TY - JOUR A1 - Kosmella, Sabine A1 - Koetz, Joachim A1 - Friberg, Stig E. A1 - Mackay, R. A T1 - Interactions of polyelectrolytes with the lyotropic liquid crystalline system Na-dodecylsulfate / decanol / water Y1 - 1996 ER - TY - JOUR A1 - Kosmella, Sabine A1 - Koetz, Joachim A1 - Friberg, Stig E. A1 - Mackay, R. A. T1 - Interactions of polyelectrolytes with the lyotropic liquid crystalline system - hexadecyltrimethylammonium bromide / decanol / water Y1 - 1996 SN - 0927-7757 ER - TY - JOUR A1 - Ruppelt, Dirk A1 - Koetz, Joachim A1 - Jaeger, Werner A1 - Friberg, Stig E. A1 - Mackay, R. A. T1 - The influence of cationic polyelectrolytes on structure formation in lamellar liquid crystalline systems Y1 - 1997 ER - TY - JOUR A1 - Bechthold, Nina A1 - Tiersch, Brigitte A1 - Koetz, Joachim A1 - Friberg, Stig E. T1 - Structure Formation in polymer-modified liquid crystals Y1 - 1999 ER - TY - JOUR A1 - Beitz, Toralf A1 - Koetz, Joachim A1 - Friberg, Stig E. T1 - Polymer-modified ionic microemulsion formed in the system SDS/Water/Xylene/Pentanol Y1 - 1999 ER - TY - JOUR A1 - Beyermann, Jochen A1 - Koetz, Joachim A1 - Jäger, Werner A1 - Friberg, Stig E. T1 - Influence of charge density of anionic polyelectrolytes on structure formation in liquid crystalline systems Y1 - 1999 ER - TY - JOUR A1 - Beitz, Toralf A1 - Koetz, Joachim A1 - Wolf, Gunter A1 - Kleinpeter, Erich A1 - Friberg, Stig E. T1 - Poly(N-vinyl-2-pyrrolidone) and 1-octyl-2-pyrrolidinone modified ionic microemulsions Y1 - 2001 ER - TY - JOUR A1 - Friberg, Stig E. A1 - Kovach, Ildiko A1 - Koetz, Joachim T1 - Equilibrium topology and partial inversion of Janus Drops - a numerical analysis JF - ChemPhysChem : a European journal of chemical physics and physical chemistry N2 - 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. KW - emulsion inversion KW - interfaces KW - janus emulsions KW - liquids KW - semiempirical calculations Y1 - 2013 U6 - https://doi.org/10.1002/cphc.201300635 SN - 1439-4235 SN - 1439-7641 VL - 14 IS - 16 SP - 3772 EP - 3776 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Kovach, Ildyko A1 - Koetz, Joachim A1 - Friberg, Stig E. T1 - Janus emulsions stabilized by phospholipids JF - Colloids and surfaces : an international journal devoted to the principles and applications of colloid and interface science ; A, Physicochemical and engineering aspects N2 - Janus emulsions were formed by mixing three immiscible liquids; this implies two oil components (i.e. olive oil (00) and silicone oil (SiO)) with water in presence of interfacial active components. The morphology and size of Janus droplets formed strongly depended on the type of surfactant used. In presence of a non-ionic surfactant, i.e. Tween 80, large engulfed Janus droplets were formed. By adding phospholipids to the system the droplet size was decreased and more stable Janus droplets formed. Interfacial tension measurements carried out using a spinning drop apparatus and a ring tensiometer demonstrate that interfacial tension is the most important factor controlling the size, morphology and stability of Janus droplets. When the interfacial tension between oil and water becomes <= 1 mN/m, smaller Janus droplets are formed. Such conditions are fulfilled when phospholipids are used in combination with non-ionic surfactant Tween 80. The morphology of the double droplets is predominantly controlled by the viscosity and interfacial tension between the two oil phases. By using different types of phospholipids, i.e. asolectin and lecithin instead of a more concentrated phosphatidylcholine (phospholipon), the interfacial tension is decreased and different morphologies of engulfing can be observed. KW - Janus emulsions KW - Spinning drop KW - Interfacial tension KW - Phospholipids Y1 - 2014 U6 - https://doi.org/10.1016/j.colsurfa.2013.08.065 SN - 0927-7757 SN - 1873-4359 VL - 441 SP - 66 EP - 71 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Hasinovic, Hida A1 - Boggs, Cami A1 - Friberg, Stig E. A1 - Kovach, Ildiko A1 - Koetz, Joachim T1 - Janus emulsions from a one-step process; optical microscopy images JF - Journal of dispersion science and technology N2 - 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. KW - Janus drops KW - Emulsification KW - microemulsions KW - emulsion microscopy Y1 - 2014 U6 - https://doi.org/10.1080/01932691.2013.801019 SN - 0193-2691 SN - 1532-2351 VL - 35 IS - 5 SP - 613 EP - 618 PB - Taylor & Francis Group CY - Philadelphia ER -