@phdthesis{Fechner2011,
  author    = {Fechner, Mabya},
  title     = {Synthetische Polyampholyte als pH-sensitive Komponente in selbstorganisierten Systemen zur Nanostrukturierung von Materialien},
  address   = {Potsdam},
  pages     = {VI, 128, XLIII S.},
  year      = {2011},
  language  = {de}
}
@article{FechnerKoetz2013,
  author    = {Fechner, Mabya and Koetz, Joachim},
  title     = {Polyampholyte/Surfactant complexes at the water-air interface a surface tension study},
  series = {Langmuir},
  volume    = {29},
  journal   = {Langmuir},
  number    = {25},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0743-7463},
  doi       = {10.1021/la401576q},
  pages     = {7600 -- 7606},
  year      = {2013},
  abstract  = {The present paper is related to interactions between strongly alternating polyampholytes, i.e., copolymers of N,N'-diallyl-N,N'-dimethylammonium chloride and maleamic acid derivatives, varying in hydrophobicity and excess charges and the oppositely charged anionic surfactant sodium dodecyl sulfate (SDS). Surface tension measurements have revealed a complex behavior with the formation of polyampholyte-SDS complexes at water air interfaces which depends on both the hydrophobic character of the polyampholyte and electrostatic attractive forces between the polyampholyte and the anionic surfactant in dependence on pH. Hereby, maleamic acid copolymers with additional carboxylic groups in the phenylic side chain show a significant lower surface tension at the critical association concentration (CAC) due to the formation of surface-active SDS complexes and multicomplexes. In the presence of only one carboxylic group in the p-position the CAC can be strongly shifted by varying the pH due to repulsive electrostatic interactions.},
  language  = {en}
}
@article{FechnerKoetz2011,
  author    = {Fechner, Mabya and Koetz, Joachim},
  title     = {Polyampholyte-Surfactant film tuning in reverse microemulsions},
  series = {Langmuir},
  volume    = {27},
  journal   = {Langmuir},
  number    = {9},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0743-7463},
  doi       = {10.1021/la200791k},
  pages     = {5316 -- 5323},
  year      = {2011},
  abstract  = {The pH-dependent influence of two different strongly alternating copolymers [poly(N,N'-diallyl-N,N'-dimethylammonium-alt-N-phenylmaleamic carboxylate) (PalPh) and poly(N,N'-diallyl-N,a-dimethylammonium-alt-3,5-bis(carboxyphenyl) maleamic carboxylate) (PalPhBisCarb)] based on N,N'-diallyl-N, -dimethylarnmonium chloride and maleamic acid derivatives on the phase behavior of a water-in-oil (w/o) microemulsion system made from toluene pentanol (1:1) and sodium dodecyl sulfate was investigated. It was shown that the optically dear phase range can be extended after incorporation of these copolymers, leading to an increased water solubilization capacity. Additionally, the required amount of surfactant to establish a clear w/o microemulsion depends on the pH value, which means the hydrophobicity of the copolymers. Conductivity measurements show that droplet droplet interactions in the w/o microemulsion are decreased at acidic but increased at alkaline pH in the presence of the copolymers. From differenctial scanning calorimetry measurements one can further conclude that these results are in agreement with a change of the position of the copolymer in the interfacial region of the surfactant film. The more hydrophobic PalPh can be directly incorporated into the surfactant film, whereas the phenyl groups of PalPhBisCarb flip into the water core by increasing the pH value.},
  language  = {en}
}
@article{FechnerKoetz2011,
  author    = {Fechner, Mabya and Koetz, Joachim},
  title     = {Potentiometric behavior of Polyampholytes based on N,N'-diallyl-N,N'-dimethylammonium chloride and maleamic acid derivatives},
  series = {Macromolecular chemistry and physics},
  volume    = {212},
  journal   = {Macromolecular chemistry and physics},
  number    = {24},
  publisher = {Wiley-Blackwell},
  address   = {Malden},
  issn      = {1022-1352},
  doi       = {10.1002/macp.201100532},
  pages     = {2691 -- 2699},
  year      = {2011},
  abstract  = {Strongly alternating copolymers (PalH, PalPh, PalPhBisCarb) composed of N,N'-diallyl-N,N'-dimethyl-ammonium chloride (DADMAC) and maleamic acid derivatives (MAD) are synthesized by a water-based free radical copolymerization using 4,4-azobis(4-cyanovaleric acid) (V501) as the initiator. The structure of the copolymers is verified by 1H-NMR, elemental analysis, and thermogravimetric measurements, and the physicochemical properties are investigated by viscometric and potentiometric techniques. Potentiometric titration curves show that the acidity of the carboxylic groups strongly depends on the degree of dissociation and the ionic strength. Since all copolymers behave as polycations at low degree of dissociation, a transition from an extended chain to a coil conformation can be identified by reaching the isoelectric point (IEP).},
  language  = {en}
}
@article{FechnerKosmellaKoetz2010,
  author    = {Fechner, Mabya and Kosmella, Sabine and Koetz, Joachim},
  title     = {pH-dependent polyampholyte SDS interactions},
  issn      = {0021-9797},
  doi       = {10.1016/j.jcis.2010.01.092},
  year      = {2010},
  abstract  = {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.},
  language  = {en}
}
@article{FechnerKramerKleinpeteretal.2009,
  author    = {Fechner, Mabya and Kramer, Markus and Kleinpeter, Erich and Koetz, Joachim},
  title     = {Polyampholyte-modified ionic microemulsions},
  issn      = {0303-402X},
  doi       = {10.1007/s00396-009-2074-4},
  year      = {2009},
  abstract  = {This paper is focused on the influence of added polyampholyte, namely poly(N,N;-diallyl-N,N;- dimethyl-alt-maleamic carboxylate) on the inverse micellar phase range of the pseudo-ternary system consisting of toluene-pentanol (1:1)/SDS/water in dependence on the pH value and the temperature. Investigations on phase behavior have revealed that a greater extension in direction to the water-rich corner can be found at pH 4 compared to pH 9. In order to understand changes in the microstructure, polymer-surfactant interactions in dependence on pH have been examined by means of diffusion-ordered spectroscopy, differential scanning calorimetry, as well as conductivity measurements. The results have proven that the present microemulsion consists of water-in-oil droplets, with the polyampholyte located more in the inner core of the water droplets at pH 9 rather than at the interphase of the surfactant film at pH 4.},
  language  = {en}
}