Smart and functional fibers have shown great potential in a wide range of applications including wearable devices and other high-tech fields, but the design and manufacture of smart fibers with manageable structures and multifunctional functions remains a huge challenge. Recently, the research team of the Suzhou Institute of Nanotechnology and Nano-Bionics, Chinese Academy of Sciences has developed an ingenious bending stiffness-oriented strategy to manufacture smart phase change fibers with different bending stiffnesses, which are suitable for various applications. Specifically, with hydrophobic Kevlar aerogel fibers (H-KAFs) as the porous body and paraffin as the functional guest, the hydrophobic Kevlar aerogel-enclosed paraffin fibers (PW@H-KAF) were prepared. H-KAF uses a two-step method to functionalize Kevlar nanofibers (KNF) using a special coagulation bath containing a mixture of ethanol and n-bromobutane. The prepared PW@H-KAFs have high latent heat (135.1-172 J/g), excellent thermal cycle stability and satisfactory mechanical properties (tensile strength of 30 MPa, tensile strain of 30%).

In addition, even in the solid state of paraffin, the bending stiffness of PW@H-KAFs is lower than the critical value (1.22 × 10–9 N•m 2 ), showing high flexibility, cleanability and high thermal management capabilities, indicating intelligence The great potential of temperature-regulating fabrics. The bending stiffness of PW@H-KAFs is higher than the critical stiffness of solid paraffin and can be used as a shape memory material. This is due to the transition between rigidity and flexibility caused by phase change. As a proof of concept, a dynamic gripper was designed based on PW@H-KAF (diameter 400 μm) to transport items by grasping in a rigid state and releasing in a flexible state. This work realizes the multi-functional application of PW@H-KAFs through the bending stiffness-oriented method, and provides ideas for the application of phase change composite materials.

Figure 1. Schematic manufacturing of Kevlar fiber and its application according to bending stiffness

Figure 2. Features and performance of PW@H-KAF with large diameter and high bending stiffness.