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Hydrophobic silicon dioxide/polyimide aerogel composite material and preparation method

A polyimide wet gel and silica technology, applied in the field of high-performance porous materials, can solve the problems of molecular weight reduction, flammability, difficulty in realizing airgel scale, rapid and efficient preparation, etc., and achieve improved hydrophobicity sexual effect

Active Publication Date: 2018-11-02
UNIV OF SCI & TECH OF CHINA
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AI Technical Summary

Problems solved by technology

[0005] In 2006, Rhine et al. used rigid dianhydride monomers and diamine monomers as raw materials to form polyamic acid in the solvent NMP, and then added chemical imidization reagents. With the increase of the degree of dehydration and cyclization of polyamic acid , the rigidity of the molecular chain gradually increases, so that its solubility in the solvent gradually decreases and gels (forming a polyimide wet gel), and then the CO 2 Polyimide airgel was obtained by supercritical drying, but the shrinkage rate of the prepared polyimide airgel was high
[0007] However, the existing method for preparing PI airgel still has the following defects. The process of supercritical drying is complex and cumbersome, the production efficiency is low, and the product cost is high, so it is difficult to realize the large-scale, fast and efficient preparation of airgel; and The polyamic acid, the product of the process, will degrade rapidly during storage, resulting in a decrease in its molecular weight, which ultimately affects the performance of polyimide aerogels; in addition, the density of cross-linked PI aerogels prepared by prior art is generally higher , which undoubtedly increases the cost of airgel as a thermal insulation material, and at the same time causes the defect of insufficient thermal insulation performance, making it difficult to meet the requirements of airgel thermal insulation basic materials
[0008] Not only that, with the vigorous development of urbanization in the past ten years, the construction industry has flourished. However, although the insulation materials in the building insulation market have good insulation, they are easy to burn and produce a lot of smoke and poisonous gas, while concrete, foam glass, Inorganic thermal insulation materials such as rock wool board consume a lot of resources; although polyimide airgel has excellent characteristics such as high strength, high temperature resistance, fire resistance, and corrosion resistance, which further expands the selection of thermal insulation materials in the construction field, its relative thermal conductivity Relatively high, mostly above 0.1, and not water resistant
Therefore, the requirements for thermal insulation materials in the construction field cannot be met.

Method used

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  • Hydrophobic silicon dioxide/polyimide aerogel composite material and preparation method
  • Hydrophobic silicon dioxide/polyimide aerogel composite material and preparation method
  • Hydrophobic silicon dioxide/polyimide aerogel composite material and preparation method

Examples

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preparation example Construction

[0082] The present invention also provides a preparation method of silica / polyimide airgel composite material, comprising the following steps:

[0083] 1) After the polyimide wet gel mixture mixed with silica airgel powder is left to stand, it is then placed in an organic solvent for replacement to obtain a substituted polyimide composite wet gel;

[0084] 2) Submerging the substituted polyimide composite wet gel obtained in the above steps in tert-butanol and / or cyclohexane for further replacement to obtain a semi-finished product;

[0085] 3) After the semi-finished product obtained in the above steps is freeze-dried, a silica / polyimide airgel composite material is obtained.

[0086] The selection, ratio and parameters of raw materials or products in the above-mentioned preparation method of the present invention, and corresponding optimization principles etc., if not specified, are similar to the selection of raw materials in the aforementioned silica / polyimide airgel compo...

Embodiment 1

[0184] Silica airgel

[0185] Take water=30ml and water glass=10ml and mix and stir in a beaker to obtain solution A. Take concentrated HCl=5ml, add solution A into the HCl solution for hydrolysis reaction, slow down the speed and test the pH when adding half of it, add a pH regulator, continue to add solution A (color from yellow to transparent, pH 1~2→5~6 ),gel.

[0186] Grind the wet gel, add HMDSO = 80Ml, n-hexane = 20ml, then add 5ml of concentrated hydrochloric acid, stir and separate layers to indicate that the modification is complete.

[0187] see figure 2 , figure 2 Appearance diagram of the layered hydrophobically modified silica airgel prepared for the present invention.

[0188] The airgel powder is obtained after the upper layer is taken and dried.

[0189] composite airgel

[0190] First, dissolve 4,4'-aminodiphenyl ether (ODA, 8mmol) in the solvent 1-methyl-2-pyrrolidone (NMP, 33ml) and stir until it is completely dissolved, then add 3,3',4,4'-biphenyl ...

Embodiment 2 and 3

[0201] Referring to the above method, composite materials with silica airgel powder addition ratios of 10% and 20% were prepared respectively.

[0202] see Figure 4 , Figure 4 Scanning electron micrographs of hydrophobic silica / polyimide airgel composites with different ratios prepared for the examples of the present invention.

[0203] Performance tests were performed on the hydrophobic silica / polyimide airgel composite materials prepared in Examples 1-3 of the present invention.

[0204] see Figure 5 , Figure 5 The mechanical property curves of the hydrophobic silica / polyimide airgel composite material with different silica airgel doping amounts prepared in Example 1 of the present invention.

[0205] Depend on Figure 5 It can be seen that, according to the compressive stress-strain curve, as the compressive strain increases, the compressive stress continues to increase. The whole process is divided into three stages, the first stage is the contact stage, the stre...

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Abstract

The invention provides a hydrophobic silicon dioxide / polyimide aerogel composite material. The hydrophobic silicon dioxide / polyimide aerogel composite material comprises hydrophobic modified silicon dioxide aerogel and polyimide aerogel, wherein the polyimide aerogel is used as a substrate of the composite material, and hydrophobic modified silicon dioxide aerogel fillers are embedded into pores of the polyimide aerogel. According to the hydrophobic silicon dioxide / polyimide aerogel composite material, the silicon dioxide aerogel is added to the polyimide aerogel; the polyimide aerogel is usedas the substrate and a framework of a composite heat insulation material to realize the supporting reinforcing effect, so that the mechanical strength of the composite heat insulation material is improved; and the silicon dioxide aerogel is used as the filler and has the hydrophobic function and outstanding heat insulation performance, so that the heat insulation effect is realized in the composite material. The hydrophobic silicon dioxide / polyimide aerogel composite material comprehensively considers the physical performance and the mechanical performance of the composite heat insulation material and has the advantages of being high in strength, high in high temperature resistance, low in volume weight, low in heat conductivity, and high in waterproofing performance, and meets the requirements on performances of the heat insulation material in actual application.

Description

technical field [0001] The invention relates to the technical field of high-performance porous materials, and relates to a silica / polyimide airgel composite material and a preparation method thereof. In particular, it relates to a hydrophobic silicon dioxide / polyimide airgel composite material and a preparation method thereof. Background technique [0002] Airgel, also known as xerogel, is a solid material form, a highly dispersed solid material that is composed of colloidal particles or polymer molecules aggregated into a nanoporous network structure, and filled with a gaseous dispersion medium in the pores , is also one of the solids with very low density in existing materials, which has properties such as ultra-low density, high specific surface area, high porosity and excellent heat insulation, and is used in super heat insulation materials, sound insulation materials, particle detectors, low dielectric The electrical constant airgel film, inertial targeting material an...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08L79/08C08K9/06C08K7/26C08G73/10
CPCC08G73/1071C08K7/26C08K9/06C08K2201/003C08K2201/011C08L79/08
Inventor 程旭东李聪聪龚伦伦
Owner UNIV OF SCI & TECH OF CHINA
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