Rare earth ternary complexes, their preparation methods, and methods for preparing linear fluorinated hydrocarbon-based polysiloxanes.

Abstract

This invention provides a rare-earth ternary complex, its preparation method, and a method for preparing linear fluorinated hydrocarbon-based polysiloxanes. The rare-earth ternary complex is constructed by coordination bonds between rare-earth ions, a nitrogen-containing heterocyclic carbene organic ligand, and an acidic active component supported within porous solid superacid channels. Within the channels, rare-earth ions simultaneously coordinate and bond with both the nitrogen-containing heterocyclic carbene and the acidic active component. This rare-earth ternary complex can be used as a catalyst to catalyze the preparation of linear fluorinated hydrocarbon-based polysiloxanes, exhibiting high catalytic activity and effectively suppressing intramolecular "backbiting," resulting in highly polymerized linear fluorinated hydrocarbon-based polysiloxanes.

Description

Technical Field

[0001] This invention belongs to the field of organosilicon materials technology, specifically relating to rare earth ternary complexes, their preparation methods, and the preparation method of linear fluorinated hydrocarbon-based polysiloxanes. Background Technology

[0002] Linear fluorinated hydrocarbon-based polysiloxanes are a class of special linear polymer materials in which fluorinated hydrocarbon side links are branched to the polysiloxane backbone. They combine the high and low temperature resistance and flexibility of organosilicon with the oil resistance, solvent resistance and low surface energy of organofluorine. They can overcome the defects of traditional silicone rubber in poor resistance to media and fluororubber in poor low temperature toughness and easy embrittlement. They have irreplaceable application value in extreme working conditions such as aerospace, automotive turbocharging, petrochemical, and electronic packaging.

[0003] Despite the superior performance of linear fluorinated hydrocarbon-based polysiloxanes, their preparation still faces numerous technical challenges. During the hydrolysis and condensation of fluorinated silanes, the active chain ends are prone to cyclization and shedding due to intramolecular "biting-back," a side reaction that not only leads to the generation of a large number of cyclic siloxane impurities but also significantly limits the effective increase in the molecular weight of polysiloxanes. Simultaneously, the strong electronegativity of fluorine atoms brings significant steric hindrance and electronic effects, reducing the polymerization activity of fluorinated monomers. Furthermore, existing catalysts exhibit low catalytic activity and poor structural selectivity, making it difficult to achieve efficient reactions and resulting in poor controllability of the product structure. Summary of the Invention

[0004] In view of the above-mentioned technical status, the present invention provides a rare earth ternary complex with a novel structure, which can be used as a catalyst to catalyze the preparation of linear fluorinated hydrocarbon-based polysiloxanes. It has high catalytic activity and can effectively suppress intramolecular "biting back" to obtain linear fluorinated hydrocarbon-based polysiloxanes.

[0005] The technical solution of the present invention is: a rare earth ternary complex, which is constructed by coordination bonds of rare earth ions, nitrogen heterocyclic carbene organic ligands, and acidic active components loaded in porous solid superacid channels; in the channels, rare earth ions simultaneously coordinate bonds with nitrogen heterocyclic carbene and acidic active components in the channels.

[0006] The nitrogen-containing heterocyclic carbene is a cyclic compound containing a carbene carbon atom, and the carbene carbon is bonded to at least one nitrogen atom, including but not limited to one or more of imidazoles, imidazolines, or triazoles.

[0007] The rare earth ions include, but are not limited to, one or more of lanthanum, cerium, neodymium, samarium, ytterbium, and yttrium ions.

[0008] Preferably, the porous solid superacid is composed of a porous support and an acidic active component, wherein the acidic active component is loaded on the porous support, including being loaded inside the pores of the porous support; wherein the porous support includes, but is not limited to, one or more of metal oxides, zeolites, porous carbon materials, porous inorganic fibers, etc.; the acidic active component includes, but is not limited to, one or more of sulfate, persulfate, phosphate, phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, fluoroantimonic acid, etc.

[0009] Preferably, in the rare earth ternary complex, the molar ratio of nitrogen heterocyclic carbene to rare earth element is (0.5~2.0):1.

[0010] Preferably, in the rare earth ternary complex, the porous solid superacid accounts for 85% to 99% of the mass of the rare earth ternary complex, and more preferably 90% to 99%.

[0011] The present invention also provides a method for preparing the rare earth ternary complex, comprising the following steps: The measured amount of nitrogen heterocyclic carbene ligand precursor was dissolved in anhydrous toluene, and an activated porous solid superacid was added. The mixture was stirred at room temperature to allow the nitrogen heterocyclic carbene ligand to impregnate and adsorb into the pores of the porous solid superacid. The reaction system was cooled to -5°C to 5°C, and an anhydrous toluene solution of rare earth amines was added dropwise with stirring to carry out the reaction. The rare earth ions simultaneously coordinated and bonded the nitrogen heterocyclic carbene and the acidic active component inside the pores to obtain the rare earth ternary complex.

[0012] The rare earth amines include, but are not limited to, one or more of the following: rare earth metal silicon-based amines, rare earth metal aryl amines, rare earth metal alkyl amines, and rare earth metal cyclic amines.

[0013] The nitrogen-containing heterocyclic carbene ligand precursors include, but are not limited to, one or more of the following: imidazoline salts, benzimidazolium salts, triazolium salts, and onium salts based on heterocycles such as pyridine and quinoxaline.

[0014] The activation treatment of porous solid superacids is mainly used to remove excess water or structural water from porous solid superacids and promote the formation or transformation of acidic active components into stable structures with superacidity. The activation treatment method is not limited; as one implementation, activation is carried out through heat treatment, such as calcination, with the preferred heat treatment temperature being 300℃~800℃.

[0015] Preferably, after the reaction is completed, the mixture is separated, precipitated, washed, and dried to obtain the rare earth ternary complex.

[0016] The rare-earth ternary complex of the present invention can be used as a catalyst to catalyze the preparation of linear fluorinated hydrocarbon-based polysiloxanes. The preparation method includes the following steps: (1) Alkylcyclosiloxanes are cyclosiloxanes with methyl as a side chain; Fluorohydrocyclosiloxane, the alkylcyclosiloxane, and the catalyst are added to a reaction vessel, and an inert gas is introduced for protection. The mixture is heated and stirred under anhydrous conditions, and the fluorohydrocyclosiloxane and the alkylcyclosiloxane undergo a ring-opening copolymerization reaction to form an intermediate product containing fluorohydrocyclosiloxane. (2) Add a capping agent to the reaction vessel and continue heating and stirring under anhydrous and inert gas protection. The capping agent undergoes a condensation reaction with the intermediate product of fluorinated hydrocarbon polysiloxane, thereby terminating the chain growth. At the same time, the low-boiling-point byproducts in the reaction system are distilled off under reduced pressure to obtain linear fluorinated hydrocarbon polysiloxane.

[0017] In step (1), the alkylcyclosiloxanes include, but are not limited to, one or more of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecylcyclohexasiloxane, etc.

[0018] In step (1), preferably, some of the methyl groups on the alkylcyclosiloxane can be replaced by other groups, such as one or more groups selected from vinyl, phenyl, chlorophenyl, cyanoalkyl, ethyl, propyl, hexyl, octyl, decyl, etc.

[0019] In step (1), the fluoroalkyl cyclosiloxanes include, but are not limited to, one or more of trifluoropropylmethylcyclotrisiloxane, trifluoropropylmethylcyclotetrasiloxane, and trifluoropropylmethylcyclopentasiloxane.

[0020] In step (1), preferably, some of the methyl groups on the fluoroalkyl cyclosiloxane can be replaced by other groups, such as one or more groups selected from vinyl, phenyl, chlorophenyl, cyanoalkyl, ethyl, propyl, hexyl, octyl, decyl, etc.

[0021] In step (1), preferably, the molar content of the fluoroalkyl cyclosiloxane chain segment is 0.1% to 100%, and more preferably 30% to 60%.

[0022] In step (1), preferably, the mass of the catalyst accounts for 0.03% to 0.18% of the sum of the masses of the fluoroalkyl cyclosiloxane and the alkyl cyclosiloxane, and more preferably 0.05% to 0.12%.

[0023] In step (1), preferably, the reaction temperature is 50℃~150℃, and more preferably 80℃~120℃.

[0024] In step (1), the reaction time is preferably 1h to 10h, and more preferably 4h to 6h.

[0025] In step (1), preferably, the stirring speed is 100 rpm to 600 rpm, and more preferably 240 rpm to 480 rpm.

[0026] In step (2), the capping agent includes, but is not limited to, one or more of alkyl capping agents, vinyl capping agents, hydrogen-containing capping agents, hydroxyl capping agents, alkoxy capping agents, or functional capping agents.

[0027] The alkyl end-capping agent is an inert alkyl group that renders the polysiloxane non-reactive, including but not limited to one or more of hexamethyldisiloxane, trimethylchlorosilane, and trimethylmethoxysilane.

[0028] The vinyl end-capping agent introduces vinyl groups to give the polysiloxane chain end an unsaturated double bond that can participate in hydrosilylation reactions, including but not limited to one or more of divinyltetramethyldisiloxane, dimethylvinylchlorosilane, etc.

[0029] The hydrogen-containing end-capping agent introduces silane-hydrogen bonds, giving the polysiloxane chain ends active hydrogen, which can be used for hydrosilylation reactions or as chain extension / crosslinking active sites, including but not limited to one or more of tetramethyldisiloxane, dimethylchlorosilane, etc.

[0030] The hydroxyl end-capping agent introduces hydroxyl groups, enabling the polysiloxane to crosslink through a condensation reaction at room temperature. This includes, but is not limited to, one or more of hydroxyl silicone oil, vinyl hydroxyl silicone oil, hydroxyl-capped phenyl silicone oil, and hydroxyl-capped fluorosilicone oil.

[0031] The alkoxy end-capping agent introduces alkoxy groups, enabling the polysiloxane to crosslink through a condensation reaction at room temperature, including but not limited to one or more of dimethyldimethoxysilane, methyltrimethoxysilane, etc.

[0032] The functional end-capping agent is used to introduce specific reaction sites or functional groups at the ends of polysiloxanes, including but not limited to one or more of dimethylphenylchlorosilane, trifluoropropyldimethylchlorosilane, γ-glycidoxypropyltrimethoxysilane, and dialkyldichlorosilane.

[0033] In step (2), preferably, the molar amount of the capping agent is 0.5% to 6% of the sum of the molar amounts of fluoroalkyl cyclosiloxane and alkyl cyclosiloxane.

[0034] In step (2), the reaction temperature is preferably 50℃~120℃, and more preferably 70℃~90℃.

[0035] In step (2), the reaction time is preferably 2h to 8h, and more preferably 3h to 6h.

[0036] In step (2), preferably, the stirring speed is 100 rpm to 600 rpm, and more preferably 240 rpm to 480 rpm.

[0037] In step (2), the absolute pressure is preferably 0.1 kPa to 2.0 kPa, and more preferably 0.8 kPa to 1.2 kPa.

[0038] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention provides a rare earth ternary complex with a novel structure. Within the pores of a porous solid superacid, rare earth ions serve as coordination centers, simultaneously forming coordination bonds with nitrogen heterocyclic carbene and the acidic active component within the pores, thus forming a dual-ligand rare earth coordination unit. Furthermore, the preparation method of this invention is simple and easy to implement.

[0039] (2) The rare earth ternary complex of the present invention can be used as a catalyst to catalyze the preparation of linear fluorinated hydrocarbon polysiloxanes. Since the active nitrogen heterocyclic carbene-rare earth center is anchored in the porous solid superacid channel, the solid superacid channel restricts the movement of polymer chains. That is, the movement of fluorinated hydrocarbon polysiloxanes is restricted by physical space, thereby effectively suppressing the chain termination side reactions such as intramolecular "biting back", and obtaining linear fluorinated hydrocarbon polysiloxanes. This achieves precise control of the polymerization process. In addition, the rare earth ternary complex catalyst has high activity and can obtain fluorinated polysiloxanes with high degree of polymerization. Therefore, it can obtain polysiloxanes with higher molecular weight and narrower molecular weight distribution. Furthermore, the solid properties of the catalyst are easy to recover and reuse, which meets the needs of large-scale production.

[0040] (3) The linear fluorinated hydrocarbon-based polysiloxanes prepared by the rare earth ternary complex catalysis of the present invention have both excellent mechanical properties and excellent oil resistance, solvent resistance and high thermal stability: Its tensile strength is greater than or equal to 9 MPa, and its elongation at break is greater than or equal to 500%, or even greater than or equal to 600%. After being immersed in fuel at 40℃ for 24 hours, the tensile strength retention rate is greater than or equal to 90% or even greater than or equal to 95%, the elongation at break retention rate is greater than or equal to 90% or even greater than or equal to 95%, the mass change rate is less than or equal to 1% or even less than or equal to 0.8%, and the volume change rate is less than or equal to 2% or even less than or equal to 1.8%. After being immersed in lubricating oil at 70℃ for 24 hours, the tensile strength retention rate is greater than or equal to 40%, the elongation at break retention rate is greater than or equal to 50%, the mass change rate is less than or equal to 30% or even less than or equal to 25%, and the volume change rate is less than or equal to 30%. After being immersed in hydraulic oil at 70℃ for 24 hours, the tensile strength retention rate is greater than or equal to 90% or even greater than or equal to 95%, the elongation at break retention rate is greater than or equal to 90% or even greater than or equal to 95%, the mass change rate is less than or equal to 1%, and the volume change rate is less than or equal to 2%. The long-term operating temperature range is -70℃ to 230℃; it maintains excellent mechanical properties during long-term use in the temperature range of -70℃ to 230℃, with tensile strength retention rate ≥80% and elongation at break retention rate ≥80%. Therefore, this linear fluorinated hydrocarbon-based polysiloxane can meet the stringent requirements of extreme working conditions in aerospace, automotive turbocharging, petrochemicals, and other fields. Detailed Implementation

[0041] The present invention will be further described in detail below with reference to the embodiments. It should be noted that the embodiments described below are intended to facilitate the understanding of the present invention and do not limit it in any way.

[0042] Example 1: The porous solid superacid is composed of a porous support titanium dioxide and an acidic active component sulfate, and is referred to as a porous sulfate / titanium dioxide solid superacid. The acidic active component is loaded on the porous support, including being loaded inside the pores of the porous support.

[0043] The rare earth ternary complex, designated as a nitrogen heterocyclic carbene / samarium / sulfate rare earth ternary complex, is constructed from samarium ions, a nitrogen heterocyclic carbene, and sulfate, an acidic active component supported within porous sulfate / titanium dioxide solid superacid channels. Within these channels, samarium ions simultaneously coordinate and bond with both the nitrogen heterocyclic carbene and the sulfate component. The porous sulfate / titanium dioxide solid superacid accounts for 95.5% of the total mass of the rare earth ternary complex; the molar ratio of the nitrogen heterocyclic carbene to the rare earth element is 0.98:1.

[0044] The preparation method of this rare earth ternary complex is as follows: The 1,3-bis(2,6-diisopropylphenyl)imidazolium chloride solution was dissolved in anhydrous toluene. A porous sulfate / titanium dioxide solid superacid, activated by calcination at 500°C for 3 hours, was added. The mixture was stirred at room temperature to allow the 1,3-bis(2,6-diisopropylphenyl)imidazolium chloride to be fully impregnated and adsorbed within the pores of the sulfate / titanium dioxide solid superacid. The reaction system was cooled to 0°C, and an anhydrous toluene solution of tris(bis(trimethylsilyl)amino)smarium was slowly added dropwise with continuous stirring. After the addition was complete, the reaction was continued at 0°C for 1 hour, then slowly raised to room temperature and continued for 8 hours. After the reaction was complete, the precipitate was separated by centrifugation, washed twice with anhydrous n-hexane, and dried under vacuum at room temperature to obtain the rare earth ternary complex.

[0045] This rare-earth ternary complex can be used as a catalyst to prepare linear fluorinated hydrocarbon-based polysiloxanes. The preparation method includes the following steps: (1) 112g of octamethylcyclotetrasiloxane, 203g of trifluoropropylmethylcyclotrisiloxane, and 0.28g of nitrogen heterocyclic carbene / samarium / sulfate rare earth ternary complex were added to the reactor and stirred for 2h under anhydrous and nitrogen protection at 80°C.

[0046] (2) 5.18g of trimethylchlorosilane end-capping agent was added to the reactor and stirred for 3h under anhydrous and nitrogen protection at 80°C. After the reaction was completed, the temperature was raised to 200°C and the pressure was reduced to 1.2kPa to distill off unreacted residues and low-boiling-point byproducts to obtain uniform and transparent linear trifluoropropylmethylpolysiloxane.

[0047] Nuclear magnetic resonance (NMR) spectroscopy analysis revealed no characteristic signal of the methylene proton (-Si-CH2-) bonded to silicon atoms in the cyclic monomer in the ¹H-NMR spectrum, while in the ²H-NMR spectrum... 9 No signal peaks belonging to cyclic oligomers were found in the Si-NMR spectrum, indicating that the linear trifluoropropylmethyl polysiloxane does not contain cyclic polysiloxane oligomers. This means that the catalyst can effectively suppress the backbiting side reaction during the synthesis process to form cyclic polysiloxane oligomers.

[0048] Gel permeation chromatography analysis revealed that the number-average molecular weight (Mn) of this linear trifluoropropylmethylpolysiloxane was 6.2 × 10⁻⁶. 5 The polydispersity index (PDI) is 1.1, which means that the target product trifluoropropylmethylpolysiloxane has a large molecular weight and a concentrated distribution.

[0049] Meanwhile, the entire synthesis process does not require harsh conditions such as high temperature and high pressure.

[0050] All the above results indicate that the rare earth ternary complex catalyst has high catalytic activity and good selectivity, and can precisely control the molecular weight and structure of the target product trifluoropropylmethylpolysiloxane.

[0051] The linear trifluoropropylmethyl polysiloxane prepared above was vulcanized at 180°C for 12 min using a peroxide vulcanizing agent. The mass of the linear trifluoropropylmethyl polysiloxane was 100 parts, and the mass of the vulcanizing agent was 0.9 parts. A sheet sample with a thickness of 3 mm was prepared. The mechanical, oil resistance, high temperature resistance, and low temperature resistance properties of the sample were tested. The results are shown in Table 1.

[0052] Table 1: Performance testing methods and results of the samples in Example 1

[0053] Example 2: The porous solid superacid is composed of a porous carrier zeolite and an acidic active component persulfate, and is referred to as a porous persulfate / zeolite solid superacid. The acidic active component is loaded on the porous carrier, including being loaded inside the pores of the porous carrier.

[0054] The rare earth ternary complex, designated as a nitrogen heterocyclic carbene / neodymium / persulfate rare earth ternary complex, is constructed from neodymium ions, a nitrogen heterocyclic carbene, and persulfate, an acidic active component supported within porous persulfate / zeolite solid superacid channels. Within these channels, neodymium ions simultaneously coordinate and bond with both the nitrogen heterocyclic carbene and the acidic active component persulfate. The porous persulfate / zeolite solid superacid accounts for 93.85% of the total mass of the rare earth ternary complex; the molar ratio of the nitrogen heterocyclic carbene to the rare earth element is 1.08:1.

[0055] The preparation method of this rare earth ternary complex is as follows: The 1,3-bis(2,4,6-trimethylphenyl)imidazolium chloride solution was dissolved in anhydrous toluene. A porous persulfate / zeolite solid superacid, activated by calcination at 620°C for 4 hours, was added. The mixture was stirred at room temperature to allow the 1,3-bis(2,4,6-trimethylphenyl)imidazolium chloride to be fully impregnated and adsorbed within the pores of the persulfate / zeolite solid superacid. The reaction system was cooled to 0°C, and an anhydrous toluene solution of tris(trimethylsilylaniline)neodymium was slowly added dropwise with continuous stirring. After the addition was complete, the reaction was continued at 0°C for 1.5 hours, then slowly raised to room temperature and continued for 10 hours. After the reaction was complete, the precipitate was separated by centrifugation, washed twice with anhydrous n-hexane, and dried under vacuum at room temperature to obtain the rare earth ternary complex.

[0056] This rare-earth ternary complex can be used as a catalyst to prepare linear fluorinated hydrocarbon-based polysiloxanes. The preparation method includes the following steps: (1) 99g of decamethylcyclopentasiloxane, 3g of heptamethylvinylcyclotetrasiloxane, 172g of trifluoropropylmethylcyclotetrasiloxane, and 0.32g of nitrogen-containing heterocyclic carbene / neodymium / persulfate rare earth ternary complex were added to the reactor and stirred for 2.5h under anhydrous and nitrogen protection at 70°C.

[0057] (2) 1.22g of dimethylvinylchlorosilane end-capping agent was added to the reactor and stirred for 4.5h under anhydrous and nitrogen protection at 70°C. After the reaction was completed, the temperature was raised to 185°C and the pressure was reduced to 1.8kPa to distill off unreacted residues and low-boiling-point byproducts to obtain a uniform and transparent linear trifluoropropylmethyl polysiloxane containing vinyl groups.

[0058] The linear trifluoropropylmethylpolysiloxane prepared above was analyzed and tested, and the following results were obtained.

[0059] Nuclear magnetic resonance (NMR) spectroscopy analysis revealed no characteristic signal of the methylene proton (-Si-CH2-) bonded to silicon atoms in the cyclic monomer in the ¹H-NMR spectrum, while in the ²H-NMR spectrum... 9 No signal peaks belonging to cyclic oligomers were found in the Si-NMR spectrum, indicating that the linear trifluoropropylmethylpolysiloxane does not contain cyclic polysiloxane oligomers. This means the catalyst can effectively suppress the backbiting side reaction during synthesis to form cyclic polysiloxane oligomers. The presence of an ethylene hydrogen group signal peak in the chemical shift region δ4.5–6.5 ppm in the ¹H-NMR spectrum indicates that the linear trifluoropropylmethylpolysiloxane contains vinyl groups.

[0060] Gel permeation chromatography analysis revealed that the number-average molecular weight (Mn) of this linear trifluoropropylmethylpolysiloxane was 7.8 × 10⁻⁶. 5 The polydispersity index (PDI) is 1.0, which means that the target product, a vinyl-containing linear trifluoropropylmethyl polysiloxane, has a large molecular weight and a concentrated distribution.

[0061] Meanwhile, the entire synthesis process does not require harsh conditions such as high temperature and high pressure.

[0062] All the above results indicate that the ternary catalyst has high catalytic activity and good selectivity, and can precisely control the molecular weight and structure of the target product, vinyl-containing linear trifluoropropylmethyl polysiloxane.

[0063] The linear trifluoropropylmethyl polysiloxane prepared above was vulcanized at 135°C for 15 min using a platinum vulcanizing agent. The mass of the linear trifluoropropylmethyl polysiloxane was 100 parts, and the mass of the platinum vulcanizing agent was 1 part. A sheet sample with a thickness of 3 mm was prepared. The mechanical, oil resistance, and high and low temperature resistance properties of the sample were tested, and the results are shown in Table 2.

[0064] Table 2: Performance testing methods and results of the samples in Example 2

[0065] Example 3: The porous solid superacid is composed of a porous carrier alumina and an acidic active component phosphotungstic acid, and is referred to as a porous phosphotungstic acid / alumina solid superacid. The acidic active component is loaded on the porous carrier, including being loaded inside the pores of the porous carrier.

[0066] The rare earth ternary complex, designated as the nitrogen heterocyclic carbene / yttrium / phosphotungstic acid rare earth ternary complex, is constructed from yttrium ions, a nitrogen heterocyclic carbene, and phosphotungstic acid, an acidic active component supported within the porous pores of a solid superacid such as phosphotungstic acid / alumina. Within these pores, yttrium ions simultaneously coordinate and bond the nitrogen heterocyclic carbene and the acidic active component phosphotungstic acid. The porous phosphotungstic acid / alumina solid superacid accounts for 87.4% of the total mass of the rare earth ternary complex; the molar ratio of the nitrogen heterocyclic carbene to the rare earth element is 0.92:1.

[0067] The preparation method of this rare earth ternary complex is as follows: The 1,3-diisopropylimidazolium boron tetrafluoride salt in the specified ratio was dissolved in anhydrous toluene. A porous phosphotungstic acid / alumina solid superacid, activated by calcination at 300°C for 4 hours, was added. The mixture was stirred at room temperature to allow the 1,3-diisopropylimidazolium boron tetrafluoride salt to fully impregnate and adsorb into the pores of the phosphotungstic acid / alumina solid superacid. The reaction system was cooled to 0°C, and an anhydrous toluene solution of yttrium di(methylcyclopentadienyl)diphenylaminoyttrium was slowly added dropwise with continuous stirring. After the addition was complete, the reaction was continued at 0°C for 1.8 hours, then slowly raised to room temperature and continued for 6 hours. After the reaction was completed, the precipitate was separated by centrifugation, washed twice with anhydrous n-hexane, and dried under vacuum at room temperature to obtain the target rare earth ternary complex.

[0068] This rare-earth ternary complex can be used as a catalyst to prepare linear fluorinated hydrocarbon-based polysiloxanes. The preparation method includes the following steps: (1) 92g of octamethylcyclotetrasiloxane, 167g of trifluoropropylethylcyclotrisiloxane, 21g of octaphenylcyclotetrasiloxane, and 0.37g of nitrogen-containing heterocyclic carbene / yttrium / phosphotungstic acid rare earth ternary complex were added to the reactor and stirred for 3h under anhydrous and nitrogen protection at 75°C.

[0069] (2) 4.73g of phenyl dimethyl chlorosilane end-capping agent was added to the reactor and stirred for 6 hours under anhydrous and nitrogen protection at 105°C. After the reaction was completed, the temperature was raised to 210°C and the pressure was reduced to 1.9kPa to distill off the unreacted residue and low-boiling-point byproducts to obtain a uniform and transparent linear trifluoropropyl methyl polysiloxane containing phenyl.

[0070] The linear trifluoropropyl ethyl polysiloxane prepared above was analyzed and tested, and the following results were obtained.

[0071] Nuclear magnetic resonance (NMR) spectroscopy analysis revealed no characteristic signal of the methylene proton (-Si-CH2-) bonded to silicon atoms in the cyclic monomer in the ¹H-NMR spectrum, while in the ²H-NMR spectrum... 9No signal peaks belonging to cyclic oligomers were found in the Si-NMR spectrum, indicating that the linear trifluoropropyl ethyl polysiloxane does not contain cyclic polysiloxane oligomers. This means that the catalyst can effectively suppress the backbiting side reaction during the synthesis process to form cyclic polysiloxane oligomers. 1 The H-NMR spectrum shows a characteristic signal peak of phenyl hydrogen in the chemical shift region of δ7.0-7.6ppm, indicating that the linear trifluoropropylethyl polysiloxane contains phenyl groups.

[0072] Gel permeation chromatography analysis revealed that the number-average molecular weight (Mn) of this linear trifluoropropylethyl polysiloxane was 7.4 × 10⁻⁶. 5 The polydispersity index (PDI) is 1.2, indicating that the target product, trifluoropropylethyl polysiloxane, has a large molecular weight and a concentrated distribution. Furthermore, the entire synthesis process does not require harsh conditions such as high temperature and high pressure. These results demonstrate that the ternary catalyst exhibits high catalytic activity and good selectivity, and can precisely control the molecular weight and structure of the target product, phenyl-containing linear trifluoropropylethyl polysiloxane.

[0073] The linear trifluoropropyl ethyl polysiloxane prepared above was vulcanized at 175°C for 10 min using a peroxide vulcanizing agent. The linear trifluoropropyl ethyl polysiloxane was 100 parts by mass, and the peroxide vulcanizing agent 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane was 0.75 parts by mass. A sheet sample with a thickness of 3 mm was prepared. Then, the mechanical, oil resistance, high temperature resistance, and low temperature resistance properties of the sample were tested. The results are shown in Table 3.

[0074] Table 3: Performance testing methods and results of the samples in Example 3

[0075] Example 4: The porous solid superacid is composed of porous carrier activated carbon and acidic active component fluoroantimony, and is referred to as porous fluoroantimony acid / activated carbon solid superacid. The acidic active component is loaded on the porous carrier, including being loaded inside the pores of the porous carrier.

[0076] The rare earth ternary complex, designated as a nitrogen heterocyclic carbene / cerium / fluoroantimony acid rare earth ternary complex, is constructed from cerium ions, a nitrogen heterocyclic carbene, and fluoroantimony acid, an acidic active component supported within the pores of a porous fluoroantimony acid / activated carbon solid superacid. Within these pores, cerium ions simultaneously coordinate and bond the nitrogen heterocyclic carbene and the acidic active component fluoroantimony acid. The porous fluoroantimony acid / activated carbon solid superacid accounts for 88.2% of the mass of this rare earth ternary complex; the molar ratio of the nitrogen heterocyclic carbene to the rare earth element is 0.89:1.

[0077] The preparation method of this rare earth ternary complex is as follows: The 1,3-dimethylimidazolium-2-carboxylate in the specified ratio was dissolved in anhydrous toluene. A porous fluoroantimonyic acid / activated carbon solid superacid, activated by baking at 450°C for 3.5 h, was added. The mixture was stirred at room temperature to allow the 1,3-dimethylimidazolium-2-carboxylate to be fully impregnated and adsorbed within the pores of the fluoroantimonyic acid / activated carbon solid superacid. The reaction system was cooled to -3°C, and an anhydrous toluene solution of tris(dimethylamino)cerium was slowly added dropwise with continuous stirring. After the addition was complete, the reaction was continued at -3°C for 2.5 h, then slowly raised to room temperature and continued for another 5.5 h. After the reaction was complete, the precipitate was separated by centrifugation, washed twice with anhydrous cyclohexane, and dried under vacuum at room temperature to obtain the target rare earth ternary complex.

[0078] This rare-earth ternary complex can be used as a catalyst to prepare linear fluorinated hydrocarbon-based polysiloxanes. The preparation method includes the following steps: (1) 95g of dodecylcyclohexasiloxane, 201g of trifluoropropylmethylcyclopentasiloxane, and 0.59g of nitrogen-containing heterocyclic carbene / cerium / fluoroantimony rare earth ternary complex were added to the reactor and stirred at 68°C for 4.2h under anhydrous and nitrogen protection.

[0079] (2) 5.06g of hydroxyl fluorosilicone oil end-capping agent with a viscosity of 100mPa·s was added to the reactor. The reaction was continued to be stirred for 4.5h under anhydrous and nitrogen protection at 135℃. After the reaction was completed, the temperature was raised to 195℃ and the pressure was reduced to 1.4kPa to distill off the unreacted residue and low-boiling-point byproducts to obtain a uniform and transparent hydroxyl-containing linear trifluoropropylmethyl polysiloxane.

[0080] The linear trifluoropropylmethylpolysiloxane prepared above was analyzed and tested, and the following results were obtained.

[0081] Nuclear magnetic resonance (NMR) spectroscopy analysis revealed no characteristic signal of the methylene proton (-Si-CH2-) bonded to silicon atoms in the cyclic monomer in the ¹H-NMR spectrum, while in the ²H-NMR spectrum... 9 No signal peaks belonging to cyclic oligomers were found in the Si-NMR spectrum, indicating that the linear trifluoropropylmethyl polysiloxane does not contain cyclic polysiloxane oligomers. This means that the catalyst can effectively suppress the backbiting side reaction during the synthesis process to form cyclic polysiloxane oligomers. 1 The H-NMR spectrum shows a characteristic signal peak of silanol in the chemical shift region of δ0.0-2.0ppm, indicating that the linear trifluoropropylmethyl polysiloxane contains silanol.

[0082] Gel permeation chromatography analysis revealed that the number-average molecular weight (Mn) of this linear trifluoropropylmethylpolysiloxane was 1.2 × 10⁻⁶. 5The polydispersity index (PDI) is 1.4, indicating that the target product, trifluoropropylmethyl polysiloxane, has a large molecular weight and a concentrated distribution. Furthermore, the entire synthesis process does not require harsh conditions such as high temperature and high pressure. These results demonstrate that the ternary catalyst exhibits high catalytic activity and good selectivity, and can precisely control the molecular weight and structure of the target product, phenyl-containing linear trifluoropropylmethyl polysiloxane.

[0083] The linear trifluoropropylmethylpolysiloxane prepared above was cured for 24 hours at 23°C and 50% relative humidity using a ketoxime-type crosslinking agent. The linear trifluoropropylmethylpolysiloxane was 100 parts by mass, the crosslinking agent was 4.5 parts by mass, the catalyst was 0.5 parts by mass, and the fumed silica was 9 parts by mass. A sheet sample with a thickness of 3 mm was prepared. The mechanical, oil resistance, high temperature resistance, and low temperature resistance properties of the sample were then tested. The results are shown in Table 4.

[0084] Table 4: Performance testing methods and results of the samples in Example 4

[0085] The above embodiments provide a detailed description of the technical solution of the present invention. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, or similar substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A rare earth ternary complex, characterized in that: It is constructed by coordination bonds of rare earth ions, nitrogen heterocyclic carbene organic ligands, and acidic active components loaded in porous solid superacid channels; in the channels, rare earth ions simultaneously coordinate bonds with nitrogen heterocyclic carbene and acidic active components in the channels.

2. The rare earth ternary complex as described in claim 1, characterized in that: At least one of the following conditions must be met: The nitrogen-containing heterocyclic carbene includes one or more of imidazoles, imidazolines, or triazoles; The rare earth ions include one or more of lanthanum, cerium, neodymium, samarium, ytterbium, and yttrium ions; In the rare earth ternary complex, the molar ratio of nitrogen heterocyclic carbene to rare earth element is (0.5~2.0):1; In the rare earth ternary complex, the porous solid superacid accounts for 85% to 99% of the mass of the rare earth ternary complex.

3. The rare earth ternary complex as described in claim 1, characterized in that: The porous solid superacid is composed of a porous support and an acidic active component, wherein the acidic active component is loaded on the porous support, including being loaded inside the pores of the porous support. Preferably, the porous support includes one or more of the following: metal oxides, zeolites, porous carbon materials, and porous inorganic fibers. Preferably, the acidic active component includes one or more of sulfate, persulfate, phosphate, phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, and fluoroantimonic acid.

4. The method for preparing the rare earth ternary complex according to any one of claims 1 to 3, characterized in that: Includes the following steps: The measured amount of nitrogen heterocyclic carbene ligand precursor was dissolved in anhydrous toluene, and an activated porous solid superacid was added. The mixture was stirred at room temperature to allow the nitrogen heterocyclic carbene ligand to impregnate and adsorb into the pores of the porous solid superacid. The reaction system was cooled to -5°C to 5°C, and an anhydrous toluene solution of rare earth amines was added dropwise with stirring to carry out the reaction. The rare earth ions simultaneously coordinated and bonded the nitrogen heterocyclic carbene and the acidic active component inside the pores to obtain the rare earth ternary complex.

5. The preparation method according to claim 4, characterized in that: At least one of the following conditions must be met: The rare earth amines include one or more of rare earth metal silicon-based amines, rare earth metal aryl amines, rare earth metal alkyl amines, and rare earth metal cyclic amines. The nitrogen-containing heterocyclic carbene ligand precursor includes one or more of the following: imidazoline salts, benzimidazolium salts, triazolium salts, and onium salts based on pyridine or quinoxaline heterocycles. The porous solid superacid is activated by heat treatment, with the preferred heat treatment temperature being 300℃~800℃. After the reaction is complete, the rare earth ternary complex is obtained by separation, precipitation, washing, and drying.

6. The rare earth ternary complex as described in any one of claims 1 to 3 is used as a catalyst in the preparation of linear fluorinated hydrocarbon-based polysiloxanes.

7. A method for preparing a linear fluorinated hydrocarbon-based polysiloxane, characterized in that: Includes the following steps: (1) Alkylcyclosiloxanes are cyclosiloxanes with methyl as a side chain; Fluorohydrocyclosiloxane, the alkylcyclosiloxane, and the catalyst are added to a reaction vessel, an inert gas is introduced for protection, and the mixture is heated and stirred under anhydrous conditions. The fluorohydrocyclosiloxane and the alkylcyclosiloxane undergo a ring-opening copolymerization reaction to form an intermediate product containing fluorohydrocyclosiloxane. The catalyst is a rare earth ternary complex as described in any one of claims 1 to 3; (2) Add a capping agent to the reaction vessel and continue heating and stirring under anhydrous and inert gas protection. The capping agent undergoes a condensation reaction with the intermediate product of fluorinated hydrocarbon polysiloxane, thereby terminating the chain growth. At the same time, the low-boiling-point byproducts in the reaction system are distilled off under reduced pressure to obtain linear fluorinated hydrocarbon polysiloxane.

8. The preparation method according to claim 7, characterized in that: At least one of the following conditions must be met: In step (1), the alkylcyclosiloxane includes one or more of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecylcyclohexasiloxane; In step (1), some of the methyl groups on the alkylcyclosiloxane are replaced by other groups, which are one or more of the groups selected from vinyl, phenyl, chlorophenyl, cyanoalkyl, ethyl, propyl, hexyl, octyl, and decyl. In step (1), the fluoroalkyl cyclosiloxane includes one or more of trifluoropropylmethylcyclotrisiloxane, trifluoropropylmethylcyclotetrasiloxane, and trifluoropropylmethylcyclopentasiloxane; In step (1), some of the methyl groups on the fluoroalkyl cyclosiloxane are replaced by other groups, which are one or more of the groups selected from vinyl, phenyl, chlorophenyl, cyanoalkyl, ethyl, propyl, hexyl, octyl, and decyl. In step (1), the molar content of the fluorocarbon-based cyclosiloxane chain segment is 0.1%~100%; In step (1), the mass of the catalyst accounts for 0.03% to 0.18% of the sum of the masses of the fluoroalkyl cyclosiloxane and the alkyl cyclosiloxane; In step (1), the reaction temperature is 50℃~150℃; In step (1), the reaction time is 1h to 10h; In step (1), the stirring speed is 100 rpm to 600 rpm; In step (2), the capping agent includes one or more of alkyl capping agents, vinyl capping agents, hydrogen-containing capping agents, hydroxyl capping agents, alkoxy capping agents, or functional capping agents; The alkyl end-capping agent includes one or more of hexamethyldisiloxane, trimethylchlorosilane, and trimethylmethoxysilane; The vinyl end-capping agent includes one or more of divinyltetramethyldisiloxane and dimethylvinylchlorosilane; The hydrogen-containing end-capping agent includes one or more of tetramethyldisiloxane and dimethylchlorosilane; The alkoxy end-capping agent includes one or more of dimethyldimethoxysilane and methyltrimethoxysilane; The functional end-capping agent includes one or more of dimethylphenylchlorosilane, trifluoropropyldimethylchlorosilane, and γ-glycidoxypropyltrimethoxysilane; In step (2), the molar amount of the capping agent is 0.5% to 6% of the sum of the molar amounts of fluoroalkyl cyclosiloxane and alkyl cyclosiloxane; In step (2), the reaction temperature is 50℃~120℃; In step (2), the reaction time is 2h~8h; In step (2), the stirring speed is 100 rpm to 600 rpm; In step (2), the absolute pressure is 0.1 kPa to 2.0 kPa.

9. The preparation method according to claim 7, characterized in that: The obtained linear fluorinated hydrocarbon-based polysiloxane has a tensile strength greater than or equal to 9 MPa and an elongation at break greater than or equal to 500%.

10. The preparation method according to claim 9, characterized in that: At least one of the following conditions must be met: After being soaked in fuel at 40°C for 24 hours, the linear fluorinated hydrocarbon-based polysiloxane exhibits a tensile strength retention rate greater than or equal to 90%, an elongation at break retention rate greater than or equal to 90%, a mass change rate less than or equal to 1%, and a volume change rate less than or equal to 2%. After being immersed in lubricating oil at 70℃ for 24 hours, the tensile strength retention rate is greater than or equal to 40%, the elongation at break retention rate is greater than or equal to 50%, the mass change rate is less than or equal to 30%, and the volume change rate is less than or equal to 30%. After being immersed in hydraulic oil at 70℃ for 24 hours, the tensile strength retention rate is greater than or equal to 90%, the elongation at break retention rate is greater than or equal to 90%, the mass change rate is less than or equal to 1%, and the volume change rate is less than or equal to 2%. The long-term operating temperature range is -70℃ to 230℃; When used for a long period of time in a temperature range of -70℃ to 230℃, the tensile strength retention rate is ≥80% and the elongation at break retention rate is ≥80%.

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