Block and gradient copoly(2-oxazoline) micelles: strikingly different on the inside

0476710 - ÚMCH 2018 RIV US eng J - Journal Article
Filippov, Sergey K. - Verbraeken, B. - Konarev, P. V. - Svergun, D. I. - Angelov, Borislav - Vishnevetskaya, N. S. - Papadakis, C. M. - Rogers, S. - Radulescu, A. - Courtin, T. - Martins, J. C. - Starovoytova, Larisa - Hrubý, Martin - Štěpánek, Petr - Kravchenko, V. S. - Potemkin, I. I. - Hoogenboom, R.
Block and gradient copoly(2-oxazoline) micelles: strikingly different on the inside.
Journal of Physical Chemistry Letters. Roč. 8, č. 16 (2017), s. 3800-3804. ISSN 1948-7185
R&D Projects: GA ČR(CZ) GA17-00973S; GA ČR(CZ) GA16-03156S; GA MZd(CZ) NV15-25781A
Institutional support: RVO:61389013 ; RVO:68378271
Keywords : poly(2-oxazolines) * micelles * gradient
OECD category: Biophysics; Biophysics (FZU-D)
Impact factor: 8.709, year: 2017

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), small-angle 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.
Permanent Link: http://hdl.handle.net/11104/0273841