Flexible Inorganic Nanofibers: Mechanisms, Regulation Strategies, and Evaluation Methods

Flexible inorganic nanofibers, leveraging the synergistic advantages of the inherent stability of inorganic materials and the flexible functionality conferred on the nanoscale, have demonstrated significant application potential in high-end fields such as thermal insulation, optoelectronics, catalysis, and biomedicine, emerging as a research hotspot in interdisciplinary science. However, the origin of their flexibility involves multiscale structural coupling and the synergistic action of multiple mechanisms. Existing research has yet to establish a universal theoretical system, which restricts the precise design and industrial application of flexible inorganic materials. This paper systematically reviews the intrinsic mechanisms of flexible inorganic nanofibers (defect regulation, dynamic interfacial regulation, surface atomic reconstruction, and microscopic bond distortion). It elucidates the logical framework for constructing flexible materials, which is "based on the cornerstones of nanoscale surface/interface effects, supported by the four intrinsic mechanisms listed above, and realized through multi-scale regulation strategies". Two core strategies for flexibility regulation, namely, intrinsic structure tailoring and interfacial engineering modulation, are summarized, along with an overview of the current state of flexibility evaluation and testing methods. This review aims to construct an integrated cognitive framework of "mechanism-regulation-evaluation" to provide theoretical support for the high-performance design and application breakthroughs of flexible inorganic nanofibers. Furthermore, future development directions are discussed, including interdisciplinary integration, innovation in in situ characterization techniques, and the establishment of standardized evaluation systems.