TY  - JOUR
A1  - Laschewsky, André
A1  - Lunkenheimer, K.
A1  - Rakotoaly, R. H.
A1  - Wattebled, Laurent
T1  - Spacer effects in dimeric cationic surfactants
N2  - A series of dimeric cationic surfactants (gemini surfactants), which have spacer groups of varying length and flexibility, was synthesized. The series is derived from the parent compounds dodecyltrimethylammonium chloride or benzyldodecyldimethylammonium chloride. Characteristic surfactant properties of the dimeric ammonium compounds such as surface activity, micellization, viscosity effects, foaming, and solubilization, were studied with respect to the influence of the spacer group on the surfactant. For all properties, the influence of the length of the spacer group was predominant though the chemical nature of the spacer cannot be neglected
Y1  - 2005
SN  - 0303-402X
ER  - 
TY  - JOUR
A1  - Lunkenheimer, K.
A1  - Laschewsky, André
A1  - Warszynski, P.
A1  - Hirte, R.
T1  - On the adsorption behaviour of soluble, surface-chemically pure hemicyanine dyes at the air/water interface
N2  - Equilibrium surface tension (se) versus concentration isotherms of surface-chemically pure aqueous solutions of the homologous series of N-n-alkyl-4'-(dimethylamino)-stilbaziumbromides ('hemicyanines') were measured at 295 K. The adsorption parameters of saturation adsorption and standard free energy of adsorption of the hemicyanines were determined from the evaluation of the se vs. c isotherms by using a two state approach to surface equation of state. The adsorption parameters reveal a very pronounced phenomenon of alternation (even/ odd- effect) which has so far not been met to a large extent like this. Thus, the cross-sectional areas of the odd members are almost twice those of the related even members. Surface activity of the odd is stronger than that of the even members. UV-Vis investigations showed that there is no indication of aggregate formation in the adsorption layer. The thermodynamic results give evidence for distinct differences between the surface conformations of the even- and the odd-chain hemicyanine dyes although the reasons for it are not known.
Y1  - 2002
ER  - 
TY  - JOUR
A1  - Lunkenheimer, K.
A1  - Winsel, K.
A1  - Fruhner, Horst
A1  - Fang, J. P.
A1  - Wantke, K.-D.
A1  - Siegler, K.
T1  - Dynamic surface tension and surface area elasticity of adsorbed pulmonary surfactant layers
Y1  - 1996
SN  - 0927-7757
ER  - 
TY  - JOUR
A1  - Fruhner, Horst
A1  - Lunkenheimer, K.
A1  - Miller, Reinhard
T1  - Adsorption kinetics and exchange of matter at liquid interfaces and microgravity
Y1  - 1996
ER  -