TY  - JOUR
A1  - Möller, Eleonore
A1  - Beuermann, Sabine
T1  - Homogeneous phase copolymerizations of vinylidene fluoride and hexafluoropropene in supercritical carbon dioxide
JF  - Macromolecular reaction engineering
N2  - Copolymerizations of vinylidene fluoride (VDF) and hexafluoropropene (HFP) were carried out in homogeneous phase with supercritical carbon dioxide up to complete VDF conversion using conventional peroxide initiators. The HFP monomer feed ratios, f(HFP), were varied between 0.65 and 0.20. Depending on f(HFP) amorphous or semi-crystalline copolymers were obtained. f(HFP) also determines the minimum pressure required to allow for homogeneous phase reactions. For example, HFP-rich copolymerizations in 70 wt.-% CO(2) at 100 degrees C require a pressure of around 500 bar. Further, bulk copolymerizations in homogenous phase were feasible for f(HFP) 0.65 at 900 bar up to complete VDF conversion. Copolymerizations in the presence of perfluorinated hexyl iodide carried out at 75 degrees C gave access to low dispersity polymers. Due to homogeneous phase conditions the use of any surfactants or fluorinated cosolvent is avoided.
KW  - copolymerization
KW  - hexafluoropropene
KW  - phase behavior
KW  - supercritical CO(2)
KW  - vinylidene fluoride
Y1  - 2011
U6  - https://doi.org/10.1002/mren.201000031
SN  - 1862-832X
VL  - 5
IS  - 1
SP  - 8
EP  - 21
PB  - Wiley-VCH
CY  - Weinheim
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  - GEN
A1  - Niebuur, Bart-Jan
A1  - Puchmayr, Jonas
A1  - Herold, Christian
A1  - Kreuzer, Lucas
A1  - Hildebrand, Viet
A1  - Müller-Buschbaum, Peter
A1  - Laschewsky, André
A1  - Papadakis, Christine M.
T1  - Polysulfobetaines in aqueous solution and in thin film geometry
T2  - Postprints der Universität Potsdam Mathematisch-Naturwissenschaftliche Reihe
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 H 2 O.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 713 
KW  - polyzwitterions
KW  - polysulfobetaines
KW  - dynamic light scattering
KW  - phase behavior
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-427363
SN  - 1866-8372
IS  - 713
ER  -