A phenylene-boron hybrid silicone resin aerogel and a method of making the same

Abstract

The application relates to a phenylene-boron hybrid silicon resin aerogel and a preparation method thereof, and belongs to the technical field of aerogel preparation. The specific scheme comprises the following steps: step 1, alkoxysilane, organic phenylboronic acid, an organic solvent and deionized water are added into a reaction container for hydrolysis-condensation under heating, oil-water separation is carried out after the reaction is completed, the oil is taken out, small-molecule organic matters and deionized water are removed through vacuum distillation, and a phenylene-boron silicon resin prepolymer is obtained; step 2, the phenylene-boron silicon resin prepolymer is dissolved in an organic solvent, a catalyst is added, and the phenylene-boron silicon resin prepolymer is poured into a mold for cross-linking and solidification to obtain a phenylene-boron silicon resin gel; and step 3, the phenylene-boron silicon resin gel is dried through normal-pressure heating, and the phenylene-boron silicon resin aerogel is obtained after heating and aging. The phenylene-boron hybrid silicon resin aerogel can be used as a novel light-weight, ablation-resistant, oxidation-resistant and high-performance ablation-resistant and heat-insulating composite material, and can expand the new use of the hybrid silicon resin in the fields of aerospace and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aerogel preparation, and particularly relates to a benzene-boron hybrid silicon resin aerogel and a preparation method thereof. BACKGROUND

[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 DEG C. When the temperature is higher, the silicon dioxide will shrink and crack, thus destroying the structure of the aerogel and reducing the heat insulation performance. Compared with inorganic aerogel, organic aerogel, especially phenolic aerogel, contains carbon elements, which has good ability to absorb thermal radiation. Phenolic aerogel will not sinter and shrink under high temperature, but will undergo carbonization reaction to generate carbon aerogel. The carbon aerogel can meet higher temperature use in an oxygen-free environment. Therefore, the high-temperature heat insulation performance of phenolic aerogel material is obviously better than that of inorganic aerogel material. However, the phenolic aerogel composite material will oxidize under high temperature in an oxygen-containing environment. After a long time of work, the oxidation causes the phenolic aerogel to fail and lose the heat insulation performance. Although the introduction of antioxidant inorganic nanoparticles into the phenolic resin improves the antioxidant performance of the phenolic resin to some extent, it still cannot meet the long-time use in an oxygen-containing environment. Therefore, how to improve the antioxidant performance of the organic resin aerogel is a key technical problem to be solved in the field.

[0003] Silicon resin is a product of organic-inorganic hybrid polymerization, which is 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 silicon resin is as high as 450 KJ / mol, which is higher than the bond energy of carbon-carbon bond (345.6 KJ / mol). The silicon resin is not easy to break and decompose in a high-temperature radiation environment. This special structure makes the silicon resin have excellent thermal oxidation performance. The introduction of the ablation-resistant benzene structure and the antioxidant boron atom into the silicon resin can generate borosilicate glass on the surface of the silicon resin under high temperature, which has a good oxygen barrier effect, and can further improve the ablation resistance and antioxidant performance of the silicon resin. As a new type of light-weight high-performance ablation-resistant heat insulation composite material resin matrix, the benzene-boron hybrid silicon resin is expected to improve the flight speed of high-speed aircraft in the atmosphere and prolong the flight time. SUMMARY

[0004] In order to solve the problems in the background art, the application provides a benzene-boron hybrid silicon resin aerogel and a preparation method thereof.

[0005] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0006] A benzene-boron hybrid silicon resin aerogel, the structural formula of the benzene-boron hybrid silicon resin aerogel is shown as formula I:

[0007]

[0008] wherein R0 is a combination of one or more of R1-R 14 each independently selected from one of phenyl or methyl.

[0009] A method of preparing the phenylene boron hybrid silicone resin aerogel, comprising the following steps:

[0010] Step 1, alkoxysilane, organic phenylboronic acid, organic solvent, deionized water are added into the reaction container in the proportion of 3-10:0.1-6:2-10:3.6-12 by mole ratio, heated hydrolysis-condensation, after the reaction, oil and water separation, take the oil distillation under reduced pressure to remove small molecule organic matter and deionized water to obtain a phenylene boron silicon resin prepolymer;

[0011] Step 2, the phenylene boron silicon resin prepolymer is dissolved in an organic solvent, a catalyst is added, and the mixture is poured into a mold to crosslink and cure to obtain a phenylene boron silicon resin gel;

[0012] Step 3, the phenylene boron silicon resin gel is dried by heating at normal pressure, and after drying, post-curing is performed to obtain a phenylene boron silicon resin aerogel.

[0013] Further, in the step 1, the alkoxysilane is a combination of at least two of methyl triethoxysilane, methyl trimethoxysilane, phenyl trimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane and phenyl triethoxysilane.

[0014] Further, in the step 1, the organic phenylboronic acid is a combination of one or more of 1,4-benzenediboronic acid, 1,3-benzenediboronic acid and 1,2-benzenediboronic acid.

[0015] Further, in the step 1, the heating temperature for hydrolysis-condensation is 60-70℃, and the heating time is 4-12h; the distillation temperature under reduced pressure is 90-120℃, and the time is 2-4h.

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

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

[0018] Further, the catalyst comprises one or more of tetrabutyl titanate, tetrapropyl titanate, (triethanolamine) titanium isopropyl alcohol complex, tetra(2-ethylhexyl) titanate, diisopropyl titanate di(acetylacetonyl).

[0019] Further, the temperature for cross-linking and curing in step 2 is 80-120 DEG C, and the curing time is 12-48 hours.

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

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

[0022] (1) The present application introduces the phenylene structure and the antioxidant boron atom into the silicon resin to improve the ablation resistance of the silicon resin, and the boron atom is oxidized to form borosilicate glass on the surface of the silicon resin at high temperature, which has good oxygen barrier effect and improves the oxidation resistance of the silicon resin.

[0023] (2) The present application uses the phenylene boron hybrid silicon resin prepolymer to prepare the aerogel material, which has high structural strength, and the aerogel material is obtained by normal pressure heating and drying, which realizes the normal pressure drying of the silicon resin aerogel and reduces the preparation cost of the silicon resin aerogel.

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

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

[0026] Figure 1 The flow chart of the preparation of the phenylene boron hybrid silicon resin aerogel according to the present application;

[0027] Figure 2 The nuclear magnetic resonance spectrum of the phenylene boron hybrid silicon resin prepolymer prepared in Example 1;

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

[0029] Figure 4 The specific surface area test result graph of the phenylene boron hybrid silicon resin aerogel prepared in Example 2;

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

[0031] The technical solutions in the present application will be described clearly and completely below in combination with the drawings and examples. Obviously, the described examples are only a part of the examples of the present application, rather than all the examples. Based on the examples in the present application, all the other examples obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0032] Example 1

[0033] A preparation method of a phenylene boron hybrid silicone resin aerogel, comprising the following steps:

[0034] 2 mol of methyltrimethoxysilane, 1 mol of phenyltrimethoxysilane, 1 mol of dimethyldiethoxysilane, 0.1 mol of 1,3-phenyldiboronic acid, 0.3 mol of 1,4-phenyldiboronic acid, 2 mol of ethanol, and 3 mol of isopropyl alcohol were weighed into a reaction container and heated at 70°C. Then, 4 mol of deionized water was slowly added dropwise into the reaction container. After the dropwise addition was completed, the reaction was continued at 70°C for 12 h. After the reaction was completed, the organic solvent and the deionized water were removed by distillation at 90°C under reduced pressure for 2 h to obtain a phenylene boron hybrid silicone resin prepolymer. The nuclear magnetic resonance spectrum of the prepolymer is shown in FIG. 1. As shown in FIG. 1, the proton peaks on the phenyl groups of 1,4-phenyldiboronic acid and the boron-hydroxyl proton absorption peaks appeared at 7.76 ppm and 8.05 ppm, respectively, which indicated that the hybrid silicone resin contained phenylboronic acid structures. Figure 2

[0035] The phenylene boron hybrid silicone resin prepolymer obtained above was dissolved in 30 g of ethanol and 30 g of isopropyl alcohol, and then 0.1 g of tetrapropyl titanate and 0.15 g of tetrakis(2-ethylhexyl) titanate were added. After being mixed uniformly, the mixture was poured into a mold and crosslinked and cured at 80°C for 24 h to obtain a phenylene boron hybrid silicone resin gel block. The gel block was dried in a blast oven at 60°C for 24 h, and then post-cured at 150°C for 4 h to obtain a phenylene boron hybrid silicone resin aerogel. The SEM image of the phenylene boron hybrid silicone resin aerogel material prepared in this example is shown in FIG. 2. As shown in FIG. 2, the aerogel was formed by the accumulation of 20-50 nm spherical particles, and the particle size distribution was uniform. Figure 3

[0036] Example 2

[0037] A preparation method of a phenylene boron hybrid silicone resin aerogel, comprising the following steps:

[0038] ​​Take 15 mol methyl trimethoxysilane, 3 mol phenyl trimethoxysilane, 5 mol methyl phenyl diethyl methoxysilane, 4 mol 1,4-benzene diboronic acid, 15 mol isopropyl alcohol into the reaction container, heat at 70℃, then slowly add 20 mol deionized water to the reaction container, continue to heat at 65℃ for 8h after the addition is completed, remove the organic solvent and deionized water by distillation at 120℃ under reduced pressure for 3h, and obtain the benzene boron hybrid silica resin prepolymer.

[0039] The benzene boron hybrid silica resin prepolymer obtained above 350g is dissolved in 650g n-butanol, then 5g of (triethanolamine) titanium isopropyl alcohol complex is added and mixed uniformly, then poured into a mold and crosslinked and cured at 90℃ for 48h to obtain a benzene boron hybrid silica resin gel block. The gel block is placed in a 80℃ air oven and dried for 36h, then post-cured at 200℃ for 4h to obtain a benzene boron hybrid silica resin aerogel. The BET surface area test chart of the benzene boron hybrid silica resin aerogel material prepared in this embodiment is shown in Figure 1, and the specific surface area of the prepared benzene boron hybrid silica resin aerogel material is >300m Figure 4 / g. The BET test results show that the adsorption curve hysteresis loop isotherm has no obvious saturation adsorption platform, which indicates that the prepared lightweight porous silica resin material has a non-uniformly distributed porous structure inside. 2 / g. The BET test results show that the adsorption curve hysteresis loop isotherm has no obvious saturation adsorption platform, which indicates that the prepared lightweight porous silica resin material has a non-uniformly distributed porous structure inside.

[0040] Example 3

[0041] A method for preparing a benzene boron hybrid silica resin aerogel, comprising the following steps:

[0042] Take 2.5 mol methyl triethoxysilane, 0.6 mol phenyl trimethoxysilane, 0.5 mol phenyl triethoxysilane, 1.5 mol diphenyl dimethoxysilane, 2 mol 1,4-benzene diboronic acid, 8 mol isopropyl alcohol into the reaction container, heat at 70℃, then slowly add 5 mol deionized water to the reaction container, continue to heat at 60℃ for 6h after the addition is completed, remove the organic solvent and deionized water by distillation at 100℃ under reduced pressure for 2h, and obtain the benzene boron hybrid silica resin prepolymer.

[0043] The above obtained phenylene boron hybrid silicone prepolymer 200 g was dissolved in 200 g of isopropyl alcohol, 300 g of t-butyl alcohol and 200 g of sec-butyl alcohol, and then 0.4 g of tetrabutyl titanate, 0.5 g of tetrapropyl titanate, 0.2 g of titanium isopropoxide (triethanolamine) complex, and 0.5 g of tetra(2-ethylhexyl) titanate were added. After mixing uniformly, it was poured into a mold and crosslinked and cured at 85°C for 36 h to obtain a phenylene boron hybrid silicone gel block. The gel block was placed in a 60°C air oven and dried for 30 h, and then post-cured at 250°C for 2 h to obtain a phenylene boron hybrid silicone aerogel. The thermogravimetric analysis of the phenylene boron hybrid silicone aerogel material prepared in this example in air and argon is shown in FIG. 10. The mass retention rate of the phenylene boron hybrid silicone aerogel in air at 1000°C was 69.4%, the mass retention rate in argon at 1000°C was 85.2%, and the temperatures at which 5% mass loss occurred in air and argon were 582.7°C and 619.9°C, respectively. Figure 5

[0044] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that those skilled in the art can understand.​

Claims

1. A method of preparing a phenylene-boron hybrid silica aerogel, characterized by, The method comprises the following steps: Step 1, adding alkoxysilane, organic phenylboronic acid, organic solvent and deionized water into a reaction container in a molar ratio of 3-10:0.1-6:2-10:3.6-12, and heating for hydrolysis-condensation; after the reaction is completed, oil and water are separated, and the oil is distilled under reduced pressure to remove small molecular organic substances and deionized water to obtain a benzene-boron-silicon resin prepolymer; the organic phenylboronic acid is one or a combination of 1,4-benzenediol, 1,3-benzenediol and 1,2-benzenediol; Step 2, dissolving the benzene-boron-silicon resin prepolymer in an organic solvent, adding a catalyst, pouring into a mold, and cross-linking and curing to obtain a benzene-boron-silicon resin gel; Step 3, drying the benzene-boron-silicon resin gel at normal pressure, and after drying, post-curing to obtain a benzene-boron-silicon resin aerogel.

2. The method of claim 1, wherein: In step 1, the alkoxysilane is a combination of at least two of methyltriethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane and phenyltriethoxysilane.

3. The method of claim 1, wherein: In step 1, the heating temperature for hydrolysis-condensation is 60-70°C, and the heating time is 4-12h; the reduced pressure distillation temperature is 90-120°C, and the time is 2-4h.

4. The method of claim 1, wherein: The organic solvent in steps 1 and 2 includes one or a combination of ethanol, propanol, isopropanol, n-butanol, isobutanol, tert-butanol and sec-butanol.

5. The method of claim 1, wherein: In step 2, the mass ratio of the benzene-boron-hybridized silicon resin prepolymer to the organic solvent is 15-40:60-85; and the mass ratio of the catalyst to the benzene-boron-hybridized silicon resin prepolymer is 0.1-2:

100.

6. The production method according to claim 1 or 5, characterized by: The catalyst includes one or more of tetrabutyl titanate, tetrapropyl titanate, (triethanolamine) titanium isopropoxide complex, tetra(2-ethylhexyl) titanate, and di(acetylacetonato) titanium diisopropyl titanate.

7. The method of claim 1, wherein: In step 2, the cross-linking and curing temperature is 80-120°C, and the curing time is 12-48h.

8. The method of claim 1, wherein: In step 3, the normal pressure heating drying temperature is 40-80°C, and the drying time is 12-72h; the post-curing temperature is 150-250°C, and the time is 2-12h.

9. A benzene-boron-hybridized silicon resin aerogel prepared by the preparation method of any one of claims 1-8.

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