Fabrication

Pathology

Nanotechnology

Kevlar

Bending

Ultimate tensile strength

Composite number

Bending stiffness

Composite material

Materials science

Alternative medicine

Aerogel

Stiffness

Flexural rigidity

Polymer

Smart polymer

Medicine

Nanofiber

ACS Nano

Smart and functional fibers have demonstrated great potentials in a wide range of applications including wearable devices and other high-tech fields, but design and fabrication of smart fibers with manageable structures as well as versatile functions are still a great challenge. Herein, an ingenious bending-stiffness-directed strategy is developed to fabricate smart phase-change fibers with different bending stiffnesses for diverse applications. Specifically, the hydrophobic Kevlar aerogel-confined paraffin wax fibers (PW@H-KAF) are fabricated by employing hydrophobic Kevlar aerogel fibers (H-KAFs) as the porous host and paraffin as the functional guest, where the H-KAF is obtained by applying a two-step process to functionalize Kevlar nanofibers (KNFs) with a special coagulation bath containing a mixture of ethanol and n-bromobutane. The prepared PW@H-KAFs exhibit high latent heat (135.1–172 J/g), outstanding thermal cyclic stability and satisfactory mechanical properties (30 MPa in tensile strength and 30% in tensile strain). In addition, the PW@H-KAFs with bending stiffness was lower than the critical one (1.22 × 10–9 N·m2) even in a solid state of paraffin wax exhibits high flexibility, washable performance, and high thermal management capability, showing great potential for smart temperature-regulating fabrics. PW@H-KAFs with a bending stiffness higher than the critical one at a solid state of paraffin wax can be utilized as shape memory materials, attributed to the transition between rigidity and flexibility caused by the phase transition. As a proof of concept, a dynamic gripper is designed based on the PW@H-KAF (400 μm in diameter) for transporting items by gripping in the rigid state and releasing in the flexible state. This work realizes versatile applications with the PW@H-KAFs through the bending stiffness-directed method, providing ideas for the application of phase-change composites.

Bending Stiffness-Directed Fabricating of Kevlar Aerogel-Confined Organic Phase-Change Fibers