TY  - JOUR
A1  - Koetz, Joachim
A1  - Brühl, Iris
A1  - Kosmella, Sabine
A1  - Reiche, Jürgen
A1  - Tiersch, Brigitte
T1  - Polyelectrolyte Complex Formation in Lamellar Liquid Crystalline Systems
N2  - The influence of polyelectrolytes on structure formation in liquid crystalline Na-dodecylsulfate/decanol/water systems was investigated by means of small angle X-ray diffraction, rheology, NMR spectroscopy, and microscopy. By adding Na-polyacrylate (PAA) into the mesophase, the one-phase region is left and phenomena of phase separation into a solvent-rich and a polymer/surfactantrich phase occurs. By incoporating an anionic and cationic polyelectrolyte step by step the tendency of phase separation is increased drastically. The self-organization process can be regulated directly by varying the water content of the system. However, at a water content of 30% the properties of the resulting liquid crystal were changed drastically. X-ray diffraction shows a multitude of Bragg peaks, NMR shows a peak-splitting, and rheology shows a change from non-Newtonian to Newtonian-flow behavior. On the basis of the experimental results an ordered multilayer associate structure can be assumed.
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Köpf, Michael H.
A1  - Harder, Heiko
A1  - Reiche, Jürgen
A1  - Santer, Svetlana
T1  - Impact of temperature on the LB patterning of DPPC on Mica
JF  - Langmuir
N2  - The influence of the subphase temperature on the stripe pattern formation during Langmuir-Blodgett transfer (LB patterning) is investigated in a combined experimental and theoretical study. According to our experiments on the LB transfer of dipalmitoylphosphatidylcholine (DPPC) on planar mica substrates, even small temperature changes between 21.5 and 24.5 degrees C lead to significant changes in the monolayer patterns. For a constant surface pressure and dipper speed, the width of the stripes and the overall spatial period of the patterns increase with increasing subphase temperature. Because the stripe patterns are ascribed to alternating monolayer domains in the liquid-expanded and the liquid-condensed phases, the working regime for the formation of stripes is found to depend strongly on the respective surface pressure-area isotherm. These experimental findings are in accordance with the results of a theoretical investigation based on a model that takes hydrodynamics and the monolayer thermodynamics into account.
Y1  - 2011
U6  - https://doi.org/10.1021/la202728t
SN  - 0743-7463
VL  - 27
IS  - 20
SP  - 12354
EP  - 12360
PB  - American Chemical Society
CY  - Washington
ER  -