@article{DolyaRojasKosmellaetal.2013,
  author    = {Dolya, Natalya and Rojas, Oscar and Kosmella, Sabine and Tiersch, Brigitte and Koetz, Joachim and Kudaibergenov, Sarkyt},
  title     = {"One-Pot" in situ frmation of Gold Nanoparticles within Poly(acrylamide) Hydrogels},
  series = {Macromolecular chemistry and physics},
  volume    = {214},
  journal   = {Macromolecular chemistry and physics},
  number    = {10},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1022-1352},
  doi       = {10.1002/macp.201200727},
  pages     = {1114 -- 1121},
  year      = {2013},
  abstract  = {This paper focuses on two different strategies to incorporate gold nanoparticles (AuNPs) into the matrix of polyacrylamide (PAAm) hydrogels. Poly(ethyleneimine) (PEI) is used as both reducing and stabilizing agent for the formation of AuNPs. In addition, the influence of an ionic liquid (IL) (i.e., 1-ethyl-3-methylimidazolium ethylsulfate) on the stability of the nanoparticles and their immobilization in the hydrogel is investigated The results show that AuNPs surrounded by a shell containing PEI and IL, synthesized according to the one-pot approach, are much better immobilized within the PAAm hydrogel. Hereby, the IL is responsible for structural changes in the hydrogel as well as the improved stabilization and embedding of the AuNPs into the polymer gel matrix.},
  language  = {en}
}
@article{BertzWoehlBruhnMietheetal.2013,
  author    = {Bertz, Andreas and W{\"o}hl-Bruhn, Stefanie and Miethe, Sebastian and Tiersch, Brigitte and Koetz, Joachim and Hust, Michael and Bunjes, Heike and Menzel, Henning},
  title     = {Encapsulation of proteins in hydrogel carrier systems for controlled drug delivery influence of network structure and drug size on release rate},
  series = {Journal of biotechnology},
  volume    = {163},
  journal   = {Journal of biotechnology},
  number    = {2},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0168-1656},
  doi       = {10.1016/j.jbiotec.2012.06.036},
  pages     = {243 -- 249},
  year      = {2013},
  abstract  = {Novel hydrogels based on hydroxyethyl starch modified with polyethylene glycol methacrylate (HES-P(EG)(6)MA) were developed as delivery system for the controlled release of proteins. Since the drug release behavior is supposed to be related to the pore structure of the hydrogel network the pore sizes were determined by cryo-SEM, which is a mild technique for imaging on a nanometer scale. The results showed a decreasing pore size and an increase in pore homogeneity with increasing polymer concentration. Furthermore, the mesh sizes of the hydrogels were calculated based on swelling data. Pore and mesh size were significantly different which indicates that both structures are present in the hydrogel. The resulting structural model was correlated with release data for bulk hydrogel cylinders loaded with FITC-dextran and hydrogel microspheres loaded with FITC-IgG and FITC-dextran of different molecular size. The initial release depended much on the relation between hydrodynamic diameter and pore size while the long term release of the incorporated substances was predominantly controlled by degradation of the network of the much smaller meshes.},
  language  = {en}
}
@article{FribergKovachKoetz2013,
  author    = {Friberg, Stig E. and Kovach, Ildiko and Koetz, Joachim},
  title     = {Equilibrium topology and partial inversion of Janus Drops - a numerical analysis},
  series = {ChemPhysChem : a European journal of chemical physics and physical chemistry},
  volume    = {14},
  journal   = {ChemPhysChem : a European journal of chemical physics and physical chemistry},
  number    = {16},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1439-4235},
  doi       = {10.1002/cphc.201300635},
  pages     = {3772 -- 3776},
  year      = {2013},
  abstract  = {The equilibrium topology of an aqueous Janus emulsion of two oils, O1 and O2, with water, W, [(O1+O2)/W], is numerically evaluated with the following realistic interfacial tensions (): (O2/W)=5 mNm(-1), (O1/O2)=1 mNm(-1), and (O1/W) varies within the range 4-5 mNm(-1), which is the limiting range for stable Janus drop topology. The relative significance of the two independently pivotal factors for the topology is evaluated, that is, the local equilibrium at the line of contact between the three liquids and the volume fraction of the two dispersed liquids within the drop. The results reveal a dominant effect of the local equilibrium on the fraction of the O2 drop surface that is covered by O1. In contrast, for a constant volume of O2, the impact of the interfacial tension balance on the limit of the coverage is modest for an infinite volume of O1. Interestingly, when the O1 volume exceeds this value, an emulsion inversion occurs, and the O1 portion of the (O1+O2)/W topology becomes a continuous phase, generating a (W+O2)/O1 Janus configuration.},
  language  = {en}
}
@article{LemkePrietzelKoetz2013,
  author    = {Lemke, Karina and Prietzel, Claudia Christina and Koetz, Joachim},
  title     = {Fluorescent gold clusters synthesized in a poly(ethyleneimine) modified reverse microemulsion},
  series = {Journal of colloid and interface science},
  volume    = {394},
  journal   = {Journal of colloid and interface science},
  publisher = {Elsevier},
  address   = {San Diego},
  issn      = {0021-9797},
  doi       = {10.1016/j.jcis.2012.11.057},
  pages     = {141 -- 146},
  year      = {2013},
  abstract  = {This paper is focused on the formation of gold clusters in a tailor-made polyelectrolyte-modified reverse microemulsion using poly(ethyleneimine) (PEI) as a cationic polyelectrolyte. PEI incorporated into a ternary w/o microemulsion consisting of water/heptanol/zwitterionic surfactant 3-(N,N-dimethyl-dodecylammonio)-propanesulfonate (SB) acts as a reducing and stabilizing agent and shows an additional template effect. The nanoparticle synthesis is performed by a simple mixing of two microemulsions, one containing the PEI and the other one containing the gold chloride precursor. UV-vis measurements in the microemulsion show two pronounced absorption maxima, one at 360 nm and the other one at 520 nm, indicating two particle fractions. The absorption maximum at 360 nm in combination to the unique fluorescence properties indicate the formation of gold clusters. After a complete solvent evaporation the redispersed nanoparticles have been characterized by using UV-vis and fluorescence spectroscopy, in combination to dynamic light scattering and transmission electron microscopy (TEM). In addition to the gold nanoparticle fraction (>5 nm) the fluorescent gold cluster fraction (<2 nm) can be redispersed without particle aggregation. By means of asymmetric flow field flow fractionation (AF-FFF) two different cluster fractions with particle diameter (<2 nm) can be identified.},
  language  = {en}
}
@article{TheteRojasNeumeyeretal.2013,
  author    = {Thete, Aniket and Rojas, Oscar and Neumeyer, David and Koetz, Joachim and Dujardin, Erik},
  title     = {Ionic liquid-assisted morphosynthesis of gold nanorods using polyethyleneimine-capped seeds},
  series = {RSC Advances},
  volume    = {3},
  journal   = {RSC Advances},
  number    = {34},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {2046-2069},
  doi       = {10.1039/c3ra22112a},
  pages     = {14294 -- 14298},
  year      = {2013},
  abstract  = {Seed-mediated gold nanorods with tunable lengths are prepared using new polyethyleneimine-capped gold nanoparticles synthesized in ionic liquid. The effect of polyethyleneimine and ionic liquid during nanorod growth is investigated and shows a marked effect on their final aspect ratio.},
  language  = {en}
}
@article{TheteRojasNeumeyeretal.2013,
  author    = {Thete, Aniket and Rojas, Oscar and Neumeyer, David and Koetz, Joachim and Dujardin, Erik},
  title     = {Ionic liquid-assisted morphosynthesis of gold nanorods using polyethyleneimine-capped seeds},
  doi       = {10.1039/C3RA22112A},
  year      = {2013},
  abstract  = {Seed-mediated gold nanorods with tunable lengths are prepared using new polyethyleneimine-capped gold nanoparticles synthesized in ionic liquid. The effect of polyethyleneimine and ionic liquid during nanorod growth is investigated and shows a marked effect on their final aspect ratio.},
  language  = {en}
}
@misc{TheteRojasNeumeyeretal.2013,
  author    = {Thete, Aniket and Rojas, Oscar and Neumeyer, David and Koetz, Joachim and Dujardin, Erik},
  title     = {Ionic liquid-assisted morphosynthesis of gold nanorods using polyethyleneimine-capped seeds},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-95196},
  pages     = {14294 -- 14298},
  year      = {2013},
  abstract  = {Seed-mediated gold nanorods with tunable lengths are prepared using new polyethyleneimine-capped gold nanoparticles synthesized in ionic liquid. The effect of polyethyleneimine and ionic liquid during nanorod growth is investigated and shows a marked effect on their final aspect ratio.},
  language  = {en}
}
@article{HasinovicFribergKovachetal.2013,
  author    = {Hasinovic, Hida and Friberg, Stieg E. and Kovach, Ildyko and Koetz, Joachim},
  title     = {Janus emulsion drops - equilibrium calculations},
  series = {Journal of dispersion science and technology},
  volume    = {34},
  journal   = {Journal of dispersion science and technology},
  number    = {12},
  publisher = {Taylor \& Francis Group},
  address   = {Philadelphia},
  issn      = {0193-2691},
  doi       = {10.1080/01932691.2013.763728},
  pages     = {1683 -- 1689},
  year      = {2013},
  abstract  = {Experimental results indicated the contact angles in the drops of Janus emulsions formed in a one-step mixing process to be invariant within a significant range the oil volume ratios, similar to the results from microfluidics emulsification. Since this result points to a connection between the kinetically formed emulsions and the local equilibrium topology of emulsion drops, the effect of interfacial tensions on the morphology of Janus emulsions was estimated from the equilibrium interfacial tensions at the line of contact. Realistic values of the tensions revealed the limited range of these to obtain Janus drops and also offered correlation between the equilibrium entities and the curvature of the interface between the two oils.},
  language  = {en}
}
@article{RojasTierschRabeetal.2013,
  author    = {Rojas, Oscar and Tiersch, Brigitte and Rabe, Christian and Stehle, Ralf and Hoell, Armin and Arlt, Bastian and Koetz, Joachim},
  title     = {Nonaqueous Microemulsions Based on N,N '-Alkylimidazolium Alkylsulfate Ionic Liquids},
  series = {Langmuir},
  volume    = {29},
  journal   = {Langmuir},
  number    = {23},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0743-7463},
  doi       = {10.1021/la401080q},
  pages     = {6833 -- 6839},
  year      = {2013},
  abstract  = {The ternary system composed of the ionic liquid surfactant (IL-S) 1-butyl-3-methylimidazolium dodecylsulfate ([Bmim][DodSO(4)]), the room temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium ethylsulfate ([Emim][EtSO4]), and toluene has been investigated. Three major mechanisms guiding the structure of the isotropic phase were identified by means of conductometric experiments, which have been correlated to the presence of oil-in-IL, bicontinuous, and IL-in-oil microemulsions. IL-S forms micelles in toluene, which swell by adding RTIL as to be shown by dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) experiments. Therefore, it is possible to form water free IL-in-oil reverse microemulsions <= 10 nm in size as a new type of nanoreactor.},
  language  = {en}
}
@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}
}