A thin layer is warmer than down? Is aerogel cold-resistant clothing a waste of money?

Winter is here, the temperature has dropped sharply, and everyone is buying thicker and warmer winter clothes. The slogan "made of aerospace-grade material - aerogel" is increasingly appearing on some winter cold-proof and warm clothing, claiming to have super warm performance, and the price is not cheap.

So what kind of material is aerogel? Can aerogel clothing really keep you warm and protected from the cold?

The picture is taken from an e-commerce platform

Let's start with what aerogel is.

What is aerogel?

Aerogel is a type of three-dimensional network structure material that encapsulates a large number of closed micropores. It can be made from inorganic materials or polymer macromolecules through a sol-gel transformation process and then a special drying process.

According to this definition, we can know that the concept of aerogel actually refers to a solid structure (rather than a chemical substance). The special feature of this structure is that its porosity is very high, which is as high as 80.0%~99.8%, and the pore size ranges from 1 to 100 nanometers.

There is dispersed static air in the closed micropores of the aerogel structure, which determines that the material with an aerogel structure has the performance characteristics of low density and low thermal conductivity. Aerogel materials generally include inorganic aerogels and organic aerogels. Inorganic aerogels include silica aerogels, titanium dioxide aerogels, etc., and organic aerogels include polyimide aerogels, polyurethane aerogels, etc.

An aerogel material. Photo provided by the author

The high thermal insulation performance of aerogel materials makes them widely used in aerospace, electronic communications, flame retardant and thermal insulation, etc. For example, in the aerospace field, aerogel materials are used in aircraft heat shields, flexible thermal protection systems for reducers, thermal insulation layers for cryotubes in space propulsion systems, space suits, etc. So from this perspective, aerogel is indeed a veritable "space-grade material."

How to make clothes with aerogel?

So, since aerogel has such good thermal insulation performance, can this material be used in our daily human body warmth and cold protection? Textile science is indeed doing research in this area, and we can take a look at the current research results.

When we wear clothes, we have to stretch, pull and rub them, which is a piece of cake for common textile fabrics. However, the mechanical properties of aerogel structural materials themselves are very poor, they are easy to break and powder, lack flexibility and drape, and are not suitable for direct use in daily textiles and clothing.

Bent aerogel material. Photo provided by the author

Textile scientists have also thought of many ways to improve this situation, hoping to use aerogels in textiles and clothing to improve cold-proof and warm performance.

For example, aerogel powder can be adhered to the surface of textile material by utilizing the adhesive or the textile material's own adhesion to aerogel; a coating finish containing aerogel can be evenly coated on the surface of the fabric; aerogel fiber can be prepared directly from the aerogel preparation solution through a specific processing technique; or aerogel particles can be added to the spinning solution to produce chemical fibers containing aerogel.

It sounds like there is some hope for the application of aerogel in clothing, but there are still many problems to be faced when it comes to actual implementation.

Is the current "aerogel clothing" reliable?

Many attempts have been made to use aerogel materials in clothing, but unfortunately, there are still some problems with these technologies and processes.

For example, the manufacturing process of aerogel fibers is very slow, and the mechanical properties are relatively poor, making it difficult to withstand the tension required in the later spinning and weaving processes. Although surface adhesion technology or aerogel coating technology can improve the thermal insulation and warmth performance of the treated fabrics, it is easy to cause the fabrics to be airtight and moisture-proof. In addition, there is also the problem of aerogel particles peeling off.

Some friends may be confused. Didn’t we say that aerogel materials are used in space suits? Why can’t they be used to make clothes? In fact, the aerogel material used in space suits is a kind of polyimide aerogel with high strength and good softness. This material is currently only used in some special fields such as space suits and protective clothing.

Although they are also called "clothing", space suits and protective clothing belong to a type of special personal equipment system rather than a simple piece of clothing. Aerogel material, as a thermal insulation material, is only a part of the system. Other materials and equipment are also needed to achieve the moisture and heat balance between the human body and the external environment. It is a system completely different from everyday clothing.

Image source: pixabay

In short, under current technical conditions, the use of aerogel materials in daily clothing for cold protection and heat preservation still has considerable limitations, and industrial large-scale production and commercialization are rare. Consumers are advised to pay attention to the materials and real effects of aerogel used in related products, and do not place orders blindly.

References

[1] Zhao Guoliang, Li Guangwu, Xue Rong, et al. Application status of aerogel in textile and clothing fields[J]. New Materials Industry, 2021, (02): 48-53. DOI: 10.19599/j.issn.1008-892x.2021.02.009

[2] Ma Xiaoyi, Hu Yanping, Wang Kai, et al. Research progress on preparation, structure and properties of polyimide aerogels [J/OL]. Polymer Materials Science and Engineering, 1-12 [2023-11-13] https://doi.org/10.16865/j.cnki.1000-7555.2023.0221.

[3]NASA: NewUltra-Thin, FlexibleAerogelsCouldbeUsedtoMakeSuper-InsulatedClothinghttps://inhabitat.com/nasa-new-ultra-thin-flexible-aerogels-could-be-used-to-make-super-insulated-clothing/

[4]DurablePolyimideAerogels(LEW-TOPS-133)https://technology.nasa.gov/patent/LEW-TOPS-133

This article is a work of Science Popularization China-Starry Sky Project

Produced by: Science Popularization Department of China Association for Science and Technology

Producer｜China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.

Author: Song Lidan China Textile Construction Planning Institute

Review丨Zhang Jie, Chief Engineer of China Textile Construction Planning Institute