Phenylene boron hybrid silicon resin aerogel and preparation method thereof

Abstract

The invention relates to a phenyleneboronic hybrid silicon resin aerogel and a preparation method thereof, and belongs to the technical field of aerogel preparation, and the specific scheme comprises the following steps: step 1, adding alkoxy silane, organic phenylboronic acid, an organic solvent and deionized water into a reaction container, heating for hydrolysis-condensation, and after the reaction is finished, carrying out oil-water separation to obtain a phenyleneboronic hybrid silicon resin aerogel; carrying out reduced pressure distillation on the oily substance to remove small molecular organic matters and deionized water to obtain a phenylene boron-containing silicon resin prepolymer; step 2, dissolving the phenyleneborosilicate resin prepolymer in an organic solvent, adding a catalyst, pouring the mixture into a mold, and performing cross-linking curing to obtain phenyleneborosilicate resin gel; and step 3, heating and drying the phenyleneborosilicate resin gel at normal pressure, and after drying is finished, heating and aging to obtain the phenyleneborosilicate resin aerogel. The phenylene boron hybrid silicon resin aerogel disclosed by the invention can be used as a novel light, ablation-resistant, anti-oxidation and high-performance ablation heat-proof and heat-insulating composite material, and new application of the hybrid silicon resin in the fields of aerospace and the like is expanded.

Description

Technical Field

[0001] The invention belongs to the technical field of aerogel preparation, and in particular relates to a phenylene boron hybrid silicone resin aerogel and a preparation method thereof. Background Art

[0002] With the development of aerospace technology, aerogel materials are mainly divided into two categories: inorganic aerogel and organic aerogel. The main component of inorganic aerogel is silicon dioxide. The use temperature of this type of aerogel does not exceed 1000°C. When the temperature is high, silicon dioxide will shrink and crack, destroying the aerogel structure, resulting in reduced thermal insulation performance. Compared with inorganic aerogel, organic aerogel, especially phenolic aerogel, contains carbon elements, which have a better ability to absorb thermal radiation. Phenolic aerogel does not sinter and shrink under high temperature, but undergoes carbonization reaction to generate carbon aerogel, which can meet higher temperature use in an oxygen-free environment. Therefore, the high-temperature thermal insulation performance of phenolic aerogel materials is significantly better than that of inorganic aerogel materials. However, phenolic aerogel composite materials will oxidize at high temperatures in an aerobic environment. After working for a long time, oxidation causes phenolic aerogel to fail and lose its thermal insulation performance. Although the introduction of antioxidant inorganic nanoparticles into phenolic resin improves the antioxidant properties of phenolic resin to a certain extent, it still cannot meet the requirements of long-term use in an aerobic environment. Therefore, how to improve the antioxidant properties of organic resin aerogels is a key technical issue that needs to be urgently solved in this field.

[0003] Silicone resin is a product of organic-inorganic hybrid polymerization, composed of Si-O-Si inorganic structure and organic groups such as methyl and phenyl. The Si-O bond energy of the inorganic Si-O-Si skeleton structure of silicone resin is as high as 450KJ / mol, which is higher than the carbon-carbon bond energy (345.6KJ / mol). It is not easy to break or decompose under high-temperature radiation environment. This special structure makes silicone resin have excellent thermal oxidation performance. The introduction of ablation-resistant phenylene structure and antioxidant boron atoms in silicone resin is oxidized at high temperature to generate borosilicate glass covering its surface, which has a good oxygen barrier effect and can further improve the ablation resistance and oxidation resistance of silicone resin. As the resin matrix of a new type of lightweight, high-performance ablation-resistant and heat-insulating composite material, phenylene boron hybrid silicone resin is expected to increase the flight speed of high-speed aircraft in the atmosphere and extend the flight time. Summary of the invention

[0004] In order to solve the problems existing in the background technology, the present invention provides a phenylene boron hybrid silicone resin aerogel and a preparation method thereof.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A phenylene boron hybrid silicone resin aerogel, the structural formula of the phenylene boron hybrid silicone resin aerogel is shown in Formula I:

[0007]

[0008] Where R0 is One or more combinations of R1-R 14 Each independently selects one of phenyl and methyl.

[0009] A method for preparing the phenylene boron hybrid silicone resin aerogel comprises the following steps:

[0010] Step 1, adding alkoxysilane, organic phenylboric acid, organic solvent and deionized water in a molar ratio of 3-10:0.1-6:2-10:3.6-12 into a reaction vessel, heating for hydrolysis-condensation, separating oil and water after the reaction, taking the oil and distilling it under reduced pressure to remove small molecular organic matter and deionized water to obtain a phenylene borosilicate resin prepolymer;

[0011] Step 2, dissolving a phenylene borosilicate resin prepolymer in an organic solvent, adding a catalyst, pouring the mixture into a mold, cross-linking and curing the mixture to obtain a phenylene borosilicate resin gel;

[0012] Step 3: heating and drying the phenylene borosilicate resin gel at normal pressure, and after drying, post-curing to obtain the phenylene borosilicate resin aerogel.

[0013] Furthermore, in step 1, the alkoxysilane is a combination of at least two of methyltriethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane and phenyltriethoxysilane.

[0014] Further, in step 1, the organic phenylboric acid is a combination of one or more of 1,4-phenyldiboric acid, 1,3-phenyldiboric acid, and 1,2-phenyldiboric acid;

[0015] Furthermore, in step 1, the heating temperature for the hydrolysis-condensation is 60-70° C., and the heating time is 4-12 hours; the reduced pressure distillation temperature is 90-120° C., and the time is 2-4 hours.

[0016] Furthermore, the organic solvent in step 1 and step 2 includes one or more combinations of ethanol, propanol, isopropanol, n-butanol, isobutanol, tert-butanol and sec-butanol.

[0017] Furthermore, in step 2, the mass ratio of the phenylene boron hybrid silicone resin prepolymer to the organic solvent is 15-40:60-85; the mass ratio of the catalyst to the phenylene boron hybrid silicone resin prepolymer is 0.1-2:100.

[0018] Furthermore, the catalyst includes one or more of tetrabutyl titanate, tetrapropyl titanate, (triethanolamine) titanium isopropoxide complex, tetra(2-ethylhexyl) titanate, and di(acetylacetonato) diisopropyl titanate.

[0019] Furthermore, in step 2, the temperature of cross-linking and curing is 80 to 120° C., and the curing time is 12 to 48 hours.

[0020] Furthermore, in step 3, the temperature of the normal pressure heating drying is 40-80° C., and the drying time is 12-72 hours; the post-curing temperature is 150-250° C., and the drying time is 2-12 hours.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention simultaneously introduces ablation-resistant phenylene structures and oxidation-resistant boron atoms into silicone resin to improve the ablation resistance of silicone resin. In addition, the boron atoms are oxidized at high temperatures to generate borosilicate glass that covers the surface of the silicone resin and has a good oxygen barrier effect, thereby improving the antioxidant properties of the silicone resin.

[0023] (2) The present invention uses phenylene boron hybrid silicone resin prepolymer to prepare aerogel materials with high structural strength. The aerogel material is obtained by heating and drying at normal pressure. This is the first time that normal pressure drying of silicone resin aerogel is achieved, thereby reducing the preparation cost of silicone resin aerogel.

[0024] (3) The present invention adjusts the content of phenylene boron in the hybrid silicone resin to control the multi-level microstructure of the aerogel at the nanoscale, thereby achieving the preparation of an aerogel with a micro-nano structure and a high specific surface area.

[0025] (4) The phenylene boron hybrid silicone resin aerogel of the present invention can be used as a new type of lightweight, ablation-resistant, oxidation-resistant, high-performance ablation-resistant and heat-insulating composite material, which will expand the new use of hybrid silicone resin in the fields of aerospace and aviation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 , a flow chart of preparing phenylene boron hybrid silicone resin aerogel according to the present invention;

[0027] Figure 2 , the NMR spectrum of the phenylene boron hybrid silicone resin prepolymer prepared in Example 1;

[0028] Figure 3 , SEM photograph of the phenylene boron hybrid silicone resin aerogel prepared in Example 1;

[0029] Figure 4 , the specific surface area test result diagram of the phenylene boron hybrid silicone resin aerogel prepared in Example 2;

[0030] Figure 5, Thermogravimetric test results of the phenylene boron hybrid silicone resin aerogel prepared in Example 3 in air and argon. DETAILED DESCRIPTION

[0031] The technical solution of the present invention will be clearly and completely described below in conjunction with the drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] A method for preparing a phenylene boron hybrid silicone resin aerogel comprises the following steps:

[0034] Weigh 2 mol of methyltrimethoxysilane, 1 mol of phenyltrimethoxysilane, 1 mol of dimethyldiethoxysilane, 0.1 mol of 1,3-phenylenediboric acid, 0.3 mol of 1,4-phenylenediboric acid, 2 mol of ethanol, and 3 mol of isopropanol, add them to a reaction container and heat at 70°C, then slowly drop 4 mol of deionized water into the reaction container, continue to heat at 70°C for 12 hours after the dropwise addition is completed, and after the reaction is completed, distill under reduced pressure at 90°C for 2 hours to remove the organic solvent and deionized water, and obtain a phenylene boron hybrid silicone resin prepolymer. The NMR spectrum of the prepolymer is shown in the attached figure. Figure 2 As shown, the proton peak on the phenyl group of 1,4-phenyldiboronic acid and the proton absorption peak of the boron hydroxyl group appeared at 7.76 ppm and 8.05 ppm, respectively, which indicates that the hybrid silicone resin contains phenylboronic acid structure.

[0035] Dissolve 40g of the above-obtained phenylene boron hybrid silicone resin prepolymer in 30g of ethanol and 30g of isopropanol, and then add 0.1g of tetrapropyl titanate and 0.15g of tetra(2-ethylhexyl) titanate. Mix well, then pour into a mold and cross-link and cure at 80°C for 24h to obtain a phenylene boron hybrid silicone resin gel block. Place the gel block in a 60°C blast oven and dry for 24h, then post-cure at 150°C for 4h to obtain a phenylene boron hybrid silicone resin aerogel. The SEM image of the phenylene boron hybrid silicone resin aerogel material prepared in this embodiment is shown in the attached figure. Figure 3 As shown, the aerogel is composed of spherical particles of 20 to 50 nanometers, and the particle size distribution is uniform.

[0036] Example 2

[0037] A method for preparing a phenylene boron hybrid silicone resin aerogel comprises the following steps:

[0038] 15 mol of methyltrimethoxysilane, 3 mol of phenyltrimethoxysilane, 5 mol of methylphenyldiethoxysilane, 4 mol of 1,4-phenyldiboric acid and 15 mol of isopropanol were weighed and added into a reaction container and heated at 70°C. Then 20 mol of deionized water was slowly added dropwise into the reaction container. After the addition was completed, the reaction was continued by heating at 65°C for 8 hours. After the reaction was completed, the organic solvent and deionized water were removed by reduced pressure distillation at 120°C for 3 hours to obtain a phenylene boron hybrid silicone resin prepolymer.

[0039] 350g of the above-obtained phenylene boron hybrid silicone resin prepolymer was dissolved in 650g of n-butanol, and then 5g of (triethanolamine) isopropanol titanium complex was added and mixed evenly, and then poured into a mold and cross-linked and cured at 90°C for 48h to obtain a phenylene boron hybrid silicone resin gel block, which was placed in an 80°C blast oven for drying for 36h, and then post-cured at 200°C for 4h to obtain a phenylene boron hybrid silicone resin aerogel. The BET surface area test diagram of the phenylene boron hybrid silicone resin aerogel material prepared in this embodiment is shown in the attached figure. Figure 4 As shown, the prepared phenylene boron hybrid silicone resin aerogel material has a specific surface area of ​​300m 2 / g, the BET test results show that the hysteresis loop isotherm of the adsorption curve has no obvious saturated adsorption platform, which indicates that there is a porous structure with uneven size distribution inside the prepared lightweight porous silicone resin material.

[0040] Example 3

[0041] A method for preparing a phenylene boron hybrid silicone resin aerogel comprises the following steps:

[0042] Weigh 2.5 mol of methyltriethoxysilane, 0.6 mol of phenyltrimethoxysilane, 0.5 mol of phenyltriethoxysilane, 1.5 mol of diphenyldimethoxysilane, 2 mol of 1,4-phenyldiboric acid, and 8 mol of isopropanol, add them into a reaction container and heat at 70°C, then slowly drop 5 mol of deionized water into the reaction container, continue to heat at 60°C for 6 hours after the dropwise addition is completed, and after the reaction is completed, perform reduced pressure distillation at 100°C for 2 hours to remove the organic solvent and deionized water to obtain a phenylene boron hybrid silicone resin prepolymer.

[0043] Dissolve 200g of the above-obtained phenylene boron hybrid silicone resin prepolymer in 200g of isopropanol, 300g of tert-butanol and 200g of sec-butanol, then add 0.4g of tetrabutyl titanate, 0.5g of tetrapropyl titanate, 0.2g of (triethanolamine) titanium isopropoxide complex and 0.5g of tetra(2-ethylhexyl) titanate. Mix well, then pour into a mold and cross-link and cure at 85°C for 36h to obtain a phenylene boron hybrid silicone resin gel block. Place the gel block in a 60°C blast oven and dry for 30h, then post-cure at 250°C for 2h to obtain a phenylene boron hybrid silicone resin aerogel. Thermogravimetric analysis of the phenylene boron hybrid silicone resin aerogel material prepared in this embodiment in air and argon is shown in the attached figure. Figure 5 As shown, the mass retention rate of phenylene boron hybrid silicone resin aerogel at 1000°C is 69.4% in air atmosphere and 85.2% in argon atmosphere. The temperatures of 5% mass loss in air and argon atmospheres are 582.7°C and 619.9°C, respectively.

[0044] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A phenylene boron hybrid silicone resin aerogel, characterized in that: The structural formula of the phenylene boron hybrid silicone resin aerogel is shown in Formula I: Where R0 is One or more combinations of R1-R 14 Each independently selects one of phenyl and methyl.

2. A method for preparing the phenylene boron hybrid silicone resin aerogel according to claim 1, characterized in that: The following steps are involved: Step 1, adding alkoxysilane, organic phenylboric acid, organic solvent and deionized water in a molar ratio of 3-10:0.1-6:2-10:3.6-12 into a reaction vessel, heating for hydrolysis-condensation, separating oil and water after the reaction, taking the oil and distilling it under reduced pressure to remove small molecular organic matter and deionized water to obtain a phenylene borosilicate resin prepolymer; Step 2, dissolving a phenylene borosilicate resin prepolymer in an organic solvent, adding a catalyst, pouring the mixture into a mold, cross-linking and curing the mixture to obtain a phenylene borosilicate resin gel; Step 3: heating and drying the phenylene borosilicate resin gel at normal pressure, and after drying, post-curing to obtain the phenylene borosilicate resin aerogel.

3. The preparation method according to claim 2, characterized in that: In the step 1, the alkoxysilane is a combination of at least two of methyltriethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane and phenyltriethoxysilane.

4. The preparation method according to claim 2, characterized in that: In the step 1, the organic phenylboric acid is a combination of one or more of 1,4-phenyldiboric acid, 1,3-phenyldiboric acid, and 1,2-phenyldiboric acid.

5. The preparation method according to claim 2, characterized in that: In the step 1, the heating temperature of the hydrolysis-condensation is 60-70° C., and the heating time is 4-12 hours; the reduced pressure distillation temperature is 90-120° C., and the time is 2-4 hours.

6. The preparation method according to claim 2, characterized in that: The organic solvent in step 1 and step 2 includes one or more combinations of ethanol, propanol, isopropanol, n-butanol, isobutanol, tert-butanol and sec-butanol.

7. The preparation method according to claim 2, characterized in that: In the step 2, the mass ratio of the phenylene boron hybrid silicone resin prepolymer to the organic solvent is 15-40:60-85; the mass ratio of the catalyst to the phenylene boron hybrid silicone resin prepolymer is 0.1-2:

100.

8. The preparation method according to claim 2 or 7, characterized in that: The catalyst includes one or more of tetrabutyl titanate, tetrapropyl titanate, (triethanolamine) titanium isopropoxide complex, tetra(2-ethylhexyl) titanate, and di(acetylacetonato) diisopropyl titanate.

9. The preparation method according to claim 2, characterized in that: The temperature of crosslinking and curing in step 2 is 80~120℃, curing time is 12~48 hours.

10. The preparation method according to claim 2, characterized in that: In the step 3, the temperature of the normal pressure heating drying is 40-80° C., and the drying time is 12-72 hours; the post-curing temperature is 150-250° C., and the drying time is 2-12 hours.

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