High-temperature-resistant organosilicon polymer as well as preparation method and application thereof

Abstract

The invention discloses a high-temperature-resistant organic silicon polymer as well as a preparation method and application thereof in the technical field of organic silicon materials. The high-temperature-resistant organic silicon polymer is a block polymer formed by trapezoidal polysiloxane and linear polysiloxane. The preparation method comprises the following steps: carrying out dehydration condensation cyclization on an end group bifunctional silanol group on one side of ladder-type polysiloxane and alkenyl boric acid, and further carrying out hydrosilylation reaction with hydrogen-terminated linear polysiloxane to extend a chain, thereby finally obtaining the organic silicon polymer with the borate group bridged ladder-line block structure. Trapezoid molecules contained in the block organosilicon polymer are heat-resistant in nature, and the heat-resistant characteristic of the material can be further enhanced by introducing boric acid ester bridging groups. The block organosilicon polymer disclosed by the invention has a heat-resistant temperature (weight loss is 1.0% during initial decomposition) up to 435 DEG C. The process for preparing the high-temperature-resistant organosilicon polymer is simple and convenient, equipment is simple, raw materials are easy to obtain, and the method is suitable for large-scale industrial production. The prepared organic silicon material is a thermoplastic polymer, is good in film-forming property, can be subjected to hot pressing to form a film, and has a wide application prospect as a high-temperature-resistant elastic film material.

Description

Technical Field

[0001] This invention belongs to the field of organosilicon materials technology, and more specifically, relates to a high-temperature resistant organosilicon block copolymer, its preparation method and application. Background Technology

[0002] Organosilicon polymers have long Si-O bonds and large Si-O-Si bond angles in their main chain, and the single bonds in the main chain are prone to internal rotation, resulting in excellent molecular chain flexibility and a very low glass transition temperature (Tg). Simultaneously, the inorganic elements in their molecular backbone endow them with excellent high-temperature resistance, thus leading to their widespread application in high-temperature materials. Among them, ladder-type polysiloxanes exhibit particularly outstanding high-temperature resistance. For example, methyl-side-group polysilsesquioxanes do not decompose after prolonged heating at 300°C, and only begin to decompose at 380°C in an oxygen atmosphere (390°C in a nitrogen atmosphere). Phenyl-side-group polysilsesquioxanes have an even higher degradation temperature of 557°C. Ladder-type polysiloxanes with multi-chain structures have even higher Tg and degradation temperatures. For instance, the Tg of a phenyl-side-group triple-chain ladder-type polysiloxane is 158°C, and the Tg of a tetra-chain ladder-type polysiloxane reaches 215°C, with a degradation temperature (dec.) as high as 609°C.

[0003] Ladder-type polysiloxanes with special double-chain (or multi-chain) structures greatly enhance the intermolecular forces. However, due to the mutual bonding and constraint between the repeating units of the tetracyclosiloxane in the ladder structure, the products are often rigid structures with a rigid conformation. The tightly arranged structural units in these ladder-type polysiloxanes cause the ladder molecules to crystallize and appear as powder, resulting in poor film-forming and processability. Therefore, ladder-type polysiloxanes are difficult to use as materials.

[0004] Although single-chain block copolymers obtained by modifying carbon chain polymers with single-chain polysiloxanes exhibit exceptional heat resistance, ladder-type molecular structures, when used as modifying polymer components, do not consistently produce linear block polymer chains. Instead, they often form cross-linked structures, a common feature of multifunctional polymers. Therefore, to date, few modified polymers with block structures have been prepared using ladder-type polysiloxanes as constituents. Summary of the Invention

[0005] This invention utilizes ladder-shaped polysiloxane molecules as blocks, which undergo addition reactions with single-chain polysiloxanes to extend the chain, thus preparing block copolymers with excellent heat resistance. Simultaneously, during the addition reaction of ladder-shaped and linear polysiloxanes, the borate ester bridges formed at the chain extension sites are themselves inorganic bridging structures. This structure further improves the high-temperature resistance of the block copolymer products. Unlike ladder-shaped polysiloxanes, which are brittle and have poor film-forming properties, the thermoplastic block copolymer organic materials obtained through the addition reaction with linear polysiloxanes exhibit good plasticity and excellent mechanical properties.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions.

[0007] A high-temperature resistant organosilicon block copolymer has the following chemical structural formula: ; Wherein, R is -Ph or -CH3; R1 is -CH2=CHPh- or CH2=CH-; R1′ is -CH2CH2Ph- or -CH2CH2-; R2 is CH3 or -Ph; R3 is CH3 or -Ph; m is 5 to 300; n is 5 to 100; x is 1 to 10.

[0008] Preferably, m is 10–50; n is 20–50; and x is 3–6.

[0009] This invention discloses a method for preparing the above-mentioned high-temperature resistant organosilicon block copolymer, comprising the following steps: preparing the above-mentioned high-temperature resistant organosilicon block copolymer by hydrosilylation of ladder-type polysiloxane alkenyl cycloboronic ester and hydrogen-terminated polysiloxane.

[0010] In this invention, the chemical structural formula of the ladder-type polysiloxane alkenyl cycloboronic ester is as follows: ; The chemical structural formula of the hydrogen-terminated polysiloxane is as follows: ; Where R is -Ph or -CH3; R1 is -CH2=CHPh- or CH2=CH-; R2 is CH3 or -Ph; R3 is CH3 or -Ph; m is 5 to 300; n is 5 to 100.

[0011] In this invention, ladder-line block polysiloxane is prepared by heating and reacting ladder-type polysiloxane alkenyl borate and hydrogen-terminated polysiloxane in the presence of a noble metal catalyst, namely the above-mentioned high-temperature resistant organosilicon block copolymer.

[0012] In this invention, the noble metal catalyst includes a platinum catalyst.

[0013] In this invention, the heating reaction temperature is room temperature to 200°C.

[0014] This invention discloses the application of the above-mentioned high-temperature resistant organosilicon block copolymer in the preparation of heat-resistant film materials.

[0015] This invention discloses the application of the above-mentioned high-temperature resistant organosilicon block copolymer in the preparation of heat-resistant thermoplastic materials.

[0016] This invention discloses a heat-resistant thermoplastic polymer, comprising the above-mentioned high-temperature resistant organosilicon block copolymer.

[0017] This invention discloses the application of the above-mentioned high-temperature resistant organosilicon block copolymer in the preparation of heat-resistant materials or as heat-resistant materials.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention cyclizes the terminal borate esters of a 4-functional ladder-type polysiloxane through an esterification reaction, and extends the chain with a single-chain polysiloxane to finally generate a ladder-line block polysiloxane with a precise linear structure. The block copolymer product composed solely of polysiloxane has excellent high-temperature resistance while unexpectedly achieving thermoplasticity.

[0019] This invention combines ladder-type polysiloxanes with single-chain polysiloxane blocks, resulting in polysiloxanes that are more heat-resistant and less prone to thermal decomposition than conventional polysiloxanes. This allows for the production of organosilicon materials with excellent high-temperature resistance and superior mechanical properties at room temperature. Furthermore, cycloborate esterification introduces borate ester groups as bridging groups, which further enhance the polymer's high-temperature resistance.

[0020] The ladder-line block polysiloxane prepared by this invention is a thermoplastic polymer with good film-forming properties and can be hot-pressed into a film. The product has broad application prospects as a high-temperature resistant material. The process for preparing the high-temperature resistant organosilicon polymer using this invention is simple, requires basic equipment, and uses readily available raw materials, making it suitable for large-scale industrial production. Attached Figure Description

[0021] Figure 1 The silicon NMR spectrum of the ladder-line block polysiloxane product prepared in Example 1 of this invention is shown.

[0022] Figure 2 The infrared spectrum of the ladder-line block polysiloxane prepared according to Embodiment 1 of the present invention.

[0023] Figure 3 The molecular weight test GPC curve of the ladder-line block polysiloxane product prepared in Example 1 of this invention is shown.

[0024] Figure 4 This is an optical image of a ladder-line block polysiloxane product hot-pressed film prepared according to Embodiment 1 of the present invention.

[0025] Figure 5 The thermogravimetric curves of the ladder-line block polysiloxane products prepared in Examples 1 and 2 of this invention are shown. The initial decomposition temperature (based on a mass loss of 1.0%) of both ladder-line block polysiloxane products is 439°C, and they no longer lose weight when heated to 668°C. The char residue of the ladder-line block polysiloxane product prepared in Example 1 is 68.1%, and the char residue of the ladder-line block polysiloxane product prepared in Example 2 is 53.2%. Detailed Implementation

[0026] Existing technology suggests that the double-chain (or multi-chain) structure of ladder-type polysiloxanes exhibits uncontrollable reactions during the preparation of block copolymers via coupling reactions. Consequently, linear polymer molecules are not obtained, often resulting in cross-linked molecular structures. Therefore, the production of thermoplastic polymers containing ladder-type polysiloxane structures is currently unsuccessful. This invention overcomes the biases of existing technology by block copolymerizing ladder-type polysiloxanes with single-chain polysiloxanes. This results in block copolymers that are more heat-resistant and less prone to thermal decomposition than conventional polysiloxanes, yielding products with superior high-temperature resistance.

[0027] The method for preparing high-temperature resistant ladder-line block polysiloxane provided by this invention is as follows: (1) synthesizing ladder-type polysiloxane; (2) cycloboronic acid esterification of ladder-type polysiloxane; (3) hydrosilylation to prepare ladder-line block polysiloxane, i.e., high-temperature resistant organosilicon block copolymer. Specific steps include: In the above steps, the cycloboronization of ladder-type polysiloxanes is autocatalyzed by alkenylboronic acid. The autocatalytic esterification reacts the dihydroxyl groups at one end of the ladder-type polysiloxane to form cycloboronates while simultaneously introducing borate groups as bridging groups. These borate groups can further improve the polymer's high-temperature resistance.

[0028] In the above steps, a platinum catalyst was added to the hydrosilylation reaction, which can efficiently catalyze the addition reaction of the end alkenyl groups of the ladder-type polysiloxane cycloboronic ester with hydrogen-based polysiloxane at high temperature, thereby obtaining a ladder-line block copolymer in which the polysiloxane ladder molecules and single-chain linear molecules are precisely segmented.

[0029] The ladder-line block polysiloxane structure, with its ladder-like molecules and borate ester groups, simultaneously endows the product with excellent high-temperature resistance.

[0030] The first step of this invention provides a method for introducing borate ester groups into ladder-type polysiloxane molecules through an esterification reaction. Under the autocatalysis of alkenylboronic acid and the action of a dehydrating agent, alkenylboronic acid esterifies with two Si-OH groups at the chain ends of the ladder-type polysiloxane to form a ring, thereby preparing ladder-type polysiloxane alkenyl cycloboronic ester.

[0031] In the synthesis of ladder-type polysiloxane alkenyl cycloboronic esters, the ladder-type polysiloxane includes phenyl ladder-type polysiloxane and methyl ladder-type polysiloxane, with the following structural formula: ; Where R is -Ph or -CH3; m is 5~300.

[0032] Preferably, the ladder-type polysiloxane is a phenyl ladder-type polysiloxane, with the following structural formula: ; Where m is 5~100.

[0033] The structural formula of the alkenylboronic acid is as follows: ; Where R1 is m -CH2=CHPh-, p -CH2=CHPh- or CH2=CH-.

[0034] The alkenylboronic acid is m-vinylphenylboronic acid, and its structural formula is: ; Or, for example, vinylphenylboronic acid, its structural formula is: ; Or vinylboric acid, with the following structural formula: .

[0035] The dehydrating agent is toluene, xylene, or cyclohexane.

[0036] When preparing ladder-type polysiloxane alkenyl borate, the mass ratio of ladder-type polysiloxane, alkenyl boric acid, and dehydrating agent is 100:0.5-20:50-300.

[0037] Preferably, the mass ratio of ladder-shaped polysiloxane, alkenyl boric acid, and dehydrating agent is 100:2-5:80-150.

[0038] The reaction formula for preparing ladder-type polysiloxane alkenyl cycloboronic ester is as follows: ; Where R1 is m -CH2=CHPh-, p -CH2=CHPh- or CH2=CH-; m is 5 to 300.

[0039] In the preparation of the ladder-shaped polysiloxane alkenyl cycloboronic ester, the reaction temperature is 60-220℃ and the reaction time is 1-24h.

[0040] Preferably, in the preparation of the ladder-type polysiloxane alkenyl cycloboronic ester, the reaction temperature is 100-140°C and the reaction time is 6-8 hours.

[0041] After the above esterification reaction is completed, the dehydrating agent is removed by vacuum evaporation to obtain the ladder-shaped polysiloxane alkenyl cycloboronic acid intermediate.

[0042] In the second step, based on the preparation of the ladder-type polysiloxane alkenyl cycloboronic ester intermediate in the first step, this invention provides a method for preparing ladder-line block polysiloxanes by hydrosilylation of ladder-type polysiloxane alkenyl cycloboronic esters with hydrogen-terminated polysiloxanes. The structural formula of the hydrogen-terminated polysiloxane used is as follows: ; Where R2 is CH3 or -Ph; R3 is CH3 or -Ph; n is 5~100.

[0043] For example, the hydrogen-terminated polysiloxane used is a hydrogen-terminated methyl polysiloxane, whose structural formula is: ; Or, a hydrogen-terminated phenylmethyl polysiloxane, with the following structural formula: ; Or a hydrogen-terminated diphenyl polysiloxane, with the following structural formula: ; Or, a hydrogen-terminated dimethyl-methylphenyl polysiloxane, with the following structural formula: ; Where y is 4-99; Or, a hydrogen-terminated dimethylbisphenyl polysiloxane, with the following structural formula: ; Where w is 4-99; Ladder-type polysiloxane alkenyl borate, hydrogen-terminated polysiloxane, and platinum catalyst were mixed uniformly in a certain proportion and heated for a certain time to prepare ladder-line block polysiloxane; the reaction formula is as follows:

[0044] Where R is -Ph or -CH3; R1 is m -CH2=CHPh-, p -CH2=CHPh- or CH2=CH-; R1′ is m -CH2CH2Ph-, p -CH2CH2Ph- or -CH2CH2-; R2 is CH3 or -Ph; R3 is CH3 or -Ph; m is 5–300; n is 5–100; x is 1–10.

[0045] Preferably, the heating reaction temperature is 50℃~150℃, and the time is 2~5 hours.

[0046] Preferably, the platinum catalyst includes any one of the Speier catalyst and the Karstedt catalyst, and the platinum concentration in the platinum catalyst is 1000ppm to 10000ppm.

[0047] During the reaction, the mass ratio of ladder-type polysiloxane alkenyl borate, hydrogen-terminated polysiloxane, and catalyst is 10–1000: 5–50: 0.1–5.

[0048] Preferably, the mass ratio of ladder-type polysiloxane alkenyl borate, hydrogen-terminated polysiloxane, and catalyst is 120–600: 5–20: 0.5–1.

[0049] Preferred embodiments of the present invention will now be described in more detail with reference to the accompanying drawings and specific examples.

[0050] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are commercially available.

[0051] The main raw materials used in the specific embodiments are as follows: Phenylacetyltrimethoxysilane (high purity, ≥98%) was purchased from Shanghai Anaiji Chemical Technology Co., Ltd. Toluene, xylene, and vinylphenylboronic acid were purchased from Jiangsu Qiangsheng Functional Chemical Co., Ltd.

[0052] Hydrogen-terminated phenylmethyl polysiloxane, hydrogen-terminated dimethyl polysiloxane, and hydrogen-terminated diphenyl polysiloxane, all with a number average molecular weight of 3000, were purchased from Shenzhen Jipeng Fluorosilicon Materials Technology Co., Ltd.

[0053] Catalyst: Karstedt catalyst, platinum content 3000 ppm, purchased from Shenzhen Kejunchi Industrial Co., Ltd.

[0054] The test methods in the following embodiments include: (1) Silicon NMR test 29 Si-NMR: The synthesized product was analyzed by silicon NMR using a solid-state wide-cavity superconducting nuclear magnetic resonance spectrometer (AvanceIII / WB-400). The solid polysiloxane product was thoroughly ground in a mortar, dried in a vacuum drying oven, and 50-100 mg was weighed and placed in a glass sample vial for testing.

[0055] (2) Fourier Transform Infrared Spectroscopy (FT-IR): The obtained samples were tested using a Thermo Scientific Nicolet iS5 infrared spectrometer. For routine powder compression testing, an appropriate amount of solid polysiloxane product was mixed with potassium bromide, ground in a mortar, dried using a high-temperature infrared lamp, pressed into thin sheets under 1 ton of pressure, and then placed inside the instrument. The measurement range was 400–4000 cm⁻¹. -1 The resolution is 4 cm. -1 Scanned 12 times.

[0056] (3) Thermogravimetric analysis (TGA) test the thermal decomposition temperature of thermoplastic ladder-line block polysiloxane products: The thermogravimetric analysis of the samples was performed using a Diamond 5700 thermogravimetric analyzer from PE Corporation, USA. The operating conditions were: approximately 10 mg of each sample, in a nitrogen and air atmosphere, with a heating rate of 5℃ / min, and a test temperature range from room temperature to 800℃.

[0057] (4) Gel permeation chromatography (GPC): The molecular weight of the prepared block polymer was tested using a TDA-302 gel permeation chromatograph manufactured by Viscotek, USA. The test was carried out at 35°C with tetrahydrofuran (THF) as the mobile phase and a flow rate of 1 mL / min. Polystyrene was used as the standard.

[0058] (5) Mechanical property testing: The mechanical properties of the organosilicon film prepared in this invention were tested using a double-arm material testing machine (INSTRON-3365, Instron Corporation, USA). During testing, the spacing length was adjusted to 20 mm, and the tensile rate was 100 mm·min. -1 Each group of film samples was tested in parallel three times to obtain the average breaking strength and elongation at break. Example 1

[0059] This embodiment provides a high-temperature resistant organosilicon polymer and a pressed film, the preparation method of which includes the following steps: S1: Synthetic ladder-type polysiloxane Hydrolysis of phenyltrimethoxysilane monomer Under a nitrogen atmosphere, 100.5 g of phenyltrimethoxysilane and 600.0 g of toluene were added to a 2 L three-necked flask equipped with a mechanical stirrer. After thorough mixing, the reaction system was placed in an ice bath at -10 °C. 200.0 g (0.1 mol / L) of prepared dilute hydrochloric acid was added dropwise to the mixture over 30 min. After the addition was complete, the mixture was stirred for 24 h to carry out the hydrolysis reaction. After the hydrolysis reaction was completed, the reaction solution was allowed to stand in a separatory funnel. The supernatant was collected and washed five times with 150 mL of deionized water until neutral to obtain the hydrolysate.

[0060] Preparation of ladder-type polysiloxanes by polycondensation The hydrolysate was transferred to a 2L three-necked flask equipped with a reflux condenser and a dropping funnel. At room temperature, 6g of KOH aqueous solution (10% by mass) was added dropwise to the hydrolysate. The mixture was stirred and refluxed at 80℃ for 24 h. After the reaction, the mixture was washed five times with 100g of deionized water, and the oil layer was dried with 2g of anhydrous magnesium sulfate. After filtering to remove the desiccant, the filtrate was rotary evaporated and vacuum dried to obtain 58.3g of a white solid ladder-shaped polysiloxane product. The half-width at half-maximum (WHM) of the silicon NMR characteristic peaks on the ladder-shaped polysiloxane backbone is usually used to characterize the regularity of the ladder-shaped polymer. The smaller the WHM, the more uniform the chemical environment of the silicon atoms on the polymer backbone, and the higher its regularity. The product was dissolved in deuterated chloroform for silicon NMR testing. The main peak of the silicon NMR spectrum of the product was found to be at a chemical shift of -79.9 ppm, which is typical of SiO₂. 2 / 3 The structure confirms that the target product is indeed a trapezoidal structure; the half-peak width of the main peak is as narrow as 5.9, which proves that the trapezoidal structure of the product has good regularity.

[0061] S2: Ladder-type polysiloxane with end-capped alkenyl cycloboronic esterification 150.0 g of xylene, 50.1 g of the ladder-type polysiloxane product synthesized in S1, and 8.1 g of 4-vinylphenylboronic acid were added to a 500 mL three-necked flask equipped with a mechanical stirrer, condenser, thermometer, and water separator. The mixture was then reacted at 140 °C for 8 h. After the reaction was completed, the mixture was washed three times with 100 g of deionized water, and the oil layer was dried with 5 g of anhydrous magnesium sulfate. After filtering to remove the desiccant, the filtrate was rotary evaporated to obtain 52.8 g of ladder-type polysiloxane with alkenyl cycloboronic acid esterification at both ends.

[0062] S3: Hydrosilylation preparation of ladder-line block polysiloxanes 150.0 g of toluene, 25.2 g of the end-terminated alkenyl cycloboronic acid ladder-type polysiloxane synthesized in S2, and 8.1 g of end-hydrogen phenylmethyl polysiloxane were added to a 500 mL three-necked flask equipped with a mechanical stirrer, condenser, thermometer, and dropping funnel. After stirring until completely dissolved, 0.1 g of Karstedt catalyst (platinum content of 3000 ppm) was added at 105 °C, and the reaction was maintained at this temperature for 3 h. Then, the product was first evaporated under reduced pressure to remove the solvent toluene, and then the low fraction was removed at 170 °C under 10 mmHg conditions for 1 h to obtain 32.8 g of white solid ladder-line block polysiloxane. The initial decomposition temperature of the product was found to be as high as 439 °C, indicating excellent thermal stability and high-temperature resistance.

[0063] Figure 1 The image shows the silicon NMR spectrum of the aforementioned ladder-line block polysiloxane product, where the chemical shift at δ = -70.6 corresponds to the silicon atom on the linear polysiloxane single chain, and the chemical shift at δ = -79.9 corresponds to the silicon atom on the ladder-line polysiloxane double chain.

[0064] Figure 2 The above-mentioned ladder-line block polysiloxane infrared spectra are shown, where λ is 3070.13, 3053.34, and 3008.64 cm⁻¹. -1 The characteristic peaks of the benzene ring observed nearby belong to the typical stretching vibrations of CH, at 1596.67 and 1434.33 cm⁻¹. -1 The characteristic peak observed nearby belongs to the CC class. (1243.22 cm) -1 The peaks at 694.92 and 738.80 cm⁻¹ are characteristic peaks of the BO-Si bond. -1 The peak at that location corresponds to the characteristic peak of the Si-C bond.

[0065] Figure 3 The GPC curves for the above ladder-line block polysiloxanes show that the number-average molecular weight of the block copolymer is 19779, the weight-average molecular weight is 30945, the Z-average molecular weight is 43821, and the molecular weight distribution coefficient is 1.56, indicating a narrow distribution.

[0066] S4: Molding and Testing The ladder-line block polysiloxane film prepared in S3 was subjected to the following hot pressing conditions: mold cavity thickness 2 mm, upper and lower template temperature controlled at 160℃, pressing time 15 min. After the first pressing, the upper and lower templates were released for 1 min to release air before the second pressing. The pressed silicone copolymer film was obtained by releasing the templates. Figure 4 The image shows an optical image of the hot-pressed film of the ladder-line block polysiloxane product. The average tensile strength of the silicone film product tested by a two-arm material testing machine is 4.24 MPa, and the elongation at break is 185.2%.

[0067] As a control, when end-capped alkenyl cycloboronized ladder polysiloxanes or end-capped hydrogen phenylmethyl polysiloxanes were pressed into films using the same method, no film was formed; instead, they became brittle powders. Comparative Example 1

[0068] When a ladder-shaped polysiloxane was prepared according to Example 1 and reacted directly with a terminal hydrogen-methyl polysiloxane, it did not react even when heated to a high temperature without a catalyst. When a conventional catalyst (potassium hydroxide) that can catalyze the condensation of silanols (i.e., silanols) was added, the reaction was gel-like. The gel product was insoluble in any solvent and did not melt (it could not be pressed into a film) and did not have thermoplasticity.

[0069] Therefore, the present invention combines brittle powdered alkenyl borate ladder polysiloxanes with linear polysiloxanes through chemical bonds, and the block polymerization product exhibits thermoplastic properties, good film-forming properties, and the resulting polymer film has excellent mechanical properties. Example 2

[0070] This embodiment provides a high-temperature resistant organosilicon polymer and a pressed film, the preparation method of which includes the following steps: A ladder-type polysiloxane with two ends of alkenyl cycloboronate was prepared according to Example 1.

[0071] Preparation of ladder-line block polysiloxanes by hydrosilylation: 150.0 g of toluene, 25.2 g of the aforementioned ladder-line polysiloxane with end-capped alkenyl borosilicates, and 7.1 g of terminal hydrogen-dimethyl polysiloxane were added to a 500 mL three-necked flask equipped with a mechanical stirrer, condenser, thermometer, and dropping funnel. After complete dissolution by stirring, 0.1 g of Karstedt catalyst (platinum content 3000 ppm) was added at 105 °C. After reacting at this temperature for 3 h, the product was first evaporated under reduced pressure to remove the solvent toluene, and then the low fraction was removed at 170 °C under 10 mmHg conditions for 1 h, yielding 30.2 g of the final ladder-line block polysiloxane white solid product. The number-average molecular weight of the block copolymer obtained in this example was measured to be 21033, the weight-average molecular weight was 34302, the Z-average molecular weight was 45221, and the molecular weight distribution coefficient was 1.63, indicating a narrow distribution. The initial decomposition temperature of the product was measured to be as high as 439 °C, indicating excellent thermal stability and high-temperature resistance.

[0072] Film pressing and testing: The ladder-line block polysiloxane film prepared above was pressed under the following hot pressing conditions: mold cavity thickness 2mm, upper and lower mold platen temperature controlled at 160℃, pressing time 15min. After the first pressing, the upper and lower mold plates were released for 1min before the second pressing. The pressed silicone copolymer film was obtained after releasing the mold plates. The silicone film product was tested using a dual-arm material testing machine, and the average tensile strength at break was 3.61 MPa, and the elongation at break was 205.1%.

[0073] Figure 5 The thermogravimetric curves of the ladder-line block polysiloxane products prepared in Examples 1 and 2 of this invention are shown. The initial decomposition temperature (based on a mass loss of 1.0%) of both ladder-line block polysiloxane products is 439°C, and they no longer lose weight when heated to 668°C. The char residue of the ladder-line block polysiloxane product prepared in Example 1 is 68.1%, and the char residue of the ladder-line block polysiloxane product prepared in Example 2 is 53.2%. Example 3

[0074] This embodiment provides a high-temperature resistant organosilicon polymer and a pressed film, the preparation method of which includes the following steps: A ladder-type polysiloxane with two ends of alkenyl cycloboronate was prepared according to Example 1.

[0075] To a 500 mL three-necked flask equipped with a mechanical stirrer, condenser, thermometer, and dropping funnel, 150.0 g of toluene, 25.2 g of the aforementioned end-terminated alkenyl cycloboronic acid-esterified ladder-type polysiloxane, and 11.3 g of end-hydrogen-terminated diphenyl polysiloxane were added. After complete dissolution by stirring, 0.1 g of Karstedt catalyst (platinum content 3000 ppm) was added at 105 °C. The reaction was maintained at this temperature for 4 h. The product was first subjected to vacuum distillation to remove the solvent toluene, and then the low-run fraction was removed at 170 °C under 10 mmHg conditions for 1 h, yielding 35.7 g of the final ladder-line block polysiloxane white solid product. The number-average molecular weight of the block copolymer obtained in this example was measured to be 25331, the weight-average molecular weight to be 32109, the Z-average molecular weight to be 42187, and the molecular weight distribution coefficient to be 1.26, indicating a narrow distribution. The initial decomposition temperature of the product was measured to be 407 °C, demonstrating excellent thermal stability and high-temperature resistance.

[0076] The ladder-line block polysiloxane press film prepared above was subjected to the following hot-pressing conditions: mold cavity thickness 2mm, upper and lower mold platen temperature controlled at 160℃, pressing time 10-15min. After the first pressing, the upper and lower mold plates were released for 1min before the second pressing. Releasing the mold plates yielded the pressed silicone copolymer film. The silicone film product was tested using a dual-arm material testing machine, and the average tensile strength at break was 3.01 MPa, and the elongation at break was 112.6%.

[0077] Currently, there are no thermoplastic organosilicones. Organosilicones are generally used as materials in the form of silicone rubber and silicone resin, both of which are cross-linked materials and lack thermoplasticity. In particular, existing technology suggests that the double-chain (or multi-chain) structure of ladder-type polysiloxanes is uncontrollable during the preparation of block molecular chains via coupling reactions, thus failing to yield linear polymer molecules and often exhibiting cross-linked molecular structures. Therefore, no thermoplastic polymers containing ladder-type polysiloxane structures have been produced. This invention overcomes the biases of existing technology by block copolymerizing ladder-type polysiloxanes with single-chain polysiloxanes. This results in block copolymers that are more heat-resistant and less prone to thermal decomposition than conventional polysiloxanes. This invention produces block copolymers with superior high-temperature resistance. Notably, this invention is the first to disclose thermoplastic organosilicones with initial decomposition temperatures (based on a 1.0% mass loss) exceeding 400°C or even 430°C, exhibiting unexpected technical advantages.

[0078] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and principles of the described embodiments, and these modifications and variations should also be considered within the scope of protection of the present invention.

Claims

1. A high-temperature resistant organosilicon block copolymer, the chemical structural formula of which is as follows: ； in, R is -Ph or -CH3; R1 is -CH2=CHPh- or CH2=CH-; R1′ is -CH2CH2Ph- or -CH2CH2-; R2 is CH3 or -Ph; R3 is CH3 or -Ph; m is 5 to 300; n is 5 to 100; x is 1 to 10.

2. The method for preparing the high-temperature resistant organosilicon block copolymer according to claim 1 includes the following steps: preparing the above-mentioned high-temperature resistant organosilicon block copolymer by hydrosilylation of a ladder-type polysiloxane alkenyl cycloboronic ester with a hydrogen-terminated polysiloxane; the chemical structural formula of the ladder-type polysiloxane alkenyl cycloboronic ester is as follows: ； The chemical structural formula of the hydrogen-terminated polysiloxane is as follows: ； in, R is -Ph or -CH3; R1 is -CH2=CHPh- or CH2=CH-; R2 is CH3 or -Ph; R3 is CH3 or -Ph; m is 5 to 300; n is 5 to 100.

3. The method for preparing the high-temperature resistant organosilicon block copolymer according to claim 2, characterized in that, The high-temperature resistant organosilicon block copolymer was prepared by heating and reacting ladder-type polysiloxane alkenyl cycloboronic ester and hydrogen-terminated polysiloxane in the presence of a noble metal catalyst.

4. The method for preparing the high-temperature resistant organosilicon block copolymer according to claim 3, characterized in that, Noble metal catalysts include platinum catalysts; the heating reaction temperature is room temperature to 200℃.

5. A ladder-shaped polysiloxane alkenyl cycloboronic ester, the chemical structural formula of which is as follows: ； in, R is -Ph or -CH3; R1 is -CH2=CHPh- or CH2=CH-; m is 5 to 300.

6. The method for preparing the ladder-shaped polysiloxane alkenyl cycloboronic ester according to claim 5, characterized in that, The ladder-shaped polysiloxane reacts with alkenylboronic acid to obtain the ladder-shaped polysiloxane alkenyl cycloboronic ester.

7. The application of the high-temperature resistant organosilicon block copolymer of claim 1 in the preparation of heat-resistant film materials; or the application of the high-temperature resistant organosilicon block copolymer in the preparation of heat-resistant materials or as a heat-resistant material.

8. The application of the high-temperature resistant organosilicon block copolymer of claim 1 in the preparation of heat-resistant thermoplastic materials.

9. The application of the ladder-type polysiloxane alkenyl cycloboronic acid ester and hydrogen-terminated polysiloxane as described in claim 5 in the preparation of thermoplastic high-temperature resistant organosilicon block copolymers.

10. A heat-resistant thermoplastic polymer, comprising the high-temperature resistant organosilicon block copolymer of claim 1.

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