1 research outputs found
Structural Characterization of Amphiphilic Homopolymer Micelles Using Light Scattering, SANS, and Cryo-TEM
We
report the aqueous solution self-assembly of a series of polyÂ(<i>N</i>-isopropylacrylamide) (PNIPAM) polymers end-functionalized
with a hydrophobic sulfur–carbon–sulfur (SCS) pincer
ligand. Although the hydrophobic ligand accounted for <5 wt % of
the overall homopolymer mass, the polymers self-assembled into well-defined
spherical micelles in aqueous solution, and these micelles are potential
precursors to solution-assembled nanoreactors for small molecule catalysis
applications. The micelle structural details were investigated using
light scattering, cryogenic transmission electron microscopy (cryo-TEM),
and small angle neutron scattering (SANS). Radial density profiles
extracted from the cryo-TEM micrographs suggested that the PNIPAM
chains formed a diffuse corona with a radially decreasing corona density
profile and provided valuable <i>a priori</i> information
about the micelle structure for SANS data modeling. SANS analysis
indicated a similar profile in which the corona surrounded a small
hydrophobic core containing the pincer ligand. The similarity between
the SANS and cryo-TEM results demonstrated that detailed information
about the micelle density profile can be obtained directly from cryo-TEM
and highlighted the complementary use of scattering and cryo-TEM in
the structural characterization of solution assemblies, such as the
SCS pincer-functionalized homopolymers described here