10.1021/la302307m.s001
Meirav Granite
Meirav
Granite
Aurel Radulescu
Aurel
Radulescu
Yachin Cohen
Yachin
Cohen
Small-Angle Neutron Scattering
from Aqueous Dispersions
of Single-Walled Carbon Nanotubes with Pluronic F127 and Poly(vinylpyrrolidone)
American Chemical Society
2012
Pluronic F 127 polymers
2O
SWCNT
PEO
PVP
Å.
Pluronic F 127
concentration
SANS
CNT
polymer chains
2012-07-31 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Small_Angle_Neutron_Scattering_from_Aqueous_Dispersions_of_Single_Walled_Carbon_Nanotubes_with_Pluronic_F127_and_Poly_vinylpyrrolidone_/2501413
Amphiphilic block copolymers are excellent dispersants
for single-walled
carbon nanotubes (SWCNT) in aqueous environments, where their noncovalent
attachments do not affect the π chemical bonding. In this small-angle
neutron scattering (SANS) study, we investigate whether the coverage
of Pluronic F127 polymers around the CNTs depends on the solution
concentration in the range of 1–6% (w/w). The observations
indicate that at these concentrations the SWCNT surface is fully saturated
at about 14 chains per unit length of 100 Å. Furthermore, we
seek to verify whether the unusual effect observed in a previous study
by contrast variation, interpreted as being due to a dense hydration
layer around the polymer chains, also appears using a homopolymer
(polyvinylpyrrolidone - PVP) that does not contain poly(ethylene oxide)
(PEO) units. The SANS patterns showed again a minimal intensity value
at much higher solvent composition (75% D<sub>2</sub>O) than the expected
value of 29% D<sub>2</sub>O. The minimum scattering curve exhibited
a nearly <i>q</i><sup>–1</sup> power law at small
angles, an indication of rodlike entities. A model of a CNT thin bundle
with loosely adsorbed polymer chains around it (core–chains)
was reasonably well fitted to the data. The polymer chains are assumed
to be surrounded by a water layer with a slightly higher density than
bulk water, having partial selectivity for D<sub>2</sub>O.