Review: Aerogel products: present and future

    Aerogels as the lightest solid materials, with high porosity and specific surface area, have been applied in more and more fields. Currently, commercial aerogel products are mainly used in the field of thermal insulation. The products are mainly based on silica aerogels, and commercial applications in catalysis, electrochemistry and other fields need to be developed.

    Irina Smirnova and Pavel Gurikov of Hamburg University of Technology in Germany published a paper entitled "Aerogel production: current status, research direction, and future opportunities. From the perspective of large-scale commercial applications, the article reviews the aerogel products' current situation, existing research areas and future development directions, and tries to analyze the potential applications of aerogels, so as to provide reference for the determination of academic research direction.

    The main products of the commercial aerogel include monomers, powders, particles, aerogel felt, etc. The list of the world's major commercial aerogel production companies is listed, and the current production process of aerogel products is introduced—it is pointed out that it is different from synthetic aerogels in laboratory. Currently, aerogels in industrial production have not undergone solvent replacement steps, and large-scale solvent replacement technology development needs to be solved. In addition, three drying methods (atmospheric drying, freeze drying, supercritical drying) of aerogels were introduced and the main application fields of aerogel products were listed. 

  Table 1 Main applications of aerogels  

    Based on the fact that commercial products are mainly inorganic aerogels, the author believes that the large-scale production and commercial application of organic aerogels have great market prospects. Organic aerogels have broad application prospects in life Science and other fields due to their good mechanical flexibility, biocompatibility, biodegradability and various functional groups. At present, the laboratory research of organic aerogels has been relatively mature. To produce organic aerogel products with a certain market competitiveness, the problems to be solved are mainly in two aspects, namely, the large-scale planning of production processes and the acquisition of raw materials. Further research should be carried out in the following areas:

1)Evaluating the production of aerogels from various aspects such as availability, environmental protection, life cycle and recyclability.

2)To deepen understanding of hybrid aerogel materials, including the relationship between structure and properties, and the effect of individual polymer properties on the final hybrid materials.

3)To achieve large-scale production of organic aerogels, including large-scale solvent replacement process.

4)Building / expanding the production equipment of organic / hybrid aerogel particles or fibers with controllable size and controllable porosity.

5)Since most operations are based on experience, in order to further optimize or expand the production process, multi-scale process simulation should be carried out for sol formation, solvent replacement, colloid expansion and shrinkage, drying and other production processes.

6)The production of aerogel is still in batches at present, and continuous production is the next step.

7)In order to promote the comparison of aerogel products from different sources, it is necessary to establish evaluation criteria for aerogel material performance (including how to measure the size of holes, irregular shape, density of samples or powders, thermal conductivity, mechanical properties, etc.), which requires further cooperation among research institutes.

    The author firmly believes that the key to the rapid development of the aerogel industry in the next few years is to strengthen the control of raw materials and production processes, further lower the price of aerogel products, and promote the combination of academic research and industrial application. At this point, the development of new aerogels should be guided by application, and understand the advantages and disadvantages of the target products from the beginning. In order to promote the development of aerogel industry, close cooperation between academic institutions and industrial companies is needed. The author thinks that the following research directions are urgently needed and most promising.

1) polymer aerogels

2) hybrid aerogels

3) conductive gel

4) optimization of aerogel production process

5) manufacture of aerogel prototyping machine

In conclusion, we should strengthen the research on application oriented aerogels, strengthen the optimization of aerogel production process, and promote the application of aerogel materials in many fields such as life Sciences, environment, electrochemistry, and promote the rapid development of aerogel products.

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