Yang Bin, Wang Lin, Zhang Meiyun, Luo Jingjing, Ding Xueyao
College of Bioresources Chemical and Materials Engineering, National Demonstration Center for Experimental Light Chemistry Engineering Education, Shaanxi Province Key Laboratory of Papermaking Technology and Specialty Paper Development , Shaanxi University of Science & Technology , No. 6, Xuefu Road , Xi'an 710021 , China.
ACS Nano. 2019 Jul 23;13(7):7886-7897. doi: 10.1021/acsnano.9b02258. Epub 2019 Jun 20.
Aramid nanofibers (ANFs) have become promising nanoscale building blocks due to their extraordinary performance. However, there are numerous challenges related to the preparation of ANFs, such as the lengthy preparation cycle (7-10 days), low preparation concentration (0.2 wt %), and high difficulty in quantitatively judging the end point of the deprotonation reaction. Herein, we report three time-saving and high-efficiency strategies (fibrillation, ultrasonication, and proton donor-assisted deprotonation) to prepare ANFs with excellent performance. The fiber micromorphology during the deprotonation and protonation recovery processes was first investigated. Then the end point of the deprotonation reaction was detected by Raman spectra and the cationic demand of the ANF/DMSO system. Finally, the size, preparation cycle, and performance of the corresponding ANFs and ANF films fabricated by different approaches were investigated in detail. The results showed that proton donor-assisted deprotonation significantly shortened the traditional preparation cycle from 7 days to 4 h, and is the most efficient method reported thus far. It is noteworthy that a high concentration of ANFs (4.0 wt %) could also be achieved within 12 h. Interestingly, the fabricated ANFs exhibit rigid morphology and a small diameter with a narrow size distribution (10.7 ± 1.0 nm). The resultant ANF film displays desired characteristics of high strength and toughness. The work offers a timesaving, feasible and effective strategy to realize the large-scale production for ANFs, which will facilitate the application of ANFs in the production of advanced nanomaterials.
芳纶纳米纤维（ANFs）因其卓越的性能已成为颇具前景的纳米级构建单元。然而，ANFs的制备存在诸多挑战，比如制备周期长（7 - 10天）、制备浓度低（0.2 wt%）以及难以定量判断去质子化反应的终点。在此，我们报道了三种省时高效的策略（原纤化、超声处理和质子供体辅助去质子化）来制备性能优异的ANFs。首次研究了去质子化和质子化恢复过程中的纤维微观形态。然后通过拉曼光谱和ANF/DMSO体系的阳离子需求量检测去质子化反应的终点。最后，详细研究了通过不同方法制备的相应ANFs和ANF薄膜的尺寸、制备周期及性能。结果表明，质子供体辅助去质子化显著缩短了传统制备周期，从7天缩短至4小时，是目前报道的最有效方法。值得注意的是，在12小时内还能实现高浓度的ANFs（4.0 wt%）。有趣的是，制备的ANFs呈现出刚性形态且直径小，尺寸分布窄（10.7±1.0 nm）。所得的ANF薄膜展现出高强度和高韧性的理想特性。这项工作为实现ANFs的大规模生产提供了一种省时、可行且有效的策略，这将促进ANFs在先进纳米材料生产中的应用。
