@article{DebsharmaSchmidtLaschewskyetal.2021,
  author    = {Debsharma, Tapas and Schmidt, Bernd and Laschewsky, Andre and Schlaad, Helmut},
  title     = {Ring-opening metathesis polymerization of unsaturated carbohydrate derivatives},
  series = {Macromolecules : a publication of the American Chemical Society},
  volume    = {54},
  journal   = {Macromolecules : a publication of the American Chemical Society},
  number    = {6},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0024-9297},
  doi       = {10.1021/acs.macromol.0c02821},
  pages     = {2720 -- 2728},
  year      = {2021},
  abstract  = {A series of biomass-derived levoglucosenyl alkyl ethers (alkyl = methyl, ethyl, n-propyl, isopropyl, and n-butyl) were synthesized and polymerized by ring-opening olefin metathesis polymerization using the Grubbs catalyst C793 at room temperature. Polymerizations were successfully performed in conventional solvents such as 1,4-dioxane and dichloromethane as well as in polar aprotic "green" solvents such as 2-methyltetrahydrofuran, dihydrolevoglucosenone (Cyrene), and ethyl acetate. The prepared polyacetals with degrees of polymerization of similar to 100 exhibit Schulz-Flory-type molar mass distributions and are thermoplastic materials with rather low glass transition temperatures in the range of 43-0 degrees C depending on the length of the alkyl substituent. Kinetic studies revealed that the polymerization proceeded rapidly to a steady state with a certain minimum monomer concentration threshold. When the steady state was reached, just about half of the [Ru] catalyst had been effective to initiate the polymerization, indicating that the initiation step was a slow process. The remaining catalyst was still active and did no longer react with monomers but with in-chain double bonds, cutting the formed polymer chains into shorter fragments. In the long term, all catalyst was consumed and propagating [Ru] chain ends were deactivated by the elimination of [Ru] from the chain ends to form inactive chains with terminal aldehyde groups.},
  language  = {en}
}
@article{HechenbichlerLaschewskyGradzielski2020,
  author    = {Hechenbichler, Michelle and Laschewsky, Andre and Gradzielski, Michael},
  title     = {Poly(N,N-bis(2-methoxyethyl)acrylamide), a thermoresponsive non-ionic polymer combining the amide and the ethyleneglycolether motifs},
  series = {Colloid and polymer science},
  volume    = {299},
  journal   = {Colloid and polymer science},
  number    = {2},
  publisher = {Springer},
  address   = {Berlin; Heidelberg},
  issn      = {0303-402X},
  doi       = {10.1007/s00396-020-04701-9},
  pages     = {205 -- 219},
  year      = {2020},
  abstract  = {Poly(N,N-bis(2-methoxyethyl)acrylamide) (PbMOEAm) featuring two classical chemical motifs from non-ionic water-soluble polymers, namely, the amide and ethyleneglycolether moieties, was synthesized by reversible addition fragmentation transfer (RAFT) polymerization. This tertiary polyacrylamide is thermoresponsive exhibiting a lower critical solution temperature (LCST)-type phase transition. A series of homo- and block copolymers with varying molar masses but low dispersities and different end groups were prepared. Their thermoresponsive behavior in aqueous solution was analyzed via turbidimetry and dynamic light scattering (DLS). The cloud points (CP) increased with increasing molar masses, converging to 46 degrees C for 1 wt\% solutions. This rise is attributed to the polymers' hydrophobic end groups incorporated via the RAFT agents. When a surfactant-like strongly hydrophobic end group was attached using a functional RAFT agent, CP was lowered to 42 degrees C, i.e., closer to human body temperature. Also, the effect of added salts, in particular, the role of the Hofmeister series, on the phase transition of PbMOEAm was investigated, exemplified for the kosmotropic fluoride, intermediate chloride, and chaotropic thiocyanate anions. A pronounced shift of the cloud point of about 10 degrees C to lower or higher temperatures was observed for 0.2 M fluoride and thiocyanate, respectively. When PbMOEAm was attached to a long hydrophilic block of poly(N,N-dimethylacrylamide) (PDMAm), the cloud points of these block copolymers were strongly shifted towards higher temperatures. While no phase transition was observed for PDMAm-b-pbMOEAm with short thermoresponsive blocks, block copolymers with about equally sized PbMOEAm and PDMAm blocks underwent the coil-to-globule transition around 60 degrees C.},
  language  = {en}
}
@misc{HechenbichlerLaschewskyGradzielski2020,
  author    = {Hechenbichler, Michelle and Laschewsky, Andre and Gradzielski, Michael},
  title     = {Poly(N,N-bis(2-methoxyethyl)acrylamide), a thermoresponsive non-ionic polymer combining the amide and the ethyleneglycolether motifs},
  series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  volume    = {299},
  journal   = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {2},
  publisher = {Springer},
  address   = {Berlin; Heidelberg},
  issn      = {0303-402X},
  doi       = {10.25932/publishup-59837},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-598378},
  pages     = {17},
  year      = {2020},
  abstract  = {Poly(N,N-bis(2-methoxyethyl)acrylamide) (PbMOEAm) featuring two classical chemical motifs from non-ionic water-soluble polymers, namely, the amide and ethyleneglycolether moieties, was synthesized by reversible addition fragmentation transfer (RAFT) polymerization. This tertiary polyacrylamide is thermoresponsive exhibiting a lower critical solution temperature (LCST)-type phase transition. A series of homo- and block copolymers with varying molar masses but low dispersities and different end groups were prepared. Their thermoresponsive behavior in aqueous solution was analyzed via turbidimetry and dynamic light scattering (DLS). The cloud points (CP) increased with increasing molar masses, converging to 46 degrees C for 1 wt\% solutions. This rise is attributed to the polymers' hydrophobic end groups incorporated via the RAFT agents. When a surfactant-like strongly hydrophobic end group was attached using a functional RAFT agent, CP was lowered to 42 degrees C, i.e., closer to human body temperature. Also, the effect of added salts, in particular, the role of the Hofmeister series, on the phase transition of PbMOEAm was investigated, exemplified for the kosmotropic fluoride, intermediate chloride, and chaotropic thiocyanate anions. A pronounced shift of the cloud point of about 10 degrees C to lower or higher temperatures was observed for 0.2 M fluoride and thiocyanate, respectively. When PbMOEAm was attached to a long hydrophilic block of poly(N,N-dimethylacrylamide) (PDMAm), the cloud points of these block copolymers were strongly shifted towards higher temperatures. While no phase transition was observed for PDMAm-b-pbMOEAm with short thermoresponsive blocks, block copolymers with about equally sized PbMOEAm and PDMAm blocks underwent the coil-to-globule transition around 60 degrees C.},
  language  = {en}
}
@article{KocSchoenemannArnuthalingametal.2019,
  author    = {Koc, Julian and Sch{\"o}nemann, Eric and Arnuthalingam, Ajitha and Clarke, Jessica L. and Finlay, John A. and Clare, Anthony S. and Laschewsky, Andre and Rosenhahn, Axel},
  title     = {Low-fouling thin hydrogel coatings made of photo-cross-linked polyzwitterions},
  series = {Langmuir},
  volume    = {35},
  journal   = {Langmuir},
  number    = {5},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0743-7463},
  doi       = {10.1021/acs.langmuir.8b02799},
  pages     = {1552 -- 1562},
  year      = {2019},
  abstract  = {Although zwitterionic chemistries are among the most promising materials for producing nonfouling surfaces, their structural diversity has been low until now. Here, we compare the in vitro fouling behavior of a set of four systematically varied sulfa-/sulfobetaine-containing zwitterionic hydrogel coatings against a series of proteins and nonmotile as well as motile marine organisms as model foulers. The coatings are prepared by simultaneous photoinduced cross-linking and surface anchoring to elucidate the effect of the molecular structure of the zwitterionic moieties on their antifouling activity. Analogously prepared coatings of poly(butyl methacrylate) and poly(oligoethylene glycol methacrylate) serve as references. Photoreactive polymers are synthesized by the statistical copolymerization of sulfobetaine or sulfabetaine methacrylates and methacrylamides with a benzophenone derivative of 2-hydroxyethyl methacrylate and are applied as a thin film coating. While keeping the density of the zwitterionic and cross-linker groups constant, the molecular structure of the zwitterionic side chains is varied systematically, as is the arrangement of the ion pairs in the side chain by changing the classical linear geometry to a novel Y-shaped geometry. All of the polyzwitterions strongly reduce fouling compared to poly(butyl methacrylate). Overall, the sulfabetaine polyzwitterion coatings studied matches the high antifouling effectiveness of oligo(ethylene glycol)-based ones used as a control. Nevertheless, performances varied individually for a given pair of polymer and fouler. The case of the polysulfobetaines exemplifies that minor chemical changes in the polymer structure affect the antifouling performance markedly. Accordingly, the antifouling performance of such polymers cannot be correlated simply to the type of zwitterion used (which could be generally ranked as better performing or poorer performing) but is a result of the polymer's precise chemical structure. Our findings underline the need to enlarge the existing structural diversity of polyzwitterions for antifouling purposes to optimize the potential of their chemical structure.},
  language  = {en}
}
@article{DebsharmaBehrendtLaschewskyetal.2019,
  author    = {Debsharma, Tapas and Behrendt, Felix Nicolas and Laschewsky, Andre and Schlaad, Helmut},
  title     = {Ring-opening metathesis polymerization of biomass-derived levoglucosenol},
  series = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker},
  volume    = {58},
  journal   = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker},
  number    = {20},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1433-7851},
  doi       = {10.1002/anie.201814501},
  pages     = {6718 -- 6721},
  year      = {2019},
  abstract  = {The readily available cellulose-derived bicyclic compound levoglucosenol was polymerized through ring-opening metathesis polymerization (ROMP) to yield polylevoglucosenol as a novel type of biomass-derived thermoplastic polyacetal, which, unlike polysaccharides, contains cyclic as well as linear segments in its main chain. High-molar-mass polyacetals with apparent weight-average molar masses of up to 100kgmol(-1) and dispersities of approximately 2 were produced despite the non-living/controlled character of the polymerization due to irreversible deactivation or termination of the catalyst/active chain ends. The resulting highly functionalized polyacetals are glassy in bulk with a glass transition temperature of around 100 degrees C. In analogy to polysaccharides, polylevoglucosenol degrades slowly in an acidic environment.},
  language  = {en}
}
@article{NieuwenhuisZhongMetwallietal.2019,
  author    = {Nieuwenhuis, Sophie and Zhong, Qi and Metwalli, Ezzeldin and Biessmann, Lorenz and Philipp, Martine and Miasnikova, Anna and Laschewsky, Andre and Papadakis, Christine M. and Cubitt, Robert and Wang, Jiping and M{\"u}ller-Buschbaum, Peter},
  title     = {Hydration and Dehydration Kinetics: Comparison between Poly(N-isopropyl methacrylamide) and Poly(methoxy diethylene glycol acrylate) Films},
  series = {Langmuir},
  volume    = {35},
  journal   = {Langmuir},
  number    = {24},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0743-7463},
  doi       = {10.1021/acs.langmuir.9b00535},
  pages     = {7691 -- 7702},
  year      = {2019},
  abstract  = {Thermoresponsive films of poly(N-isopropyl methacrylamide) (PNIPMAM) and poly(methoxy diethylene glycol acrylate) (PMDEGA) are compared with respect to their hydration and dehydration kinetics using in situ neutron reflectivity. Both as-prepared films present a homogeneous single-layer structure and have similar transition temperatures of the lower critical solution temperature type (TT, PNIPMAM 38 degrees C and PMDEGA 41 degrees C). After hydration in unsaturated D2O vapor at 23 degrees C, a D2O enrichment layer is observed in PNIPMAM films adjacent to the Si substrate. In contrast, two enrichment layers are present in PMDEGA films (close to the vapor interface and the Si substrate). PNIPMAM films exhibit a higher hydration capability, ascribed to having both donor (N-H) and acceptor (C=O) units for hydrogen bonds. "While the swelling of the PMDEGA films is mainly caused by the increase of the enrichment layers, the thickness of the entire PNIPMAM films increases with time. The observed longer relaxation time for swelling of PNIPMAM films is attributed to the much higher glass transition temperature of PNIPMAM. When dehydrating both films by increasing the temperature above the TT, they react with a complex response consisting of three stages (shrinkage, rearrangement, and reswelling). PNIPMAM films respond faster than PMDEGA films. After dehydration, both films still contain a large amount of D2O, and no completely dry film state is reached for a temperature above their TTs.},
  language  = {en}
}
@article{PapadakisMuellerBuschbaumLaschewsky2019,
  author    = {Papadakis, Christine M. and M{\"u}ller-Buschbaum, Peter and Laschewsky, Andre},
  title     = {Switch It Inside-Out: "Schizophrenic" Behavior of All Thermoresponsive UCST-LCST Diblock Copolymers},
  series = {Langmuir},
  volume    = {35},
  journal   = {Langmuir},
  number    = {30},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0743-7463},
  doi       = {10.1021/acs.langmuir.9b01444},
  pages     = {9660 -- 9676},
  year      = {2019},
  abstract  = {This feature article reviews our recent advancements on the synthesis, phase behavior, and micellar structures of diblock copolymers consisting of oppositely thermoresponsive blocks in aqueous environments. These copolymers combine a nonionic block, which shows lower critical solution temperature (LCST) behavior, with a zwitterionic block that exhibits an upper critical solution temperature (UCST). The transition temperature of the latter class of polymers is strongly controlled by its molar mass and by the salt concentration, in contrast to the rather invariant transition of nonionic polymers with type II LCST behavior such as poly(N-isopropylacrylamide) or poly(N-isopropyl methacrylamide). This allows for implementing the sequence of the UCST and LCST transitions of the polymers at will by adjusting either molecular or, alternatively, physical parameters. Depending on the location of the transition temperatures of both blocks, different switching scenarios are realized from micelles to inverse micelles, namely via the molecularly dissolved state, the aggregated state, or directly. In addition to studies of (semi)dilute aqueous solutions, highly concentrated systems have also been explored, namely water-swollen thin films. Concerning applications, we discuss the possible use of the diblock copolymers as "smart" nanocarriers.},
  language  = {en}
}
@article{SchoenemannLaschewskyRosenhahn2018,
  author    = {Sch{\"o}nemann, Eric and Laschewsky, Andre and Rosenhahn, Axel},
  title     = {Exploring the long-term hydrolytic behavior of zwitterionic polymethacrylates and polymethacrylamides},
  series = {Polymers},
  volume    = {10},
  journal   = {Polymers},
  number    = {6},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2073-4360},
  doi       = {10.3390/polym10060639},
  pages     = {23},
  year      = {2018},
  abstract  = {The hydrolytic stability of polymers to be used for coatings in aqueous environments, for example, to confer anti-fouling properties, is crucial. However, long-term exposure studies on such polymers are virtually missing. In this context, we synthesized a set of nine polymers that are typically used for low-fouling coatings, comprising the well-established poly(oligoethylene glycol methylether methacrylate), poly(3-(N-2-methacryloylethyl-N,N-dimethyl) ammoniopropanesulfonate) (sulfobetaine methacrylate), and poly(3-(N-3-methacryamidopropyl-N,N-dimethyl)ammoniopropanesulfonate) (sulfobetaine methacrylamide) as well as a series of hitherto rarely studied polysulfabetaines, which had been suggested to be particularly hydrolysis-stable. Hydrolysis resistance upon extended storage in aqueous solution is followed by H-1 NMR at ambient temperature in various pH regimes. Whereas the monomers suffered slow (in PBS) to very fast hydrolysis (in 1 M NaOH), the polymers, including the polymethacrylates, proved to be highly stable. No degradation of the carboxyl ester or amide was observed after one year in PBS, 1 M HCl, or in sodium carbonate buffer of pH 10. This demonstrates their basic suitability for anti-fouling applications. Poly(sulfobetaine methacrylamide) proved even to be stable for one year in 1 M NaOH without any signs of degradation. The stability is ascribed to a steric shielding effect. The hemisulfate group in the polysulfabetaines, however, was found to be partially labile.},
  language  = {en}
}
@article{NiebuurPuchmayrHeroldetal.2018,
  author    = {Niebuur, Bart-Jan and Puchmayr, Jonas and Herold, Christian and Kreuzer, Lucas and Hildebrand, Viet and M{\"u}ller-Buschbaum, Peter and Laschewsky, Andre and Papadakis, Christine M.},
  title     = {Polysulfobetaines in aqueous solution and in thin film geometry},
  series = {Materials},
  volume    = {11},
  journal   = {Materials},
  number    = {5},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1996-1944},
  doi       = {10.3390/ma11050850},
  pages     = {11},
  year      = {2018},
  abstract  = {Polysulfobetaines in aqueous solution show upper critical solution temperature (UCST) behavior. We investigate here the representative of this class of materials, poly (N,N-dimethyl-N-(3-methacrylamidopropyl) ammonio propane sulfonate) (PSPP), with respect to: (i) the dynamics in aqueous solution above the cloud point as function of NaBr concentration; and (ii) the swelling behavior of thin films in water vapor as function of the initial film thickness. For PSPP solutions with a concentration of 5 wt.\%, the temperature dependence of the intensity autocorrelation functions is measured with dynamic light scattering as function of molar mass and NaBr concentration (0-8 mM). We found a scaling of behavior for the scattered intensity and dynamic correlation length. The resulting spinodal temperatures showed a maximum at a certain (small) NaBr concentration, which is similar to the behavior of the cloud points measured previously by turbidimetry. The critical exponent of susceptibility depends on NaBr concentration, with a minimum value where the spinodal temperature is maximum and a trend towards the mean-field value of unity with increasing NaBr concentration. In contrast, the critical exponent of the correlation length does not depend on NaBr concentration and is lower than the value of 0.5 predicted by mean-field theory. For PSPP thin films, the swelling behavior was found to depend on film thickness. A film thickness of about 100 nm turns out to be the optimum thickness needed to obtain fast hydration with H2O.},
  language  = {en}
}
@article{AravopoulouKyriakosMiasnikovaetal.2018,
  author    = {Aravopoulou, Dionysia and Kyriakos, Konstantinos and Miasnikova, Anna and Laschewsky, Andre and Papadakis, Christine M. and Kyritsis, Apostolos},
  title     = {Comparative Investigation of the Thermoresponsive Behavior of Two Diblock Copolymers Comprising PNIPAM and PMDEGA Blocks},
  series = {The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces \& biophysical chemistry},
  volume    = {122},
  journal   = {The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces \& biophysical chemistry},
  number    = {9},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1520-6106},
  doi       = {10.1021/acs.jpcb.7b09647},
  pages     = {2655 -- 2668},
  year      = {2018},
  abstract  = {The thermoresponsive behavior of two diblock copolymers PS-b-PNIPAM and PS-b-PMDEGA, which both comprise a hydrophobic polystyrene (PS) block but different thermoresponsive blocks, also differing in length, poly(N-isopropylacrylamide) (PNIPAM) and poly(methoxy diethylene glycol acrylate) (PMDEGA), respectively, was comparatively investigated in a wide temperature range. Concentrated aqueous solutions containing 25 wt \% polymer were studied by small-angle X-ray scattering (SAXS), differential scanning calorimetry (DSC), and broadband dielectric spectroscopy (BDS). DSC measurements show that, during the demixing phase transition, the hydration number per oligo(ethylene glycol) side chain in the PS-b-PMDEGA solution decreases rather gradually, even up to 20 °C above the onset of the transition, i.e., the cloud point (CP). In contrast, the PS-b-PNIPAM solution exhibits an abrupt, stepwise dehydration behavior at its CP, indicated by the sharp, narrow endothermic peak. BDS measurements suggest that the organization of the expelled water during the phase transition and the subsequent evolution of the micellar aggregates are different for the two copolymers. In the PS-b-PMDEGA solution, the long-range charge transport process changes significantly at its CP and strong interfacial polarization processes appear, probably due to charge accumulation at the interfaces between the micellar aggregates and the aqueous medium. On the contrary, in the PS-b-PNIPAM solution, the phase transition has only a marginal effect on the long-range conduction process and is accompanied by a reduction in the high-frequency (1 MHz) dielectric permittivity, ε′. The latter effect is attributed to the reduced polarization strength of local chain modes due to an enhancement of intra- and interchain hydrogen bonds (HBs) in the polymer-rich phase during the water detaching process. Surprisingly, our BDS measurements indicate that prior to both the demixing and remixing processes the local chain mobility increases temporally. Our dielectric studies suggest that for PS-b-PNIPAM the water detaching process initiates a few degrees below CP and that the local chain mobility and intra- and/or interchain HBs of the PNIPAM blocks may control its thermoresponsive behavior. Dielectric "jump" experiments show that the kinetics of micellar aggregation in the PS-b-PMDEGA solution is slower than that in the PS-b-PNIPAM solution and is independent of the target temperature within the two-phase region. From the experimental point of view, it is shown that the dielectric susceptibility, especially, the dielectric permittivity, ε′, is a well-suited probe for monitoring both the reversible changes in the molecular dipolar bond polarizability and the long-range interfacial polarization at the phase transition.},
  language  = {en}
}
@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{ZhongMiMetwallietal.2018,
  author    = {Zhong, Qi and Mi, Lei and Metwalli, Ezzeldin and Biessmann, Lorenz and Philipp, Martine and Miasnikova, Anna and Laschewsky, Andre and Papadakis, Christine M. and Cubitt, Robert and Schwartzkopf, Matthias and Roth, Stephan V. and Wang, Jiping and M{\"u}ller-Buschbaum, Peter},
  title     = {Effect of chain architecture on the swelling and thermal response of star-shaped thermo-responsive (poly(methoxy diethylene glycol acrylate)-block-polystyrene)(3) block copolymer films},
  series = {Soft matter},
  volume    = {14},
  journal   = {Soft matter},
  number    = {31},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1744-683X},
  doi       = {10.1039/c8sm00965a},
  pages     = {6582 -- 6594},
  year      = {2018},
  abstract  = {The effect of chain architecture on the swelling and thermal response of thin films obtained from an amphiphilic three-arm star-shaped thermo-responsive block copolymer poly(methoxy diethylene glycol acrylate)-block-polystyrene ((PMDEGA-b-PS)(3)) is investigated by in situ neutron reflectivity (NR) measurements. The PMDEGA and PS blocks are micro-phase separated with randomly distributed PS nanodomains. The (PMDEGA-b-PS)(3) films show a transition temperature (TT) at 33 degrees C in white light interferometry. The swelling capability of the (PMDEGA-b-PS)(3) films in a D2O vapor atmosphere is better than that of films from linear PS-b-PMDEGA-b-PS triblock copolymers, which can be attributed to the hydrophilic end groups and limited size of the PS blocks in (PMDEGA-b-PS)(3). However, the swelling kinetics of the as-prepared (PMDEGA-b-PS)(3) films and the response of the swollen film to a temperature change above the TT are significantly slower than that in the PS-b-PMDEGA-b-PS films, which may be related to the conformation restriction by the star-shape. Unlike in the PS-b-PMDEGA-b-PS films, the amount of residual D2O in the collapsed (PMDEGA-b-PS)(3) films depends on the final temperature. It decreases from (9.7 +/- 0.3)\% to (7.0 +/- 0.3)\% or (6.0 +/- 0.3)\% when the final temperatures are set to 35 degrees C, 45 degrees C and 50 degrees C, respectively. This temperature-dependent reduction of embedded D2O originates from the hindrance of chain conformation from the star-shaped chain architecture.},
  language  = {en}
}
@article{NizardoSchanzenbachSchoenemannetal.2018,
  author    = {Nizardo, Noverra M. and Schanzenbach, Dirk and Sch{\"o}nemann, Eric and Laschewsky, Andre},
  title     = {Exploring poly(ethylene glycol)-polyzwitterion diblock copolymers as biocompatible smart macrosurfactants featuring UCST-phase behavior in normal saline solution},
  series = {Polymers},
  volume    = {10},
  journal   = {Polymers},
  number    = {3},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2073-4360},
  doi       = {10.3390/polym10030325},
  pages     = {22},
  year      = {2018},
  abstract  = {Nonionic-zwitterionic diblock copolymers are designed to feature a coil-to-globule collapse transition with an upper critical solution temperature (UCST) in aqueous media, including physiological saline solution. The block copolymers that combine presumably highly biocompatible blocks are synthesized by chain extension of a poly(ethylene glycol) (PEG) macroinitiator via atom transfer radical polymerization (ATRP) of sulfobetaine and sulfabetaine methacrylates. Their thermoresponsive behavior is studied by variable temperature turbidimetry and H-1 NMR spectroscopy. While the polymers with polysulfobetaine blocks exhibit phase transitions in the physiologically interesting window of 30-50 degrees C only in pure aqueous solution, the polymers bearing polysulfabetaine blocks enabled phase transitions only in physiological saline solution. By copolymerizing a pair of structurally closely related sulfo-and sulfabetaine monomers, thermoresponsive behavior can be implemented in aqueous solutions of both low and high salinity. Surprisingly, the presence of the PEG blocks can affect the UCST-transitions of the polyzwitterions notably. In specific cases, this results in "schizophrenic" thermoresponsive behavior displaying simultaneously an UCST and an LCST (lower critical solution temperature) transition. Exploratory experiments on the UCST-transition triggered the encapsulation and release of various solvatochromic fluorescent dyes as model "cargos" failed, apparently due to the poor affinity even of charged organic compounds to the collapsed state of the polyzwitterions.},
  language  = {en}
}
@article{HildebrandLaschewskyPaechetal.2017,
  author    = {Hildebrand, Viet and Laschewsky, Andre and P{\"a}ch, Michael and M{\"u}ller-Buschbaum, Peter and Papadakis, Christine M.},
  title     = {Effect of the zwitterion structure on the thermo-responsive behaviour of poly(sulfobetaine methacrylates)},
  series = {Polymer Chemistry},
  volume    = {8},
  journal   = {Polymer Chemistry},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1759-9954},
  doi       = {10.1039/c6py01220e},
  pages     = {310 -- 322},
  year      = {2017},
  abstract  = {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.},
  language  = {en}
}
@article{ZhongMetwalliRawolleetal.2017,
  author    = {Zhong, Qi and Metwalli, Ezzeldin and Rawolle, Monika and Kaune, Gunar and Bivigou Koumba, Achille Mayelle and Laschewsky, Andre and Papadakis, Christine M. and Cubitt, Robert and Wang, Jiping and M{\"u}ller-Buschbaum, Peter},
  title     = {Vacuum induced dehydration of swollen poly(methoxy diethylene glycol acrylate) and polystyrene-block-poly(methoxy diethylene glycol acrylate)-block-polystyrene films probed by in-situ neutron reflectivity},
  series = {Polymer : the international journal for the science and technology of polymers},
  volume    = {124},
  journal   = {Polymer : the international journal for the science and technology of polymers},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0032-3861},
  doi       = {10.1016/j.polymer.2017.07.066},
  pages     = {263 -- 273},
  year      = {2017},
  abstract  = {The isothermal vacuum-induced dehydration of thin films made of poly(methoxy diethylene glycol acrylate) (PMDEGA), which were swollen under ambient conditions, is studied. The dehydration behavior of the homopolymer film as well as of a nanostructured film of the amphiphilic triblock copolymer polystyrene-block-poly(methoxy diethylene glycol acrylate)-block-polystyrene, abbreviated as PS-b-PMDEGA-b-PS, are probed, and compared to the thermally induced dehydration behavior of such thin thermo-responsive films when they pass through their LCST-type coil-to globule collapse transition. The dehydration kinetics is followed by in-situ neutron reflectivity measurements. Contrast results from the use of deuterated water. Water content and film thickness are significantly reduced during the process, which can be explained by Schott second order kinetics theory for both films. The water content of the dehydrated equilibrium state from this model is very close to the residual water content obtained from the final static measurements, indicating that residual water still remains in the film even after prolonged exposure to the vacuum. In the PS-b-PMDEGA-b-PS film that shows micro-phase separation, the hydrophobic PS domains modify the dehydration process by hindering the water removal, and thus retarding dehydration by about 30\%. Whereas residual water remains tightly bound in the PMDEGA domains, water is completely removed from the PS domains of the block copolymer film. (C) 2017 Elsevier Ltd. All rights reserved.},
  language  = {en}
}
@article{HildebrandHeydenreichLaschewskyetal.2017,
  author    = {Hildebrand, Viet and Heydenreich, Matthias and Laschewsky, Andre and Moeller, Heiko M. and M{\"u}ller-Buschbaum, Peter and Papadakis, Christine M. and Schanzenbach, Dirk and Wischerhoff, Erik},
  title     = {"Schizophrenic" self-assembly of dual thermoresponsive block copolymers bearing a zwitterionic and a non-ionic hydrophilic block},
  series = {Polymer : the international journal for the science and technology of polymers},
  volume    = {122},
  journal   = {Polymer : the international journal for the science and technology of polymers},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0032-3861},
  doi       = {10.1016/j.polymer.2017.06.063},
  pages     = {347 -- 357},
  year      = {2017},
  abstract  = {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.},
  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}
}
@article{CouturierWischerhoffBerninetal.2016,
  author    = {Couturier, Jean-Philippe and Wischerhoff, Erik and Bernin, Robert and Hettrich, Cornelia and Koetz, Joachim and Sutterlin, Martin and Tiersch, Brigitte and Laschewsky, Andre},
  title     = {Thermoresponsive Polymers and Inverse Opal Hydrogels for the Detection of Diols},
  series = {Langmuir},
  volume    = {32},
  journal   = {Langmuir},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0743-7463},
  doi       = {10.1021/acs.langmuir.6b00803},
  pages     = {4333 -- 4345},
  year      = {2016},
  abstract  = {Responsive inverse opal hydrogels functionalized by boroxole moieties were synthesized and explored as sensor platforms for various low molar mass as well as polymeric diols and polyols, including saccharides, glycopolymers and catechols, by exploiting the diol induced modulation of their structural color. The underlying thermoresponsive water-soluble copolymers and hydrogels exhibit a coil-to-globule or volume phase transition, respectively, of the LCST-type. They were prepared from oligoethylene oxide methacrylate (macro)monomers and functionalized via copolymerization to bear benzoboroxole moieties. The resulting copolymers represent weak polyacids, which can bind specifically to diols within an appropriate pH window. Due to the resulting modulation of the overall hydrophilicity of the systems and the consequent shift of their phase transition temperature, the usefulness of such systems for indicating the presence of catechols, saccharides, and glycopolymers was studied, exploiting the diol/polyol induced shifts of the soluble polymers' cloud point, or the induced changes of the hydrogels' swelling. In particular, the increased acidity of benzoboroxoles compared to standard phenylboronic acids allowed performing the studies in PBS buffer (phosphate buffered saline) at the physiologically relevant pH of 7.4. The inverse opals constructed of these thermo- and analyte-responsive hydrogels enabled following the binding of specific diols by the induced shift of the optical stop band. Their highly porous structure enabled the facile and specific optical detection of not only low molar mass but also of high molar mass diol/polyol analytes such as glycopolymers. Accordingly, such thermoresponsive inverse opal systems functionalized with recognition units represent attractive and promising platforms for the facile sensing of even rather big analytes by simple optical means, or even by the bare eye.},
  language  = {en}
}
@article{KopecRozpedzikLapoketal.2016,
  author    = {Kopec, Maciej and Rozpedzik, Anna and Lapok, Lukasz and Geue, Thomas and Laschewsky, Andre and Zapotoczny, Szczepan},
  title     = {Stratified Micellar Multilayers-Toward Nanostructured Photoreactors},
  series = {Chemistry of materials : a publication of the American Chemical Society},
  volume    = {28},
  journal   = {Chemistry of materials : a publication of the American Chemical Society},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0897-4756},
  doi       = {10.1021/acs.chemmater.6b00161},
  pages     = {2219 -- 2228},
  year      = {2016},
  abstract  = {Polyelectrolyte multilayers (PEMs) with stratification of the internal structure were assembled from statistical amphiphilic copolyelectrolytes of opposite charges. These polyelectrolytes organize in aqueous solutions into micellar structures with fluoroalkyl and aromatic nanodomains, respectively, that were also preserved after deposition as thin films via layer-by-layer (LbL) electrostatic self-assembly. The unimolecular micelles, formed due to statistical compositions of amphiphilic polyelectrolytes used, were shown to suppress chain interdiffusion between adjacent layers in resulting micellar PEMs, as evidenced by spectroscopic ellipsometry, atomic force microscopy (AFM), and neutron reflectometry (NR) measurements. Additionally, hydrophobic cores of the micelles were used as hosts for photoactive molecules, namely, ferrocene and perfluorinated magnesium phthalocyanine. Stratified micellar multilayers were then deposited as hollow capsules using CaCO3 microparticles as templates. Photoinduced electron transfer (PET) between ferrocene and phthalocyanine solubilized in the polymer micelles was demonstrated to occur efficiently inside the stratified, polyelectrolyte walls of the capsules, due to the polarity gradient created by the incompatible aromatic and fluoroalkyl domains. The obtained results present a new approach to construct well-organized, self-assembled nanostructured materials for solar energy conversion.},
  language  = {en}
}
@article{HerfurthLaschewskyNoirezetal.2016,
  author    = {Herfurth, Christoph and Laschewsky, Andre and Noirez, Laurence and von Lospichl, Benjamin and Gradzielski, Michael},
  title     = {Thermoresponsive (star) block copolymers from one-pot sequential RAFT polymerizations and their self-assembly in aqueous solution},
  series = {Polymer : the international journal for the science and technology of polymers},
  volume    = {107},
  journal   = {Polymer : the international journal for the science and technology of polymers},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0032-3861},
  doi       = {10.1016/j.polymer.2016.09.089},
  pages     = {422 -- 433},
  year      = {2016},
  abstract  = {A series of hydrophobically end-capped linear triblock copolymers as well as of three-arm and four-arm star block copolymers was synthesized in a one-pot procedure from N,N-dimethylacrylamide (DMA) and N, N-diethylacrylamide (DEA). The sequential reversible addition-fragmentation chain transfer (RAFT) polymerization of these monomers via the R-approach using bi-, tri- and tetrafunctional chain transfer agents (CrAs) bearing hydrophobic dodecyl moieties proceeded in a well-controlled manner up to almost quantitative conversion. Polymers with molar masses up to 150 kDa, narrow molar mass distribution (PDI <= 1.3) and high end group functionality were obtained, which are thermoresponsive in aqueous solution showing a LCST (lower critical solution temperature) transition. The temperature-dependent associative behavior of the polymers was examined using turbidimetry, static and dynamic light scattering (SLS, DLS), and small angle neutron scattering (SANS) for structural analysis. At 25 degrees C, the polymers form weak transient networks, and rather small hydrophobic domains are already present for polymer concentrations of 5 wt\%. However, when heating above the LCST transition (35-40 degrees C) of the PDEA blocks, the enhanced formation of hydrophobic domains is observed by means of light and neutron scattering. These domains have a size of about 12-15 nm and must be effectively physically cross-linked as they induce high viscosity for the more concentrated samples. SANS shows that these domains are ordered as evidenced by the appearance of a correlation peak. The copolymer architecture affects in particular the extent of ordering as the four-arm star block copolymer shows much more repulsive interactions compared to the analogous copolymers with a lower number of arms. (C) 2016 Elsevier Ltd. All rights reserved.},
  language  = {en}
}
@article{PinyouRuffPoelleretal.2016,
  author    = {Pinyou, Piyanut and Ruff, Adrian and Poeller, Sascha and Barwe, Stefan and Nebel, Michaela and Alburquerque, Natalia Guerrero and Wischerhoff, Erik and Laschewsky, Andre and Schmaderer, Sebastian and Szeponik, Jan and Plumere, Nicolas and Schuhmann, Wolfgang},
  title     = {Thermoresponsive amperometric glucose biosensor},
  series = {Biointerphases},
  volume    = {11},
  journal   = {Biointerphases},
  publisher = {American Institute of Physics},
  address   = {Melville},
  issn      = {1934-8630},
  doi       = {10.1116/1.4938382},
  pages     = {7},
  year      = {2016},
  abstract  = {The authors report on the fabrication of a thermoresponsive biosensor for the amperometric detection of glucose. Screen printed electrodes with heatable gold working electrodes were modified by a thermoresponsive statistical copolymer [polymer I: poly(omega-ethoxytriethylenglycol methacrylate-omega-3-(N,N-dimethyl-N-2-methacryloyloxyethyl ammonio) propanesulfonate-co-omega-butoxydiethylenglycol methacrylate-co-2-(4-benzoyl-phenoxy)ethyl methacrylate)] with a lower critical solution temperature of around 28 degrees C in aqueous solution via electrochemically induced codeposition with a pH-responsive redox-polymer [polymer II: poly(glycidyl methacrylate-co-allyl methacrylate-co-poly(ethylene glycol) methacrylate-co-butyl acrylate-co-2-(dimethylamino) ethyl methacrylate)-[Os(bpy)(2)(4-(((2-(2-(2-aminoethoxy) ethoxy) ethyl) amino) methyl)-N,N-dimethylpicolinamide)](2+)] and pyrroloquinoline quinone-soluble glucose dehydrogenase acting as biological recognition element. Polymer II bears covalently bound Os-complexes that act as redox mediators for shuttling electrons between the enzyme and the electrode surface. Polymer I acts as a temperature triggered immobilization matrix. Probing the catalytic current as a function of the working electrode temperature shows that the activity of the biosensor is dramatically reduced above the phase transition temperature of polymer I. Thus, the local modulation of the temperature at the interphase between the electrode and the bioactive layer allows switching the biosensor from an on-to an off-state without heating of the surrounding analyte solution. (C) 2015 American Vacuum Society.},
  language  = {en}
}
@article{HildebrandLaschewskyWischerhoff2016,
  author    = {Hildebrand, Viet and Laschewsky, Andre and Wischerhoff, Erik},
  title     = {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},
  series = {Polymer Chemistry},
  volume    = {7},
  journal   = {Polymer Chemistry},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1759-9954},
  doi       = {10.1039/c5py01642h},
  pages     = {731 -- 740},
  year      = {2016},
  abstract  = {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.},
  language  = {en}
}
@article{EnzenbergLaschewskyBoeffeletal.2016,
  author    = {Enzenberg, Anne and Laschewsky, Andre and Boeffel, Christine and Wischerhoff, Erik},
  title     = {Influence of the Near Molecular Vicinity on the Temperature Regulated Fluorescence Response of Poly(N-vinylcaprolactam)},
  series = {Polymers},
  volume    = {8},
  journal   = {Polymers},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2073-4360},
  doi       = {10.3390/polym8040109},
  pages     = {21},
  year      = {2016},
  abstract  = {A series of new fluorescent dye bearing monomers, including glycomonomers, based on maleamide and maleic esteramide was synthesized. The dye monomers were incorporated by radical copolymerization into thermo-responsive poly(N\&\#8209;vinyl-caprolactam) that displays a lower critical solution temperature (LCST) in aqueous solution. The effects of the local molecular environment on the polymers' luminescence, in particular on the fluorescence intensity and the extent of solvatochromism, were investigated below as well as above the phase transition. By attaching substituents of varying size and polarity in the close vicinity of the fluorophore, and by varying the spacer groups connecting the dyes to the polymer backbone, we explored the underlying structure-property relationships, in order to establish rules for successful sensor designs, e.g., for molecular thermometers. Most importantly, spacer groups of sufficient length separating the fluorophore from the polymer backbone proved to be crucial for obtaining pronounced temperature regulated fluorescence responses. View Full-Text},
  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{KyriakosPhilippLinetal.2016,
  author    = {Kyriakos, Konstantinos and Philipp, Martine and Lin, Che-Hung and Dyakonova, Margarita and Vishnevetskaya, Natalya and Grillo, Isabelle and Zaccone, Alessio and Miasnikova, Anna and Laschewsky, Andre and M{\"u}ller-Buschbaum, Peter and Papadakis, Christine M.},
  title     = {Quantifying the Interactions in the Aggregation of Thermoresponsive Polymers: The Effect of Cononsolvency},
  series = {Macromolecular rapid communications},
  volume    = {37},
  journal   = {Macromolecular rapid communications},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1022-1336},
  doi       = {10.1002/marc.201500583},
  pages     = {420 -- 425},
  year      = {2016},
  abstract  = {The aggregation kinetics of thermoresponsive core-shell micelles with a poly(N-isopropyl acrylamide) shell in pure water or in mixtures of water with the cosolvents methanol or ethanol at mole fractions of 5\% is investigated during a temperature jump across the respective cloud point. Characteristically, these mixtures give rise to cononsolvency behavior. At the cloud point, aggregates are formed, and their growth is followed with time-resolved small-angle neutron scattering. Using the reversible association model, the interaction potential between the aggregates is determined from their growth rate in dependence on the cosolvents. The effect of the cosolvent is attributed to the interaction potential on the structured layer of hydration water around the aggregates. It is surmised that the latter is perturbed by the cosolvent and thus the residual repulsive hydration force between the aggregates is reduced. The larger the molar volume of the cosolvent, the more pronounced is the effect. This framework provides a molecular-level understanding of solvent-mediated effective interactions in polymer solutions and new opportunities for the rational control of self-assembly in complex soft matter systems.},
  language  = {en}
}
@article{ZhongMetwalliRawolleetal.2016,
  author    = {Zhong, Qi and Metwalli, Ezzeldin and Rawolle, Monika and Kaune, Gunar and Bivigou Koumba, Achille Mayelle and Laschewsky, Andre and Papadakis, Christine M. and Cubitt, Robert and Wang, Jiping and M{\"u}ller-Buschbaum, Peter},
  title     = {Influence of Hydrophobic Polystyrene Blocks on the Rehydration of Polystyrene-block-poly(methoxy diethylene glycol acrylate)-block-polystyrene Films Investigated by in Situ Neutron Reflectivity},
  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.5b02279},
  pages     = {317 -- 326},
  year      = {2016},
  abstract  = {The rehydration of thermoresponsive polystyrene-block-poly(methoxy diethylene glycol acrylate)-block-polystyrene (PS-b-PMDEGA-b-PS) films forming a lamellar microphase-separated structure is investigated by in situ neutron reflectivity in a D2O vapor atmosphere. The rehydration of collapsed PS-b-PMDEGA-b-PS films is realized by a temperature change from 45 to 23 degrees C and comprises (1) condensation and absorption of D2O, (2) evaporation of D2O, and (3) reswelling of the film due to internal rearrangement. The hydrophobic PS layers hinder the absorption of condensed D2O, and a redistribution of embedded D2O between the hydrophobic PS layers and the hydrophilic PMDEGA layers is observed. In contrast, the rehydration of semiswollen PS-b-PMDEGA-b-PS films (temperature change from 35 to 23 degrees C) shows two prominent differences: A thicker D2O layer condenses on the surface, causing a more enhanced evaporation of D2O. The rehydrated films differ in film thickness and volume fraction of D2O, which is due to the different thermal protocols, although the final temperature is identical.},
  language  = {en}
}
@article{GarnierLaschewsky2006,
  author    = {Garnier, Sebastien and Laschewsky, Andre},
  title     = {Non-ionic amphiphilic block copolymers by RAFT-polymerization and their self-organization},
  series = {Colloid and polymer science : official journal of the Kolloid-Gesellschaft},
  volume    = {284},
  journal   = {Colloid and polymer science : official journal of the Kolloid-Gesellschaft},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {0303-402X},
  doi       = {10.1007/s00396-006-1484-9},
  pages     = {1243 -- 1254},
  year      = {2006},
  abstract  = {Water-soluble, amphiphilic diblock copolymers were synthesized by reversible addition fragmentation chain transfer polymerization. They consist of poly(butyl acrylate) as hydrophobic block with a low glass transition temperature and three different nonionic water-soluble blocks, namely, the classical hydrophilic block poly(dimethylacrylamide), the strongly hydrophilic poly(acryloyloxyethyl methylsulfoxide), and the thermally sensitive poly(N-acryloylpyrrolidine). Aqueous micellar solutions of the block copolymers were prepared and characterized by static and dynamic light scattering analysis (DLS and SLS). No critical micelle concentration could be detected. The micellization was thermodynamically favored, although kinetically slow, exhibiting a marked dependence on the preparation conditions. The polymers formed micelles with a hydrodynamic diameter from 20 to 100 nm, which were stable upon dilution. The micellar size was correlated with the composition of the block copolymers and their overall molar mass. The micelles formed with the two most hydrophilic blocks were particularly stable upon temperature cycles, whereas the thermally sensitive poly(N-acryloylpyrrolidine) block showed a temperature-induced precipitation. According to combined SLS and DLS analysis, the micelles exhibited an elongated shape such as rods or worms. It should be noted that the block copolymers with the most hydrophilic poly(sulfoxide) block formed inverse micelles in certain organic solvents.},
  language  = {en}
}
@misc{LutzKristenSkrabaniaetal.2006,
  author    = {Lutz, Jean-Francois and Kristen, Juliane and Skrabania, Katja and Laschewsky, Andre},
  title     = {POLY 14-Synthetic strategies for preparing multicompartment micelles},
  series = {Abstracts of papers / American Chemical Society},
  volume    = {232},
  journal   = {Abstracts of papers / American Chemical Society},
  publisher = {American Chemical Society},
  address   = {Washington},
  isbn      = {0-8412-7426-6},
  issn      = {0065-7727},
  pages     = {1},
  year      = {2006},
  abstract  = {The fabrication of compartmented micellar systems is an exciting new area of research in the field of polymer self-assembly. Multicompartment micelles composed of a water-soluble shell and a segregated hydrophobic core can be obtained via direct aqueous self-assembly of preformed polymeric amphiphiles possessing one hydrophilic segment and two incompatible hydrophobic segments (e.g. hydrocarbon and fluorocarbon blocks). Such macromolecular building-blocks were prepared in the present work principally via reversible addition-fragmentation transfer polymerization (RAFT). Polysoaps or triblock macrosurfactants can be synthesized in high yields by RAFT under relatively straightforward experimental conditions.},
  language  = {en}
}