TY  - JOUR
A1  - Müller, Katharina
A1  - Foerstendorf, Harald
A1  - Steudtner, Robin
A1  - Tsushima, Satoru
A1  - Kumke, Michael Uwe
A1  - Lefèvre, Grégory
A1  - Rothe, Jörg
A1  - Mason, Harris
A1  - Szabó, Zoltán
A1  - Yang, Ping
A1  - Adam, Christian K. R.
A1  - André, Rémi
A1  - Brennenstuhl, Katlen
A1  - Chiorescu, Ion
A1  - Cho, Herman M.
A1  - Creff, Gaëlle
A1  - Coppin, Frédéric
A1  - Dardenne, Kathy
A1  - Den Auwer, Christophe
A1  - Drobot, Björn
A1  - Eidner, Sascha
A1  - Hess, Nancy J.
A1  - Kaden, Peter
A1  - Kremleva, Alena
A1  - Kretzschmar, Jerome
A1  - Krüger, Sven
A1  - Platts, James A.
A1  - Panak, Petra
A1  - Polly, Robert
A1  - Powell, Brian A.
A1  - Rabung, Thomas
A1  - Redon, Roland
A1  - Reiller, Pascal E.
A1  - Rösch, Notker
A1  - Rossberg, André
A1  - Scheinost, Andreas C.
A1  - Schimmelpfennig, Bernd
A1  - Schreckenbach, Georg
A1  - Skerencak-Frech, Andrej
A1  - Sladkov, Vladimir
A1  - Solari, Pier Lorenzo
A1  - Wang, Zheming
A1  - Washton, Nancy M.
A1  - Zhang, Xiaobin
T1  - Interdisciplinary Round-Robin Test on molecular spectroscopy of the U(VI) Acetate System
JF  - ACS omega / American Chemical Society
N2  - A comprehensive molecular analysis of a simple aqueous complexing system. U(VI) acetate. selected to be independently investigated by various spectroscopic (vibrational, luminescence, X-ray absorption, and nuclear magnetic resonance spectroscopy) and quantum chemical methods was achieved by an international round-robin test (RRT). Twenty laboratories from six different countries with a focus on actinide or geochemical research participated and contributed to this scientific endeavor. The outcomes of this RRT were considered on two levels of complexity: first, within each technical discipline, conformities as well as discrepancies of the results and their sources were evaluated. The raw data from the different experimental approaches were found to be generally consistent. In particular, for complex setups such as accelerator-based X-ray absorption spectroscopy, the agreement between the raw data was high. By contrast, luminescence spectroscopic data turned out to be strongly related to the chosen acquisition parameters. Second, the potentials and limitations of coupling various spectroscopic and theoretical approaches for the comprehensive study of actinide molecular complexes were assessed. Previous spectroscopic data from the literature were revised and the benchmark data on the U(VI) acetate system provided an unambiguous molecular interpretation based on the correlation of spectroscopic and theoretical results. The multimethodologic approach and the conclusions drawn address not only important aspects of actinide spectroscopy but particularly general aspects of modern molecular analytical chemistry.
Y1  - 2019
U6  - https://doi.org/10.1021/acsomega.9b00164
SN  - 2470-1343
VL  - 4
IS  - 5
SP  - 8167
EP  - 8177
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Warrington, Nicole
A1  - Beaumont, Robin
A1  - Horikoshi, Momoko
A1  - Day, Felix R.
A1  - Helgeland, Øyvind
A1  - Laurin, Charles
A1  - Bacelis, Jonas
A1  - Peng, Shouneng
A1  - Hao, Ke
A1  - Feenstra, Bjarke
A1  - Wood, Andrew R.
A1  - Mahajan, Anubha
A1  - Tyrrell, Jessica
A1  - Robertson, Neil R.
A1  - Rayner, N. William
A1  - Qiao, Zhen
A1  - Moen, Gunn-Helen
A1  - Vaudel, Marc
A1  - Marsit, Carmen
A1  - Chen, Jia
A1  - Nodzenski, Michael
A1  - Schnurr, Theresia M.
A1  - Zafarmand, Mohammad Hadi
A1  - Bradfield, Jonathan P.
A1  - Grarup, Niels
A1  - Kooijman, Marjolein N.
A1  - Li-Gao, Ruifang
A1  - Geller, Frank
A1  - Ahluwalia, Tarunveer Singh
A1  - Paternoster, Lavinia
A1  - Rueedi, Rico
A1  - Huikari, Ville
A1  - Hottenga, Jouke-Jan
A1  - Lyytikäinen, Leo-Pekka
A1  - Cavadino, Alana
A1  - Metrustry, Sarah
A1  - Cousminer, Diana L.
A1  - Wu, Ying
A1  - Thiering, Elisabeth Paula
A1  - Wang, Carol A.
A1  - Have, Christian Theil
A1  - Vilor-Tejedor, Natalia
A1  - Joshi, Peter K.
A1  - Painter, Jodie N.
A1  - Ntalla, Ioanna
A1  - Myhre, Ronny
A1  - Pitkänen, Niina
A1  - van Leeuwen, Elisabeth M.
A1  - Joro, Raimo
A1  - Lagou, Vasiliki
A1  - Richmond, Rebecca C.
A1  - Espinosa, Ana
A1  - Barton, Sheila J.
A1  - Inskip, Hazel M.
A1  - Holloway, John W.
A1  - Santa-Marina, Loreto
A1  - Estivill, Xavier
A1  - Ang, Wei
A1  - Marsh, Julie A.
A1  - Reichetzeder, Christoph
A1  - Marullo, Letizia
A1  - Hocher, Berthold
A1  - Lunetta, Kathryn L.
A1  - Murabito, Joanne M.
A1  - Relton, Caroline L.
A1  - Kogevinas, Manolis
A1  - Chatzi, Leda
A1  - Allard, Catherine
A1  - Bouchard, Luigi
A1  - Hivert, Marie-France
A1  - Zhang, Ge
A1  - Muglia, Louis J.
A1  - Heikkinen, Jani
A1  - Morgen, Camilla S.
A1  - van Kampen, Antoine H. C.
A1  - van Schaik, Barbera D. C.
A1  - Mentch, Frank D.
A1  - Langenberg, Claudia
A1  - Scott, Robert A.
A1  - Zhao, Jing Hua
A1  - Hemani, Gibran
A1  - Ring, Susan M.
A1  - Bennett, Amanda J.
A1  - Gaulton, Kyle J.
A1  - Fernandez-Tajes, Juan
A1  - van Zuydam, Natalie R.
A1  - Medina-Gomez, Carolina
A1  - de Haan, Hugoline G.
A1  - Rosendaal, Frits R.
A1  - Kutalik, Zoltán
A1  - Marques-Vidal, Pedro
A1  - Das, Shikta
A1  - Willemsen, Gonneke
A1  - Mbarek, Hamdi
A1  - Müller-Nurasyid, Martina
A1  - Standl, Marie
A1  - Appel, Emil V. R.
A1  - Fonvig, Cilius Esmann
A1  - Trier, Caecilie
A1  - van Beijsterveldt, Catharina E. M.
A1  - Murcia, Mario
A1  - Bustamante, Mariona
A1  - Bonàs-Guarch, Sílvia
A1  - Hougaard, David M.
A1  - Mercader, Josep M.
A1  - Linneberg, Allan
A1  - Schraut, Katharina E.
A1  - Lind, Penelope A.
A1  - Medland, Sarah Elizabeth
A1  - Shields, Beverley M.
A1  - Knight, Bridget A.
A1  - Chai, Jin-Fang
A1  - Panoutsopoulou, Kalliope
A1  - Bartels, Meike
A1  - Sánchez, Friman
A1  - Stokholm, Jakob
A1  - Torrents, David
A1  - Vinding, Rebecca K.
A1  - Willems, Sara M.
A1  - Atalay, Mustafa
A1  - Chawes, Bo L.
A1  - Kovacs, Peter
A1  - Prokopenko, Inga
A1  - Tuke, Marcus A.
A1  - Yaghootkar, Hanieh
A1  - Ruth, Katherine S.
A1  - Jones, Samuel E.
A1  - Loh, Po-Ru
A1  - Murray, Anna
A1  - Weedon, Michael N.
A1  - Tönjes, Anke
A1  - Stumvoll, Michael
A1  - Michaelsen, Kim Fleischer
A1  - Eloranta, Aino-Maija
A1  - Lakka, Timo A.
A1  - van Duijn, Cornelia M.
A1  - Kiess, Wieland
A1  - Koerner, Antje
A1  - Niinikoski, Harri
A1  - Pahkala, Katja
A1  - Raitakari, Olli T.
A1  - Jacobsson, Bo
A1  - Zeggini, Eleftheria
A1  - Dedoussis, George V.
A1  - Teo, Yik-Ying
A1  - Saw, Seang-Mei
A1  - Montgomery, Grant W.
A1  - Campbell, Harry
A1  - Wilson, James F.
A1  - Vrijkotte, Tanja G. M.
A1  - Vrijheid, Martine
A1  - de Geus, Eco J. C. N.
A1  - Hayes, M. Geoffrey
A1  - Kadarmideen, Haja N.
A1  - Holm, Jens-Christian
A1  - Beilin, Lawrence J.
A1  - Pennell, Craig E.
A1  - Heinrich, Joachim
A1  - Adair, Linda S.
A1  - Borja, Judith B.
A1  - Mohlke, Karen L.
A1  - Eriksson, Johan G.
A1  - Widen, Elisabeth E.
A1  - Hattersley, Andrew T.
A1  - Spector, Tim D.
A1  - Kaehoenen, Mika
A1  - Viikari, Jorma S.
A1  - Lehtimaeki, Terho
A1  - Boomsma, Dorret I.
A1  - Sebert, Sylvain
A1  - Vollenweider, Peter
A1  - Sorensen, Thorkild I. A.
A1  - Bisgaard, Hans
A1  - Bonnelykke, Klaus
A1  - Murray, Jeffrey C.
A1  - Melbye, Mads
A1  - Nohr, Ellen A.
A1  - Mook-Kanamori, Dennis O.
A1  - Rivadeneira, Fernando
A1  - Hofman, Albert
A1  - Felix, Janine F.
A1  - Jaddoe, Vincent W. V.
A1  - Hansen, Torben
A1  - Pisinger, Charlotta
A1  - Vaag, Allan A.
A1  - Pedersen, Oluf
A1  - Uitterlinden, Andre G.
A1  - Jarvelin, Marjo-Riitta
A1  - Power, Christine
A1  - Hypponen, Elina
A1  - Scholtens, Denise M.
A1  - Lowe, William L.
A1  - Smith, George Davey
A1  - Timpson, Nicholas J.
A1  - Morris, Andrew P.
A1  - Wareham, Nicholas J.
A1  - Hakonarson, Hakon
A1  - Grant, Struan F. A.
A1  - Frayling, Timothy M.
A1  - Lawlor, Debbie A.
A1  - Njolstad, Pal R.
A1  - Johansson, Stefan
A1  - Ong, Ken K.
A1  - McCarthy, Mark I.
A1  - Perry, John R. B.
A1  - Evans, David M.
A1  - Freathy, Rachel M.
T1  - Maternal and fetal genetic effects on birth weight and their relevance to cardio-metabolic risk factors
JF  - Nature genetics
N2  - Birth weight variation is influenced by fetal and maternal genetic and non-genetic factors, and has been reproducibly associated with future cardio-metabolic health outcomes. In expanded genome-wide association analyses of own birth weight (n = 321,223) and offspring birth weight (n = 230,069 mothers), we identified 190 independent association signals (129 of which are novel). We used structural equation modeling to decompose the contributions of direct fetal and indirect maternal genetic effects, then applied Mendelian randomization to illuminate causal pathways. For example, both indirect maternal and direct fetal genetic effects drive the observational relationship between lower birth weight and higher later blood pressure: maternal blood pressure-raising alleles reduce offspring birth weight, but only direct fetal effects of these alleles, once inherited, increase later offspring blood pressure. Using maternal birth weight-lowering genotypes to proxy for an adverse intrauterine environment provided no evidence that it causally raises offspring blood pressure, indicating that the inverse birth weight-blood pressure association is attributable to genetic effects, and not to intrauterine programming.
Y1  - 2019
SN  - 1061-4036
SN  - 1546-1718
VL  - 51
IS  - 5
SP  - 804
EP  - +
PB  - Nature Publ. Group
CY  - New York
ER  - 
TY  - JOUR
A1  - Wang, Weijia
A1  - Kaune, Gunar
A1  - Perlich, Jan
A1  - Paradakis, Christine M.
A1  - Bivigou Koumba, Achille Mayelle
A1  - Laschewsky, André
A1  - Schlage, K.
A1  - Röhlsberger, Ralf
A1  - Roth, Stephan V.
A1  - Cubitt, Robert
A1  - Müller-Buschbaum, Peter
T1  - Swelling and switching kinetics of gold coated end-capped poly(N-isopropylacrylamide) thin films
N2  - Thin thermoresponsive hydrogel films of poly(N-isopropylacrylamide) end-capped with n-butyltrithiocarbonate(nbc- PNIPAM) oil si I icon supports with a gold layer on top, causing an asymmetric confinement, are investigated. For two different gold layer thicknesses (nominally 0.4 and 5 rim), the swelling and switching kinetics are probed with in situ neutron reflectivity. With a temperature jump from 23 to 40 degrees C the film is switched from a swollen into a collapsed state. For the thin gold layer this switching is faster as compared to the thick gold layer. The switching is a two-step process of water release and a subsequent structural relaxation. fit swelling and deswelling cycles, aging of the films is probed. After five cycles, the film exhibits enhanced water storage capacity. Grazing-incidence small-angle X-ray scattering (GISAXS) shows that these gold coated nbc-PNIPAM films do not age with respect to the inner structure but slightly roughen at the gold surface. As revealed by atomic force microscopy, the morphology of the gold layer is changed by the water uptake and release.
Y1  - 2010
UR  - http://pubs.acs.org/journal/mamobx
U6  - https://doi.org/10.1021/Ma902637a
SN  - 0024-9297
ER  - 
TY  - JOUR
A1  - Harms, Stephan
A1  - Raetzke, Klaus
A1  - Faupel, Franz
A1  - Egger, Werner
A1  - Ravello, Lori Boyd de
A1  - Laschewsky, André
A1  - Wang, Weinan
A1  - Müller-Buschbaum, Peter
T1  - Free volume and swelling in thin films of poly(n-isopropylacrylamide) end-capped with n-butyltrithiocarbonate
N2  - The free volume in thin films of poly(N-isopropylacrylamid) end-capped with n-butyltrio-carbonate (nbc-PNIPAM) is probed with positron annihilation lifetime spectroscopy (PALS). The PALS measurements are performed as function of energy to obtain depth profiles of the free volume of nbc-PNIPAM films. The range of nbc-PNIPAM films with thicknesses from 40 to 200 nm is focused. With decreasing film thickness the free volume increases in good agreement with an increase in the maximum swelling capability of the nbc-PNIPAM films. Thus in thin hydrogel films the sorption and swelling behavior is governed by free volume.
Y1  - 2010
UR  - http://www3.interscience.wiley.com/cgi-bin/jhome/10003270
U6  - https://doi.org/10.1002/marc.201000067
SN  - 1022-1336
ER  - 
TY  - JOUR
A1  - Sumpf, Bernd
A1  - Maiwald, Martin
A1  - Muller, Andre
A1  - Ginolas, Arnim
A1  - Haeusler, Karl
A1  - Erbert, Goetz
A1  - Traenkle, Guenther
T1  - Reliable operation for 14 500 h of a wavelength-stabilized Diode Laser System on a Microoptical Bench at 671 nm
JF  - IEEE transactions on components, packaging and manufacturing technology
N2  - Reliability tests for wavelength-stabilized compact diode laser systems emitting at 671 nm are presented. The devices were mounted on microoptical benches with the dimensions of 13 mm x 4 mm. Reflecting Bragg gratings were used for wavelength stabilization and emission width narrowing. The reliability tests were performed at 25 degrees C and at an output power up to 10 mW per micrometer stripe width of the gain medium. Reliable operation could be demonstrated over a test time up to 14 500 h at an output power up to 1.0 W. Environmental tests using random vibrations with acceleration up to 29 g were performed without deterioration of the devices.
KW  - High-power lasers
KW  - laser resonators
KW  - Raman spectroscopy
KW  - reliability
KW  - semiconductor lasers
Y1  - 2012
U6  - https://doi.org/10.1109/TCPMT.2011.2171342
SN  - 2156-3950
VL  - 2
IS  - 1
SP  - 116
EP  - 121
PB  - Inst. of Electr. and Electronics Engineers
CY  - Piscataway
ER  - 
TY  - JOUR
A1  - Kreuzer, Lucas
A1  - Lindenmeir, Christoph
A1  - Geiger, Christina
A1  - Widmann, Tobias
A1  - Hildebrand, Viet
A1  - Laschewsky, André
A1  - Papadakis, Christine M.
A1  - Müller-Buschbaum, Peter
T1  - Poly(sulfobetaine) versus poly(N-isopropylmethacrylamide)
BT  - co-nonsolvency-type behavior of thin films in a water/methanol atmosphere
JF  - Macromolecules : a publication of the American Chemical Society
N2  - The swelling and co-nonsolvency behaviors in pure H2O and in a mixed H2O/CH3OH vapor atmosphere of two different polar, water-soluble polymers in thin film geometry are studied in situ. Films of a zwitterionic poly(sulfobetaine), namely, poly[3-((2-(methacryloyloxy)ethyl)dimethylammonio) propane-1-sulfonate] (PSPE), and a polar nonionic polymer, namely, poly(N-isopropylmethacrylamide) (PNIPMAM), are investigated in real time by spectral reflectance (SR) measurements and Fourier transform infrared (FTIR) spectroscopy. Whereas PSPE is insoluble in methanol, PNIPMAM is soluble but exhibits cononsolvency behavior in water/methanol mixtures. First, the swelling of PSPE and PNIPMAM thin films in H2O vapor is followed. Subsequently, CH3OH is added to the vapor atmosphere, and its contracting effect on the water-swollen films is monitored, revealing a co-nonsolvency-type behavior for PNIPMAM and PSPE. SR measurements indicate that PSPE and PNIPMAM behave significantly different during the H2O swelling and subsequent exposure to CH3OH, not only with respect to the amounts of absorbed water and CH3OH, but also to the cosolvent-induced contraction mechanisms. While PSPE thin films exhibit an abrupt one-step contraction, the contraction of PNIPMAM thin films occurs in two steps. FTIR studies corroborate these findings on a molecular scale and reveal the role of the specific functional groups, both during the swelling and the cosolvent-induced switching of the solvation state.
Y1  - 2021
U6  - https://doi.org/10.1021/acs.macromol.0c02281
SN  - 0024-9297
SN  - 1520-5835
VL  - 54
IS  - 3
SP  - 1548
EP  - 1556
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Kreuzer, Lucas
A1  - Widmann, Tobias
A1  - Geiger, Christina
A1  - Wang, Peixi
A1  - Vagias, Apostolos N.
A1  - Heger, Julian Eliah
A1  - Haese, Martin
A1  - Hildebrand, Viet
A1  - Laschewsky, André
A1  - Papadakis, Christine M.
A1  - Müller-Buschbaum, Peter
T1  - Salt-dependent phase transition behavior of doubly thermoresponsive poly(sulfobetaine)-based diblock copolymer thin films
JF  - Langmuir : the ACS journal of surfaces and colloids / American Chemical Society
N2  - The water vapor-induced swelling, as well as subsequent phase-transition kinetics, of thin films of a diblock copolymer (DBC) loaded with different amounts of the salt NaBr, is investigated in situ. In dilute aqueous solution, the DBC features an orthogonally thermoresponsive behavior. It consists of a zwitterionic poly(sulfobetaine) block, namely, poly(4-(N-(3'-methacrylamidopropyl)-N, N-dimethylammonio) butane-1-sulfonate) (PSBP), showing an upper critical solution temperature, and a nonionic block, namely, poly(N-isopropylmethacrylamide) (PNIPMAM), exhibiting a lower critical solution temperature. The swelling kinetics in D2O vapor at 15 degrees C and the phase transition kinetics upon heating the swollen film to 60 degrees C and cooling back to 15 degrees C are followed with simultaneous time-of-flight neutron reflectometry and spectral reflectance measurements. These are complemented by Fourier transform infrared spectroscopy. The collapse temperature of PNIPMAM and the swelling temperature of PSBP are found at lower temperatures than in aqueous solution, which is attributed to the high polymer concentration in the thin-film geometry. Upon inclusion of sub-stoichiometric amounts (relative to the monomer units) of NaBr in the films, the water incorporation is significantly increased. This increase is mainly attributed to a salting-in effect on the zwitterionic PSBP block. Whereas the addition of NaBr notably shifts the swelling temperature of PSBP to lower temperatures, the collapse temperature of PNIPMAM remains unaffected by the presence of salt in the films.
Y1  - 2021
U6  - https://doi.org/10.1021/acs.langmuir.1c01342
SN  - 0743-7463
SN  - 1520-5827
VL  - 37
IS  - 30
SP  - 9179
EP  - 9191
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Wang, Peixi
A1  - Geiger, Christina
A1  - Kreuzer, Lucas
A1  - Widmann, Tobias
A1  - Reitenbach, Julija
A1  - Liang, Suzhe
A1  - Cubitt, Robert
A1  - Henschel, Cristiane
A1  - Laschewsky, André
A1  - Papadakis, Christine M.
A1  - Müller-Buschbaum, Peter
T1  - Poly(sulfobetaine)-based diblock copolymer thin films in water/acetone atmosphere: modulation of water hydration and co-nonsolvency-triggered film contraction
JF  - Langmuir : the ACS journal of surfaces and colloids
N2  - The water swelling and subsequent solvent exchange including co-nonsolvency behavior of thin films of a doubly thermo-responsive diblock copolymer (DBC) are studied viaspectral reflectance, time-of-flight neutron reflectometry, and Fourier transform infrared spectroscopy. 
The DBC consists of a thermo-responsive zwitterionic (poly(4-((3-methacrylamidopropyl) dimethylammonio) butane-1-sulfonate)) (PSBP) block, featuring an upper critical solution temperature transition in aqueous media but being insoluble in acetone, and a nonionic poly(N-isopropylmethacrylamide) (PNIPMAM) block, featuring a lower critical solution temperature transition in water, while being soluble in acetone. 
Homogeneous DBC films of 50-100 nm thickness are first swollen in saturated water vapor (H2OorD2O), before they are subjected to a contraction process by exposure to mixed saturated water/acetone vapor (H2OorD2O/acetone-d6 = 9:1 v/v).
The affinity of the DBC film toward H2O is stronger than for D2O, as inferred from the higher film thickness in the swollen state and the higher absorbed water content, thus revealing a pronounced isotope sensitivity. 
During the co-solvent-induced switching by mixed water/acetone vapor, a two-step film contraction is observed, which is attributed to the delayed expulsion of water molecules and uptake of acetone molecules. 
The swelling kinetics are compared for both mixed vapors (H2O/acetone-d6 and D2O/acetone-d6) and with those of the related homopolymer films. 
Moreover, the concomitant variations of the local environment around the hydrophilic groups located in the PSBP and PNIPMAM blocks are followed. 
The first contraction step turns out to be dominated by the behavior of the PSBP block, where as the second one is dominated by the PNIPMAM block. 
The unusual swelling and contraction behavior of the latter block is attributed to its co-nonsolvency behavior. 
Furthermore, we observe cooperative hydration effects in the DBC films, that is, both polymer blocks influence each other's solvation behavior.
Y1  - 2022
U6  - https://doi.org/10.1021/acs.langmuir.2c00451
SN  - 0743-7463
SN  - 1520-5827
VL  - 38
IS  - 22
SP  - 6934
EP  - 6948
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Niebuur, Bart-Jan
A1  - Puchmayr, Jonas
A1  - Herold, Christian
A1  - Kreuzer, Lucas
A1  - Hildebrand, Viet
A1  - Müller-Buschbaum, Peter
A1  - Laschewsky, Andre
A1  - Papadakis, Christine M.
T1  - Polysulfobetaines in aqueous solution and in thin film geometry
JF  - Materials
N2  - 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.
KW  - polyzwitterions
KW  - polysulfobetaines
KW  - dynamic light scattering
KW  - phase behavior
Y1  - 2018
U6  - https://doi.org/10.3390/ma11050850
SN  - 1996-1944
VL  - 11
IS  - 5
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Adelsberger, Joseph
A1  - Grillo, Isabelle
A1  - Kulkarni, Amit
A1  - Sharp, Melissa
A1  - Bivigou Koumba, Achille Mayelle
A1  - Laschewsky, André
A1  - Müller-Buschbaum, Peter
A1  - Papadakis, Christine M.
T1  - Kinetics of aggregation in micellar solutions of thermoresponsive triblock copolymers - influence of concentration, start and target temperatures
JF  - Soft matter
N2  - In aqueous solution, symmetric triblock copolymers with a thermoresponsive middle block and hydrophobic end blocks form flower-like core-shell micelles which collapse and aggregate upon heating through the cloud point (CP). The collapse of the micellar shell and the intermicellar aggregation are followed in situ and in real-time using time-resolved small-angle neutron scattering (SANS), while heating micellar solutions of a poly((styrene-d(8))-b-(N-isopropyl acrylamide)-b-(styrene-d(8))) triblock copolymer in D2O rapidly through their CP. The influence of polymer concentration as well as of the start and target temperatures is addressed. In all cases, the micellar collapse is very fast. The collapsed micelles immediately form small clusters which contain voids. They densify which slows down or even stops their growth. For low concentrations and target temperatures just above the CP, i.e. shallow temperature jumps, the subsequent growth of the clusters is described by diffusion-limited aggregation. In contrast, for higher concentrations and/or higher target temperatures, i.e. deep temperature jumps, intermicellar bridges dominate the growth. Eventually, in all cases, the clusters coagulate which results in macroscopic phase separation. For shallow temperature jumps, the cluster surfaces stay rough; whereas for deep temperature jumps, a concentration gradient develops at late stages. These results are important for the development of conditions for thermal switching in applications, e.g. for the use of thermoresponsive micellar systems for transport and delivery purposes.
Y1  - 2013
U6  - https://doi.org/10.1039/c2sm27152d
SN  - 1744-683X
VL  - 9
IS  - 5
SP  - 1685
EP  - 1699
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Miasnikova, Anna
A1  - Laschewsky, André
A1  - De Paoli, Gabriele
A1  - Papadakis, Christine M.
A1  - Müller-Buschbaum, Peter
A1  - Funari, Sergio S.
T1  - Thermoresponsive Hydrogels from Symmetrical Triblock Copolymers Poly(styrene-block-(methoxy diethylene glycol acrylate)-block-styrene)
JF  - Langmuir
N2  - A series of symmetrical, thermo-responsive triblock copolymers was prepared by reversible addition fragmentation chain transfer (RAFT) polymerization, and studied in aqueous solution with respect to their ability to form hydrogels. Triblock copolymers were composed of two identical, permanently hydrophobic outer blocks, made of low molar mass polystyrene, and of a hydrophilic inner block of variable length, consisting of poly(methoxy diethylene glycol acrylate) PMDEGA. The polymers exhibited a LCST-type phase transition in the range of 20-40 degrees C, which markedly depended on molar mass and concentration. Accordingly, the triblock copolymers behaved as amphiphiles at low temperatures, but became water-insoluble at high temperatures. The temperature dependent self-assembly of the amphiphilic block copolymers in aqueous solution was studied by turbidimetry and rheology at concentrations up to 30 wt %, to elucidate the impact of the inner thermoresponsive block on the gel properties. Additionally, small-angle X-ray scattering (SAXS) was performed to access the structural changes in the gel with temperature. For all polymers a gel phase was obtained at low temperatures, which underwent a gel-sol transition at intermediate temperatures, well below the cloud point where phase separation occurred. With increasing length of the PMDEGA inner block, the gel-sol transition shifts to markedly lower concentrations, as well as to higher transition temperatures. For the longest PMDEGA block studied (DPn about 450), gels had already formed at 3.5 wt % at low temperatures. The gel-sol transition of the hydrogels and the LCST-type phase transition of the hydrophilic inner block were found to be independent of each other.
Y1  - 2012
U6  - https://doi.org/10.1021/la204665q
SN  - 0743-7463
VL  - 28
IS  - 9
SP  - 4479
EP  - 4490
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Zhong, Qi
A1  - Adelsberger, Joseph
A1  - Niedermeier, M. A.
A1  - Golosova, Anastasi
A1  - Bivigou Koumba, Achille Mayelle
A1  - Laschewsky, André
A1  - Funari, S. S.
A1  - Papadakis, Christine M.
A1  - Müller-Buschbaum, Peter
T1  - The influence of selective solvents on the transition behavior of poly(styrene-b-monomethoxydiethylenglycol-acrylate-b-styrene) thick films
JF  - Colloid and polymer science : official journal of the Kolloid-Gesellschaft
N2  - Thick poly(styrene-b-monomethoxydiethylenglycol-acrylate-b-styrene) [P(S-b-MDEGA-b-S)] films (thickness 5 mu m) are prepared from different solvents on flexible substrates by solution casting and investigated with small-angle X-ray scattering. As the solvents are either PS- or PMDEGA-selective, micelles with different core-shell micellar structures are formed. In PMDEGA-selective solvents, the PS block is the core and PMDEGA is the shell, whereas in PS-selective solvents, the order is reversed. After exposing the films to liquid D2O, the micellar structure inside the films prepared from PMDEGA-selective solvents remains unchanged and only the PMDEGA (shell part) swells. On the contrary, in the films prepared from PS-selective solvents, the micelles revert the core and the shell. This reversal causes more entanglements of the PMDEGA chains between the micelles. Moreover, the thermal collapse transition of the PMDEGA block in liquid D2O is significantly broadened. Irrespective of the solvent used for film preparation, the swollen PMDEGA shell does not show a prominent shrinkage when passing the phase transition, and the transition process occurs via compaction. The collapsed micelles have a tendency to densely pack above the transition temperature.
KW  - Hydrogel
KW  - Thin film
KW  - Thermo-responsive
KW  - LCST behavior
KW  - SAXS
Y1  - 2013
U6  - https://doi.org/10.1007/s00396-012-2879-4
SN  - 0303-402X
VL  - 291
IS  - 6
SP  - 1439
EP  - 1451
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Adelsberger, Joseph
A1  - Kulkarni, Amit
A1  - Jain, Abhinav
A1  - Wang, Weinan
A1  - Bivigou Koumba, Achille Mayelle
A1  - Busch, Peter
A1  - Pipich, Vitaliy
A1  - Holderer, Olaf
A1  - Hellweg, Thomas
A1  - Laschewsky, André
A1  - Müller-Buschbaum, Peter
A1  - Papadakis, Christine M.
T1  - Thermoresponsive PS-b-PNIPAM-b-PS micelles : aggregation behavior, segmental dynamics, and thermal response
N2  - We have studied I lie thermal behavior of amphiphilic, symmetric triblock copolymers having short, deuterated polystyrene (PS) end blocks and a large poly(N-isopropylacrylarnicle) (PNIPAM) middle block exhibiting a lower critical solution temperature (LCST) in aqueous solution. A wide range of concentrations (0.1-300 mg/mL) is investigated using it number of analytical methods such as fluorescence correlation spectroscopy (FCS), turbidimetry, dynamic light scattering (DLS), small-angle neutron scattering (SANS), and neutron spin-echo spectroscopy (NSE). The critical micelle concentration is determined using FCS to be 1 mu M or less. The collapse of the micelles at the LCST is investigated using turbidimetry and DLS and shows a weak dependence on the degree of polymerization of the PNIPAM block. SANS with contrast matching allows its to reveal the core-shell Structure of the micelles as well as their correlation as a function of temperature. The segmental dynamics of the PNIPAM shell are studied as a function of temperature and arc found to be faster in the collapsed state than in the swollen state. The mode detected has a linear dispersion in q(2) and is found to be faster in the collapsed state as compared to the swollen state. We attribute this result to the averaging over mobile and immobilized segments.
Y1  - 2010
UR  - http://pubs.acs.org/journal/mamobx
U6  - https://doi.org/10.1021/Ma902714p
SN  - 0024-9297
ER  - 
TY  - JOUR
A1  - Bivigou Koumba, Achille Mayelle
A1  - Goernitz, Eckhard
A1  - Laschewsky, André
A1  - Müller-Buschbaum, Peter
A1  - Papadakis, Christine M.
T1  - Thermoresponsive amphiphilic symmetrical triblock copolymers with a hydrophilic middle block made of poly(N- isopropylacrylamide) : synthesis, self-organization, and hydrogel formation
N2  - Several series of symmetrical triblock copolymers were synthesized by the reversible addition fragmentation chain transfer method. They consist of a long block of poly(N-isopropylacrylamide) as hydrophilic, thermoresponsive middle block, which is end-capped by two small strongly hydrophobic blocks made from five different vinyl polymers. The association of the amphiphilic polymers was studied in dilute and concentrated aqueous solution. The polymer micelles found at low concentrations form hydrogels at high concentrations, typically above 30-35 wt.%. Hydrogel formation and the thermosensitive rheological behavior were studied exemplarily for copolymers with hydrophobic blocks of polystyrene, poly(2-ethylhexyl acrylate), and poly(n-octadecyl acrylate). All systems exhibited a cloud point around 30 A degrees C. Heating beyond the cloud point initially favors hydrogel formation but continued heating results in macroscopic phase separation. The rheological behavior suggests that the copolymers associate into flower-like micelles, with only a small share of polymers that bridge the micelles and act as physical cross-linkers, even at high concentrations.
Y1  - 2010
UR  - http://www.springerlink.com/content/101551
U6  - https://doi.org/10.1007/s00396-009-2179-9
SN  - 0303-402X
ER  - 
TY  - JOUR
A1  - Bivigou Koumba, Achille Mayelle
A1  - Kristen, Juliane
A1  - Laschewsky, André
A1  - Müller-Buschbaum, Peter
A1  - Papadakis, Christine M.
T1  - Synthesis of symmetrical triblock copolymers of styrene and N-isopropylacrylamide using bifunctional bis(trithiocarbonate)s as RAFT agents
N2  - Six new bifunctional bis(trithiocarbonate)s were explored as RAFT agents for synthesizing amphiphilic triblock copolymers ABA and BAB, with hydrophilic "A" blocks made from N-isopropylacrylamide and hydrophobic "B" blocks made from styrene. Whereas the extension of poly(N-isopropylacrylamide) by styrene was not effective, polystyrene macroRAFT agents provided the block copolymers efficiently. End group analysis by H-1 NMR spectroscopy supported molar mass analysis and revealed an unexpected side reaction for certain bis(trithiocarbonate)s, namely a fragmentation to simple trithiocarbonates while extruding ethylene-trithiocarbonate. The amphiphilic block copolymers with short polystyrene blocks are directly soluble in water and self-organize into thermo-responsive micellar aggregates.
Y1  - 2009
UR  - http://onlinelibrary.wiley.com/journal/10.1002/%28ISSN%291521-3935
U6  - https://doi.org/10.1002/macp.200800575
SN  - 1022-1352
ER  - 
TY  - JOUR
A1  - Kyriakos, Konstantinos
A1  - Aravopoulou, Dionysia
A1  - Augsbach, Lukas
A1  - Sapper, Josef
A1  - Ottinger, Sarah
A1  - Psylla, Christina
A1  - Rafat, Ali Aghebat
A1  - Benitez-Montoya, Carlos Adrian
A1  - Miasnikova, Anna
A1  - Di, Zhenyu
A1  - Laschewsky, André
A1  - Müller-Buschbaum, Peter
A1  - Kyritsis, Apostolos
A1  - Papadakis, Christine M.
T1  - Novel thermoresponsive block copolymers having different architectures-structural, rheological, thermal, and dielectric investigations
JF  - Colloid and polymer science : official journal of the Kolloid-Gesellschaft
N2  - Thermoresponsive block copolymers comprising long, hydrophilic, nonionic poly(methoxy diethylene glycol acrylate) (PMDEGA) blocks and short hydrophobic polystyrene (PS) blocks are investigated in aqueous solution. Various architectures, namely diblock, triblock, and starblock copolymers are studied as well as a PMDEGA homopolymer as reference, over a wide concentration range. For specific characterization methods, polymers were labeled, either by partial deuteration (for neutron scattering studies) or by fluorophores. Using fluorescence correlation spectroscopy, critical micellization concentrations are identified and the hydrodynamic radii of the micelles, r (h) (mic) , are determined. Using dynamic light scattering, the behavior of r (h) (mic) in dependence on temperature and the cloud points are measured. Small-angle neutron scattering enabled the detailed structural investigation of the micelles and their aggregates below and above the cloud point. Viscosity measurements are carried out to determine the activation energies in dependence on the molecular architecture. Differential scanning calorimetry at high polymer concentration reveals the glass transition of the polymers, the fraction of uncrystallized water and effects of the phase transition at the cloud point. Dielectric relaxation spectroscopy shows that the polarization changes reversibly at the cloud point, which reflects the formation of large aggregates upon heating through the cloud point and their redissolution upon cooling.
KW  - Block copolymers
KW  - Thermoresponsive
KW  - Structural investigations
KW  - Mechanical properties
KW  - Thermal behavior
KW  - Dielectric properties
Y1  - 2014
U6  - https://doi.org/10.1007/s00396-014-3282-0
SN  - 0303-402X
SN  - 1435-1536
VL  - 292
IS  - 8
SP  - 1757
EP  - 1774
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Kyriakos, Konstantinos
A1  - Philipp, Martine
A1  - Adelsberger, Joseph
A1  - Jaksch, Sebastian
A1  - Berezkin, Anatoly V.
A1  - Lugo, Dersy M.
A1  - Richtering, Walter
A1  - Grillo, Isabelle
A1  - Miasnikova, Anna
A1  - Laschewsky, André
A1  - Müller-Buschbaum, Peter
A1  - Papadakis, Christine M.
T1  - Cononsolvency of water/methanol mixtures for PNIPAM and PS-b-PNIPAM: pathway of aggregate formation investigated using time-resolved SANS
JF  - Macromolecules : a publication of the American Chemical Society
N2  - We investigate the cononsolvency effect of poly(N-isopropylacrylamide) (PNIPAM) in mixtures of water and methanol. Two systems are studied: micellar solutions of polystyrene-b-poly(N-isopropylacrylamide) (PS-b-PNIPAM) diblock copolymers and, as a reference, solutions of PNIPAM homopolymers, both at a concentration of 20 mg/mL in DO. Using a stopped-flow instrument, fully deuterated methanol was rapidly added to these solutions at volume fractions between 10 and 20%. Time-resolved turbidimetry revealed aggregate formation within 10-100 s. The structural changes on mesoscopic length scales were followed by time-resolved small-angle neutron scattering (TR-SANS) with a time resolution of 0.1 s. In both systems, the pathway of the aggregation depends on the content of deuterated methanol; however, it is fundamentally different for homopolymer and diblock copolymer solutions: In the former, very large aggregates (>150 nm) are formed within the dead time of the setup, gradient appears at their surface in the late stages. In contrast, the growth of the aggregates in the latter system features different regimes, and the final aggregate size is 50 nm, thus much smaller than for the homopolymer. For the diblock copolymer, the time dependence of the aggregate radius can be described by two models: In the initial stage, the diffusion-limited coalescence model describes the data well; however, the resulting coalescence time is unreasonably high. In the late stage, a logarithmic coalescence model based on an energy barrier which is proportional to the aggregate radius is successfully applied. and a concentration
Y1  - 2014
U6  - https://doi.org/10.1021/ma501434e
SN  - 0024-9297
SN  - 1520-5835
VL  - 47
IS  - 19
SP  - 6867
EP  - 6879
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Adelsberger, Joseph
A1  - Bivigou Koumba, Achille Mayelle
A1  - Miasnikova, Anna
A1  - Busch, Peter
A1  - Laschewsky, André
A1  - Müller-Buschbaum, Peter
A1  - Papadakis, Christine M.
T1  - Polystyrene-block-poly (methoxy diethylene glycol acrylate)-block-polystyrene triblock copolymers in aqueous solution-a SANS study of the temperature-induced switching behavior
JF  - Colloid and polymer science : official journal of the Kolloid-Gesellschaft
N2  - A concentrated solution of a symmetric triblock copolymer with a thermoresponsive poly(methoxy diethylene glycol acrylate) (PMDEGA) middle block and short hydrophobic, fully deuterated polystyrene end blocks is investigated in D2O where it undergoes a lower critical solution temperature-type phase transition at ca. 36 A degrees C. Small-angle neutron scattering (SANS) in a wide temperature range (15-50 A degrees C) is used to characterize the size and inner structure of the micelles as well as the correlation between the micelles and the formation of aggregates by the micelles above the cloud point (CP). A model featuring spherical core-shell micelles, which are correlated by a hard-sphere potential or a sticky hard-sphere potential together with a Guinier form factor describing aggregates formed by the micelles above the CP, fits the SANS curves well in the entire temperature range. The thickness of the thermoresponsive micellar PMDEGA shell as well as the hard-sphere radius increase slightly already below the cloud point. Whereas the thickness of the thermoresponsive micellar shell hardly shrinks when heating through the CP and up to 50 A degrees C, the hard-sphere radius decreases within 3.5 K at the CP. The volume fraction decreases already significantly below the CP, which may be at the origin of the previously observed gel-sol transition far below the CP (Miasnikova et al., Langmuir 28: 4479-4490, 2012). Above the CP, small, and at higher temperatures, large aggregates are formed by the micelles.
KW  - Hydrogel
KW  - Thermoresponsive
KW  - LCST behavior
KW  - SANS
Y1  - 2015
U6  - https://doi.org/10.1007/s00396-015-3535-6
SN  - 0303-402X
SN  - 1435-1536
VL  - 293
IS  - 5
SP  - 1515
EP  - 1523
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Zhong, Qi
A1  - Wang, Weinan
A1  - Adelsberger, Joseph
A1  - Golosova, Anastasia
A1  - Koumba, Achille M. Bivigou
A1  - Laschewsky, André
A1  - Funari, Sergio S.
A1  - Perlich, Jan
A1  - Roth, Stephan V.
A1  - Papadakis, Christine M.
A1  - Müller-Buschbaum, Peter
T1  - Collapse transition in thin films of poly(methoxydiethylenglycol acrylate)
JF  - Colloid and polymer science : official journal of the Kolloid-Gesellschaft
N2  - The thermal behavior of poly(methoxydiethylenglycol acrylate) (PMDEGA) is studied in thin hydrogel films on solid supports and is compared with the behavior in aqueous solution. The PMDEGA hydrogel film thickness is varied from 2 to 422 nm. Initially, these films are homogenous, as measured with optical microscopy, atomic force microscopy, X-ray reflectivity, and grazing-incidence small-angle X-ray scattering (GISAXS). However, they tend to de-wet when stored under ambient conditions. Along the surface normal, no long-ranged correlations between substrate and film surface are detected with GISAXS, due to the high mobility of the polymer at room temperature. The swelling of the hydrogel films as a function of the water vapor pressure and the temperature are probed for saturated water vapor pressures between 2,380 and 3,170 Pa. While the swelling capability is found to increase with water vapor pressure, swelling in dependence on the temperature revealed a collapse phase transition of a lower critical solution temperature type. The transition temperature decreases from 40.6 A degrees C to 36.6 A degrees C with increasing film thickness, but is independent of the thickness for very thin films below a thickness of 40 nm. The observed transition temperature range compares well with the cloud points observed in dilute (0.1 wt.%) and semi-dilute (5 wt.%) solution which decrease from 45 A degrees C to 39 A degrees C with increasing concentration.
KW  - Hydrogel
KW  - Thin film
KW  - Thermoresponsive
KW  - LCST behavior
KW  - GISAXS
KW  - AFM
Y1  - 2011
U6  - https://doi.org/10.1007/s00396-011-2384-1
SN  - 0303-402X
VL  - 289
IS  - 5-6
SP  - 569
EP  - 581
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Zhong, Qi
A1  - Metwalli, Ezzeldin
A1  - Kaune, Gunar
A1  - Rawolle, Monika
A1  - Bivigou Koumba, Achille Mayelle
A1  - Laschewsky, André
A1  - Papadakis, Christine M.
A1  - Cubitt, Robert
A1  - Müller-Buschbaum, Peter
T1  - Switching kinetics of thin thermo-responsive hydrogel films of poly(monomethoxy-diethyleneglycol-acrylate) probed with in situ neutron reflectivity
JF  - Soft matter
N2  - The switching kinetics of thin thermo-responsive hydrogel films of poly(monomethoxy-diethyleneglycol-acrylate) (PMDEGA) are investigated. Homogeneous and smooth PMDEGA films with a thickness of 35.9 nm are prepared on silicon substrates by spin coating. As probed with white light interferometry, PMDEGA films with a thickness of 35.9 nm exhibit a phase transition temperature of the lower critical solution temperature (LCST) type of 40 degrees C. In situ neutron reflectivity is performed to investigate the thermo-responsive behavior of these PMDEGA hydrogel films in response to a sudden thermal stimulus in deuterated water vapor atmosphere. The collapse transition proceeds in a complex way which can be seen as three steps. The first step is the shrinkage of the initially swollen film by a release of water. In the second step the thickness remains constant with water molecules embedded in the film. In the third step, perhaps due to a conformational rearrangement of the collapsed PMDEGA chains, water is reabsorbed from the vapor atmosphere, thereby giving rise to a relaxation process. Both the shrinkage and relaxation processes can be described by a simple model of hydrogel deswelling.
Y1  - 2012
U6  - https://doi.org/10.1039/c2sm25401h
SN  - 1744-683X
VL  - 8
IS  - 19
SP  - 5241
EP  - 5249
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  -