TY  - JOUR
A1  - Fechner, Mabya
A1  - Kosmella, Sabine
A1  - Koetz, Joachim
T1  - pH-dependent polyampholyte SDS interactions
N2  - Aqueous solutions of sodium dodecylsulfate (SDS) and poly(N,N'-diallyl-N,N'-dimethyl-alt-maleamic carboxylate) (PalH), a synthetic pH-tuneable polyelectrolyte (PEL), have been investigated by various techniques at different pH-values in absence and presence of NaCl. Potentiometric measurements using a surfactant-selective electrode indicate a quite complex interaction mechanism, which can be subdivided into different regions, where non-cooperative, electrostatic and cooperative hydrophobic interactions are of relevance. It was concluded, that in dependence on pH, conformational changes are responsible for the different interaction behavior in the NaCl-free system. Isothermal titration calorimetry (ITC) suggests that early stage hydrophobic binding is an exothermic process followed by electrostatic interactions, which are endothermic in nature and entropy driven. After NaCl addition the interaction mechanism becomes independent of pH due to a screening of (i) attractive interactions between the surfactant head groups and oppositely charged binding sites and (ii) repulsive forces between the surfactant head groups. Furthermore, the ITC investigations have revealed that after salt-addition surfactant micelles interact with the polymer instead of separated SDS molecules due to a depression of the CMC.
Y1  - 2010
UR  - http://www.sciencedirect.com/science/journal/00219797
U6  - https://doi.org/10.1016/j.jcis.2010.01.092
SN  - 0021-9797
ER  - 
TY  - JOUR
A1  - Schwarz, Guntram
A1  - Bodenthin, Yves
A1  - Geue, Thomas
A1  - Koetz, Joachim
A1  - Kurth, Dirk G.
T1  - Structure and properties of dynamic rigid rod-like metallo-supramolecular polyelectrolytes in solution
N2  - Metal-ion-induced self-assembly in aqueous solution of the rigid ligand 1,4-bis(2,2':6',2 ''-terpyridine-4'-yl)benzene (1) with Fe(OAc)(2) and Ni(OAc)(2) is investigated with viscosimetry, SANS, and AFM. Ligand 1 forms extended, rigid-rod like metallo-supramolecular coordination polyeectrolytes (MEPEs) with a molar mass of up to 200 000 g mol(-1) under the Current experimental conditions. The molar mass depends oil concentration, stoichiometry, and time. By spin-coating MEPEs oil a solid surface, we call image the MEPEs in real space by AFM. Both AFM and SANS confirm the extended rigid-rod-type structure of the MEPEs. As a control experiment, we also studied the flexible ligand 1,3-bis[4'-oxa(2,2':6',2 ''-terpyridinyl)]propane (2). Ligand 2 does not form extended macro-assemblies but likely ringlike structures with three 10 four repeat units. Finally, we present it protocol to control the stoichiometry during self-assembly using conductometry, which is of paramount importance to obtain meaningful and reproducible results.
Y1  - 2010
UR  - http://pubs.acs.org/doi/full/10.1021/ma902057f
U6  - https://doi.org/10.1021/Ma902057f
SN  - 0024-9297
ER  - 
TY  - JOUR
A1  - Schwarz, Guntram
A1  - Sievers, Torsten K.
A1  - Bodenthin, Yves
A1  - Hasslauer, Ires
A1  - Geue, Thomas
A1  - Koetz, Joachim
A1  - Kurth, Dirk G.
T1  - The structure of metallo-supramolecular polyelectrolytes in solution and on surfaces
N2  - Metal ion induced self-assembly of the rigid ligand 1,4-bis(2,2':6',2 ''-terpyridine- 4'-yl) benzene (1) with Fe(II), Co(II), Ni(II) and Zn(II) acetate in aqueous solution results in extended, rigid- rod like metallosupramolecular coordination polyelectrolytes (MEPE-1). Under the current experimental conditions the molar masses range from 1000 g mol(-1) up to 500 000 g mol(-1). The molar mass depends on concentration, stoichiometry, metal-ion and time. In addition, we present viscosity measurements, small angle neutron scattering and AFM data. We introduce a protocol to precisely control the stoichiometry during self-assembly using conductometry. The protocol can be used with different terpyridine ligands and the above-mentioned metal ions and is of paramount importance to obtain meaningful and reproducible results. As a control experiment we studied the mononuclear 4'- (phenyl)2,2':6',2 ''-terpyridine (3) complex with Ni(II) and Zn(II) and the flexible ligand 1,3- bis[4'-oxa(2,2': 6',2 ''-terpyridinyl)] propane (2) with Ni(II) acetate (Ni-MEPE-2). This ligand does not form extended macroassemblies but likely ring-like structures with 3 to 4 repeat units. Through spin- coating of Ni-MEPE-1 on a solid surface we can image the MEPEs in real space by AFM. SANS measurements of Fe-MEPE-1 verify the extended rigid-rod type structure of the MEPEs in aqueous solution.
Y1  - 2010
UR  - http://pubs.rsc.org/en/content/articlehtml/2010/jm/b926783b
U6  - https://doi.org/10.1039/B926783b
SN  - 0959-9428
ER  -