Chen Zeyu, Yu Chuying, Zhong Wenbin
College of Materials Science and Engineering, Hunan University, Changsha 410082, China.
Materials (Basel). 2025 Mar 4;18(5):1142. doi: 10.3390/ma18051142.
Aramid nanofiber (ANF), a nanoscale building block with a prominently complex structure, can be prepared by splitting poly(p-phenylene terephthalamide) (PPTA) fibers into negatively charged ANFs in a deprotonating manner in a DMSO/KOH solvent system, followed by a subsequent re-protonation process using a proton-donor reagent. There are rare reports regarding the utilization of an aprotic donor reagent to convert deprotonated ANF dispersion into film or gel with a controllable structure and high mechanical properties. In this work, dichloromethane, as an anhydrous aprotic donor solvent, has been introduced into the deprotonated ANF dispersion to replace DMSO, containing PPTA molecules and hydroxyl ions, leading to the gelation of deprotonated ANF dispersions, forming a film (ANF) possessing a surprisingly highly entangled and oriented structure, as proven by SEM results. Due to the attenuation of electrostatic repulsion in the dispersion, partially deprotonated ANFs intertwined and cross-linked through π-π conjugation among a large number of benzene rings in PPTA molecules. After treating ANF with water for re-protonation, the as-prepared film (ANF) exhibited high tensile strength (307.7 MPa) and toughness (74.7 MJ m).
芳纶纳米纤维（ANF）是一种具有显著复杂结构的纳米级构建单元，可通过在二甲基亚砜/氢氧化钾溶剂体系中以去质子化方式将聚对苯二甲酰对苯二胺（PPTA）纤维分裂成带负电荷的ANF来制备，随后使用质子供体试剂进行再质子化过程。关于使用非质子供体试剂将去质子化的ANF分散体转化为具有可控结构和高机械性能的薄膜或凝胶的报道很少。在这项工作中，二氯甲烷作为一种无水非质子供体溶剂，已被引入去质子化的ANF分散体中，以取代含有PPTA分子和氢氧根离子的二甲基亚砜，导致去质子化的ANF分散体凝胶化，形成具有令人惊讶的高度缠结和取向结构的薄膜（ANF），扫描电子显微镜结果证明了这一点。由于分散体中静电排斥的减弱，部分去质子化的ANF通过PPTA分子中大量苯环之间的π-π共轭相互缠绕和交联。用水对ANF进行再质子化处理后，制备的薄膜（ANF）表现出高拉伸强度（307.7MPa）和韧性（74.7MJ/m）。
