Name: Conference "Dynamic Wetting of Flexible, Adaptive, and Switchable Substrates"
Start: 2021-11-08T08:00:00+01:00
End: 2021-11-10T17:00:00+01:00
Location: University of Freiburg

Conference "Dynamic Wetting of Flexible, Adaptive, and Switchable Substrates"

von Montag, 8. November 2021(08:00) bis Mittwoch, 10. November 2021(17:00)

Montag, 8. November 2021
09:30 Introduction - Uwe Thiele (WWU Münster)
Introduction
- Uwe Thiele (WWU Münster)
09:30 - 09:45
Room: Aula, Kollegiengebäude I
09:45 Wetting of Polymer surfaces: Effect of Swelling and Droplet Evaporation - Regine von Klitzing (Institute for Condensed Matter Physics, TU Darmstadt)
Wetting of Polymer surfaces: Effect of Swelling and Droplet Evaporation
- Regine von Klitzing (Institute for Condensed Matter Physics, TU Darmstadt)
09:45 - 10:30
Room: Aula, Kollegiengebäude I Wetting of polymer coating is of specific interest for the adhesion of cells or proteins and the technical control of wetting. Cells or proteins are in a physiological environment, i.e. an aqueous solution and the polymer coatings are often hydrophilic or partially hydrophobized. Therefore, the coatings often swell in water which changes the wettability during the wetting process. This complex process is not well understood. A few studies on the water wettability of polyelectrolyte-coated surfaces exist [e.g. 1-4]. Tay et al. found an effect of osmotic pressure on the contact line in wetting studies of charged and uncharged polymeric coatings [5]. That makes the wetting process rather complex, since different time scales but also different length scales come into play. The adaptive surface needs a certain time until the swelling process is finished. The swelling doesn’t stop at the three phase contact line, and the liquid sucks laterally into the region in contact with the gas phase. Hansen and Miotto called that it peripherical thickness [6]. This deforms the surface and the contact line is not well-defined anymore. We studied the wettability by water of polyelectrolyte mono- and multilayers with different polycations or polyanions as the outermost layer using the sessile drop technique [3]. Measurements in a water-saturated atmosphere and in ambient conditions [40% relative humidity (r.h.)] are made to study the effect of swelling and evaporation on the contact angle. It is found that these effects strongly depend on the outermost layer of the polyelectrolyte coating. For several kinds of polyelectrolytes as outermost layer the polyelectrolyte-coated surface can be equilibrated by pre-swelling in saturated vapor. Depositing a water droplet leads to a fixed contact angle against vapor. For other types polyelectrolytes as the outermost layer the water contact angle also indicates a change in the swelling state when the pre-equilibrated film is directly in contact with liquid water, resulting in a decrease in contact angle with time. The studies show that a highly sophisticated interplay between hydrophobic backbone and charge density determines the wetting behavior, irrespective of the sign of surface charge. The stability of the wetting film on polyelectrolyte surface is analysed by disjoining pressure isotherms [7]. There surface charge seems to be the most dominant factor for stability of the wetting film. [1] Yoo, D., Shiratori, S.S., and Rubner, M.F., Macromolecules 1998, 31, 4309. [2] Kolasinska, M. and Warszynski, P. Bioelectrochemistry 2005, 66, 65. [3] K. Hänni–Ciunel, G. H. Findenegg, R. v. Klitzing, Soft Materials 1998, 5 61. [4] H.-J. Butt, R. Berger, W. Steffen, S. Vollmer, S. A. L. Weber, Langmuir 2018 34, 112992. [5] Tay, A., Lequeux, F., Bendejacq, D., Monteux, C., Soft Matter 2011, 7, 4715. [6] Hansen, R. S.; Miotto, M., JACS 1957, 79, 1765. [7] K. Ciunel, M. Armelin, G. H. Findenegg, R. v. Klitzing, Langmuir 2005, 21 4790.
10:30 Coffee break
Coffee break
10:30 - 11:00
Room: Aula, Kollegiengebäude I
11:00
11:00 - 12:20
Room: Aula, Kollegiengebäude I
Beiträge

11:00 Efficient simulation of wetting dynamics on elastic substrates - Sebastian Aland (TU Freiberg)

11:20 Memory effects of PNiPAAm brushes in different atmospheres - Simon Schubotz (Leibniz-Institut für Polymerforschung Dresden e.V.)

11:40 Lattice Boltzmann simulations of liquid lens coalescence - Thomas Scheel (Helmholtz Institute Erlangen-Nürnberg for Renewable Energy)

12:00 HySS – a new wetting regime for on-demand trapping and release of drops - Anil Rajak (IMTEK, University of Freiburg)
12:20 Lunch break + discussion
Lunch break + discussion
12:20 - 13:45
Room: Aula, Kollegiengebäude I
13:45
13:45 - 15:30
Room: Aula, Kollegiengebäude I
Beiträge

13:45 Smart surfaces with wetting-programmed topography - Leonid Ionov (Faculty of Engineering Sciences, University of Bayreuth)

14:10 Droplets on substrates with moving and oscillating wettability patterns - Josua Grawitter (Technische Universität Berlin, Institut für Theoretische Physik)

14:35 Wetting of bio-inspired, stimulus-responsive polymer surfaces by lipid vesicles - Lucia Wesenberg (Institut für Theoretische Physik, Georg-August Universität Göttingen) Felix Weißenfeld (Institute of Physical Chemistry, Heidelberg University)

15:00 Drop impact on very thin liquid films ontop hard solid substrates - Kirsten Harth (TH Brandenburg; OVGU Magdeburg)
15:30 Coffee break
Coffee break
15:30 - 16:00
Room: Aula, Kollegiengebäude I
16:00 Energy harvesting due to charge redistribution upon drop impact & Swelling of partly saturated hydrophobic polymer brush layers - Frieder Mugele (Physics of Complex Fluids, University of Twente)
Energy harvesting due to charge redistribution upon drop impact & Swelling of partly saturated hydrophobic polymer brush layers
- Frieder Mugele (Physics of Complex Fluids, University of Twente)
16:00 - 16:45
Room: Aula, Kollegiengebäude I The first part of this lecture I discuss how the energy of falling drops impacting onto pre-charged hydrophobic polymer surfaces can be harvested in an external electrical circuit as screening charges redistribute within the drop. High speed video imaging and simultaneous electrical measurements lead to a physical model of the energy conversion process including a quantitative analysis of the conversion efficiency [1, 2]. Part two addresses preliminary experiments on the spreading of oil drops with a low vapor pressure on hydrophobic polymer brushes. Within a few hours the swelling process leads to the formation of a pronounced halo around the macroscopic contact line, where the thickness of the partially swollen brush layer varies by a few hundred nanometers over a lateral width of the order of 1mm. The experiments suggest that this seemingly static configuration is in fact stabilized by a very slow gradual evaporation and therefore intrinsically a non-equilibrium phenomenon. [1] Wu, H., et al., Energy Harvesting from Drops Impacting onto Charged Surfaces. Physical Review Letters, 2020. 125: 078301. [2] Wu, H., et al., Charge Trapping-Based Electricity Generator (CTEG): An Ultrarobust and High Efficiency Nanogenerator for Energy Harvesting from Water Droplets. Advanced Materials, 2020. 32: 2001699.
16:45
16:45 - 18:15
Room: Aula, Kollegiengebäude I
Beiträge

17:05 Droplets on compressed soft solids - Stefan Karpitschka (Max Planck Institute for Dynamics and Self-Organization)

17:25 Rigid and Soft Wetting at Nanoscale - Nikolai Kubochkin (Institute for Technical Thermodynamics, Technische Universität Darmstadt)

17:45 Measuring dynamic forces between droplets and polymeric surfaces - Lukas Hauer (Max Planck Institut for Polymer Research)

17:55 Tuning elastic membrane instabilities for adaptive single and multi-phase fluid transport - Claas-Hendrik Stamp (University of Freiburg)

17:55 Adaptation of polymer surfaces - Xiaomei Li (Max-Planck-Institut für Polymerforschung)

17:55 Evaluation of photoswitchable wetting properties of hydrophobic surfaces - Niloofar Nekoonam (University of Freiburg, Department of Microsystems Engineering)

17:55 Lattice models of fluids with Density Functional Theory - Michael Zimmermann (Universität Tübingen)

17:55 Swalbe.jl - Droplets, Dewetting, Dynamic Contact Angles - Stefan Zitz (Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK-11))

17:55 Gradient Dynamics Model for Spreading and Coarsening Drops on soft Substrates - Christopher Henkel (WWU Münster)

17:55 Dynamics of liquid droplets on switchable substrates – from microscopic to mesoscopic models - Leon Topp (WWU Münster) Moritz Stieneker (WWU Münster)

17:55 Wetting of Photoswitchable Substrates and Polymer Brushes and Their Investigation with Vibrational Sum-Frequency Generation - Christian Honnigfort (WWU Münster)

17:55 Characteristics of the Dewetting Dynamics and Equilibrium Droplets from Elastic to Visco-Elastic Substrates - Khalil Remini (Saarland University)

17:55 Wetting of bio-inspired, stimulus-responsive polymer surfaces by lipid vesicles - Lucia Wesenberg (Institut für Theoretische Physik, Georg-August Universität Göttingen) Felix Weißenfeld (Institute of Physical Chemistry, Heidelberg University)
Dienstag, 9. November 2021
09:00 Keynote talk - David Quéré (ESPCI Paris; École polytechnique)
Keynote talk
- David Quéré (ESPCI Paris; École polytechnique)
09:00 - 09:45
Room: Aula, Kollegiengebäude I details to be announced
09:45
09:45 - 10:30
Room: Aula, Kollegiengebäude I
Beiträge

09:45 Dynamic Wetting of Self-Assembled Monolayers functionalized with Photoresponsive Arylazopyrazoles - Niklas Björn Arndt (WWU Münster)

10:10 Rigid and Soft Wetting at Nanoscale - Nikolai Kubochkin (Institute for Technical Thermodynamics, Technische Universität Darmstadt)
10:30 Coffee break
Coffee break
10:30 - 11:00
Room: Aula, Kollegiengebäude I
11:00
11:00 - 12:15
Room: Aula, Kollegiengebäude I
Beiträge

11:00 Dynamic wetting phenomena and contact angle hysteresis on polymer brushes and gels - Lukas Hauer (Max Planck Institute for Polymer Research) Rodrique Badr (Institut für Physik, Johannes Gutenberg-Universität Mainz)

11:25 Switchable and Adjustable Fluid Transport and Wetting Properties in Polypyrrol-Silicon and Ceramic-based Inverse Opal Structures - Laura Gallardo Domínguez (Hamburg University of Technology)

11:50 Dynamics of liquid droplets on switchable substrates – from microscopic to mesoscopic models - Svetlana Gurevich (WWU Münster) Andreas Heuer (WWU Münster)
12:15 Lunch break + discussion
Lunch break + discussion
12:15 - 13:45
Room: Aula, Kollegiengebäude I
13:45
13:45 - 15:30
Room: Aula, Kollegiengebäude I
Beiträge

13:45 Dynamic Wetting and Molecular Switching of Photo-Responsive Arylazopyrazole Phosphonic Acid Monolayers on Aluminum Oxide Surfaces - Björn Braunschweig (WWU Münster)

14:10 Droplet motion directed by reversible stiffness gradient on soft switchable surfaces - Niloofar Nekoonam (University of Freiburg, Department of Microsystems Engineering)

14:35 Superhydrophobic surfaces using ultra-short pulse structuring of thin metals - Fabian Schäfer (Hochschule Aalen)

15:00 Liquid Dewetting from Visco-Elastic Substrates - Khalil Remini (Universität des Saarlandes) Leonie Schmeller (Weierstrass Institute Berlin)
15:30 Coffee break
Coffee break
15:30 - 16:00
Room: Aula, Kollegiengebäude I
16:00 Elastocapillary Adhesion of Compliant Microspheres - Katharine Jensen (Williams College)
Elastocapillary Adhesion of Compliant Microspheres
- Katharine Jensen (Williams College)
16:00 - 16:45
Room: Aula, Kollegiengebäude I Establishing an adhesive contact between two materials requires both that the surface energies favor the creation of interfacial area and that it is possible to form contact area given the geometry and material properties. While elasticity has long been understood to be important in determining the relative “stickiness” between non-conformal surfaces, in recent years capillarity has also emerged as playing key roles in adhesion with highly compliant materials in multiple ways. For example, recent studies have demonstrated that solid surface tension can compete with or dominate over bulk elasticity in governing contact mechanics on small length scales, and mounting evidence suggests that the internal free fluid phase of compliant polymer gels also contributes significantly to mechanical response via both poroelasticity and classic capillary wetting. In this work, we investigate the adhesion between polydimethylsiloxane (PDMS) gel microspheres and rigid glass substrates. By varying the stiffness and size of the microspheres as well as the surface energy of the substrate and directly imaging the adhered microspheres, we observe a range of adhesive contact geometries from classic elastic to quantitatively wetting-like behavior, always mediated by a phase-separated fluid contact zone. We understand our data with a theoretical model that incorporates elasticity, capillarity, and phase separation to capture the complete range of adhesive contact behavior.
19:00 Conference Dinner
Conference Dinner
19:00 - 21:00
Mittwoch, 10. November 2021
09:00 Dewetting as a probe of properties of polymers at interfaces and in thin films - Günter Reiter (Institute of Physics, University of Freiburg)
Dewetting as a probe of properties of polymers at interfaces and in thin films
- Günter Reiter (Institute of Physics, University of Freiburg)
09:00 - 09:45
Room: Aula, Kollegiengebäude I The process of dewetting allows to probe the dynamic behavior of polymers within thin films as the response to an applied force, generated directly and intrinsically by interfacial forces and forces acting within the film itself. In addition, taking advantage of the fact that on a single sample the process of dewetting is not initiated everywhere at the same time, one can follow the evolution of a sequence of temporally delayed dewetting processes. Thus, one can examine how nonequilibrium properties of thin polymer films evolve in time. Such sequential dewetting experiments provide a means for determining the time required for equilibration and how viscoelastic properties of the polymer film evolve in time. As one example, the relaxation of residual stresses in thin polymer films can be quantified through the measurement of characteristic parameters of dewetting.
09:45
09:45 - 10:30
Room: Aula, Kollegiengebäude I
Beiträge

09:45 Dynamic wetting and dewetting processes on adaptive surfaces - Xiaomei Li (Max-Planck-Institut für Polymerforschung)

10:10 Water Induced Polymer Reorientation at a Polystyrene/Polyacrylic Acid Surface - Mirela Encheva (University of Vienna)
10:30 Coffee break
Coffee break
10:30 - 11:00
Room: Aula, Kollegiengebäude I
11:00
11:00 - 12:15
Room: Aula, Kollegiengebäude I
Beiträge

11:00 Mathematical modeling and simulation of substrate-flow interaction using generalized gradient flows - Dirk Peschka (Weierstrass Institute Berlin)

11:25 Moving wetting ridges: Impact of surface rheology? - Hansol Jeon (Max Planck Institute for Dynamics and Self-Organization)

11:50 Condensing drops on soft substrates - Ambre Bouillant (Physics of Fluids, University of Twente) Martin Essink (Physics of Fluids, University of Twente) Christopher Henkel (WWU Münster)
12:15 Lunch break + discussion
Lunch break + discussion
12:15 - 13:15
Room: Aula, Kollegiengebäude I
13:15
13:15 - 14:00
Room: Aula, Kollegiengebäude I
Beiträge

13:15 A highly accurate extended discontinuous Galerkin method for multiphase problems with contact lines - Lauritz Beck (TU Darmstadt)

13:40 News from adaptive transport through coupled flow paths - Thomas Pfohl (University of Freiburg)
14:00 Final words + end - Uwe Thiele (WWU Münster)
Final words + end
- Uwe Thiele (WWU Münster)
14:00 - 14:20
Room: Aula, Kollegiengebäude I