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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 8: Crystallization and Self Assembly I

CPP 8.4: Vortrag

Montag, 22. März 2010, 12:00–12:15, H48

Small Angle X-Ray Scattering Study of Thermodynamic and Conformational Changes in Ion-Containing Symmetric Diblock Copolymers — •Ilja Gunkel^1,2 and Thomas Thurn-Albrecht² — ¹Max Planck Institute of Microstructure Physics, Halle, Germany — ²Institute of Physics, Martin Luther University Halle Wittenberg, Halle, Germany

We present temperature-dependent SAXS measurements on two different symmetric block copolymers with added salt (Lithiumtriflate, LiCF₃SO₃). For both studied systems, Polystyrene-b-Poly-2-vinylpyridine (PS-b-P2VP) and Polystyrene-b-Polyethyleneoxide (PS-b-PEO), the salt selectively dissolved in one block leading to large increases of the order-disorder transition temperatures (T_ODT). In addition, the lamellar thickness of these ion-containing block copolymers nontrivially changed above a certain salt concentration - in PS-b-P2VP the lamellae became thicker whereas their thickness decreased in PS-b-PEO. Using basic arguments of the thermodynamics of block copolymers we were able to separate the ion-induced increase of T_ODT due to a higher incompatibility between the different blocks from changes in the thickness of the lamellae at T_ODT resulting from changes in the conformation of the ion-containing blocks.