Silica airgel fiber with adjustable transparency and hydrophobicity, preparation method and application

Abstract

The invention discloses a silica airgel fiber with adjustable transparency and hydrophobicity, a preparation method and an application. The silica airgel fiber has a connected three-dimensional porous network structure, its transparency is 20-95%, the contact angle with water is 0-158°, the porosity is 80-99.9%, and the specific surface area is 100-2000m 2 / g, the thermal conductivity is 0.010~0.030W / (m*K), the diameter is 10μm~3mm, and the aspect ratio is greater than 10. The preparation method includes: providing a spinning solution containing a linear organosiloxane polymer with a multifunctional group; using a wet spinning method, injecting the spinning solution into an alkaline coagulation bath to obtain a coagulated silica The rubber fiber is then dried to obtain the silica airgel fiber. The silica airgel fiber of the invention has low thermal conductivity, spinnability, adjustable transparency and controllable hydrophobicity, and has great application prospects.

Description

technical field [0001] The invention relates to a novel functional fiber, in particular to a silica aerogel fiber with adjustable transparency and hydrophobicity, a preparation method and application thereof, and belongs to the technical field of nanoporous materials and functional fibers. Background technique [0002] Aerogel material is a material obtained by replacing the liquid component in the gel with gas while keeping the gel network from collapsing. Aerogel was originally born in the 1830s and was invented by chemist Sterven.S.Kistler of California Pacific University. It is the first time to use supercritical drying technology to replace the liquid components in the wet gel with gas and keep the gel skeleton structure intact, thereby obtaining aerogels. Aerogels have a very low apparent density (0.003 to 0.3 g / cm 3 ), large specific surface area (100~2400m 2 / g), high porosity (80-99.8%) and low thermal conductivity [10-40mW / (m·K)]. There are three main reasons f...

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Problems solved by technology

2. The pore size of airgel is generally below 40nm, which is smaller than the molecular free path of air, so it will prevent the heat conduction of gas molecules inside the aerogel

3. The air inside the airgel is still, and the existence of still air will prevent the heat convection of the air inside the airgel

However, since the sol-gel process of airgel is a dynamic and slow process, and is also affected by weak mechanical properties during the drying process, the preparation of airgel fibers of various components, especially silica airgel fibers has been a huge challenge

Due to its combination of visible transparency and low thermal conductivity, silica airgel fibers are suitable for transparent thermal insulation buildings and other fields, however, the brittleness of silica is still inevitable for the continuous spinning of airgel fibers. obstacles

The most promising method to overcome this shortcoming is to form organic-inorganic hybrid aerogels, or to coat the surface with other materials to strengthen the gel network, but increasing the organic content will lead to the inhomogeneity of the nanostructure and reduce the Slow gel speed, these solutions will have a great impact on the transparency and thermal insulation performance of airgel, and cannot meet the requirements of fiber preparation

[0005] Furthermore, the existing aerogels are mainly three-dimensional blocks and powders. Due to the slow gelation process of airgel, an external container must be used as a shape support, and its three-dimensional shape is limited by the shape of the container.

Moreover, due to the brittleness of aerogels, especially silica aerogels, the processability and cuttability of three-dimensional blocks are limited.

Powder aerogels can only be used as coatings or fillers, and the scope of use is very limited

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