WETTING & SURFACE TENSION
Dr. Günter K. Auernhammer
Group leader Surface Tension & Wetting
at the Leibniz-Institut für Polymerforschung Dresden e.V.
Hohe Strasse 6
Phone: +49 (0)351 4658-486
Fax: +49 (0)351 4658-474
- Kathrin Pöschel
- Stefan Michel
Controlling wetting and interfacial tension of polymeric materials is relevant for different applications and technologies such as coating, printing, joining, compatibility, self-cleaning, patterning and microfluidics. For processes the quasi-static and the dynamic wetting properties of are relevant. A board range of mechanisms is involved in the interaction of liquids with substrates, ranging perfectly non-interacting to adaptive to reactive surfaces. Powerful tools to study the liquid-solid interaction are contact angle measurements and the determination of the surface tension of liquids (simple liquids, mixtures, solutions, polymer melts) by drop shape analysis and modified Wilhelmy techniques. Depending on the question, these parameters have to be determined in quasi-static or dynamic situations.
For the determination of the surface tension of solid polymers, we use indirect methods based on wetting (contact angle) measurements in combination with specific approaches of interfacial energetics (e.g. equation of state approach for solid-liquid interfacial tensions). In the case of porous polymeric systems, such as powders, granules, fiber bundles or membranes, we developed a new strategy to characterize the surface-energetic properties of these materials by capillary penetration experiments with liquids of different surface tension and polarity.
Dynamic wetting experiments can be performed over a wide range of contact line velocities. For forced wetting and dewetting experiments we use a rotating drum setup, which can be equipped with various surfaces. Spontaneous wetting is studied with high speed cameras that allow a simultaneous observation under two orthogonal optical directions (e.g. top view and side view).
In the focus of our work are interrelations between dynamics of wetting, surface tension, wettability of polymer surfaces, adhesion phenomena and the correlation of these macroscopic interfacial properties with the microscopic and molecular surface structure. Contact angle measurements carried out with different organic liquids can be also used to describe the reactivity of a substrate surface in the frame of the well-established electron pair acceptor and donator concepts.
Sessile, pendant drop and captive (adhering) bubble techniques
- DataPhysics OCA35L(DataPhysics, Germany)
- DataPhysics OCA40 micro(DataPhysics, Germany)
- FibroDat 1100(Fibro System AB, Sweden)
- FibroDat 1129 Automatic tilt table(Fibro System AB, Sweden)
- Different experimental set-up for Axisymmetric Drop Shape Analysis -Profile (ADSA-P)(in-house development)
Wilhelmy balance techniques
- Tensiometer K12(Kruess GmbH, Germany)
- Tensiometer DCAT21 (DataPhysics, Germany)
- Tensiometer DCAT21SF (single fiber (DataPhysics, Germany)
- OBS2 (in-house development tensiometer)
More details can be found here.
5 important publications
- Henrich, F., D. Fell, D. Truszkowska, M. Weirich, M. Anyfantakis, T.-H. Nguyen, M. Wagner, G. K. Auernhammer and H.-J. Butt (2016). "Influence of surfactants in forced dynamic dewetting." Soft Matter 12: 7782 - 7791.
- Grundke, K.; Pöschel, K.; Synytska, A.; Frenzel, R.; Drechsler, A.; Nitschke, M.; Cordeiro, A.L.; Uhlmann, P.; Welzel, P.B., Advances in Colloid and Interfaces Science 2015, 222, 350-376.
- Grundke, K., Characterization of polymer surfaces by wetting and electrokinetic measurements- contact angle, interfacial tension, zeta potential, in Polymer Surfaces and Interfaces – Characterization, Modification and Applications (Chapter 6), ed. by Stamm, M., Springer-Verlag GmbH, Heidelberg, 2008, 103-138.
- Grundke, K., Surface-energetic properties of polymers in controlled architecture, in Molecular Interfacial Phenomena of Polymers and Biopolymers (Chapter 10), ed. by Chen, P., Woodhead Publishing Ltd., Sawston, UK, 2005, 323-374.
- Grundke, K., Wetting, Spreading and Penetration, in Handbook of Applied Surface and Colloid Chemistry (Chapter 7), ed. by Holmberg, K., John Wiley & Sons, Inc., New York, NY, USA, 2002, 119-140.