Project Details
Projekt
Wetting on Patterned Adaptive Conducting Polymer Surfaces for Microfluidic Applications (PolySurf)
Subject Area
Polymer Materials
Applied Mechanics, Statics and Dynamics
Applied Mechanics, Statics and Dynamics
Term
since 2022
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 505840677
The project “Wetting on Patterned Adaptive Conducting Polymer Surfaces for Microfluidic Applications (PolySurf)”, shall be implemented into current activities of the SPP 2171 on “Dynamic Wetting of Flexible, Adaptive and Switchable Surfaces”. PolySurf is based on the coupled interdisciplinary expertise of Sabine Ludwigs (polymer materials science, electrochemistry) and Holger Steeb (microfluidics, material modelling) and aims at hierarchically patterned soft surfaces which can adapt their wetting properties to externally applied electric fields. In addition to water contact angle measurements the fluid dynamics within microfluidic applications shall be explored. For adaptive surface preparation the class of conducting polymers (CPs) has been identified. CPs are gaining increasing interest for flexible actuator and sensor applications, and the interfaces of the CP polymer surfaces with liquids are extremely relevant in this context. Conducting polymers cannot only change their optical and electronic properties as function of the degree of doping, but also the wetting properties are highly influenced. In the literature extreme changes of the surface properties from superhydrophobic to superhydrophilic are reported between neutral and doped films.Within PolySurf a systematic understanding of the dynamic wetting behavior of the conducting polymer surfaces shall be established. On the materials science side both solution-processable films of poly(ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as well as electropolymerized films from branched monomers shall be prepared. Surface patterning techniques involve imprint lithography and electropolymerisation on structured electrodes and are targeted at hierarchical patterning to increase the surface roughness.Characterization of the conducting polymer surfaces will involve systematic electrochemical studies in aqueous electrolytes alongside morphological and functional property analysis by absorption spectroscopy and conductivity measurements to determine the degree of doping.In terms of wetting characterization first systematic contact angle measurements (sessile droplet, advancing/ receding contact angles) will be performed. The focus lies on water and water/ion electrolytes. Surfaces with no potential and with potential applied (during in-situ electrochemical measurements) shall be monitored in terms of their wetting behavior. As complementary method spectroscopic ellipsometry will be used alongside to identify surface variations, e.g. by swelling, when the surfaces are brought in contact with the water and the aqueous electrolytes. This shall also give information about the adaptivity of the surfaces. Beyond the study of the dynamics of three phase contact lines on surfaces, the effect on evolving wetting properties on multi-phase fluid dynamics within microfluidic applications shall be explored. Ultimately, electrochemically-switchable microfluidic devices are envisioned.
DFG Programme
Priority Programmes
