Dispersions of Aramid Nanofibers: A New Nanoscale Building Block

Abstract

Stable dispersions of nanofibers are virtually unknown for synthetic polymers. They can complement analogous dispersions of inorganic components, such as nanoparticles, nanowires, nanosheets, etc as a fundamental component of a toolset for design of nanostructures and metamaterials via numerous solvent-based processing methods. As such, strong flexible polymeric nanofibers are very desirable for the effective utilization within composites of nanoscale inorganic components such as nanowires, carbon nanotubes, graphene, and others. Here stable dispersions of uniform high-aspect-ratio aramid nanofibers (ANFs) with diameters between 3 and 30 nm and up to 10 μm in length were successfully obtained. Unlike the traditional approaches based on polymerization of monomers, they are made by controlled dissolution of standard macroscale form of the aramid polymer, i.e. well known Kevlar threads, and revealed distinct morphological features similar to carbon nanotubes. ANFs are successfully processed into films using layer-by-layer (LBL) assembly as one of the potential methods of preparation of composites from ANFs. The resultant films are transparent and highly temperature resilient. They also display enhanced mechanical characteristics making ANF films highly desirable as protective coatings, ultrastrong membranes, as well as building blocks of other high performance materials in place of or in combination with carbon nanotubes.

Heterocyclic aramid nanoparticle-assisted graphene exfoliation for fabrication of pristine graphene-based composite paper

“…As shown in Fig. 1b, like production of aramid nanofibers from aramid yarns reported by Kotov's group (Yang et al 2011;Cao et al 2013), the HA yarns were similarly treated by adding HA yarns (0.5 g) in DMSO (500 mL) and KOH (1.5 g) followed with stirring for about 1 week until the brown HA macroscopic fibers were all disappeared. The red-brown transparent and homogeneous HANs/DMSO dispersion was finally obtained.…”

“…The red-brown transparent and homogeneous HANs/DMSO dispersion was finally obtained. By abstraction of mobile hydrogen from[NH groups and substantial reduction of the strength of hydrogen bonds between HA polymer chains (Yang et al 2011;Cao et al 2013), the HA macroscopic fibers can be split into the individual HA polymer chains. Then, the individual block copolymer chains of HA can be shrink and twined into the HANs through the hydrophobic attraction and p-p stacking.…”

“…The peak for carbonyl groups of C=O (Amide I) appeared at 1651 cm -1 . The wavenumbers of absorption bands for Amide II and Amide III were severally located at 1549 and 1246 cm -1 , which were attributed to the transformation-coupled vibration of C-N stretching vibration and N-H bending vibration Yang et al 2011). In addition, the vibration peak at 1593 cm -1 was derived from the linked benzene and benzimidazole rings (Zhou et al 2006).…”

A dendrite-suppressing composite ion conductor from aramid nanofibres

“…The resulting membranes also exhibit low Ohmic resistance and high mechanical flexibility, which are essential for battery safety. As a ''building block'' for the new ICM, we decided to use aramid nanofibres (ANFs), whose preparation was described recently 26 . The macro-scale version of ANFs is Kevlar, one of the paragons of mechanical performance.…”

Non-aqueous colloidal processing route for fabrication of highly dispersed aramid nanofibers attached with Ag nanoparticles and their stability in epoxy matrixes

“…1. First, a DMSO solution of ANFs was prepared according to the method in the previous report [31]. A 0.20 g portion of aramid yarns was cut into pieces of length ∼20 mm and added into DMSO (110 g).…”