Journal Article

PreJuSER-14023

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Interactions between block copolymers and single-walled carbon nanotubes in aqueous solutions: a small-angle neutron scattering study

Granite, M. ; Radulescu, A.FZJ* ; Pyckhout-Hintzen, W.FZJ* ; Cohen, Y.

2011
ACS Publ. Washington, DC

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Please use a persistent id in citations: doi:10.1021/la103096n

Abstract: The amphiphilic copolymers of the Pluronic family are known to be excellent dispersants for single-walled carbon nanotubes (SWCNT) in water, especially F108 and F127, which have rather long end-blocks of poly(ethylene oxide) (PEO). In this study, the structure of the CNT/polymer hybrid formed in water is evaluated by measurements of small-angle neutron scattering (SANS) with contrast variation, as supported by cryo-transmission electron microscopy (cryo-TEM) imaging. The homogeneous, stable, inklike dispersions exhibited very small isolated bundles of carbon nanotubes in cryo-TEM images. SANS experiments were conducted at different D(2)O/H(2)O content of the dispersing solvent. The data for both systems showed surprisingly minimal intensity values at 70% D(2)O solvent composition, which is much higher than the expected value of 17% D(2)O that is based on the scattering length density (SLD) of PEO. At this near match point, the data exhibited a q(-1) power law relation of intensity to the scattering vector (q), indicating rodlike entities. Two models are evaluated, as extensions to Pederson's block copolymer micelles models. One is loosely adsorbed polymer chains on a rodlike CNT bundle. In the other, the hydrophobic block is considered to form a continuous hydrated shell on the CNT surface, whereas the hydrophilic blocks emanate into the solvent. Both models were found to fit the experimental data reasonably well. The model fit required special considerations of the tight association of water molecules around PEO chains and slight isotopic selectivity.

Keyword(s): Nanotubes, Carbon: chemistry (MeSH) ; Polymers: chemistry (MeSH) ; Scattering, Small Angle (MeSH) ; Solutions (MeSH) ; Water: chemistry (MeSH) ; X-Ray Diffraction (MeSH) ; Nanotubes, Carbon ; Polymers ; Solutions ; Water ; J

Note: We thank Dr. Y. Dror, Prof. R. Yerushalmi-Rozen, and Dr. R. Shvartzman-Cohen for many fruitful discussions and Dr. E. Kesselman, B. Shdemati, and J. Schmidt for their generous help with cryo-TEM. This research was supported by the Israel Science Foundation (grant no. 191/07). This work is based in part on experiments performed at the Julich Centre for Neutron Science JCNS, Forschungszentrum Julich, Germany. This project has been supported by the European Commission under the Seventh Framework Program through the key action "Strengthening the European Research Area, Research Infrastructures" (contract no. 226507 (NMI3)).

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Contributing Institute(s):

1. Streumethoden (PGI-4)
2. Neutronenstreuung (ICS-1)
3. JCNS (Jülich Centre for Neutron Science JCNS (JCNS) ; JCNS)
4. Neutronenstreuung (JCNS-1)
5. Streumethoden (JCNS-2)

Research Program(s):

1. BioSoft: Makromolekulare Systeme und biologische Informationsverarbeitung (P45)
2. Großgeräte für die Forschung mit Photonen, Neutronen und Ionen (PNI) (P55)

Experiment(s):

1. KWS-2: Small angle scattering diffractometer (NL3ao)

Appears in the scientific report 2011

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