State-of-the-art contact angle measurements usually involve image analysis of sessile drops. The drops are symmetric and images can be taken at high-resolution. The analysis of videos of drops sliding down a tilted plate is hampered due to the low-resolution of the cutout area where the drop is visible. The challenge is to analyze all video images automatically, while the drops are not...
Fluorescent dyes are widely used in fluorescence microscopy, providing important advantages such as the detection of specific components or changes in the surrounding medium of a component of interest. The variety of commercial fluorescent dyes and their stability make these tools ideal for potential implementation as probes of molecular-scale changes. In particular, we are interested in...
This poster will give insights into current research activities of the Ludwigs team. In our interdisciplinary and international research team of polymer chemists, physical chemists and materials scientists we are developing functional and intelligent polymer materials and devices for electrochemical, pharmaceutical and soft robotics applications. One of our aims is to control and manipulate...
In 1903, von Schroeder reported that gelatin swelled more in water or salt solutions than in the corresponding saturated vapors.[1] Since these phases are in equilibrium, it is surprising that they display different partitioning behaviour, and hence this result has become known as Schroeder’s paradox. It has since been found to occur in other cross-linked polymer systems as well, and has...
Water drops moving down inclined hydrophobic and insulating surfaces acquire a charge and deposit counter charges onto the solid surface. This charge separation by sliding drops is also called slide electrification. One of the general observations on fluorinated polymers is that sliding drops leave negative charges on surfaces. Our aim here is to determine if charging processes can be...
Droplet spreading and evaporating on complex surfaces is inherent to various natural and industrial processes. While understanding of the wetting dynamics at the macro- and microscale has essentially advanced over the last decades, nanoscale phenomena still leave many questioned unanswered. Since a droplet of a volatile liquid eventually reaches the state when it is comparable to the range of...
Polymer brushes are highly responsive materials that have a broad spectrum of possible applications, therefore an understanding of their interfacial behavior is essential. The degree of swelling of a polymer brush can be influenced by various external stimuli, such as the presence of a solvent. Under good solvent conditions, drop spreading causes changes in the wettability of the brush surface...
Young model describes the wetting behavior of an ideal surface. Recently, Butt et al., presented a model which connects adaptation processes of the surface to dynamic contact angles.[1] In the first phase of the SPP project, we developed an experimental setup which allows measuring adaptation processes. Li et al., used random copolymer surfaces to confirm the adaptation model.[2] Now, in the...
The dynamics of a droplet deposited on a porous substrate is a combination of three phenomena: spreading, imbibition and evaporation. Here we present a study on the interactions of droplets on nanoporous silicon prepared by electrochemical etching as a function of time. The evolution of the droplet volume is analyzed theoretically and experimentally considering the evaporation and the...