TY - JOUR A1 - Vishnevetskaya, Natalya S. A1 - Hildebrand, Viet A1 - Niebuur, Bart-Jan A1 - Grillo, Isabelle A1 - Filippov, Sergey K. A1 - Laschewsky, Andre A1 - Mueller-Buschbaum, Peter A1 - Papadakis, Christine M. T1 - "Schizophrenic" Micelles from Doubly Thermoresponsive Polysulfobetaine-b-poly(N-isopropylmethacrylamide) Diblock Copolymers JF - Macromolecules : a publication of the American Chemical Society Y1 - 2017 U6 - https://doi.org/10.1021/acs.macromol.7b00356 SN - 0024-9297 SN - 1520-5835 VL - 50 SP - 3985 EP - 3999 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Hildebrand, Viet A1 - Heydenreich, Matthias A1 - Laschewsky, Andre A1 - Moeller, Heiko M. A1 - Mueller-Buschbaum, Peter A1 - Papadakis, Christine M. A1 - Schanzenbach, Dirk A1 - Wischerhoff, Erik T1 - "Schizophrenic" self-assembly of dual thermoresponsive block copolymers bearing a zwitterionic and a non-ionic hydrophilic block JF - Polymer : the international journal for the science and technology of polymers N2 - Several series of presumed dual thermo-responsive diblock copolymers consisting of one non-ionic and one zwitterionic block were synthesized via consecutive reversible addition-fragmentation chain transfer (RAFT) polymerization. For all copolymers, poly(N-isopropylmethacrylamide) was chosen as non-ionic block that shows a coil-to-globule collapse transition of the lower critical solution temperature (LCST) type. In contrast, the chemical structure of zwitterionic blocks, which all belonged to the class of poly(sulfobetaine methacrylate)s, was varied broadly, in order to tune their coil-to-globule collapse transition of the upper critical solution temperature (UCST) type. All polymers were labeled with a solvatochromic fluorescent end-group. The dual thermo-responsive behavior and the resulting multifarious temperature-dependent self-assembly in aqueous solution were mapped by temperature resolved turbidimetry, H-1 NMR spectroscopy, dynamic light scattering (DLS), and fluorescence spectroscopy. Depending on the relative positions between the UCST-type and LCST-type transition temperatures, as well as on the width of the window in-between, all the four possible modes of stimulus induced micellization can be realized. This includes classical induced micellization due to a transition from a double hydrophilic, or respectively, from a double hydrophobic to an amphiphilic state, as well as "schizophrenic" behavior, where the core- and shell-forming blocks are inverted. The exchange of the roles of the hydrophilic and hydrophobic block in the amphiphilic states is possible through a homogeneous intermediate state or a heterogeneous one. (C) 2017 Elsevier Ltd. All rights reserved. KW - RAFT polymerization KW - Block copolymer KW - Sulfobetaine methacrylate KW - Responsive polymer KW - LCST KW - UCST KW - Schizophrenic self-assembly Y1 - 2017 U6 - https://doi.org/10.1016/j.polymer.2017.06.063 SN - 0032-3861 SN - 1873-2291 VL - 122 SP - 347 EP - 357 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Vishnevetskaya, Natalya S. A1 - Hildebrand, Viet A1 - Niebuur, Bart-Jan A1 - Grillo, Isabelle A1 - Filippov, Sergey K. A1 - Laschewsky, Andre A1 - Müller-Buschbaum, Peter A1 - Papadakis, Christine M. T1 - Aggregation Behavior of Doubly Thermoresponsive Polysulfobetaine-b-poly(N-isopropylacrylamide) Diblock Copolymers JF - Macromolecules : a publication of the American Chemical Society N2 - 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. Y1 - 2016 U6 - https://doi.org/10.1021/acs.macromol.6b01186 SN - 0024-9297 SN - 1520-5835 VL - 49 SP - 6655 EP - 6668 PB - American Chemical Society CY - Washington ER - 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 - TY - JOUR A1 - Vishnevetskaya, Natalya S. A1 - Hildebrand, Viet A1 - Dyakonova, Margarita A. A1 - Niebuur, Bart-Jan A1 - Kyriakos, Konstantinos A1 - Raftopoulos, Konstantinos N. A1 - Di, Zhenyu A1 - Müller-Buschbaum, Peter A1 - Laschewsky, Andre A1 - Papadakis, Christine M. T1 - Dual orthogonal switching of the "Schizophrenic" self-assembly of diblock copolymers JF - Macromolecules : a publication of the American Chemical Society N2 - 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. Y1 - 2018 U6 - https://doi.org/10.1021/acs.macromol.8b00096 SN - 0024-9297 SN - 1520-5835 VL - 51 IS - 7 SP - 2604 EP - 2614 PB - American Chemical Society CY - Washington ER - TY - GEN A1 - Hildebrand, Viet A1 - Laschewsky, André A1 - Päch, Michael A1 - Müller-Buschbaum, Peter A1 - Papadakis, Christine M. T1 - Effect of the zwitterion structure on the thermo-responsive behaviour of poly(sulfobetaine methacrylates) N2 - A series of new sulfobetaine methacrylates, including nitrogen-containing saturated heterocycles, was synthesised by systematically varying the substituents of the zwitterionic group. Radical polymerisation via the RAFT (reversible addition–fragmentation chain transfer) method in trifluoroethanol proceeded smoothly and was well controlled, yielding polymers with predictable molar masses. Molar mass analysis and control of the end-group fidelity were facilitated by end-group labeling with a fluorescent dye. The polymers showed distinct thermo-responsive behaviour of the UCST (upper critical solution temperature) type in an aqueous solution, which could not be simply correlated to their molecular structure via an incremental analysis of the hydrophilic and hydrophobic elements incorporated within them. Increasing the spacer length separating the ammonium and the sulfonate groups of the zwitterion moiety from three to four carbons increased the phase transition temperatures markedly, whereas increasing the length of the spacer separating the ammonium group and the carboxylate ester group on the backbone from two to three carbons provoked the opposite effect. Moreover, the phase transition temperatures of the analogous polyzwitterions decreased in the order dimethylammonio > morpholinio > piperidinio alkanesulfonates. In addition to the basic effect of the polymers’ precise molecular structure, the concentration and the molar mass dependence of the phase transition temperatures were studied. Furthermore, we investigated the influence of added low molar mass salts on the aqueous-phase behaviour for sodium chloride and sodium bromide as well as sodium and ammonium sulfate. The strong effects evolved in a complex way with the salt concentration. The strength of these effects depended on the nature of the anion added, increasing in the order sulfate < chloride < bromide, thus following the empirical Hofmeister series. In contrast, no significant differences were observed when changing the cation, i.e. when adding sodium or ammonium sulfate. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 298 Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-102028 ER - TY - JOUR A1 - Hildebrand, Viet A1 - Laschewsky, Andre A1 - Päch, Michael A1 - Müller-Buschbaum, Peter A1 - Papadakis, Christine M. T1 - Effect of the zwitterion structure on the thermo-responsive behaviour of poly(sulfobetaine methacrylates) JF - Polymer Chemistry N2 - A series of new sulfobetaine methacrylates, including nitrogen-containing saturated heterocycles, was synthesised by systematically varying the substituents of the zwitterionic group. Radical polymerisation via the RAFT (reversible addition–fragmentation chain transfer) method in trifluoroethanol proceeded smoothly and was well controlled, yielding polymers with predictable molar masses. Molar mass analysis and control of the end-group fidelity were facilitated by end-group labeling with a fluorescent dye. The polymers showed distinct thermo-responsive behaviour of the UCST (upper critical solution temperature) type in an aqueous solution, which could not be simply correlated to their molecular structure via an incremental analysis of the hydrophilic and hydrophobic elements incorporated within them. Increasing the spacer length separating the ammonium and the sulfonate groups of the zwitterion moiety from three to four carbons increased the phase transition temperatures markedly, whereas increasing the length of the spacer separating the ammonium group and the carboxylate ester group on the backbone from two to three carbons provoked the opposite effect. Moreover, the phase transition temperatures of the analogous polyzwitterions decreased in the order dimethylammonio > morpholinio > piperidinio alkanesulfonates. In addition to the basic effect of the polymers’ precise molecular structure, the concentration and the molar mass dependence of the phase transition temperatures were studied. Furthermore, we investigated the influence of added low molar mass salts on the aqueous-phase behaviour for sodium chloride and sodium bromide as well as sodium and ammonium sulfate. The strong effects evolved in a complex way with the salt concentration. The strength of these effects depended on the nature of the anion added, increasing in the order sulfate < chloride < bromide, thus following the empirical Hofmeister series. In contrast, no significant differences were observed when changing the cation, i.e. when adding sodium or ammonium sulfate. Y1 - 2016 U6 - https://doi.org/10.1039/c6py01220e SN - 1759-9954 SN - 1759-9962 VL - 8 SP - 310 EP - 322 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Hu, Neng A1 - Lin, Li A1 - Metwalli, Ezzeldin A1 - Bießmann, Lorenz A1 - Philipp, Martine A1 - Hildebrand, Viet A1 - Laschewsky, André A1 - Papadakis, Christine M. A1 - Cubitt, Robert A1 - Zhong, Qi A1 - Müller-Buschbaum, Peter T1 - Kinetics of water transfer between the LCST and UCST thermoresponsive blocks in diblock copolymer thin films monitored by in situ neutron reflectivity JF - Advanced materials interfaces N2 - The kinetics of water transfer between the lower critical solution temperature (LCST) and upper critical solution temperature (UCST) thermoresponsive blocks in about 10 nm thin films of a diblock copolymer is monitored by in situ neutron reflectivity. The UCST-exhibiting block in the copolymer consists of the zwitterionic poly(4((3-methacrylamidopropyl)dimethylammonio)butane-1-sulfonate), abbreviated as PSBP. The LCST-exhibiting block consists of the nonionic poly(N-isopropylacrylamide), abbreviated as PNIPAM. The as-prepared PSBP80-b-PNIPAM(400) films feature a three-layer structure, i.e., PNIPAM, mixed PNIPAM and PSBP, and PSBP. Both blocks have similar transition temperatures (TTs), namely around 32 degrees C for PNIPAM, and around 35 degrees C for PSBP, and with a two-step heating protocol (20 degrees C to 40 degrees C and 40 degrees C to 80 degrees C), both TTs are passed. The response to such a thermal stimulus turns out to be complex. Besides a three-step process (shrinkage, rearrangement, and reswelling), a continuous transfer of D2O from the PNIPAM to the PSBP block is observed. Due to the existence of both, LCST and UCST blocks in the PSBP80-b-PNIPAM(400 )film, the water transfer from the contracting PNIPAM, and mixed layers to the expanding PSBP layer occurs. Thus, the hydration kinetics and thermal response differ markedly from a thermoresponsive polymer film with a single LCST transition. KW - block copolymer KW - dual thermoresponsive KW - kinetic water transfer KW - neutron KW - reflectivity KW - thin film Y1 - 2022 U6 - https://doi.org/10.1002/admi.202201913 SN - 2196-7350 VL - 10 IS - 3 PB - Wiley-VCH CY - Weinheim ER - TY - GEN A1 - Hildebrand, Viet A1 - Laschewsky, André A1 - Wischerhoff, Erik T1 - Modulating the solubility of zwitterionic poly((3- methacrylamidopropyl)ammonioalkane sulfonate)s in water and aqueous salt solutions via the spacer group separating the cationic and the anionic moieties N2 - Complementary to the well-established zwitterionic monomer 3-((3-methacrylamidopropyl)dimethylammonio) propane-1-sulfonate (SPP), the closely related monomers 2-hydroxy-3-((3-methacrylamidopropyl) dimethylammonio)propane-1-sulfonate (SHPP) and 4-((3-methacrylamidopropyl)dimethylammonio)-butane-1-sulfonate (SBP) were synthesised and polymerised by reversible addition–fragmentation chain transfer (RAFT) polymerisation, using a fluorophore labeled RAFT agent. The polyzwitterions of systematically varied molar masses were characterised with respect to their solubility in water and aqueous salt solutions. Both poly(sulfobetaine)s show thermoresponsive behaviour in water, exhibiting phase separation at low temperatures and upper critical solution temperatures (UCST). For both polySHPP and polySBP, cloud points depend notably on the molar mass, and are much higher in D2O than in H2O. Also, the cloud points are effectively modulated by the addition of salts. The individual effects can be in parts correlated to the Hofmeister series for the anions studied. Still, they depend in a complex way on the concentration and the nature of the added electrolytes, on the one hand, and on the detailed nature of the spacer group separating the anionic and the cationic charges of the betaine moiety, on the other hand. As anticipated, the cloud points of polySBP are much higher than the ones of the analogous polySPP of identical molar mass. Surprisingly, the cloud points of polySHPP are also somewhat higher than the ones of their polySPP analogues, despite the additional hydrophilic hydroxyl group present in the spacer separating the ammonium and the sulfonate moieties. These findings point to a complicated interplay of the various hydrophilic components in polyzwitterions with respect to their overall hydrophilicity. Thus, the spacer group in the betaine moiety proves to be an effective additional molecular design parameter, apparently small variations of which strongly influence the phase behaviour of the polyzwitterions in specific aqueous environments. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 309 Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-103040 SP - 731 EP - 740 ER - TY - JOUR A1 - Hildebrand, Viet A1 - Laschewsky, Andre A1 - Wischerhoff, Erik T1 - Modulating the solubility of zwitterionic poly((3methacrylamidopropyl)ammonioalkane sulfonate)s in water and aqueous salt solutions via the spacer group separating the cationic and the anionic moieties JF - Polymer Chemistry N2 - Complementary to the well-established zwitterionic monomer 3-((3-methacrylamidopropyl) dimethylammonio) propane-1-sulfonate (SPP), the closely related monomers 2-hydroxy-3-((3-methacrylamidopropyl) dimethylammonio) propane-1-sulfonate (SHPP) and 4-((3-methacrylamidopropyl) dimethylammonio)butane- 1-sulfonate (SBP) were synthesised and polymerised by reversible addition-fragmentation chain transfer (RAFT) polymerisation, using a fluorophore labeled RAFT agent. The polyzwitterions of systematically varied molar masses were characterised with respect to their solubility in water and aqueous salt solutions. Both poly(sulfobetaine)s show thermoresponsive behaviour in water, exhibiting phase separation at low temperatures and upper critical solution temperatures (UCST). For both polySHPP and polySBP, cloud points depend notably on the molar mass, and are much higher in D2O than in H2O. Also, the cloud points are effectively modulated by the addition of salts. The individual effects can be in parts correlated to the Hofmeister series for the anions studied. Still, they depend in a complex way on the concentration and the nature of the added electrolytes, on the one hand, and on the detailed nature of the spacer group separating the anionic and the cationic charges of the betaine moiety, on the other hand. As anticipated, the cloud points of polySBP are much higher than the ones of the analogous polySPP of identical molar mass. Surprisingly, the cloud points of polySHPP are also somewhat higher than the ones of their polySPP analogues, despite the additional hydrophilic hydroxyl group present in the spacer separating the ammonium and the sulfonate moieties. These findings point to a complicated interplay of the various hydrophilic components in polyzwitterions with respect to their overall hydrophilicity. Thus, the spacer group in the betaine moiety proves to be an effective additional molecular design parameter, apparently small variations of which strongly influence the phase behaviour of the polyzwitterions in specific aqueous environments. Y1 - 2016 U6 - https://doi.org/10.1039/c5py01642h SN - 1759-9954 SN - 1759-9962 VL - 7 SP - 731 EP - 740 PB - Royal Society of Chemistry CY - Cambridge ER -