Aramid Nanofibers by Deprotonation: Preparation Optimization, Endpoint Determination, and Applications

Abstract

As a nanoscale derivative of poly(p‐phenylene terephthalamide) (PPTA), para‐aramid nanofibers (ANFs) largely retain the exceptional mechanical and thermal stability of bulk PPTA fibers while offering high specific surface area, abundant surface active sites, and remarkable nanoscale effects. These advantages make ANFs highly promising for high‐performance composites and functional devices. However, the rigid molecular structure and strong intermolecular interactions of PPTA pose great challenges to controllable ANF fabrication. Among various preparation strategies, the deprotonation method has become the most widely used route owing to its mild conditions, good controllability, low energy consumption, and scalability. This review summarizes the recent progress of deprotonation‐based ANF fabrication, focusing on key optimization strategies including temperature control, mechanical force assistance, alkaline system regulation, and proton donor introduction. We further systematically compare three reliable methods for determining the nanofibrillation endpoint. Finally, we highlight the structure‐dependent applications of ANFs in composite reinforcement, battery separators, and aerogels, and discuss the remaining challenges and future directions toward controllable synthesis, green processing, and high‐value applications.