2009/03/31 by Micah J. Green, A. Nicholas G. Parra-Vasquez, A. Nicholas G. Parra‐Vasquez +2
Chemistry · Earth and Planetary Sciences · Materials Science · Physics and Astronomy · #Advanced Physical and Chemical Molecular Interactions #Carbon nanotube #Chemical and Physical Properties of Materials #Chemical physics #Chemistry #Composite material #Dispersity #Isotropy #Materials science #Nanotechnology #Optics #Organic chemistry #Phase (matter) #Physics #Polymer chemistry #Range (aeronautics) #Rod #Superacid #cond-mat.soft #nanoparticles nucleation surface interactions
paper · pdf · doi:10.1063/1.3204024
arxiv created 2009/06/12 · openalex publication_date 2009/08/24 · arxiv updated 2015/05/13 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The phase behavior of rodlike molecules with polydisperse length and solvent-mediated attraction and repulsion is described by an extension of the Onsager theory for rigid rods. A phenomenological square-well potential is used to model these long-range interactions, and the model is used to compute phase separation and length fractionation as a function of well depth and rod concentration. The model closely captures experimental data points for isotropic/liquid crystalline phase coexistence of single-walled carbon nanotubes (SWCNTs) in superacids. The model also predicts that the isotropic-biphasic boundary approaches zero as the acid strength diminishes, with the possibility of coexistence of isotropic and liquid crystalline phases at very low concentrations; this counterintuitive prediction is confirmed experimentally. Experimental deviations from classical theories for rodlike liquid crystals are explained in terms of polydispersity and the balance between short-range repulsion and long-range attractions. The predictions of the model also hold practical importance for applications of SWCNT/superacid solutions, particularly in the processing of fibers and films from liquid crystalline SWCNT/superacid mixtures.