

[0099] The present invention also relates to the use of silicone rubber or poly(dimethyl-co-diethyl)siloxane of formula (V) in the aerospace industry, particularly in space rovers. More specifically, the present invention also relates to the use of poly(dimethyl-co-diethyl)siloxane of formula (V) as a silicone oil for electric motors at low temperatures, specifically below -100°C.

[0100] The present invention ultimately relates to the use of poly(methylhydro-co-diethyl)siloxane having formula (IIIb) according to the present invention as a crosslinking agent for preparing silicone rubber.

[0101] The aforementioned and other features of the present invention will be better understood by reading the following description of some exemplary embodiments of the invention, which are given without limitation for illustrative purposes. [Examples]

[0102] [Example 1: Synthesis of poly(diethyl-co-dimethyl)siloxane (50 / 50) (PDIES-50 / 50)] <Process 1 (Process a)> First, 1 kg of dichlorodiethylsilane (SID3402.0-1KG, Gelest, USA) was distilled at 40-50°C under a vacuum of 20 mbar in a 2 L flask cooled to -79°C using dry ice. The resulting silane was a clear liquid.

[0103] The synthesis of poly(diethyl-co-dimethyl)siloxane (50 / 50) was carried out without prior removal of oxygen from the water. An 8 L glass cylinder was placed in an ice bath (polypropylene box) and cooled to 0-5°C. The reactor was equipped with a bubbler to confirm the final gas generation. Deionized water (3.7 L) was added to the glass reactor, which had been cooled to 5°C in the ice bath. The stirring speed was set to 200 rpm. Next, 306 g of diethyldichlorosilane and 251.37 g of dichlorodimethylsilane (ThermoScientific, lot A0439125) were added to a glass column equipped with a Teflon valve (the glass was dried under vacuum at 100°C and maintained under a small N2 flow). These silanes were mixed using a Teflon bar and then added dropwise to the 3.7 L of water at a rate of approximately 3 drops per second. The temperature of the reaction mixture was maintained at 5-7°C. Silane hydrolysis was performed at 300 rpm for 2 hours.

[0104] Next, the reactor was placed in a polypropylene water bath heated to 40°C, and the reaction mixture temperature was adjusted to 30-35°C. The silanol was stirred at 300 rpm for a further 2 hours. Then, 1.5 L of heptane was added to separate the silanol from the aqueous phase, and the HCl(aq) solution was passed below the silanol oligomer layer using a silicone tube (slightly under vacuum). The silanol oligomer was extracted with 1 L of heptane, and the reactor and separation funnel (500 ml funnel) were washed with another 1.5 L of heptane. 25 g of MgSO4 was added, and the silanol oligomer was dried by stirring at 200 rpm. The moist MgSO4 was filtered, and the silanol oligomer was kept overnight under nitrogen in 2 L of heptane. Under vacuum, the organic solvent was removed at 90°C using a rotary evaporator. 313.2 g of silanol oligomer (theoretical value 369.4 g) was obtained, with a yield of 85%. Viscosity according to ASTM E3116-18 standard as of January 25, 2018: 35 mPa.s (Viscosimeter Model: VSC-N4 (Bioevopeak, China), measurement range: 20~2,000,000 mPa.s).

[0105] Silanol was placed in a 2 L glass flask and heated at 145°C for 120 minutes (without air or vacuum). After 2 hours at 145°C, it was cooled to 25°C (using a thermostat), and the viscosity was measured. The viscosity was 38 mPa·s. The silanol was purged with nitrogen, sealed in a 1 L container with a silicone septum, and stored at -20°C (to prevent further condensation with water).

[0106] <Process 2 (Process b)> 298 g of the silanol oligomer obtained in step 1 was heated at 145°C for 15 minutes, and while still hot, it was exposed to vacuum (vacuum < 2 mbar) for 30 minutes until no more bubbles were observed. Next, the silanol oligomer was poured while still hot into a dry 1 L flask equipped with a silicon septum, magnetic stirrer, and nitrogen flow. Subsequently, 35 mg of indium(III) triflate per 100 g of silanol oligomer was added under nitrogen flow. The catalyst was dispersed in the silanol oligomer by stirring at 500 rpm. The reaction was then allowed to proceed overnight (17 hours) in a sealed container without stirring. An increase in viscosity was observed. The following day, 57 mg of tris(pentafluorophenyl)borane catalyst (Sigma-Aldrich, #442593) was added under nitrogen, mixed at 500 rpm for 5 minutes, and the reaction was allowed to proceed for a further 24 hours.

[0107] <Process 3 (Process c)> 35 mg of tris(pentafluorophenyl)borane catalyst (Sigma-Aldrich, #442593) was added to the reaction mixture, followed by 1.5 ml of vinyldimethylmethoxysilane (AB106075, ABCR-Germany). The reaction mixture was stirred for 5 minutes, and then the reaction was continued for another 5 hours without stirring. Finally, the reaction product was transferred to a rotary evaporator, and excess vinyldimethylmethoxysilane and other volatile components were removed by distillation at 95°C / vacuum 30 mbar.

[0108] <Step 4. Catalyst removal (step d)> The siloxane polymer obtained in step 3 was cooled to room temperature, and 150 g of neutral aluminum oxide (#199974, Sigma Aldrich) was added along with 600 ml of heptane. The suspension was stirred at 300 rpm for 20 minutes. The solids were then removed by filtration through a ceramic filter with porosity 2, then porosity 4, and finally a 0.45 µm PTFE filter. The solvent was removed by distillation using a rotary evaporator, heating to 95°C and then reducing to a vacuum of 30 mbar. Finally, the siloxane polymer was heated at 150°C for 1 hour under a vacuum of <1 mbar (vacuum oven). No significant mass loss was measured between -80 and 200°C by DSC.

[0109] Viscosity according to ASTM E3116-18 standard as of January 25, 2018: 4012 mPa.s, Mw = 45000 g / mol (Viscosimeter Model: VSC-N4 (Bioevopeak, China), measurement range: 20~2,000,000 mPa.s).

[0110] According to the ASTM E1356 standard of May 15, 2014, the temperature of this material in a DSC (Diagram Spectroscopy) was Tg = -139°C (2°C / min, N2) (Model: DSC 3, Mettler Toledo, Switzerland).

[0111] The multivariance index (PD) calculated by GPC was 1.63.

[0112] The GPC requirements are as follows: GPC (Gel Permeation Chromatography): Agilent 1260 Infinity connected to a 390-MDS detector (Agilent, USA). Refractive index detector: 1260 Infinity RID (Agilent, USA) The heating unit is a Mistral column oven (Spark, Netherlands). Column set configuration: 1x pre-column PSS SDV (PSS / Agilent) Linear XL 2x column for PSS SDV analysis (PSS / Agilent) The polymer sample was dissolved in 1 mL of toluene before injection. Toluene, HPLC Plus, for HPLC (#650579-1L, Merck) Experimental conditions: - Eluent: Toluene - Flow rate: 1mL / min - Temperature: 35℃

[0113] The calibration was the conventional method using narrow polystyrene standards ranging from 682 to 130,000 g / mol.

[0114] The software used for Mw calculation was Cirrus GPC Software (Agilent, USA).

[0115] [Example 2: Silicone compound example for the manufacture of silicone rubber] 50g of siloxane polymer with a mass of 45500g / mol (synthesized in steps 1-4 above) 15g SiO2 (HDK H2000, Wacker Germany) 7g 1-Ethinyl-1-cyclohexanol, 99% (E51406, Sigma-Aldrich) (Pt inhibitor) 140 mg Pt catalyst* (Platinum(0)-2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane complex solution (Sigma Aldrich, #479543)) 1.35g HMS-H271 crosslinking agent (Gelest, USA) (25-30% methylhydro)-dimethylsiloxane copolymer, hydride-terminated, 24-60 cSt)

[0116] The ingredients were mixed using a mixer at 2000 rpm and cured at 150°C for 1 hour, or at room temperature for 24 hours.

[0117] The elastic crosslinked silicone rubber (30 wt% SiO2) has a Tg of -138°C and did not crystallize or melt between -150°C and +250°C as measured by a DSC (Model: DSC 3, Mettler Toledo, Switzerland) in accordance with the ASTM E1356 standard of May 15, 2014. Shore A hardness: 35-40 (measured using HBA100-0 (Kern, Switzerland) in accordance with the ASTM D2240-15 standard of July 23, 2021). Elongation at break: 348% (measured in September 1988 using INSTRON 34TM-10, France, in accordance with H2, AFNOR NF T 46002 standard).

[0118] [Example 3: Triethylsilyl-terminated poly(dimethyl-CO-diethyl)siloxane (50 / 50) silicone oil] Step (a): Hydrolysis A 1 L flask equipped with four inlets, a condenser, side arms, a vent outlet, and a magnetic stirrer bar was filled with 370 ml of deionized water. The apparatus was then cooled to 5°C, and 30.0 g of dichlorodiethylsilane (Gelest, SID3402.0, Gelest) and 24.6 g of dichlorodimethylsilane (ThermoScientific, #113312500), both cooled to 5°C and mixed, were added dropwise over 1 hour (at a rate of 3 drops per second). The reaction mixture was stirred at 600 rpm. The reaction temperature was then raised to 30°C, and the mixture was stirred for another 1 hour. 500 ml of heptane was added, and the silicone was separated from the aqueous phase using a separation funnel. The organic phase was washed with deionized water until the pH was neutral.

[0119] The reaction product in heptane was transferred to a 1 L flask, and the residual water was dried with 50 g of anhydrous MgSO4. The product was filtered using a porous P4 ceramic filter and a 0.45 μm PTFE microfilter. Heptane and volatile components were removed using a rotary evaporator at 90°C / vacuum up to 18 mbar. No volatile components were observed when the mixture was further vacuumed to 1 mbar at room temperature.

[0120] Step (b): Chain extension The product was transferred to a dry 100 ml round-bottom flask equipped with a magnetic stirrer under a nitrogen flow. Next, 14 mg of In(III) triflate was added and the mixture was stirred for 30 minutes. Subsequently, 14 mg of tris(pentafluorophenyl)borane catalyst (Sigma-Aldrich, #442593) dissolved in 2 ml of anhydrous toluene (Sigma-Aldrich, #244511) was added. The reaction mixture was stirred for a further 30 minutes.

[0121] Process (c2): Finally, 5 ml of triethylsilane (Sigma 230197-25G) and 6.5 mg of tris(pentafluorophenyl)borane were dissolved in 1 ml of toluene. The solution was stirred for 30 minutes until foaming stopped. The catalyst was adsorbed onto 25 g of neutral Al2O3 while stirring at a constant speed of 400 rpm. After stirring the reaction mixture for 10 minutes, 200 ml of heptane was added, and the suspension was filtered through ceramic P2 and P4 filters, and then through a 0.45 μm PTFE microfilter. The solvent was removed by distillation at 90°C / vacuum 20 mbar, followed by a vacuum <1 mbar at room temperature. The product was identified by FTIR and Raman spectroscopy. The glass transition Tg = -140°C was measured by DSC at a rate of 2°C / min under a nitrogen flow.

[0122] [Example 4: Triethylsilyl-terminated poly(methylhydro-CO-diethyl)siloxane (50 / 50) silicone oil (crosslinking agent)] Step a): Hydrolysis A 1 L flask equipped with four inlets, a condenser, side arms, a vent outlet, and a magnetic stirrer was purged at 25°C with a small nitrogen flow. Next, 22 g of diethyldiethoxysilane (Gelest, SID3404) and 16.8 g of methyldiethoxysilane (Sigma-Aldrich, #66612) were added while stirring at a constant speed of 400 rpm.

[0123] Steps b) and c1) Finally, 7.5 mg of In(III) triflate catalyst was added directly to the monomer mixture using a Pasteur pipette, followed by the addition of 11 ml of deionized water at 10-minute intervals (3 × 3 ml + 2 ml) using a pipette while stirring at 29°C and 400 rpm. After stirring for 1 hour, the reaction product was transferred to a 250 ml flask, and 25 g of anhydrous MgSO4 was added to dry the water. The product was dissolved in 100 ml of heptane, filtered through a 0.45 μm PTFE filter, and volatile components / solvent were removed using a rotary evaporator at 80°C / vacuum 35 mbar. Further reduction to a vacuum of 1 mbar at room temperature revealed no volatile components.

[0124] To the reaction product obtained in the previous step, 4 mg of tris(pentafluorophenyl)borane catalyst (Sigma-Aldrich, #442593), dissolved in 1 ml of anhydrous toluene (Sigma Aldrich, #244511) and 5 ml of triethylsilane (Sigma 230197-25G), was added while stirring at a constant speed of 400 rpm under N2 flow. The solution was stirred for 30 minutes until foaming stopped. The borane catalyst was adsorbed onto 25 g of neutral Al2O3. After stirring the reaction mixture for 10 minutes (using a magnetic Teflon stirring bar), 100 ml of heptane was added, and the suspension was filtered through ceramic P2 and P4 filters, and then through a 0.45 µm PTFE microfilter. The solvent was removed by distillation at 90°C / vacuum 20 mbar, and the vacuum was reduced to <1 mbar at room temperature. The product (clear liquid) was identified by FTIR and Raman spectroscopy. The glass transition Tg = -144.7°C was measured by DSC under nitrogen flow at a rate of 2°C / min.

[0125] [Example 5: Synthesis of poly(ethyl-co-methylsiloxane)-PEMS] Step a (hydrolysis) Ethylmethyldichlorosilane (#AB111135, ABCR Germany) was used as is (97% purity). Its appearance was that of a clear, pink liquid.

[0126] This synthesis was carried out in an air atmosphere. A 20 L glass reactor was cooled to 5°C. A 1 L side arm used for the dropwise addition of silane was equipped with a bubbler and maintained under a slight nitrogen flow during silane addition. Deionized water (1.4 L) was cooled and maintained at 4-6°C during chlorosilane addition. The stirring speed was set to 200 rpm. First, 213.0 g of ethylmethyldichlorosilane (instead of 210 g) was added dropwise to 1.4 L of water (3 drops per second). Then, the temperature of the reaction mixture was gradually raised to 30°C and stirred at 200 rpm for 2 hours and 30 minutes. A clear silanol layer formed on the surface of the water.

[0127] Silanol was extracted with 1.25 L of heptane and dried with 250 g of MgSO4. Heptane was removed by distillation at 90-95°C using a rotary evaporator, and then the mixture was further vacuumed to 1 mbar at room temperature. The viscosity of the obtained silanol was 31.7 mPa·s. The silanol in a 1 L round-bottom flask was then placed in an oven at 145°C for 20 minutes. The silanol was cooled to room temperature. Subsequently, 100 mg of indium(III) triflate was added while stirring at a constant speed of 200 rpm. The silanol was then polymerized over the weekend. 115.0 g of silicone (theoretical value 131.83 g) was obtained, with a yield of 87%.

[0128] Step b (chain extension) 50 g of PEMS silanol obtained in step a) was mixed with 50 mg of In(III) triflate (#422151, Sigma-Aldrich), stirred at 200 rpm for 5 minutes, and then polymerized over the weekend (no stirring). Next, water and volatile components were removed from the silicone using a rotary evaporator at 30 mbar and 95°C. Then, the silanol was mixed with 125 g of anhydrous MgSO4 and dissolved in 400 ml of heptane. The solid was filtered through a P4 ceramic filter, and the heptane was removed by distillation at 95°C. The silanol was heated at 145°C for 10 minutes under a vacuum of 1 mbar. Next, the silanol was cooled to room temperature, 25 mg of tris(pentafluorophenyl)borane followed by 2 ml of toluene was added, mixed for 2 minutes, and held in a 1 L flask sealed with a silicone septum under an N2 atmosphere (no stirring). The silanol was left overnight to polymerize.

[0129] Process c1 The silanol obtained in step b was heated to 95°C under a vacuum of 25 mbar to remove water and volatile components. Next, 0.33 g of vinyl-1,1,3,3-tetramethyldisiloxane 98% (SIV9097.5, Gelest, USA) and 25 mg of tris(pentafluorophenyl)borane 95% (#442593, Sigma Aldrich), followed by 2 ml of toluene, were added. The silicone was mixed at 200 rpm for 5 minutes and reacted at 25°C for 2 hours. Finally, a vacuum line was connected and volatile components were removed by distillation at 95°C under a vacuum of 30 mbar. The silicone was diluted with 200 ml of hexane and mixed with 25 g of Al2O3 (neutral alumina), and the suspension was stirred for 10 minutes. The catalyst adsorbed on the alumina was removed by filtration through a ceramic P4 filter and then through a 0.45 µm PTFE microfilter. The solvent was removed at 95°C using a rotary evaporator, and the polymer was transferred to a dry 250 ml glass flask and exposed to 150°C and then 170°C under a vacuum of 1 mbar (20 minutes each). The viscosity was 5500 mPa.s.

[0130] The obtained substance was measured by DSC. Under N2 conditions at 2°C / min, the Tg was measured at -141°C. FTIR and Raman measurements showed that no cyclic products were present. The FTIR and Raman spectra of the product were consistent with the PEMS spectra calculated using B3LYP / 6-311G(d,p) levels (Gaussian16).

[0131] Viscosity according to ASTM E3116-18 standard as of January 25, 2018: 25 mPa.s, Mw = 2000 g / mol (Viscosimeter Model: VSC-N4 (Bioevopeak, China) - Measurement range: 20~2,000,000 mPa.s).

[0132] The polyvariance index (PD) calculated by GPC was 2.41. The GPC conditions were the same as in Example 1.

[0133] Crosslinking: 5g of PEMS silicone (step c1), 1.5g of SiO2 (HDK H2000), 14mg of Pt(0) tetravinylcyclotetrasiloxane (Sigma Aldrich, #479543), and 135mg of HMS H271 (Gelest, USA) were crosslinked at 35°C overnight, followed by 150°C for 20 minutes.

[0134] The elastic crosslinked silicone rubber achieved a Tg of -139°C, and neither crystallization nor melting occurred between -139°C and +250°C.

[0135] No crystallization of silicon was observed from +25 to -130°C under an N2 atmosphere at a rate of 2°C / min.

Claims

1. Step a) Hydrolysis reaction of the silanol precursor; Step b) The chain of the silanol-terminated siloxane oligomer obtained in step a) is extended by Lewis acid-induced polycondensation by adding a triflate salt catalyst and then a perfluoroborane catalyst. Includes, The triflate salt catalyst is at least one selected from the group consisting of In(III) triflate, Bi(III) triflate, and Al(III) triflate. The perfluoroborane catalyst is tris(pentafluorophenyl)borane. A method for producing polysiloxanes containing methyl and ethyl groups.

2. The polysiloxane containing a methyl group and an ethyl group is - Poly(dimethyl-co-diethyl)siloxane or poly(methylhydro-co-diethyl)siloxane of the following formula (I): 【Chemistry 1】 A represents a methyl group or a hydrogen atom. m and n are repeating motifs -O-Si(Me)(A) and -O-Si(Et 2 This represents the mole fraction of ) m = 0.5 to 0.8, n = 0.2 to 0.5, and m + n = 1. p represents the number of repeating motifs required to obtain a weight-average molecular weight in the range of 20,000 g / mol to 150,000 g / mol when A represents a methyl group, and in the range of 300 g / mol to 3,500 g / mol when A represents a hydrogen atom. And, - Poly(ethylmethylsiloxane) of the following formula (II): 【Chemistry 2】 q represents the number of repeating motifs. Characterized by being selected from the group consisting of, The method according to claim 1.

3. The silanol precursor in step a) (R1) 2 Ethylmethylsilane and (R1) 2 Dimethylsilane and (R1) 2 A mixture of diethylsilanes and (R1) 2 Methylsilane and (R1) 2 A mixture of diethylsilanes is selected from among, where R1 is a chlorine atom, (C 1 -C 6 ) Characterized by representing an alkoxy group, an acetoxy group, or an oxime group, The method according to claim 2.

4. The triflate salt catalyst is characterized by being present in an amount of 0.1 mg to 1 mg per gram of oligomer. The method according to claim 1.

5. Step b) is characterized by being carried out at room temperature. The method according to claim 1.

6. Step b) is characterized by being carried out in bulk without the use of a solvent. The method according to claim 1.

7. - The poly(dimethyl-co-diethyl)siloxane obtained in step b) has a weight-average molecular weight in the range of 20,000 g / mol to 150,000 g / mol. - The poly(methylhydro-co-diethyl)siloxane obtained in step b) has a weight-average molecular weight in the range of 300 g / mol to 3500 g / mol, and - The poly(ethylmethylsiloxane) obtained in step b) has a weight-average molecular weight in the range of 1,000 g / mol to 200,000 g / mol. Characterized by, The method according to claim 2.

8. In(III) triflate without solvent, B(C in toluene as a solvent or without solvent 6 F 5 ) 3 , or In(III) triflate and B(C 6 F 5 ) 3 further comprising step c1) of adding a vinyl terminal group by reacting the polymer obtained in step b) with vinyldimethylmethoxysilane or vinyl-1,1,3,3-tetramethyldisiloxane at a temperature of 20 to 70°C in the presence of a Lewis acid catalyst selected from a mixture with Step c1) is - Polymer having the following formula (III) 【Transformation 3】 A represents a methyl group or a hydrogen atom. m and n are repeating motifs -O-Si(Me)(A) and -O-Si(Et 2 This represents the mole fraction of ) m = 0.5 to 0.8, n = 0.2 to 0.5, and m + n = 1. p represents the number of repeating motifs required to obtain a weight-average molecular weight in the range of 20,000 g / mol to 150,000 g / mol when A represents a methyl group, and in the range of 300 g / mol to 3,500 g / mol when A represents a hydrogen atom. R 2 =-Si(CH) 3 ) 2 CH=CH 2 : or - Polymer having the following formula (IV) 【Chemistry 4】 q represents the number of repeating motifs, R 2 =-Si(CH) 3 ) 2 CH=CH 2 : Characterized by being for the purpose of obtaining The method according to claim 1.

9. - The poly(dimethyl-co-diethyl)siloxane obtained in step c1) has a glass transition temperature in the range of -130°C to -142°C. - The poly(methylhydro-co-diethyl)siloxane obtained in step c1) has a glass transition temperature in the range of -130°C to -146°C, and - The poly(ethylmethylsiloxane) obtained in step c1) has a glass transition temperature in the range of -130°C to -142°C: The method according to claim 8.

10. B(C) in toluene as a solvent 6 F 5 ) 3 The process further includes step c2), in which a trialkylsilyl terminal group is added by the reaction of the polymer obtained in step b) with a trialkylsilane in the presence of a Lewis acid catalyst. Step c2) is Polymer having the following formula (V) 【Transformation 5】 A represents a methyl group or a hydrogen atom. m and n are repeating motifs -O-Si(Me)(A) and -O-Si(Et 2 This represents the mole fraction of ) m = 0.5 to 0.8, n = 0.2 to 0.5, and m + n = 1. p represents the number of repeating motifs required to obtain a weight-average molecular weight in the range of 20,000 g / mol to 150,000 g / mol when A represents a methyl group, and in the range of 300 g / mol to 3,500 g / mol when A represents a hydrogen atom. Each R 3 These are mutually independent saturated, linear, or branched C 1 -C 6 It is an alkyl group: or - A polymer having the following formula (VI) 【Transformation 6】 q represents the number of repeating motifs, Each R 3 These are saturated, linear, or branched C, independently of each other. 1 -C 6 It is an alkyl group: Characterized by being for the purpose of obtaining The method according to claim 1.

11. The present invention relates to a method for producing 50 / 50 poly(dimethyl-co-diethyl)siloxane or 50 / 50 poly(methylhydro-co-diethyl)siloxane. The method according to claim 2.

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