Synthesis and use of aramid nanofibers
Dissociation of a macroscale version of an aramid fiber leads to the nanofiber form of this polymer. Indefinitely stable dispersions of uniform high-aspect-ratio aramid nanofibers (ANFs) with diameters between 3 and 30 nm controlled by the media composition and up to 10 μm in length are obtained. ANFs can be processed in transparent thin films using layer-by-layer assembly (LBL) with superior mechanical performance.
1. A transparent film comprising a layer-by-layer assembled composite comprising a plurality of deposited layers, said layers comprising hydrolyzed aramid nanofibers and a crosslinker,
wherein said aramid nanofibers have diameters of 3 to 50 nm and lengths of 0.1-10 micrometers, and wherein said composite is 10 to 2,000 deposited layers.
2. The film of claim 1 , wherein said composite is 10 to 1,000 deposited layers.
3. The film of claim 1 , wherein said composite is 100 to 500 deposited layers.
4. A hierarchical transparent film comprising:
at least one layer comprising hydrolyzed aramid nanofibers and a crosslinker, wherein the aramid nanofibers have diameters of 3 to 50 nm and lengths of 0.1-10 micrometers; and
at least one layer of a polymeric material, wherein said polymeric material comprises polyurethane or polyacrylic acid.
5. A transparent film comprising a layer-by-layer assembled composite comprising a plurality of deposited layers, said layers comprising hydrolyzed aramid nanofibers and a crosslinker,
wherein said aramid nanofibers have diameters of 3 to 50 nm and lengths of 0.1-10 mmicrometers, wherein said crosslinker is glutaraldehyde.