Electrospinner: Wet-spun aerogel fibers: large-scale continuous preparation and refined functional regulation!

Background

Aerogel fiber is a lightweight, porous, flexible and multifunctional material with the advantages of aerogel and fiber materials. It has broad application prospects in thermal insulation, pollution adsorption, biomedicine, energy storage and aerospace. However, its fragile mechanical properties limit its application and large-scale continuous preparation.

Recently, the team of Professor Wei Qufu of Jiangnan University published a review article entitled "Wet Spinning Technology for Aerogel Fiber: Pioneering the Frontier of High-performance and Multifunctional Materials" in Advanced Fiber Materials, which introduced the role of wet spinning in the preparation of continuous aerogel fibers, discussed the regulation of aerogel fiber structure and performance optimization by various wet spinning processes, compared and analyzed various wet spinning technologies, and summarized the outstanding advantages of aerogel fibers in thermal, adsorption, optical, electrical and other properties. Finally, the opportunities and challenges of aerogel fibers in production and manufacturing and flexible applications are prospected.

The main point of this paper

First, the preparation method of aerogel fibers is introduced, as shown in Figure 1, including template spinning (Figure 1a), freeze spinning (Figure 1b) and wet spinning (Figure 1c). Template spinning requires specific template assistance, and the gel speed is usually slow, making it difficult to achieve continuous large-scale production; freeze spinning can achieve continuous fiber production and control the porous structure by adjusting process parameters, but the aerogel fibers prepared by it have large pore sizes and a narrow processing range; wet spinning can achieve continuous gel fiber molding, and has excellent processing characteristics, and can achieve fine control of fiber structure. Therefore, wet spinning is currently one of the most promising methods for the continuous preparation of aerogel fibers. Compared with block aerogels, aerogel fibers are highly flexible and weavable, and can be integrated and applied in various shapes and sizes.

Secondly, the process of wet spinning aerogel fiber was analyzed (Figure 2), including (1) spinning solution preparation: preparing a stable sol solution by sol-gel method or nanocomponent cross-linking method; (2) spinning solution extrusion: extruding the spinning solution into a coagulation bath through a needle, spinneret, etc. at a certain speed; (3) gel fiber molding in the coagulation bath: a double diffusion process of solvent and non-solvent occurs in the coagulation bath, resulting in phase separation to form gel fiber; (4) stretching and aging: stretching and aging the gel fiber to further enhance the network structure; (5) drying: using supercritical drying, freeze drying or atmospheric pressure drying to remove the liquid phase inside the gel fiber and retain the network structure. By adjusting the process conditions, the network structure and mechanical properties of the aerogel fiber can be optimized, which can not only achieve continuous production, but also improve the quality and function of the fiber according to demand. In addition, a post-finishing process (Figure 3) can be adopted to give the aerogel fiber more functions, improve thermal stability and mechanical properties, and obtain a variety of appearances through surface modification, structural optimization, textile design and other means.

Secondly, the advanced wet spinning technologies are summarized, such as liquid crystal spinning (Figure 4a), reactive spinning (Figure 4b), coaxial spinning (Figure 4c), microfluidic spinning (Figure 4d), dry-wet spinning (Figure 4e), liquid template (Figure 4f), UV-assisted cross-linking (Figure 4g) and directional freezing wet spinning (Figure 4h). These advanced technologies can meet the specific requirements in the continuous and large-scale production of aerogel fibers, such as improving mechanical properties, controlling pore structure and enhancing the processability of aerogel materials.

Finally, the development trend of aerogel fibers is prospected. Since aerogel fibers have very rich functions and are easy to weave or integrate into textiles and composite materials, they are suitable for thermal insulation clothing, filtration materials, personal protective fabrics and smart textiles. At present, the real continuous production process of aerogel fibers has not been realized. The bottlenecks are: (1) the strength of gel fibers is not enough to withstand the tension of industrial spinning equipment; (2) the difficulty of conventional industrial drying methods. By optimizing the synthesis technology of nanomaterials, finely controlling the fiber microstructure, innovating the wet spinning process, exploring new drying methods, etc., the mechanical strength of the fiber and the feasibility of the production process can be improved. Continuously expanding the application potential of aerogel fibers can bring diversified and functional products.

Electrospinning Nanofibers Article Source:

https://link.springer.com/article/10.1007/s42765-024-00440-6