Method for preparing electrospun nanofiber reinforced silica aerogel

Abstract

The invention relates to a method for rapidly preparing electrospun nanofiber reinforced silica aerogel blocks with excellent mechanical properties by atmospheric pressure drying. Used nanofibers areprepared by electrospinning; the prepared nanofiber reinforced silica aerogel not only maintains the advantages of low density and high porosity, but also overcomes the disadvantages of poor integrityand large brittleness. Silica sol formed by hydrolysis of alkoxysilane is used as a receiving body of electrospinning, and the nanofibers are evenly dispersed in the silica sol; the silica sol is allowed to form gel with ammonia water as a catalyst, then the gel is aged and modified, and the electrospun nanofiber reinforced silica aerogel is obtained. The method has the prominent characteristicsthat the method does not need dangerous or expensive supercritical drying, the operation is simple, the process is controllable, the cycle is short, the cost is low, and the product can be produced continuously; the obtained product has excellent physical properties and excellent mechanical properties.

Description

Technical field [0001] The invention relates to a reinforced composite silica aerogel block, especially designed to use electrospun nanofibers as reinforcements, and prepare electrospun nanofiber reinforced types through composite technology, solvent exchange, surface modification and atmospheric drying Silica aerogel method. Background technique [0002] Silica aerogel is a new type of porous functional material with nano-scale solid phase particles and pores, and its continuous three-dimensional network structure can also be controlled and tailored on the nanoscale. Silica aerogel has many unique properties, such as high porosity, high specific surface area, low density, ultra-low dielectric constant and thermal conductivity. The excellent properties of silica aerogel make it have broad application prospects in the fields of heat insulation, thermal insulation, aerospace, catalysts and their carriers, energy saving and environmental protection, petrochemicals, drug release and...

AI Technical Summary

Problems solved by technology

[0004] 1. There is no mature and simple preparation process. At present, silica airgel is mainly obtained by supercritical drying method, but this drying method is dangerous, harsh conditions and high cost

In recent years, a large number of mild atmospheric drying processes have been studied and applied to the preparation of silica aerogels. Although the physical properties of silica aerogels prepared by these methods are close to those obtained by supercritical drying, these The method has complex preparation process, long preparation cycle, large solvent consumption, large amount of waste liquid and polluted modified by-products, so it is difficult to be mass-produced;

[0005] 2. The mechanical properties of silica airgel are poor, and there are defects of high brittleness and low strength, especially the products prepared by drying under normal pressure are severely brittle and cracked during the drying process, making it difficult to be used as a single type of material in practical engineering;

For example, glass fibers are dispersed in silica sol, and after aging, solvent exchange and hydrophobic modification of trimethylchlorosilane, fiber-reinforced silica airgel blocks are prepared under normal pressure drying conditions (publication number: CN101973752A), the composite airgel prepared by this method has a certain integrity, and the porous property of the airgel is excellent, but the composite airgel still has relatively large brittleness, easy fracture, and poor mechanical properties, and the preparation process involves complicated The normal pressure drying process is difficult to produce on a large scale

In addition, the silica sol is infiltrated into the three-dimensional skeleton of the fiber mat by impregnation, and the airgel is combined with the fiber mat or the three-dimensional porous skeleton structure to prepare silica composite airgel (such as the publication number: CN102701700A), but this The physical properties of the product prepared by the method are poor. Although the mechanical strength has been improved, the flexibility of the composite airgel cannot be improved, and it is easy to cause the airgel substrate and the reinforcing material to separate and fall off under the action of bending.

The patent with the publication number CN1592651A mentions that a continuous fiber matrix made of low-denier fibers is used as a reinforcing material to prepare a composite airgel. The composite airgel has high flexibility, but this method requires complicated weaving to form fluffy fibers tire, and the filling combination of airgel and fiber tire makes the bonding strength of the composite material limited

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