Siloxane toughened and modified SiO2 aerogel and preparation method thereof

Abstract

The invention relates to a siloxane toughened and modified SiO2 aerogel and a preparation method thereof. The siloxane toughened and modified SiO2 aerogel is obtained in the way that ethyl orthosilicate and ethyl alcohol are mixed, then hydroxy-terminated polydimethylsiloxane and methyl triethoxysilane are added, after that, a catalyst is added, a sol-gel method is adopted to prepare a SiO2 aerogel, and solvent exchange and hydrophobic modification are performed on the SiO2 to obtain the siloxane toughened and modified SiO2 aerogel. The siloxane toughened and modified SiO2 aerogel is low in density, big in specific surface area and excellent in hydrophobicity and toughness, and has the maximum compressive strength of 38.99-68.48 Kg / m<2>, the lowest density of 0.087-0.35 g / cm<3> and the hydrophobic angle of 108-145.1 degrees.

Description

technical field [0001] The invention relates to a siloxane toughened modified SiO 2 Aerogels and methods of making them. Background technique [0002] SiO 2 Airgel, as a lightweight, three-dimensional nanoporous material with ultrahigh porosity, has higher porosity and lower intrinsic thermal conductivity than inorganic aerogels such as polycrystalline titania and polycrystalline alumina. ; Compared with carbon aerogels and cellulose aerogels, SiO 2 Aerogels can obtain nanoscale pores, which have extremely low gas thermal conductivity. The core technology of airgel preparation is to ensure that the airgel does not shrink during the drying process, thereby ensuring the structure of the airgel. [0003] At present, silica airgel is mostly prepared by the sol-gel method, which is prepared by hydrolysis and polycondensation of silicon sources such as tetraethyl orthosilicate. The airgel obtained by this method cracks when exposed to water, and its microstructure is easily co...

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Problems solved by technology

However, PDMS (-OH) only formed a coating layer (coat) with a thickness of about 1 nm on the surface of the gel, and did not reach the molecular level modification (Sanli D, Erkey C. Monolithic composites of silica aerogels by reactive supercritical deposition of hydroxyl -terminatedpoly(dimethylsiloxane)[J].Applied Materials & Interfaces,2013,5(22):11708-11717.)

[0005] The purpose of the present invention is exactly for SiO 2 Insufficient airgel toughness provides a siloxane-toughened modified SiO 2 The preparation method of airgel uses polydimethylsiloxane and methyltriethoxysilane to modify the gel at the molecular level, so that it has excellent mechanical properties, good hydrophobic properties, and at the same time Low density with aerogel itself

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