Dresden 2009 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 28: POSTERS Interfaces and Thin Films
CPP 28.7: Poster
Mittwoch, 25. März 2009, 17:00–19:00, P3
Designing the interfacial properties of Langmuir monolayers from amphiphilic diblock copolymers — Katja Trenkenschuh1, Felix Schacher2, Axel H. E. Müller2, and •Larisa Tsarkova1 — 1Physikalische Chemie II, Universität Bayreuth, D 95440 Bayreuth, Deutschland — 2Macromolecular Chemie II, Universität Bayreuth, D 95440 Bayreuth, Deutschland
We followed changes in the molecular arrangement of amphiphilic diblock copolymers at air-water interface which were associated with the variation of the molecular composition. We demonstrate that the main characteristics of the surface pressure − area per molecule (π − A) isotherms strongly depend on the mechanical properties of the hydrophobic block (polystyrene (PS) or polybutadiene (PB)), and on the volume fraction of the hydrophilic block poly(N, N-dimethylaminoethyl-methacrylate) (PDMAEMA). In the case of a majority PB block, the interfacial assembling shows clear dependence on the chain relaxation, while a PS majority block leads to a significantly larger mechanical stability of the monolayers. The contribution of the PDMAEMA block is noticeable at low compressions and at low pH values due to the protonation of the chains. The nanostructure of Langmuir-Blodgett films was investigated with scanning force microscopy (SFM). We captured the details of the phase transition from a network of PS-core worm-like micelles to densely packed PS-core spherical domains through increasing the monolayer compression. Our results further establish the generality of the molecular-structure guided assembling phenomena.