N. S. Vishnevetskaya, V. Hildebrand, N. M. Nizardo, C. H. Ko, Z. Di, A. Radulescu, L. C. Barnsley, P. Müller Buschbaum, A. Laschewsky, C. M. Papadakis
All-in-One \"Schizophrenic\" Self-assembly of Orthogonally Tuned Thermo-responsive Diblock Copolymers
Langmuir 2019, 35, 6441
DOI: 10.1021/acs.langmuir.9b00241
Smart, fully orthogonal switching is implemented in a diblock copolymer system with variable trigger-induced aqueous self-assembly. The polymers are made of a non-ionic and a zwitterionic block, which exhibit either lower or upper critical solution temperature in aqueous solutions. Here poly(N-isopropyl methacrylamide) PNIPMAM and a poly(sulfobetaine methacrylamide) PSBP are combined. Successive thermal switching of the block copolymers results in \"schizophrenic\" micellization, in which the roles of the hydrophobic core block and the hydrophilic shell block are interchanged in dependence on temperature. In these systems, the UCST can be efficiently modulated by adding specific amounts of electrolytes. This allows for realizing the switching between the two types of micelles via two distinct scenarios: (i) via a molecularly dissolved state, if the LCST-type cloud point is lower than the UCST-type cloud point, which is the case at low salt concentrations. Or (ii) via an insoluble state, if the LCST-type cloud point is higher than the UCST-type cloud point, which is the case at high salt concentrations.
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