Sai P. R. Kobaku

Ice accretion has a negative impact on critical infrastructure, as well as a range of commercial and residential activities. Icephobic surfaces are defined by an ice adhesion strength τice < 100 kPa. However, the passive removal of ice requires much lower values of τice, such as on airplane wings or power lines (τice < 20 kPa). Such low τice values are scarcely reported, and robust coatings that maintain these low values have not been reported previously. We show that, irrespective of material chemistry, by tailoring the cross-link density of different elastomeric coatings and by enabling interfacial slippage, it is possible to systematically design coatings with extremely low ice adhesion (τice < 0.2 kPa). These newfound mechanisms allow for the rational design of icephobic coatings with virtually any desired ice adhesion strength. By using these mechanisms, we fabricate extremely durable coatings that maintain τice < 10 kPa after severe mechanical abrasion, acid/base exposure, 100 icing/deicing cycles, thermal cycling, accelerated corrosion, and exposure to Michigan wintery conditions over several months.

In this work, a facile methodology is discussed, involving fluoro‐silanization followed by oxygen plasma etching, for the fabrication of surfaces with extreme wettabilities, i.e., surfaces that display all four possible combinations of wettabilities with water and different oils: hydrophobic–oleophilic, hydrophilic–oleophobic, omniphobic, and omniphilic. Open‐channel, paper‐based microfluidic devices fabricated using these surfaces with extreme wettabilities allow for the localization, manipulation, and transport of virtually all high‐ and low‐surface tension liquids. This in turn expands the utility of paper‐based microfluidic devices to a range of applications never before considered. These include, as demonstrated here, continuous oil–water separation, liquid–liquid extraction, open‐channel microfluidic emulsification, microparticle fabrication, and precise measurement of mixtures' composition. Finally, the biocompatibility of the developed microfluidic devices and their utility for cell patterning are demonstrated.

Patterned surfaces: The fabrication of patterned superomniphobic–superomniphilic surfaces is reported. Such patterned surfaces are expected to be useful in developing well-defined microreactors for liquid-phase reactions, significantly enhancing heat transfer during condensation and boiling of various low-surface-tension liquids, and in fabricating precisely tailored arrays of polymers and microparticles of different sizes and shapes.

Precise control over the geometry and chemistry of multiphasic particles is of significant importance for a wide range of applications. In this work, we have developed one of the simplest methodologies for fabricating monodisperse, multiphasic micro- and nanoparticles possessing almost any composition, projected shape, modulus, and dimensions as small as 25 nm. The synthesis methodology involves the fabrication of a nonwettable surface patterned with monodisperse, wettable domains of different sizes and shapes. When such patterned templates are dip-coated with polymer solutions or particle dispersions, the liquids, and consequently the polymer or the particles, preferentially self-assemble within the wettable domains. Utilizing this phenomenon, we fabricate multiphasic assemblies with precisely controlled geometry and composition through multiple, layered depositions of polymers and/or particles within the patterned domains. Upon releasing these multiphasic assemblies from the template using a sacrificial layer, we obtain multiphasic particles. The templates can then be readily reused (over 20 times in our experiments) for fabricating a new batch of particles, enabling a rapid, inexpensive, and easily reproducible method for large-scale manufacturing of multiphasic particles.

Intelligente Oberflächen: Strukturierte superomniphobe und superomniphile Oberflächen wurden hergestellt. Die möglichen Anwendungen dieser Oberflächen sind vielfältig, z. B. für Mikroreaktoren zur Verbesserung des Wärmetransfers beim Kondensieren und Sieden von Flüssigkeiten mit niedriger Oberflächenspannung und zur Herstellung von maßgeschneiderten Polymerarrays und Mikropartikeln unterschiedlicher Größe und Form.