Structure of Semidilute Single-Wall Carbon Nanotube Suspensions and Gels

• Published in: Nano letters Vol. 6; no. 2; pp. 313 - 317
• Main Authors: Hough, L. A, Islam, M. F, Hammouda, B, Yodh, A. G, Heiney, P. A
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.02.2006
• Subjects: Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Gels - chemistry; Materials science; Nanoscale materials and structures: fabrication and characterization; Nanotubes; Nanotubes, Carbon - chemistry; Particle Size; Physics; Sensitivity and Specificity; Surface Properties; Surface-Active Agents - chemistry; Water - chemistry; X-Rays; Network structure; Singlewalled nanotube; Quantity ratio; Small angle neutron scattering; Carbon nanotubes; Dispersions; Surfactants; Small angle X ray scattering; Experimental study; Mesh method
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl051871f

The microscopic network structure of surfactant-stabilized single-wall carbon nanotubes (SWNTs) in water was investigated as a function of SWNT concentration in the semidilute (overlapping) regime using small-angle neutron scattering (SANS). Most of the samples exhibit rigid rod behavior (i.e., Q -1 intensity variation) at large scattering wavevector, Q, and a crossover to network behavior (i.e., ∼Q -2 intensity variation) at low Q. The mesh size, ξ, of the network was determined from the crossover of rigid rod to network behavior in the SANS intensity profile and was found to decrease with increasing SWNT concentration. When the dispersion quality of these associating rigid rods was degraded, only ∼Q -2 intensity variation was observed at both high and low Q. Small-angle X-ray scattering measurements of the same stable dispersions were relatively insensitive to network structure because of poor contrast between SWNTs and surfactant.