TY  - JOUR
A1  - Vishnevetskaya, Natalya S.
A1  - Hildebrand, Viet
A1  - Nizardo, Noverra Mardhatillah
A1  - Ko, Chia-Hsin
A1  - Di, Zhenyu
A1  - Radulescu, Aurel
A1  - Barnsley, Lester C.
A1  - Müller-Buschbaum, Peter
A1  - Laschewsky, André
A1  - Papadakis, Christine M.
T1  - All-in-One "Schizophrenic" self-assembly of orthogonally tuned thermoresponsive diblock copolymers
JF  - Langmuir
N2  - Smart, fully orthogonal switching was realized in a highly biocompatible diblock copolymer system with variable trigger-induced aqueous self-assembly. The polymers are composed of nonionic and zwitterionic blocks featuring lower and upper critical solution temperatures (LCSTs and UCSTs). In the system investigated, diblock copolymers from poly(N-isopropyl methacrylamide) (PNIPMAM) and a poly(sulfobetaine methacrylamide), systematic variation of the molar mass of the latter block allowed for shifting the UCST of the latter above the LCST of the PNIPMAM block in a salt-free condition. Thus, successive thermal switching results in "schizophrenic" micellization, in which the roles of the hydrophobic core block and the hydrophilic shell block are interchanged depending on the temperature. Furthermore, by virtue of the strong electrolyte-sensitivity of the zwitterionic polysulfobetaine block, we succeeded to shift its UCST below the LCST of the PNIPMAM block by adding small amounts of an electrolyte, thus inverting the pathway of switching. This superimposed orthogonal switching by electrolyte addition enabled us to control the switching scenarios between the two types of micelles (i) via an insoluble state, if the LCST-type cloud point is below the UCST-type cloud point, which is the case at low salt concentrations or (ii) via a molecularly dissolved state, if the LCST-type cloud point is above the UCST-type cloud point, which is the case at high salt concentrations. Systematic variation of the block lengths allowed for verifying the anticipated behavior and identifying the molecular architecture needed. The versatile and tunable self-assembly offers manifold opportunities, for example, for smart emulsifiers or for sophisticated carrier systems.
Y1  - 2019
U6  - https://doi.org/10.1021/acs.langmuir.9b00241
SN  - 0743-7463
VL  - 35
IS  - 19
SP  - 6441
EP  - 6452
PB  - American Chemical Society
CY  - Washington
ER  -