Monoschichten und Multischichten an der Oberfläche einzelner Tropfen bzw. Kapseln Scope 1. Typical routine methods based on single drops and bubbles 2. Oscillating drops and bubbles and drop pressure experiments 3. Exchange of drop volume by a double capillary design 4. Direct drop-drop and bubble-bubble interactions 5. Summary Reinhard Miller Max-Planck-Institut für Kolloid- und Grenzflächenforschung Reinhard Miller 1
General Overview of Experimental Methods Time scale of tensiometry methods Capillary Pressure Reinhard Miller 2
Maximum bubble pressure tensiometry 1 ms Bubble pressure tensiometry provides shortest adsorption time data, even down to 100 µs Reinhard Miller 3
Drop and bubble profile analysis Drop profile analysis tensiometry Gauss Laplace Equation Principle of the drop profile method: the coordinates of a drop are taken from a video image and compared with the Gauss Laplace equation yields the only fitting parameter γ Reinhard Miller 4
Drop and bubble profile analysis Reinhard Miller 5
Drop and bubble profile analysis Water drop in Hexane Adsorption of C 13 DMPO at the Water/Hexane Interface; Hexane phase is initially free of Surfactant; Water/Hexane Ratio Q=0.001 γ interfacial tension, t time The adsorption of a non-ionic surfactant at the water-hexane interface leads to minima in the dynamic surface tensions. Reinhard Miller 6
Drop and bubble profile analysis Hexane drop in Water C 13 DMPO at the Water/Hexane Interface; Hexane phase is initially free of Surfactant; Water/Hexane Ratio Q=1000 γ interfacial tension, t time The adsorption of a non-ionic surfactant at the water-hexane interface does not lead to minima in the dynamic surface tensions when the phases are inverted. Reinhard Miller 7
Drop and bubble profile analysis C 13 DMPO at the Water/Hexane Interface; Hexane drop in Water Water drop in Hexane The explanation for the existence of minima in the dynamic surface tension curves is the amount of surfactant available in the bulk reservoir. Here the reservoir is huge in compare to the demand to fill up the hexane drop with molecules originally present in the aqueous phase. Reinhard Miller 8
Monoschichten und Multischichten an der Oberfläche einzelner Tropfen bzw. Kapseln 2. Oscillating drops and bubbles and drop pressure experiments Reinhard Miller 9
Oscillating drops and bubbles Oscillating bubble technique original design by Kretzschmar and Lunkenheimer. Lunkenheimer, Thesis Berlin 1971 Reinhard Miller 10
Interfacial Dilational Rheometry Drop/ Bubble Profile Tensiometry 0.001-0.1 0.1 Hz Das Dosiersystem erlaubt eine langsame Oszillation eines Tropfens oder einer Blase. Reinhard Miller 11
Interfacial Rheology Interfacial deformations Expansion / Compression Shear Reinhard Miller 12
Interfacial Dilational Rheometry 60 50 40 30 Surface Tension in mn/m Drop Area in mm² Drop Volume in mm³ 20 10 0 5000 5010 5020 5030 5040 5050 time Eine harmonische Flächenänderung führt zu harmonischen Oberflächenspannungsänderungen. Reinhard Miller 13
Interfacial Dilational Rheometry Die Phasenverschiebung zwischen Flächenänderung und Oberflächenspannungsänderung ist ein Maß für die Dilatationsviskosität. Reinhard Miller 14
Interfacial Dilational Rheometry Die Amplitude der Oberflächenspannungsänderung ist ein Maß für die Dilatationselastizität. Reinhard Miller 15
Surface rheology Oscillating Drop / Bubble Tensiometry drop of normal size small spherical drop Reinhard Miller 16
Oscillating drops and bubbles Extra Equipment for PAT-1 Fast Drop/ Bubble Oscillations with ODBA-1 0.1-100(0) 100(0) Hz Reinhard Miller 17
Oscillating drops and bubbles Capillary pressure cell - A. Passerone et al. 1991 Reinhard Miller 18
Oscillating drops and bubbles Oscillating Drop and Bubble Analyser ODBA - SINTERFACE Drop and Bubble Analyser - Optrel Reinhard Miller 19
Monoschichten und Multischichten an der Oberfläche einzelner Tropfen bzw. Kapseln 3. Exchange of drop volume by a double capillary Reinhard Miller 20
Special experiment tools for profile analysis Double Dosing System with Coaxial Capillary Drop profile tensiometry can be equipped by a second dosing system, which provides various additional experimental protocols. Reinhard Miller 21
Special experiment tools for profile analysis Coaxial Capillary Double co-axial capillary for subsequent adsorption of two different compounds. Reinhard Miller 22
Special experiment tools for profile analysis Coaxial Capillary Reinhard Miller 23
Special experiment tools for profile analysis Coaxial Capillary (1) Deposit/Compress (lipid) (3) Wash (NaCl) (2) Exchange (PC) O[nm] Repeat (2) - (5) (4) Exchange (PA) / (5) Wash (NaCl) Reinhard Miller 24
Special experiment tools for profile analysis Dependence of isotropic surface stress response to area dilation of nanocomposite on template charge density a.) DMPG-(PAH/PSS)n=1, b.) DMPG-(PAH/PSS)n=2, c.) DMPG-(PAH/PSS)n=3 Reinhard Miller 25
Special experiment tools for profile analysis Coaxial Capillary Investigation of the permeability of different model membranes = present studies water oil or water phase Reinhard Miller 26
Special experiment tools for profile analysis Coaxial Capillary Reinhard Miller 27
Monoschichten und Multischichten an der Oberfläche einzelner Tropfen bzw. Kapseln 4. Direct drop-drop and bubble-bubble interactions Reinhard Miller 28
Drop-drop interactions Profile Analysis Tensiometer PAT-1 Drop-Bubble-Micro-Manipulator Reinhard Miller 29
Drop-drop interactions Drop-Bubble-Micro-Manipulator Valves xyz-stage Piezo drives Pressure sensors Reinhard Miller 30
Drop-drop interactions Drop-Bubble-Micro-Manipulator Micro capillaries Reinhard Miller 31
Drop-drop interactions Drop-Bubble-Micro-Manipulator Reinhard Miller 32
Drop-drop interactions Drop-Bubble-Micro-Manipulator 4e-3 M SDS-SDS Pressure, left cell 900 895 890 885 880 875 870 865 860 0 20 40 60 Time, s System: hexane/water Reinhard Miller 33
Drop-drop interactions Drop-Bubble-Micro-Manipulator System: water/diesel (containing a polymeric surfactant) Reinhard Miller 34
Literature Recently published books on this topic: Interfacial Tensiometry By A.I. Rusanov, V.A. Prokhorov Studies in Interface Science Vol. 3 D. Möbius and R. Miller (Eds.), Elsevier, Amsterdam, 1996 ISBN-13: 978-0-444-82128-7 Drops and Bubbles in Interfacial Research Studies in Interface Science - Vol. 6 D. Möbius and R. Miller (Eds.), Elsevier, Amsterdam, 1998 ISBN-13: 978-0-444-82894-1 Novel Methods to Study Interfacial Layers Studies in Interface Science Vol. 11 D. Möbius and R. Miller (Eds.), Elsevier, Amsterdam, 2001 ISBN-13: 978-0-444-50948-2 New book to be published on this topic: Bubble and Drop Interfaces Studies in Interface Science Vol. 23? / 24? / 25? L. Liggieri, D. Möbius and R. Miller (Eds.), Elsevier, Amsterdam, 2007 Reinhard Miller 35
Lessons Learned Single drops and bubbles are most frequently used in surface science. Bubble pressure and drop capillary pressure tensiometry are the fastest dynamic surface and interfacial tension method, respectively. Drop and bubble profile tensiometry is a very flexible method that provides a large number of unique experiments. Double capillary is a versatile tool for multilayer built up and mechanical studies of surface layers and membranes. Microfluidics based on drop and bubble formations combined with classical tools (capillary pressure) provides new options for a quantitative understanding of elementary processes of various technologies. Reinhard Miller 36