TY  - JOUR
A1  - Kovach, Ildiko
A1  - Won, Jooyoung
A1  - Friberg, Stig E.
A1  - Koetz, Joachim
T1  - Completely engulfed olive/silicone oil Janus emulsions with gelatin and
chitosan
JF  - Colloid and polymer science : official journal of the Kolloid-Gesellschaft
N2  - 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.
KW  - Janus emulsions
KW  - Interfacial tension
KW  - Ring method
KW  - Drop profile analysis tensiometry
KW  - Gelatin-chitosan composites
Y1  - 2016
U6  - https://doi.org/10.1007/s00396-016-3828-4
SN  - 0303-402X
SN  - 1435-1536
VL  - 294
SP  - 705
EP  - 713
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Moradi, N.
A1  - Zakrevskyy, Yuriy
A1  - Javadi, A.
A1  - Aksenenko, E. V.
A1  - Fainerman, V. B.
A1  - Lomadze, Nino
A1  - Santer, Svetlana
A1  - Miller, R.
T1  - Surface tension and dilation rheology of DNA solutions in mixtures with azobenzene-containing cationic surfactant
JF  - Colloids and surfaces : an international journal devoted to the principles and applications of colloid and interface science ; A, Physicochemical and engineering aspects
N2  - The surface tension and dilational surface visco-elasticity of the individual solutions of the biopolymer DNA and the azobenzene-containing cationic surfactant AzoTAB, as well as their mixtures were measured using the drop profile analysis tensiometry. The negatively charged DNA molecules form complexes with the cationic surfactant AzoTAB. Mixed DNA + AzoTAB solutions exhibit high surface activity and surface layer elasticity. Extremes in the dependence of these characteristics on the AzoTAB concentration exist within the concentration range of 3 x 10(-6)-5 x 10(-5) M. The surface tension of the mixture shows a minimum with a subsequent maximum. In the same concentration range the elasticity shows first a maximum and then a subsequent minimum. A recently developed thermodynamic model was modified to account for the dependence of the adsorption equilibrium constant of the adsorbed complex on the cationic surfactant concentration. This modified theory shows good agreement with the experimental data both for the surface tension and the elasticity values over the entire range of studied AzoTAB concentrations. (C) 2016 Elsevier B.V. All rights reserved.
KW  - Mixed adsorption layers
KW  - Polymer/surfactant interaction
KW  - Water/air interface
KW  - Thermodynamics of adsorption
KW  - Dilational rheology
KW  - Drop profile analysis tensiometry
Y1  - 2016
U6  - https://doi.org/10.1016/j.colsurfa.2016.04.021
SN  - 0927-7757
SN  - 1873-4359
VL  - 505
SP  - 186
EP  - 192
PB  - Elsevier
CY  - Amsterdam
ER  -