@article{KovachWonFribergetal.2016,
  author    = {Kovach, Ildiko and Won, Jooyoung and Friberg, Stig E. and Koetz, Joachim},
  title     = {Completely engulfed olive/silicone oil Janus emulsions with gelatin and chitosan},
  series = {Colloid and polymer science : official journal of the Kolloid-Gesellschaft},
  volume    = {294},
  journal   = {Colloid and polymer science : official journal of the Kolloid-Gesellschaft},
  publisher = {Springer},
  address   = {New York},
  issn      = {0303-402X},
  doi       = {10.1007/s00396-016-3828-4},
  pages     = {705 -- 713},
  year      = {2016},
  abstract  = {Janus emulsions, formed by mixing two oil components (i.e., olive oil (OO) and silicone oil (SiO)) with water in the presence of two surface active biopolymers, i.e., gelatin and chitosan, are investigated in more detail. The stability of Janus droplets formed strongly depends on the polymer components used. The mixture of both biopolymers represents an extraordinary effect which can be related to the complex formation of gelatin and chitosan. Taken into account that under the given pH conditions, in the acidic pH range between 4 and 6, below the isoelectric point of gelatin, both polymers are polycations, one can conclude that non-Coulombic interactions are of relevance for the enhanced surface activity of the complexes. Dynamic interfacial tension (gamma) measurements by using the drop profile analysis tensiometry (PAT) indicate a strong adsorption of the polymer complexes at the olive oil/water interface in contrast to the silicone/water interface. In a first step, the polymer complexes are adsorbed at the interface, and in a second step, a more rigid skin-like polymer layer is formed. This first example of a polymer-stabilized Janus emulsion opens new perspectives for the application, e.g., in food emulsions or for making scaffold materials.},
  language  = {en}
}
@article{KovachRumschoettelFribergetal.2016,
  author    = {Kovach, Ildiko and Rumsch{\"o}ttel, Jens and Friberg, Stig E. and Koetz, Joachim},
  title     = {Janus emulsion mediated porous scaffold bio-fabrication},
  series = {Colloids and surfaces : an international journal devoted to fundamental and applied research on colloid and interfacial phenomena in relation to systems of biological origin ; B, Biointerfaces},
  volume    = {145},
  journal   = {Colloids and surfaces : an international journal devoted to fundamental and applied research on colloid and interfacial phenomena in relation to systems of biological origin ; B, Biointerfaces},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0927-7765},
  doi       = {10.1016/j.colsurfb.2016.05.018},
  pages     = {347 -- 352},
  year      = {2016},
  abstract  = {A three dimensional biopolymer network structure with incorporated nano-porous calcium phosphate (CaP) balls was fabricated by using gelatin-chitosan (GC) polymer blend and GC stabilized olive/silicone oil Janus emulsions, respectively. The emulsions were freeze-dried, and the oil droplets were washed out in order to prepare porous scaffolds with larger surface area. The morphology, pore size, chemical composition, thermal and swelling behavior was studied by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and micro-Differential Scanning Calorimetry (micro-DSC). Microscopic analysis confirmed that the pore size of the GC based sponges after freeze-drying may be drastically reduced by using Janus emulsions. Besides, the incorporation of nanoporous calcium phosphate balls is also lowering the pore size and enhancing thermal stability. (C) 2016 Elsevier B.V. All rights reserved.},
  language  = {en}
}
@article{HasinovicBoggsFribergetal.2014,
  author    = {Hasinovic, Hida and Boggs, Cami and Friberg, Stig E. and Kovach, Ildiko and Koetz, Joachim},
  title     = {Janus emulsions from a one-step process; optical microscopy images},
  series = {Journal of dispersion science and technology},
  volume    = {35},
  journal   = {Journal of dispersion science and technology},
  number    = {5},
  publisher = {Taylor \& Francis Group},
  address   = {Philadelphia},
  issn      = {0193-2691},
  doi       = {10.1080/01932691.2013.801019},
  pages     = {613 -- 618},
  year      = {2014},
  abstract  = {The optical microscopy images of an emulsion are commonly distorted when viewed between a cover glass and a planar microscopy slide. An alternative method is to place the sample on a slide with a cavity, which in turn suffers from incomplete information for high internal phase ratio (HIPR) emulsions, due to the inevitable crowding of the drops. This problem is particularly acute for more complex emulsions, such as those with Janus drops, for which a detailed image of the drop is essential. A number of publications have recently described Janus emulsions prepared by a one-step high energy emulsification process with microscopy images obtained by the sample between a planar slide and a cover glass. The correlation to the morphology of emulsions in bulk of these images is critical, but, so far, a potential equivalence has not been established. Since the images are central in order to understand why Janus emulsions should form under such conditions, the need to ascertain any such association is urgent. With this contribution, we compare images from different microscopy methods to those of gently diluted HIPR emulsions. The results reveal that the images of the emulsion samples between a cover glass and a planar microscope slide actually present a realistic representation of the drop topology in bulk emulsions.},
  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}
}