טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentDror Yael
SubjectCharacterization and Processing of Single-Walled Carbon
Nanotubes Dispersions
DepartmentDepartment of Chemical Engineering
Supervisor Professor Yachin Cohen


Abstract

 Single-walled carbon nanotubes (SWCNT) exhibit superior and formidable molecular properties which offer a wide range of potential applications. Nevertheless, the realization of these properties in macroscopic effects is hampered by several synthesis and processing issues It is necessary to separate as-synthesized nanotube bundles, disperse them individually in a medium which can be further used to align them in the desired order and shape. The overall aim of the presented work was to characterize the microstructure and processability of SWCNT dispersions in water.

Stable aqueous dispersions of SWCNT were obtained by using two amphiphilic polyectrolytes: gum arabic (GA) - a natural complex and highly branched polysaccharide and a linear alternating copolymer of styrene and sodium maleate (PSSty). GA was found to consist of spheroidal aggregates with a few large coils of the polysaccharide-protein complex. PSSty, on the other hand, forms flat objects by self-assembly. The dispersions contained mainly isolated long nanotubes and thin bundles as was revealed by cryo-transmission electron microscopy. Small angle neutron scattering revealed thick cylindrical hybrids, composed of a thin nanotube core (20Ǻ) surrounded by a thick water-swollen polymer corona (radius of gyration about 150Ǻ) which introduces a significant steric barrier.

Composite nanofibers, made of polyethylene oxide reinforced with carbon nanotubes, were fabricated by electrospinning. Their structure shows a high degree of distribution and alignment of the SWCNTs within the nanofibers, which is attributed to the high quality of the precursor liquid dispersions.