Review: research progress of cellulose-based directional frozen aerogels

Cellulose-based aerogels derived from renewable resources exhibit significant potential for environmental remediation and energy storage applications, owing to their ultra-low density, interconnected macroporous structure, and exceptionally high specific surface area. However, the traditional cellulose aerogels, limited by their structural properties, significantly hinder large-scale industrial production and practical application. Therefore, developing novel strategies to enhance their performance is imperative. Directional freezing is an advanced technique for controlling the porous architecture of materials, building upon conventional freeze-drying methods. By precisely controlling the ice crystal growth during the freezing process, anisotropic structures with well-aligned pore arrangements can be fabricated, enabling directional structural design for the preparation of highly porous aerogel materials. In this paper, we systematically review recent advances in cellulose-based aerogels fabricated via directional freezing technology. The pore-forming mechanisms and structural characteristics of three representative methods—unidirectional, bidirectional, and radial freezing—are comprehensively analyzed. Furthermore, we evaluate the enhancement of material properties through functionalization strategies and summarize current applications with future development trends.

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