Berlin 2012 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
CPP: Fachverband Chemische Physik und Polymerphysik
CPP 13: Poster: Interfaces and Thin Films
CPP 13.32: Poster
Dienstag, 27. März 2012, 18:15–20:45, Poster A
Phase transitions of Polypeptides in confined geometries — •Renate Reiter1, Frédéric Wintzenrith2, and Günter Reiter1 — 1Physikalisches Institut, Universität Freiburg, Germany — 2Ecole Polytechnique, France
Poly-γ-benzly-glutamte (PBLG) is a synthetic polypeptide which can adopt α-helical conformation in aprotic solvents and thus forms rigid rods with flexible side chains. The experimentally observed phase diagram in organic solvents corresponds well to the theoretical one of Flory which predicts a coexistence region of isotropic, liquid crystalline and network phases. Networks were observed experimentally by cooling the isotropic phase to the transition temperature followed by quenching.
We demonstrate that quasi two dimensional network like structures are obtained by preparing Langmuir films of PBLG from helicogenic solvent. With this technique molecules are confined to the air water interface and changing the molecular density via movable barriers allows inducing phase transitions which appear as discontinuities in the isotherms. BAM and AFM micrographs reveal fibrils and networks directly on the water surface and in films transferred to solid substrates. Unusual hysteric and relaxation behavior of the isotherms are observed and discussed. A correlation between morphological changes and phase transitions is targeted.