@article{VishnevetskayaHildebrandDyakonovaetal.2018,
  author    = {Vishnevetskaya, Natalya S. and Hildebrand, Viet and Dyakonova, Margarita A. and Niebuur, Bart-Jan and Kyriakos, Konstantinos and Raftopoulos, Konstantinos N. and Di, Zhenyu and M{\"u}ller-Buschbaum, Peter and Laschewsky, Andre and Papadakis, Christine M.},
  title     = {Dual orthogonal switching of the "Schizophrenic" self-assembly of diblock copolymers},
  series = {Macromolecules : a publication of the American Chemical Society},
  volume    = {51},
  journal   = {Macromolecules : a publication of the American Chemical Society},
  number    = {7},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0024-9297},
  doi       = {10.1021/acs.macromol.8b00096},
  pages     = {2604 -- 2614},
  year      = {2018},
  abstract  = {Based on diblock copolymers, a pair of "schizophrenic" micellar systems is designed by combining a nonionic and thermoresponsive block with a zwitterionic block, which is thermoresponsive and salt-sensitive. The nonionic block is poly(N-isopropylacrylamide) (PNIPAM) or poly(N-isopropylmethacrylamide) (PNIPMAM) and exhibits a lower critical solution temperature (LCST) behavior in aqueous solution. The zwitterionic block is a polysulfobetaine, i.e., poly(4((3-methacrylamidopropyl)dimethylammonio)butane-1-sulfonate) (PSBP), and has an upper critical solution temperature (UCST) behavior with the clearing point decreasing with increasing salt concentration. The PSBP-b-PNIPAM and PSBP-b-PNIPMAM diblock copolymers are prepared by successive reversible addition-fragmentation chain transfer (RAFT) polymerizations. The PSBP block is chosen such that the clearing point of the homopolymer is significantly higher in pure water than the cloud point of PNIPAM or PNIPMAM. Using turbidimetry, H-1 NMR, and small-angle neutron scattering, we investigate the overall phase behavior as well as the structure and interaction between the micelles and the intermediate phase, both in salt-free D2O and in 0.004 M NaBr in D2O in a wide temperature range. We find that PSBP-b-PNIPAM at 50 g L-1 in salt-free D2O is turbid in the entire temperature range. It forms spherical micelles below the cloud point of PNIPAM and cylindrical micelles above. Similar behavior is observed for PSBP-b-PNIPMAM at 50 g L-1 in salt-free D2O with a slight and smooth increase of the light transmission below the cloud point of PNIPMAM and an abrupt decrease above. Upon addition of 0.004 M NaBr, the UCST-type cloud point of the PSBP-block is notably decreased, and an intermediate regime is encountered below the cloud point of PNIPMAM, where the light transmission is slightly enhanced. In this regime, the polymer solution exhibits behavior typical for polyelectrolyte solutions. Thus, double thermosensitive and salt-sensitive behavior with "schizophrenic" micelle formation is found, and the width of the intermediate regime, where both blocks are hydrophilic, can be tuned by the addition of electrolyte.},
  language  = {en}
}
@article{VishnevetskayaHildebrandNizardoetal.2019,
  author    = {Vishnevetskaya, Natalya S. and Hildebrand, Viet and Nizardo, Noverra Mardhatillah and Ko, Chia-Hsin and Di, Zhenyu and Radulescu, Aurel and Barnsley, Lester C. and M{\"u}ller-Buschbaum, Peter and Laschewsky, Andr{\´e} and Papadakis, Christine M.},
  title     = {All-in-One "Schizophrenic" self-assembly of orthogonally tuned thermoresponsive diblock copolymers},
  series = {Langmuir},
  volume    = {35},
  journal   = {Langmuir},
  number    = {19},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0743-7463},
  doi       = {10.1021/acs.langmuir.9b00241},
  pages     = {6441 -- 6452},
  year      = {2019},
  abstract  = {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.},
  language  = {en}
}
@article{VishnevetskayaHildebrandNiebuuretal.2016,
  author    = {Vishnevetskaya, Natalya S. and Hildebrand, Viet and Niebuur, Bart-Jan and Grillo, Isabelle and Filippov, Sergey K. and Laschewsky, Andre and M{\"u}ller-Buschbaum, Peter and Papadakis, Christine M.},
  title     = {Aggregation Behavior of Doubly Thermoresponsive Polysulfobetaine-b-poly(N-isopropylacrylamide) Diblock Copolymers},
  series = {Macromolecules : a publication of the American Chemical Society},
  volume    = {49},
  journal   = {Macromolecules : a publication of the American Chemical Society},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0024-9297},
  doi       = {10.1021/acs.macromol.6b01186},
  pages     = {6655 -- 6668},
  year      = {2016},
  abstract  = {A 2-fold thermoresponsive diblock copolymer PSPP430-b-PNIPAM(200) consisting of a zwitterionic polysulfobetaine (PSPP) block and a nonionic poly(N-isopropylacrylamide) (PNIPAM) block is prepared by successive RAFT polymerizations. In aqueous solution, the corresponding homopolymers PSPP and PNIPAM feature both upper and lower critical solution temperature (UCST and LCST) behavior, respectively. The diblock copolymer exhibits thermally induced "schizophrenic" aggregation behavior in aqueous solutions. Moreover, the ion sensitivity of the, cloud point of the zwitterionic PSPP block to both the ionic strength and the nature of the salt offers the possibility to create switchable systems which respond sensitively to changes of the temperature and of the electrolyte type and concentration. The diblock copolymer solutions in D2O are investigated by means of turbidimetry and small-angle neutron scattering (SANS) with respect to the phase behavior and the self-assembled structures in dependence on temperature and electrolyte content. Marked, differences of the aggregation below the UCST-type and above the LCST-type transition are observed. The addition of a small amount of NaBr (0.004 M) does not affect the overall behavior, and only the UCST-type transition and aggregate structures are slightly altered, reflecting the well-known ion sensitivity of the zwitterionic PSPP block.},
  language  = {en}
}
@article{VishnevetskayaHildebrandNiebuuretal.2017,
  author    = {Vishnevetskaya, Natalya S. and Hildebrand, Viet and Niebuur, Bart-Jan and Grillo, Isabelle and Filippov, Sergey K. and Laschewsky, Andre and M{\"u}ller-Buschbaum, Peter and Papadakis, Christine M.},
  title     = {"Schizophrenic" Micelles from Doubly Thermoresponsive Polysulfobetaine-b-poly(N-isopropylmethacrylamide) Diblock Copolymers},
  series = {Macromolecules : a publication of the American Chemical Society},
  volume    = {50},
  journal   = {Macromolecules : a publication of the American Chemical Society},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0024-9297},
  doi       = {10.1021/acs.macromol.7b00356},
  pages     = {3985 -- 3999},
  year      = {2017},
  language  = {en}
}