Dresden 2009 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 3: Focus: Amphiphilic systems III
CPP 3.4: Vortrag
Montag, 23. März 2009, 19:00–19:15, ZEU 222
Self-Assembly of Symmetric Single-Chain Bolaamphiphiles: The Formation of Temperature, Ionic Strength and pH-responsive Hydrogels — •Annette Meister1, Simon Drescher2, Martin Bastrop1, Göran Karlsson3, Vasil Garamus4, Bodo Dobner2, and Alfred Blume1 — 1Martin-Luther-University Halle-Wittenberg, Institute of Chemistry, Halle, Germany — 2Martin-Luther-University Halle-Wittenberg, Institute of Pharmacy, Halle, Germany — 3Uppsala University, Department of Physical Chemistry, Uppsala, Sweden — 4GKSS Research Centre, Geesthacht, Germany
The bolaamphiphile dotriacontane-1,w-diyl-bis[2-(dimethylammonio)-ethylphosphate] was found to be an excellent hydrogelator by forming a dense network of nanofibers [1]. The temperature, ionic strength and pH dependent aggregation behaviour of this bolaamphiphile in water was investigated using DSC, rheological measurements, SANS and cryo-TEM. SANS and cryo-TEM indicate the formation of a dense network of nanofibers below the first and second DSC transition temperature and the presence of micelles above the second and third transition temperature. However, rheological measurements point out that the formation of stable hydrogels is only possible at low pH, where the headgroups are in a zwitterionic state. At higher pH values, where the headgroup is deprotonated and negatively charged, a fluid with Newtonian behaviour is obtained.
[1] Meister, A.; Bastrop, M.; Koschoreck, S.; Garamus, V. M.; Sinemus, T.; Hempel, G.; Drescher, S.; Dobner, B.; Richtering, W.; Huber, K.; Blume, A. Langmuir, 2007, 23, 7715.