Ultrafine aramid nanofibers prepared by high-efficiency wet ball-milling-assisted deprotonation for high-performance nanopaper

Abstract

Aramid nanofibers (ANF) with nanoscale diameter, large aspect ratio, exposed electron-negative surface, as well as ultrahigh thermal/chemical inertness and extreme mechanical properties, provide promising applications in many emerging fields, but...

Visible Microfluidic Deprotonation for Aramid Nanofibers as Building Blocks of Cascade‐Microfluidic‐Processed Colloidal Aerogels

“…The characteristic peak of the amide II band has blue‐shifted from 1567 cm −1 for the raw aramid particles to 1574 cm −1 for M‐ANFs, and compared with raw aramid particles, the signal of the amide I band for M‐ANFs was significantly weakened, proving the successful deprotonation of ANF. [ 28 ] With the in situ monitoring, the deprotonation process could be observed more intuitively and easily, which was a significant improvement compared with the deprotonation process of ANFs reported elsewhere. [ 44 ] Figure 1d is the photograph of the collected dispersions in a microfluidic channel at different residence time points by using 0.5 wt% aramid precursor as the starting mixture under 70 °C.…”

“…[ 27 ] However, the preparation efficiency of ANFs is very low so far and often takes at least several days or even more than 1 week due to the slow mass/heat transfer processes. [ 21 ] Recently, Liu and his co‐workers [ 28 ] reported a wet ball‐milling‐assisted deprotonation strategy to improve the preparation efficiency of ANFs. The resulting production rate could be up to 20 g L −1 h −1 .…”

Strong, Tough, and Recyclable Aramid Aerogel Fibers with Homogeneous Nanoscale Structures for High-Temperature Thermal Insulation Applications

“…Direct spinning of polymer precursor into aerogel fibers could significantly simplify the fabrication process and save the cost, but it is difficult to deal with PPTA because of its extremely poor processability. 24,25 Thus, it is still a big challenge to develop high-performance AAFs with controlled porous structures and optimized thermal/mechanical properties.…”

Translucent and Anti-ultraviolet Aramid Nanofiber Films with Efficient Light Management Fabricated by Sol–Gel Transformation

“…Aramid nanofibers (ANFs) have attracted extensive attention since they were first reported by Kotov and co-workers, where PPTA fibers were dissolved in the alkaline solution of DMSO, and ANFs with diameters of 3–30 nm and length of 10 μm were obtained by the deprotonation method . Anyway, it is a great challenge to fabricate ANFs, and the few available techniques can be classified into “bottom-up” and “top-down” strategies. , Electrospinning, mechanical disintegration synergized by alkali, and alkaline dissolution and its improvement belonged to the “top-down” strategy, ,, while the “bottom-up” strategy refers to the polymerization-induced self-assembly . Electrospinning has become the most widely used technology to prepare the polymer nanofibers due to its advantages of high versatility, low cost, and high controllability.…”

“…16 Anyway, it is a great challenge to fabricate ANFs, and the few available techniques can be classified into "bottomup" and "top-down" strategies. 17,18 Electrospinning, 19 mechanical disintegration synergized by alkali, and alkaline dissolution and its improvement belonged to the "top-down" strategy, 16,20,21 while the "bottom-up" strategy refers to the polymerization-induced self-assembly. 22 Electrospinning has become the most widely used technology to prepare the polymer nanofibers due to its advantages of high versatility, low cost, and high controllability.…”