Spontaneous Partition of Carbon Nanotubes in Polymer-Modified Aqueous Phases

Abstract

The distribution of nanoparticles in different aqueous environments is a fundamental problem underlying a number of processes, ranging from biomedical applications of nanoparticles to their effects on the environment, health, and safety. Here, we study distribution of carbon nanotubes (CNTs) in two immiscible aqueous phases formed by the addition of polyethylene glycol (PEG) and dextran. This well-defined model system exhibits a strikingly robust phenomenon: CNTs spontaneously partition between the PEG- and the dextran-rich phases according to nanotube's diameter and metallicity. Thermodynamic analysis suggests that this chirality-dependent partition is determined by nanotube's intrinsic hydrophobicity and reveals two distinct regimes in hydrophobicity-chirality relation: a small diameter (<1 nm) regime, where curvature effect makes larger diameter tubes more hydrophobic than small diameter ones, and a large diameter (>1.2 nm) regime, where nanotube's polarizability renders semiconducting tubes more hydrophobic than metallic ones. These findings reveal a general rule governing CNT behaviors in aqueous phase and provide an extremely simple way to achieve spatial separation of CNTs by their electronic structures.

Asymmetric excitation profiles in the resonance Raman response of armchair carbon nanotubes

“…Additionally, enrichment of the (5,5) (from CoMoCAT SG65EX source material) and (8,8) (from Rice-produced HiPco 107.1r source material) structures was provided via the recently introduced aqueous two-phase extraction technique (ATPE) [21][22][23] . Complementary results obtained on samples enriched from HiPco source material (batch HPR 189.2) using a density gradient ultracentrifugation (DGU) approach 19,24 are presented in the supporting material 25 .…”

Thickness-dependent thermoelectric power factor of polymer-functionalized semiconducting carbon nanotube thin films

“…Firstly, most SWNTs are obtained as the ensembles of various structural forms, and their electronic types vary from metallic (m-) to semiconducting (s-), depending on chirality [2]. Many applications require separation of SWNTs with a certain electronic type, and considerable progress has been made recently in this area [3–7]. Secondly, the controlled doping that modulates the Fermi level energy, carrier density, and carrier polarity is similarly required.…”

Semiconducting single-walled carbon nanotubes sorting with a removable solubilizer based on dynamic supramolecular coordination chemistry

“…In order to preserve the intrinsic SWNT properties, the latter method has an advantage over the former one. Recently, various methods for the separation of sem-and met-SWNTs including wrapping by SWNT solubilizers, such as DNAs 20,21 and p-conjugated or non-conjugated copolymers 11,[22][23][24] , density gradient ultracentrifugation 25,26 and gel chromatography techniques 12,14,[27][28][29][30][31][32][33][34][35][36][37][38][39] , have been reported. However, the reported techniques are rather complex and the efficiency is not very high.…”