Block and Gradient Copoly(2-oxazoline) Micelles: Strikingly different on the Insideстатья
Статья опубликована в высокорейтинговом журнале
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Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 28 сентября 2017 г.
Аннотация:Herein, we provide a direct proof for differences in the micellar
structure of amphiphilic diblock and gradient copolymers, thereby unambiguously
demonstrating the influence of monomer distribution along the polymer chains on
the micellization behavior. The internal structure of amphiphilic block and gradient
co poly(2-oxazolines) based on the hydrophilic poly(2-methyl-2-oxazoline)
(PMeOx) and the hydrophobic poly(2-phenyl-2-oxazoline) (PPhOx) was studied
in water and water−ethanol mixtures by small-angle X-ray scattering (SAXS), smallangle
neutron scattering (SANS), static and dynamic light scattering (SLS/DLS),
and 1H NMR spectroscopy. Contrast matching SANS experiments revealed that
block copolymers form micelles with a uniform density profile of the core. In
contrast to popular assumption, the outer part of the core of the gradient copolymer
micelles has a distinctly higher density than the middle of the core. We attribute the
latter finding to back-folding of chains resulting from hydrophilic−hydrophobic
interactions, leading to a new type of micelles that we refer to as micelles with a “bitterball-core” structure.