Aerogel Fiber: A One‐Dimensional Programmable Porous Matter for Next Thermal Management Materials

Aerogel fibers have emerged as a new class of one‐dimensional porous materials that overcome the intrinsic brittleness of conventional aerogel monoliths, enabling their integration into flexible and wearable thermal‐management systems. However, their performance is governed not only by intrinsic material properties, but by the generation, reconstruction, and coupling of transport pathways across multiple length scales. In this review, we propose a unified pathway‐centered framework that redefines aerogel fibers as programmable transport systems rather than passive porous materials. At the molecular scale, nano‐building‐block selection and dynamic gelation define the origin of nanoporous pathways. At the fiber scale, non‐equilibrium processing introduces orientation, radial heterogeneity, and hierarchical porosity, reconstructing pathway connectivity and enabling anisotropic transport. At the textile scale, assembly into yarns and fabrics integrates these pathways into system‐level networks, where multiscale coupling governs macroscopic thermal and hygrothermal performance. Despite significant advances, practical applications remain limited by pathway instability under mechanical‐environmental coupling, competition between functional integration and insulation, intrinsic heat‐moisture transport paradoxes, and the lack of operando characterization. Future progress requires a shift from pathway construction to pathway control through physics‐informed design, scalable manufacturing, and cross‐scale decoupled architectures for adaptive regulation. This review highlights a new paradigm in which aerogel fibers evolve from passive insulating materials into programmable and adaptive thermal‐management platforms.