Deutsche Tagung f ¨ur Forschung mit ... - SNI-Portal

Weiche Materie Poster: Do., 13:00–15:30 D-P330
Investigation of mixed micelles of a bolamphiphile and SDS using protonated
and deuterated SDS
Sven Gerber 1 , Götz Milkereit 1 , Vollkmar Vill 1 , Vasil Garamus 2 , Regine
Willumeit 2
1 University of Hamburg, Inst. of Organic Chemistry, Martin-Luther-King-Platz 6,
20146 Hamburg, Germany – 2 GKSS Research Centre, Max-Planck-Str. 1, 21502
Geesthacht, Germany
In this work we investigated the interaction of a carbohydrate-based bolaamphiphile
with sodium dodecyl sulfate (SDS). SDS-mixtures in particular gained much interest
in mixed surfactant systems, therefore much data is available that can be compared
with results from our studies. It is known that SDS shows synergism in mixtures with
non ionic surfactants. Experiments were carried out using deuterated and protonated
SDS to obtain information about mixing with the bolaamphiphile and it ′ s location in
mixed micelles. The main feature, which has to be compared for both curves, is the
position of the maximum. The position of the maximum is connected with the average
distance between aggregates qmax ∼ 1/d 1/3 which is determined by the concentration
of aggregates. The constant value of qmax supports the idea that the concentration of
aggregates, there we observe SDS and MDM (solution with protonated SDS) and there
we can observe only MDM (solution with deuterated SDS), is the same. It means that
we observe the same aggregates i.e., mixed micelles of SDS and MDM. It is well-known
for non-ionic/ionic mixtures. Analysis of solutions with h-SDS and d-SDS gives the
same parameters of aggregates. It points that the chosen model of one population of
mixed micelles (without demixing within the micelle) is correct for the length scale l >
π/q > 10 ˚A. Aggregates are of a non-spherical (oblate) shape which is in accordance
with pure SDS micelles . The total aggregation number is 30 % less than for pure SDS
micelles but it should be taken into account that MDM molecules are significant larger
than SDS ones. The observed slightly oblate shape shape of aggregates is in agreement
with a preferably planar geometry of bola amphiphiles.
Fig. 1: a) Principal structure
of bolaamphiphiles;
b) investigated compound:
1,12-bis-[4 ′′ -O-
(α-D-glucopyranosyl)-β-Dglucopyranosyl]-dodecane
(MDM)