Abnormal High-Temperature-Enhanced Hydrogen Bond-Related π–π Hybrid Interaction in Heterocyclic Aramid Fiber-Assisted Chain Self-Ordering

In this article, unique intermolecular resonance-assisted hydrogen bonding (RAHB) is found to be activated by high temperature, which constructs an abnormal thermal-enhanced hydrogen bond-related π–π hybrid interaction, and plays a crucial role in the spontaneous ordering of the as-spun aramid fiber. This spontaneous ordering profoundly influences the orientation and self-elongation within aramid fiber, ultimately determining their high mechanical strength. Additionally, utilizing the temperature-dependent relaxation characterization of the as-spun aramid fiber, a specific multistage thermal stretching strategy with tunable tension was then designed to match different relaxation levels as the temperature increased. Specifically, a unique tension-free heat treatment procedure was intended for the high-temperature stage, which induces fiber self-ordering through RAHB. This approach effectively prevents fiber overloading across various temperatures, thereby significantly inhibiting the propagation of nanosized defects and producing aramid fiber with unexpectedly high mechanical strength (>5.3 GPa).