title: Use of a chondroitin sulfate isomer as an effective and removable dispersant of single-walled carbon nanotubes.
abstract: Three isomers of chondroitin sulfate (CS), i.e., CS-A, CS-B, and CS-C, are investigated as nanotube dispersants and are found to have vastly different abilities to disperse single-walled carbon nanotubes (SWNTs) in water due to their different intramolecular interactions. Only CS-A and CS-C effectively disperse SWNTs into small bundles or individual tubes while CS-B disperses SWNTs poorly. Computer simulation and circular dichrosim show that neat CS-A and CS-C have weak intramolecular hydrogen bonding and extended conformations in solution resulting in energetically more favorable interactions with nanotubes. CS-B has relatively strong intramolecular Coulombic interaction and more alpha-helical secondary structure in solution resulting in energetically less favorable interaction with the nanotubes. Atomic force microscopy images show helical wrappings of CS-A and CS-C around the SWNTs. Transmission electron microscopy corroborates the helical wrapping of CS-A. Different isomeric forms of a polymer can have vastly different dispersing power because of their different intramolecular interactions and conformations. The easy removability of CS-A from nanotubes is confirmed with X-ray photoelectron spectroscopy showing almost no detectable sulphur content after washing with water and by application of washed CS-A dispersed SWNTs in field-effect transistors.
authors: School of Chemical & Biomedical EngineeringNanyang Technological University, 62 Nanyang Drive, Singapore 637459, Singapore.
authors: Liang Yu
authors: LY
authors: Yan
authors: Weifeng
authors: W
authors: Li
authors: Sara
authors: S
authors: Mesgari
authors: Susanna S J
authors: SS
authors: Leong
authors: Yuan
authors: Y
authors: Chen
authors: Leslie S
authors: LS
authors: Loo
authors: Yuguang
authors: Y
authors: Mu
authors: Mary B
authors: MB
authors: Chan-Park
mesh_terms: D002809:Chondroitin Sulfates / Q000737:chemistry*; D002942:Circular Dichroism; D003198:Computer Simulation; D007536:Isomerism; D008163:Luminescent Measurements; D008958:Models, Molecular; D008968:Molecular Conformation; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D056951:Photoelectron Spectroscopy; D011108:Polymers / Q000737:chemistry; D011721:Pyrenes / Q000737:chemistry; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D019265:Spectroscopy, Near-Infrared; D013816:Thermodynamics
chemical_list: C550269:HiPco compound; D037742:Nanotubes, Carbon; D011108:Polymers; D011721:Pyrenes; D012967:Sodium Dodecyl Sulfate; D002809:Chondroitin Sulfates