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CPP: Chemische Physik und Polymerphysik
CPP 14: SYMPOSIUM: Understanding and Controlling Complex Structures: From Synthetic Polymers to Biomaterials II
CPP 14.4: Vortrag
Dienstag, 9. März 2004, 15:15–15:30, H 37
Structure and elastic properties of a block-copolymer bilayer doped with cationic surfactant — •Thomas Hellweg, Holger Egger, and Gerhard Findenegg — TU Berlin, Stranski Laboratorium f. Physikalische und Theoretische Chemie, Strasse des 17.Juni 112, 10623 Berlin
In recent years much attention was paid to the commercially available triblock copolymers poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO). The phase behavior of these polymers, often called pluronics, is investigated intensively in binary systems with water, as well as in ternary systems containing water and oil or in polymer mixtures by a lot of different research groups.
In the present work we study the influence of the cationic
surfactant n-octyltrimethyl-ammonium-bromide (C8TAB) on the
triblock copolymer based system
(EO37-PO58-EO37)/water/o-xylene.
At sufficient high surfactant concentration the system shows an
extended lamellar phase (Lα). This phase is characterized
in terms of interlamellar spacing, thickness, and
internal structure of the bilayers as a function of composition.
The Caillé-model is used to correlate the profile of
the first order Bragg peak with the elastic constants of the
amphiphilic film. It is possible to obtain general
trends for the dependence of the elastic constants κ and
B of the block-copolymer-film on the surfactant
concentration.