A Kinetic Model for the Deterministic Prediction of Gel-Based Single-Chirality Single-Walled Carbon Nanotube Separation

We propose a kinetic model that describes the separation of single-chirality semiconducting carbon nanotubes based on the chirality-selective adsorption to specific hydrogels. Experimental elution profiles of the (7,3), (6,4), (6,5), (8,3), (8,6), (7,5), and (7,6) species are well described by an irreversible, first-order site association kinetic model with a single rate constant describing the adsorption of each SWNT to the immobile gel phase. Specifically, we find first-order binding rate constants for seven experimentally separated nanotubes normalized by the binding site molarity (M-theta): k(7,3) = 3.5 x 10(-5) M-theta(-1) s(-1), k(6,4) = 7.7 x 10(-8) M-theta(-1) s(-1), k(8,3) = 2.3 x 10(-9) M-theta(-1) s(-1), k(6,5) = 3.8 x 10(-9) M-theta(-1) s(-1), k(7,5) = 1.9 x 10(-11) M-theta(-1) s(-1),k(8,6) = 7.7 x 10(-12) M-theta(-1) s(-1), and k(7,6) = 3.8 x 10(-12) M-theta(-1) s(-1). These results, as well as additional control experiments, unambiguously identify the separation process as a selective adsorption. Unlike certain chromatographic processes with retention time dependence, this separation procedure can be scaled to arbitrarily large volumes, as we demonstrate. This study provides a foundation for both the mechanistic understanding of gel-based SWNT separation as well as the potential industrial-scale realization of single-chirality production of carbon nanotubes.