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Normal-pressure drying preparation method and application of polyimide aerogel product

A polyimide, atmospheric drying technology, used in textiles and papermaking, one-component synthetic polymer rayon, chemical post-processing of synthetic polymer rayon, etc. The problem of high cost, to achieve the effect of low cost, simple preparation process and reduced volume shrinkage

Active Publication Date: 2021-12-21
DONGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In order to solve the problems of complex process, high cost, low efficiency and incapable of large-scale production in the preparation of polyimide airgel products by existing freeze-drying and supercritical drying methods, the present invention provides a polyimide airgel The preparation method of gel products is dry under normal pressure, by grafting fluorine-containing polyimide with photosensitive groups as a precursor solution, by casting, scraping, 3D printing, spinning and other molding methods, ultraviolet light irradiation, solvent replacement , drying at normal pressure to obtain a polyimide airgel product with different macrostructures

Method used

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  • Normal-pressure drying preparation method and application of polyimide aerogel product
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  • Normal-pressure drying preparation method and application of polyimide aerogel product

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] (1) Preparation of copolymerized polyimide:

[0043] Under nitrogen protection, in a three-neck round bottom flask, add 3,5-diaminobenzoic acid (DABA, 0.7608g), 4,4-diaminodiphenyl ether (ODA, 1.001g) and N-methylpyrrolidone in sequence (NMP, 25 ml), mechanically stirred until DABA and ODA were completely dissolved, then added 4,4'-(hexafluoroisopropene) diphthalic anhydride (6FDA, 4.4423 g), reacted at 25 °C for 24 h, and raised the temperature to 120 °C Heat preservation reaction for 1 hour, continue to heat up to 160°C for heat preservation reaction for 1 hour, continue to heat up to 190°C for heat preservation reaction for 12 hours, and obtain a soluble polyimide solution.

[0044] (2) Preparation of polyimide grafted with hydroxyethyl methacrylate:

[0045] Hydroxyethyl methacrylate (HEMA, 5 mmol, 0.65 g), N , N '-dicyclohexylcarboimide (5 mmol, 1.03 g) and 4-dimethylaminopyridine (0.50 mmol, 0.0608 g) and stirred until the solid disappeared, added to the above-m...

Embodiment 2

[0051] The difference from Example 1 is that the amount of grafted hydroxyethyl methacrylate is 50%, that is, hydroxyethyl methacrylate (HEMA, 2.5 mmol, 0.325 g), N , N '-bicyclic Hexylcarbimide (2.5 mmol, 0.515 g) and 4-dimethylaminopyridine (0.25 mmol, 0.0304 g), and the obtained polyimide airgel fiber was designated as HFPI-50.

Embodiment 3

[0053] The difference from Example 1 is that the amount of grafted hydroxyethyl methacrylate is 25%, that is, hydroxyethyl methacrylate (HEMA, 1.25 mmol, 0.1625 g), N, N '-bicyclic Hexylcarbimide (1.25 mmol, 0.2575 g) and 4-dimethylaminopyridine (0.125 mmol, 0.0152 g), and the obtained polyimide airgel fiber was designated as HFPI-25.

[0054] figure 1 It is a scanning electron microscope image of the polyimide airgel fiber of Example 1. It can be seen that the cross section of the fiber presents a regular circle, and it can be seen from the enlarged scanning electron microscope that the interior presents a three-dimensional porous structure.

[0055] figure 2 It is the scanning electron micrograph of the polyimide airgel fiber of embodiment 2, and fiber presents pea shape, and internal hole skeleton is bonded together, and this is because only 50% of the hydroxyethyl methacrylate of grafting, wet gel The low cross-linking density leads to the collapse and shrinkage of the sk...

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Abstract

The invention discloses a normal-pressure drying preparation method and application of a polyimide aerogel product. The method comprises the following steps of copolymerizing diamine containing carboxyl or hydroxyl and other diamines with dicarboxylic anhydride, grafting a photosensitive group to obtain photosensitive fluorine-containing polyimide, and taking the photosensitive fluorine-containing polyimide as a precursor solution; carrying out molding means such as casting, blade coating, 3D printing, spinning and the like; and performing ultraviolet irradiation, solvent replacement and normal-pressure drying to obtain the polyimide aerogel product with different macrostructures. According to the normal-pressure drying preparation method and the application of the polyimide aerogel product provided by the invention, the photosensitive group is introduced, and a cross-linked structure is initiated through light, so that the framework strength of wet gel can be effectively improved, and shrinkage caused by surface tension generated in the solvent evaporation process is reduced; and secondly, the fluorine-containing binary anhydride or diamine is selected, so that the surface tension can be effectively reduced, and the shrinkage rate of a product in the normal-pressure drying process is reduced. The method effectively solves the problems of complex process, high cost, low efficiency and incapability of large-scale production in the existing freeze drying and supercritical drying methods for preparing the polyimide aerogel product.

Description

technical field [0001] The invention relates to the technical field of airgel preparation, in particular to an atmospheric pressure drying preparation method of polyimide airgel products. Background technique [0002] Airgel is a new type of material with a micro-nano three-dimensional porous structure. It has the characteristics of high porosity, low density, and high specific surface area. Due to its low thermal conductivity, it can be as low as 0.025 W m -1 K -1 (air at similar ambient conditions, 0.026 Wm -1 K -1 ), it has broad application prospects in aerospace, energy-saving buildings, clothing and other thermal insulation fields. Among them, silica airgel has very excellent thermal insulation properties, so it has been comprehensively studied. However, silica aerogels suffer from poor mechanical properties, exhibit brittleness, and are hygroscopic, thus limiting their further applications. As a special engineering material with excellent comprehensive perfor...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): D01F6/78D01F11/08
CPCD01F6/78D01F11/08
Inventor 刘天西薛甜甜樊玮朱晨宇
Owner DONGHUA UNIV
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