Method of making reinforced filament with doubly-embedded nanotubes

Abstract

Strengthened filaments and fibers are realized by mixing and dissolving monomer and catalyst in a solvent into open-ended nanotubes to form a polymer precursor prior to polymerization in which the open nanotubes are filled with monomer and catalyst. The remaining steps for forming a stabilized filament may follow the conventional sequence. The result is that the nanotubes are 'doubly-embedded' in the polymer matrix (bonds to the polymer inside and extending through the nanotube and bonds to other polymer chains outside the nanotube) in the filament. These additional bonds provide additional mechanical strength. The number of bonds may be further enhanced by pretreating the nanotubes to create defects in the nanotubes to form sites along the inner and outer walls for additional polymer-to-nanotube bonds. The aligned filaments may be radiated to create additional polymer-to-nanotube bonds such as between the polymer chain inside the nanotube and the inner walls of the nanotube and to create nanotube-to-nanotube bonds. In the case of carbon fiber, the carbonized filament may be radiated to create additional carbon-carbon bonds prior to twisting the filaments into the fiber.